Merge branch 'master' into powerpencil

1 files changed, 1666 insertions, 0 deletions

diff --git a/src/ui/shape-editor-knotholders.cpp b/src/ui/shape-editor-knotholders.cpp
new file mode 100644
index 000000000..b2e41bac4
--- /dev/null
+++ b/src/ui/shape-editor-knotholders.cpp
@@ -0,0 +1,1666 @@
+/*
+ * Node editing extension to objects
+ *
+ * Authors:
+ *   Lauris Kaplinski <lauris@kaplinski.com>
+ *   Mitsuru Oka
+ *   Maximilian Albert <maximilian.albert@gmail.com>
+ *   Abhishek Sharma
+ *   Jon A. Cruz <jon@joncruz.org>
+ *
+ * Licensed under GNU GPL
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "sp-item.h"
+#include "sp-rect.h"
+#include "box3d.h"
+#include "sp-ellipse.h"
+#include "sp-star.h"
+#include "sp-spiral.h"
+#include "sp-offset.h"
+#include "sp-flowtext.h"
+#include "preferences.h"
+#include "style.h"
+#include "desktop.h"
+
+#include "sp-namedview.h"
+#include "live_effects/effect.h"
+#include "sp-pattern.h"
+#include <glibmm/i18n.h>
+#include "knotholder.h"
+#include "knot-holder-entity.h"
+
+#define sp_round(v,m) (((v) < 0.0) ? ((ceil((v) / (m) - 0.5)) * (m)) : ((floor((v) / (m) + 0.5)) * (m)))
+
+class RectKnotHolder : public KnotHolder {
+public:
+    RectKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler);
+    virtual ~RectKnotHolder() {};
+};
+
+class Box3DKnotHolder : public KnotHolder {
+public:
+    Box3DKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler);
+    virtual ~Box3DKnotHolder() {};
+};
+
+class ArcKnotHolder : public KnotHolder {
+public:
+    ArcKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler);
+    virtual ~ArcKnotHolder() {};
+};
+
+class StarKnotHolder : public KnotHolder {
+public:
+    StarKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler);
+    virtual ~StarKnotHolder() {};
+};
+
+class SpiralKnotHolder : public KnotHolder {
+public:
+    SpiralKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler);
+    virtual ~SpiralKnotHolder() {};
+};
+
+class OffsetKnotHolder : public KnotHolder {
+public:
+    OffsetKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler);
+    virtual ~OffsetKnotHolder() {};
+};
+
+class FlowtextKnotHolder : public KnotHolder {
+public:
+    FlowtextKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler);
+    virtual ~FlowtextKnotHolder() {};
+};
+
+class MiscKnotHolder : public KnotHolder {
+public:
+    MiscKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler);
+    virtual ~MiscKnotHolder() {};
+};
+
+namespace {
+
+static KnotHolder *sp_lpe_knot_holder(SPLPEItem *item, SPDesktop *desktop)
+{
+    KnotHolder *knot_holder = new KnotHolder(desktop, item, NULL);
+
+    Inkscape::LivePathEffect::Effect *effect = item->getCurrentLPE();
+    effect->addHandles(knot_holder, item);
+
+    return knot_holder;
+}
+
+} // namespace
+
+namespace Inkscape {
+namespace UI {
+
+KnotHolder *createKnotHolder(SPItem *item, SPDesktop *desktop)
+{
+    KnotHolder *knotholder = NULL;
+
+    SPLPEItem *lpe = dynamic_cast<SPLPEItem *>(item);
+    if (lpe &&
+        lpe->getCurrentLPE() &&
+        lpe->getCurrentLPE()->isVisible() &&
+        lpe->getCurrentLPE()->providesKnotholder()) {
+        knotholder = sp_lpe_knot_holder(lpe, desktop);
+    } else if (dynamic_cast<SPRect *>(item)) {
+        knotholder = new RectKnotHolder(desktop, item, NULL);
+    } else if (dynamic_cast<SPBox3D *>(item)) {
+        knotholder = new Box3DKnotHolder(desktop, item, NULL);
+    } else if (dynamic_cast<SPGenericEllipse *>(item)) {
+        knotholder = new ArcKnotHolder(desktop, item, NULL);
+    } else if (dynamic_cast<SPStar *>(item)) {
+        knotholder = new StarKnotHolder(desktop, item, NULL);
+    } else if (dynamic_cast<SPSpiral *>(item)) {
+        knotholder = new SpiralKnotHolder(desktop, item, NULL);
+    } else if (dynamic_cast<SPOffset *>(item)) {
+        knotholder = new OffsetKnotHolder(desktop, item, NULL);
+    } else {
+        SPFlowtext *flowtext = dynamic_cast<SPFlowtext *>(item);
+        if (flowtext && flowtext->has_internal_frame()) {
+            knotholder = new FlowtextKnotHolder(desktop, flowtext->get_frame(NULL), NULL);
+        } else if ((item->style->fill.isPaintserver() && dynamic_cast<SPPattern *>(item->style->getFillPaintServer())) ||
+                   (item->style->stroke.isPaintserver() && dynamic_cast<SPPattern *>(item->style->getStrokePaintServer()))) {
+            knotholder = new KnotHolder(desktop, item, NULL);
+            knotholder->add_pattern_knotholder();
+        }
+    }
+
+    return knotholder;
+}
+
+}
+} // namespace Inkscape
+
+/* SPRect */
+
+/* handle for horizontal rounding radius */
+class RectKnotHolderEntityRX : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+    virtual void knot_click(unsigned int state);
+};
+
+/* handle for vertical rounding radius */
+class RectKnotHolderEntityRY : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+    virtual void knot_click(unsigned int state);
+};
+
+/* handle for width/height adjustment */
+class RectKnotHolderEntityWH : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+
+protected:
+    void set_internal(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+/* handle for x/y adjustment */
+class RectKnotHolderEntityXY : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+/* handle for position */
+class RectKnotHolderEntityCenter : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+Geom::Point
+RectKnotHolderEntityRX::knot_get() const
+{
+    SPRect *rect = dynamic_cast<SPRect *>(item);
+    g_assert(rect != NULL);
+
+    return Geom::Point(rect->x.computed + rect->width.computed - rect->rx.computed, rect->y.computed);
+}
+
+void
+RectKnotHolderEntityRX::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    SPRect *rect = dynamic_cast<SPRect *>(item);
+    g_assert(rect != NULL);
+
+    //In general we cannot just snap this radius to an arbitrary point, as we have only a single
+    //degree of freedom. For snapping to an arbitrary point we need two DOF. If we're going to snap
+    //the radius then we should have a constrained snap. snap_knot_position() is unconstrained
+    Geom::Point const s = snap_knot_position_constrained(p, Inkscape::Snapper::SnapConstraint(Geom::Point(rect->x.computed + rect->width.computed, rect->y.computed), Geom::Point(-1, 0)), state);
+
+    if (state & GDK_CONTROL_MASK) {
+        gdouble temp = MIN(rect->height.computed, rect->width.computed) / 2.0;
+        rect->rx = rect->ry = CLAMP(rect->x.computed + rect->width.computed - s[Geom::X], 0.0, temp);
+    } else {
+        rect->rx = CLAMP(rect->x.computed + rect->width.computed - s[Geom::X], 0.0, rect->width.computed / 2.0);
+    }
+
+    update_knot();
+
+    rect->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+void
+RectKnotHolderEntityRX::knot_click(unsigned int state)
+{
+    SPRect *rect = dynamic_cast<SPRect *>(item);
+    g_assert(rect != NULL);
+
+    if (state & GDK_SHIFT_MASK) {
+        /* remove rounding from rectangle */
+        rect->getRepr()->setAttribute("rx", NULL);
+        rect->getRepr()->setAttribute("ry", NULL);
+    } else if (state & GDK_CONTROL_MASK) {
+        /* Ctrl-click sets the vertical rounding to be the same as the horizontal */
+        rect->getRepr()->setAttribute("ry", rect->getRepr()->attribute("rx"));
+    }
+
+}
+
+Geom::Point
+RectKnotHolderEntityRY::knot_get() const
+{
+    SPRect *rect = dynamic_cast<SPRect *>(item);
+    g_assert(rect != NULL);
+
+    return Geom::Point(rect->x.computed + rect->width.computed, rect->y.computed + rect->ry.computed);
+}
+
+void
+RectKnotHolderEntityRY::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    SPRect *rect = dynamic_cast<SPRect *>(item);
+    g_assert(rect != NULL);
+
+    //In general we cannot just snap this radius to an arbitrary point, as we have only a single
+    //degree of freedom. For snapping to an arbitrary point we need two DOF. If we're going to snap
+    //the radius then we should have a constrained snap. snap_knot_position() is unconstrained
+    Geom::Point const s = snap_knot_position_constrained(p, Inkscape::Snapper::SnapConstraint(Geom::Point(rect->x.computed + rect->width.computed, rect->y.computed), Geom::Point(0, 1)), state);
+
+    if (state & GDK_CONTROL_MASK) { // When holding control then rx will be kept equal to ry,
+                                    // resulting in a perfect circle (and not an ellipse)
+        gdouble temp = MIN(rect->height.computed, rect->width.computed) / 2.0;
+        rect->rx = rect->ry = CLAMP(s[Geom::Y] - rect->y.computed, 0.0, temp);
+    } else {
+        if (!rect->rx._set || rect->rx.computed == 0) {
+            rect->ry = CLAMP(s[Geom::Y] - rect->y.computed,
+                             0.0,
+                             MIN(rect->height.computed / 2.0, rect->width.computed / 2.0));
+        } else {
+            rect->ry = CLAMP(s[Geom::Y] - rect->y.computed,
+                             0.0,
+                             rect->height.computed / 2.0);
+        }
+    }
+
+    update_knot();
+
+    rect->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+void
+RectKnotHolderEntityRY::knot_click(unsigned int state)
+{
+    SPRect *rect = dynamic_cast<SPRect *>(item);
+    g_assert(rect != NULL);
+
+    if (state & GDK_SHIFT_MASK) {
+        /* remove rounding */
+        rect->getRepr()->setAttribute("rx", NULL);
+        rect->getRepr()->setAttribute("ry", NULL);
+    } else if (state & GDK_CONTROL_MASK) {
+        /* Ctrl-click sets the vertical rounding to be the same as the horizontal */
+        rect->getRepr()->setAttribute("rx", rect->getRepr()->attribute("ry"));
+    }
+}
+
+#define SGN(x) ((x)>0?1:((x)<0?-1:0))
+
+static void sp_rect_clamp_radii(SPRect *rect)
+{
+    // clamp rounding radii so that they do not exceed width/height
+    if (2 * rect->rx.computed > rect->width.computed) {
+        rect->rx = 0.5 * rect->width.computed;
+    }
+    if (2 * rect->ry.computed > rect->height.computed) {
+        rect->ry = 0.5 * rect->height.computed;
+    }
+}
+
+Geom::Point
+RectKnotHolderEntityWH::knot_get() const
+{
+    SPRect *rect = dynamic_cast<SPRect *>(item);
+    g_assert(rect != NULL);
+
+    return Geom::Point(rect->x.computed + rect->width.computed, rect->y.computed + rect->height.computed);
+}
+
+void
+RectKnotHolderEntityWH::set_internal(Geom::Point const &p, Geom::Point const &origin, unsigned int state)
+{
+    SPRect *rect = dynamic_cast<SPRect *>(item);
+    g_assert(rect != NULL);
+
+    Geom::Point s = p;
+
+    if (state & GDK_CONTROL_MASK) {
+        // original width/height when drag started
+        gdouble const w_orig = (origin[Geom::X] - rect->x.computed);
+        gdouble const h_orig = (origin[Geom::Y] - rect->y.computed);
+
+        //original ratio
+        gdouble ratio = (w_orig / h_orig);
+
+        // mouse displacement since drag started
+        gdouble minx = p[Geom::X] - origin[Geom::X];
+        gdouble miny = p[Geom::Y] - origin[Geom::Y];
+
+        Geom::Point p_handle(rect->x.computed + rect->width.computed, rect->y.computed + rect->height.computed);
+
+        if (fabs(minx) > fabs(miny)) {
+            // snap to horizontal or diagonal
+            if (minx != 0 && fabs(miny/minx) > 0.5 * 1/ratio && (SGN(minx) == SGN(miny))) {
+                // closer to the diagonal and in same-sign quarters, change both using ratio
+                s = snap_knot_position_constrained(p, Inkscape::Snapper::SnapConstraint(p_handle, Geom::Point(-ratio, -1)), state);
+                minx = s[Geom::X] - origin[Geom::X];
+                // Dead assignment: Value stored to 'miny' is never read
+                //miny = s[Geom::Y] - origin[Geom::Y];
+                rect->height = MAX(h_orig + minx / ratio, 0);
+            } else {
+                // closer to the horizontal, change only width, height is h_orig
+                s = snap_knot_position_constrained(p, Inkscape::Snapper::SnapConstraint(p_handle, Geom::Point(-1, 0)), state);
+                minx = s[Geom::X] - origin[Geom::X];
+                // Dead assignment: Value stored to 'miny' is never read
+                //miny = s[Geom::Y] - origin[Geom::Y];
+                rect->height = MAX(h_orig, 0);
+            }
+            rect->width = MAX(w_orig + minx, 0);
+
+        } else {
+            // snap to vertical or diagonal
+            if (miny != 0 && fabs(minx/miny) > 0.5 * ratio && (SGN(minx) == SGN(miny))) {
+                // closer to the diagonal and in same-sign quarters, change both using ratio
+                s = snap_knot_position_constrained(p, Inkscape::Snapper::SnapConstraint(p_handle, Geom::Point(-ratio, -1)), state);
+                // Dead assignment: Value stored to 'minx' is never read
+                //minx = s[Geom::X] - origin[Geom::X];
+                miny = s[Geom::Y] - origin[Geom::Y];
+                rect->width = MAX(w_orig + miny * ratio, 0);
+            } else {
+                // closer to the vertical, change only height, width is w_orig
+                s = snap_knot_position_constrained(p, Inkscape::Snapper::SnapConstraint(p_handle, Geom::Point(0, -1)), state);
+                // Dead assignment: Value stored to 'minx' is never read
+                //minx = s[Geom::X] - origin[Geom::X];
+                miny = s[Geom::Y] - origin[Geom::Y];
+                rect->width = MAX(w_orig, 0);
+            }
+            rect->height = MAX(h_orig + miny, 0);
+
+        }
+
+    } else {
+        // move freely
+        s = snap_knot_position(p, state);
+        rect->width = MAX(s[Geom::X] - rect->x.computed, 0);
+        rect->height = MAX(s[Geom::Y] - rect->y.computed, 0);
+    }
+
+    sp_rect_clamp_radii(rect);
+
+    rect->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+void
+RectKnotHolderEntityWH::knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state)
+{
+    set_internal(p, origin, state);
+    update_knot();
+}
+
+Geom::Point
+RectKnotHolderEntityXY::knot_get() const
+{
+    SPRect *rect = dynamic_cast<SPRect *>(item);
+    g_assert(rect != NULL);
+
+    return Geom::Point(rect->x.computed, rect->y.computed);
+}
+
+void
+RectKnotHolderEntityXY::knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state)
+{
+    SPRect *rect = dynamic_cast<SPRect *>(item);
+    g_assert(rect != NULL);
+
+    // opposite corner (unmoved)
+    gdouble opposite_x = (rect->x.computed + rect->width.computed);
+    gdouble opposite_y = (rect->y.computed + rect->height.computed);
+
+    // original width/height when drag started
+    gdouble w_orig = opposite_x - origin[Geom::X];
+    gdouble h_orig = opposite_y - origin[Geom::Y];
+
+    Geom::Point s = p;
+    Geom::Point p_handle(rect->x.computed, rect->y.computed);
+
+    // mouse displacement since drag started
+    gdouble minx = p[Geom::X] - origin[Geom::X];
+    gdouble miny = p[Geom::Y] - origin[Geom::Y];
+
+    if (state & GDK_CONTROL_MASK) {
+        //original ratio
+        gdouble ratio = (w_orig / h_orig);
+
+        if (fabs(minx) > fabs(miny)) {
+            // snap to horizontal or diagonal
+            if (minx != 0 && fabs(miny/minx) > 0.5 * 1/ratio && (SGN(minx) == SGN(miny))) {
+                // closer to the diagonal and in same-sign quarters, change both using ratio
+                s = snap_knot_position_constrained(p, Inkscape::Snapper::SnapConstraint(p_handle, Geom::Point(-ratio, -1)), state);
+                minx = s[Geom::X] - origin[Geom::X];
+                // Dead assignment: Value stored to 'miny' is never read
+                //miny = s[Geom::Y] - origin[Geom::Y];
+                rect->y = MIN(origin[Geom::Y] + minx / ratio, opposite_y);
+                rect->height = MAX(h_orig - minx / ratio, 0);
+            } else {
+                // closer to the horizontal, change only width, height is h_orig
+                s = snap_knot_position_constrained(p, Inkscape::Snapper::SnapConstraint(p_handle, Geom::Point(-1, 0)), state);
+                minx = s[Geom::X] - origin[Geom::X];
+                // Dead assignment: Value stored to 'miny' is never read
+                //miny = s[Geom::Y] - origin[Geom::Y];
+                rect->y = MIN(origin[Geom::Y], opposite_y);
+                rect->height = MAX(h_orig, 0);
+            }
+            rect->x = MIN(s[Geom::X], opposite_x);
+            rect->width = MAX(w_orig - minx, 0);
+        } else {
+            // snap to vertical or diagonal
+            if (miny != 0 && fabs(minx/miny) > 0.5 *ratio && (SGN(minx) == SGN(miny))) {
+                // closer to the diagonal and in same-sign quarters, change both using ratio
+                s = snap_knot_position_constrained(p, Inkscape::Snapper::SnapConstraint(p_handle, Geom::Point(-ratio, -1)), state);
+                // Dead assignment: Value stored to 'minx' is never read
+                //minx = s[Geom::X] - origin[Geom::X];
+                miny = s[Geom::Y] - origin[Geom::Y];
+                rect->x = MIN(origin[Geom::X] + miny * ratio, opposite_x);
+                rect->width = MAX(w_orig - miny * ratio, 0);
+            } else {
+                // closer to the vertical, change only height, width is w_orig
+                s = snap_knot_position_constrained(p, Inkscape::Snapper::SnapConstraint(p_handle, Geom::Point(0, -1)), state);
+                // Dead assignment: Value stored to 'minx' is never read
+                //minx = s[Geom::X] - origin[Geom::X];
+                miny = s[Geom::Y] - origin[Geom::Y];
+                rect->x = MIN(origin[Geom::X], opposite_x);
+                rect->width = MAX(w_orig, 0);
+            }
+            rect->y = MIN(s[Geom::Y], opposite_y);
+            rect->height = MAX(h_orig - miny, 0);
+        }
+
+    } else {
+        // move freely
+        s = snap_knot_position(p, state);
+        minx = s[Geom::X] - origin[Geom::X];
+        miny = s[Geom::Y] - origin[Geom::Y];
+
+        rect->x = MIN(s[Geom::X], opposite_x);
+        rect->y = MIN(s[Geom::Y], opposite_y);
+        rect->width = MAX(w_orig - minx, 0);
+        rect->height = MAX(h_orig - miny, 0);
+    }
+
+    sp_rect_clamp_radii(rect);
+
+    update_knot();
+
+    rect->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+Geom::Point
+RectKnotHolderEntityCenter::knot_get() const
+{
+    SPRect *rect = dynamic_cast<SPRect *>(item);
+    g_assert(rect != NULL);
+
+    return Geom::Point(rect->x.computed + (rect->width.computed / 2.), rect->y.computed + (rect->height.computed / 2.));
+}
+
+void
+RectKnotHolderEntityCenter::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    SPRect *rect = dynamic_cast<SPRect *>(item);
+    g_assert(rect != NULL);
+
+    Geom::Point const s = snap_knot_position(p, state);
+
+    rect->x = s[Geom::X] - (rect->width.computed / 2.);
+    rect->y = s[Geom::Y] - (rect->height.computed / 2.);
+
+    // No need to call sp_rect_clamp_radii(): width and height haven't changed.
+    // No need to call update_knot(): the knot is set directly by the user.
+
+    rect->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+RectKnotHolder::RectKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler) :
+    KnotHolder(desktop, item, relhandler)
+{
+    RectKnotHolderEntityRX *entity_rx = new RectKnotHolderEntityRX();
+    RectKnotHolderEntityRY *entity_ry = new RectKnotHolderEntityRY();
+    RectKnotHolderEntityWH *entity_wh = new RectKnotHolderEntityWH();
+    RectKnotHolderEntityXY *entity_xy = new RectKnotHolderEntityXY();
+    RectKnotHolderEntityCenter *entity_center = new RectKnotHolderEntityCenter();
+
+    entity_rx->create(desktop, item, this, Inkscape::CTRL_TYPE_ROTATE,
+                      _("Adjust the <b>horizontal rounding</b> radius; with <b>Ctrl</b> "
+                        "to make the vertical radius the same"),
+                      SP_KNOT_SHAPE_CIRCLE, SP_KNOT_MODE_XOR);
+
+    entity_ry->create(desktop, item, this, Inkscape::CTRL_TYPE_ROTATE,
+                      _("Adjust the <b>vertical rounding</b> radius; with <b>Ctrl</b> "
+                        "to make the horizontal radius the same"),
+                      SP_KNOT_SHAPE_CIRCLE, SP_KNOT_MODE_XOR);
+
+    entity_wh->create(desktop, item, this, Inkscape::CTRL_TYPE_SIZER,
+                      _("Adjust the <b>width and height</b> of the rectangle; with <b>Ctrl</b> "
+                        "to lock ratio or stretch in one dimension only"),
+                      SP_KNOT_SHAPE_SQUARE, SP_KNOT_MODE_XOR);
+
+    entity_xy->create(desktop, item, this, Inkscape::CTRL_TYPE_SIZER,
+                      _("Adjust the <b>width and height</b> of the rectangle; with <b>Ctrl</b> "
+                        "to lock ratio or stretch in one dimension only"),
+                      SP_KNOT_SHAPE_SQUARE, SP_KNOT_MODE_XOR);
+
+    entity_center->create(desktop, item, this, Inkscape::CTRL_TYPE_POINT,
+                          _("Drag to move the rectangle"),
+                          SP_KNOT_SHAPE_CROSS);
+
+    entity.push_back(entity_rx);
+    entity.push_back(entity_ry);
+    entity.push_back(entity_wh);
+    entity.push_back(entity_xy);
+    entity.push_back(entity_center);
+
+    add_pattern_knotholder();
+}
+
+/* Box3D (= the new 3D box structure) */
+
+class Box3DKnotHolderEntity : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const = 0;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state) = 0;
+
+    Geom::Point knot_get_generic(SPItem *item, unsigned int knot_id) const;
+    void knot_set_generic(SPItem *item, unsigned int knot_id, Geom::Point const &p, unsigned int state);
+};
+
+Geom::Point
+Box3DKnotHolderEntity::knot_get_generic(SPItem *item, unsigned int knot_id) const
+{
+    SPBox3D *box = dynamic_cast<SPBox3D *>(item);
+    if (box) {
+        return box3d_get_corner_screen(box, knot_id);
+    } else {
+        return Geom::Point(); // TODO investigate proper fallback
+    }
+}
+
+void
+Box3DKnotHolderEntity::knot_set_generic(SPItem *item, unsigned int knot_id, Geom::Point const &new_pos, unsigned int state)
+{
+    Geom::Point const s = snap_knot_position(new_pos, state);
+
+    g_assert(item != NULL);
+    SPBox3D *box = dynamic_cast<SPBox3D *>(item);
+    g_assert(box != NULL);
+    Geom::Affine const i2dt (item->i2dt_affine ());
+
+    Box3D::Axis movement;
+    if ((knot_id < 4) != (state & GDK_SHIFT_MASK)) {
+        movement = Box3D::XY;
+    } else {
+        movement = Box3D::Z;
+    }
+
+    box3d_set_corner (box, knot_id, s * i2dt, movement, (state & GDK_CONTROL_MASK));
+    box3d_set_z_orders(box);
+    box3d_position_set(box);
+}
+
+class Box3DKnotHolderEntity0 : public Box3DKnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+class Box3DKnotHolderEntity1 : public Box3DKnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+class Box3DKnotHolderEntity2 : public Box3DKnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+class Box3DKnotHolderEntity3 : public Box3DKnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+class Box3DKnotHolderEntity4 : public Box3DKnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+class Box3DKnotHolderEntity5 : public Box3DKnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+class Box3DKnotHolderEntity6 : public Box3DKnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+class Box3DKnotHolderEntity7 : public Box3DKnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+class Box3DKnotHolderEntityCenter : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+Geom::Point
+Box3DKnotHolderEntity0::knot_get() const
+{
+    return knot_get_generic(item, 0);
+}
+
+Geom::Point
+Box3DKnotHolderEntity1::knot_get() const
+{
+    return knot_get_generic(item, 1);
+}
+
+Geom::Point
+Box3DKnotHolderEntity2::knot_get() const
+{
+    return knot_get_generic(item, 2);
+}
+
+Geom::Point
+Box3DKnotHolderEntity3::knot_get() const
+{
+    return knot_get_generic(item, 3);
+}
+
+Geom::Point
+Box3DKnotHolderEntity4::knot_get() const
+{
+    return knot_get_generic(item, 4);
+}
+
+Geom::Point
+Box3DKnotHolderEntity5::knot_get() const
+{
+    return knot_get_generic(item, 5);
+}
+
+Geom::Point
+Box3DKnotHolderEntity6::knot_get() const
+{
+    return knot_get_generic(item, 6);
+}
+
+Geom::Point
+Box3DKnotHolderEntity7::knot_get() const
+{
+    return knot_get_generic(item, 7);
+}
+
+Geom::Point
+Box3DKnotHolderEntityCenter::knot_get() const
+{
+    SPBox3D *box = dynamic_cast<SPBox3D *>(item);
+    if (box) {
+        return box3d_get_center_screen(box);
+    } else {
+        return Geom::Point(); // TODO investigate proper fallback
+    }
+}
+
+void
+Box3DKnotHolderEntity0::knot_set(Geom::Point const &new_pos, Geom::Point const &/*origin*/, unsigned int state)
+{
+    knot_set_generic(item, 0, new_pos, state);
+}
+
+void
+Box3DKnotHolderEntity1::knot_set(Geom::Point const &new_pos, Geom::Point const &/*origin*/, unsigned int state)
+{
+    knot_set_generic(item, 1, new_pos, state);
+}
+
+void
+Box3DKnotHolderEntity2::knot_set(Geom::Point const &new_pos, Geom::Point const &/*origin*/, unsigned int state)
+{
+    knot_set_generic(item, 2, new_pos, state);
+}
+
+void
+Box3DKnotHolderEntity3::knot_set(Geom::Point const &new_pos, Geom::Point const &/*origin*/, unsigned int state)
+{
+    knot_set_generic(item, 3, new_pos, state);
+}
+
+void
+Box3DKnotHolderEntity4::knot_set(Geom::Point const &new_pos, Geom::Point const &/*origin*/, unsigned int state)
+{
+    knot_set_generic(item, 4, new_pos, state);
+}
+
+void
+Box3DKnotHolderEntity5::knot_set(Geom::Point const &new_pos, Geom::Point const &/*origin*/, unsigned int state)
+{
+    knot_set_generic(item, 5, new_pos, state);
+}
+
+void
+Box3DKnotHolderEntity6::knot_set(Geom::Point const &new_pos, Geom::Point const &/*origin*/, unsigned int state)
+{
+    knot_set_generic(item, 6, new_pos, state);
+}
+
+void
+Box3DKnotHolderEntity7::knot_set(Geom::Point const &new_pos, Geom::Point const &/*origin*/, unsigned int state)
+{
+    knot_set_generic(item, 7, new_pos, state);
+}
+
+void
+Box3DKnotHolderEntityCenter::knot_set(Geom::Point const &new_pos, Geom::Point const &origin, unsigned int state)
+{
+    Geom::Point const s = snap_knot_position(new_pos, state);
+
+    SPBox3D *box = dynamic_cast<SPBox3D *>(item);
+    g_assert(box != NULL);
+    Geom::Affine const i2dt (item->i2dt_affine ());
+
+    box3d_set_center(box, s * i2dt, origin * i2dt, !(state & GDK_SHIFT_MASK) ? Box3D::XY : Box3D::Z,
+                      state & GDK_CONTROL_MASK);
+
+    box3d_set_z_orders(box);
+    box3d_position_set(box);
+}
+
+Box3DKnotHolder::Box3DKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler) :
+    KnotHolder(desktop, item, relhandler)
+{
+    Box3DKnotHolderEntity0 *entity_corner0 = new Box3DKnotHolderEntity0();
+    Box3DKnotHolderEntity1 *entity_corner1 = new Box3DKnotHolderEntity1();
+    Box3DKnotHolderEntity2 *entity_corner2 = new Box3DKnotHolderEntity2();
+    Box3DKnotHolderEntity3 *entity_corner3 = new Box3DKnotHolderEntity3();
+    Box3DKnotHolderEntity4 *entity_corner4 = new Box3DKnotHolderEntity4();
+    Box3DKnotHolderEntity5 *entity_corner5 = new Box3DKnotHolderEntity5();
+    Box3DKnotHolderEntity6 *entity_corner6 = new Box3DKnotHolderEntity6();
+    Box3DKnotHolderEntity7 *entity_corner7 = new Box3DKnotHolderEntity7();
+    Box3DKnotHolderEntityCenter *entity_center = new Box3DKnotHolderEntityCenter();
+
+    entity_corner0->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                           _("Resize box in X/Y direction; with <b>Shift</b> along the Z axis; "
+                             "with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+
+    entity_corner1->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                           _("Resize box in X/Y direction; with <b>Shift</b> along the Z axis; "
+                             "with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+
+    entity_corner2->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                           _("Resize box in X/Y direction; with <b>Shift</b> along the Z axis; "
+                             "with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+
+    entity_corner3->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                           _("Resize box in X/Y direction; with <b>Shift</b> along the Z axis; "
+                             "with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+
+    entity_corner4->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                     _("Resize box along the Z axis; with <b>Shift</b> in X/Y direction; "
+                       "with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+
+    entity_corner5->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                     _("Resize box along the Z axis; with <b>Shift</b> in X/Y direction; "
+                       "with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+
+    entity_corner6->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                     _("Resize box along the Z axis; with <b>Shift</b> in X/Y direction; "
+                       "with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+
+    entity_corner7->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                     _("Resize box along the Z axis; with <b>Shift</b> in X/Y direction; "
+                       "with <b>Ctrl</b> to constrain to the directions of edges or diagonals"));
+
+    entity_center->create(desktop, item, this, Inkscape::CTRL_TYPE_POINT,
+                          _("Move the box in perspective"),
+                          SP_KNOT_SHAPE_CROSS);
+
+    entity.push_back(entity_corner0);
+    entity.push_back(entity_corner1);
+    entity.push_back(entity_corner2);
+    entity.push_back(entity_corner3);
+    entity.push_back(entity_corner4);
+    entity.push_back(entity_corner5);
+    entity.push_back(entity_corner6);
+    entity.push_back(entity_corner7);
+    entity.push_back(entity_center);
+
+    add_pattern_knotholder();
+}
+
+/* SPArc */
+
+class ArcKnotHolderEntityStart : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+    virtual void knot_click(unsigned int state);
+};
+
+class ArcKnotHolderEntityEnd : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+    virtual void knot_click(unsigned int state);
+};
+
+class ArcKnotHolderEntityRX : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+    virtual void knot_click(unsigned int state);
+};
+
+class ArcKnotHolderEntityRY : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+    virtual void knot_click(unsigned int state);
+};
+
+class ArcKnotHolderEntityCenter : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+/*
+ * return values:
+ *   1  : inside
+ *   0  : on the curves
+ *   -1 : outside
+ */
+static gint
+sp_genericellipse_side(SPGenericEllipse *ellipse, Geom::Point const &p)
+{
+    gdouble dx = (p[Geom::X] - ellipse->cx.computed) / ellipse->rx.computed;
+    gdouble dy = (p[Geom::Y] - ellipse->cy.computed) / ellipse->ry.computed;
+
+    gdouble s = dx * dx + dy * dy;
+    // We add a bit of a buffer, so there's a decent chance the user will
+    // be able to adjust the arc without the closed status flipping between
+    // open and closed during micro mouse movements.
+    if (s < 0.75) return 1;
+    if (s > 1.25) return -1;
+    return 0;
+}
+
+void
+ArcKnotHolderEntityStart::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    int snaps = Inkscape::Preferences::get()->getInt("/options/rotationsnapsperpi/value", 12);
+
+    SPGenericEllipse *arc = dynamic_cast<SPGenericEllipse *>(item);
+    g_assert(arc != NULL);
+
+    gint side = sp_genericellipse_side(arc, p);
+    if(side != 0) { arc->setArcType( (side == -1) ?
+                                     SP_GENERIC_ELLIPSE_ARC_TYPE_SLICE :
+                                     SP_GENERIC_ELLIPSE_ARC_TYPE_ARC); }
+
+    Geom::Point delta = p - Geom::Point(arc->cx.computed, arc->cy.computed);
+    Geom::Scale sc(arc->rx.computed, arc->ry.computed);
+
+    double offset = arc->start - atan2(delta * sc.inverse());
+    arc->start -= offset;
+
+    if ((state & GDK_CONTROL_MASK) && snaps) {
+        arc->start = sp_round(arc->start, M_PI / snaps);
+    }
+    if (state & GDK_SHIFT_MASK) {
+        arc->end -= offset;
+    }
+
+    arc->normalize();
+    arc->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+Geom::Point
+ArcKnotHolderEntityStart::knot_get() const
+{
+    SPGenericEllipse const *ge = dynamic_cast<SPGenericEllipse const *>(item);
+    g_assert(ge != NULL);
+
+    return ge->getPointAtAngle(ge->start);
+}
+
+void
+ArcKnotHolderEntityStart::knot_click(unsigned int state)
+{
+    SPGenericEllipse *ge = dynamic_cast<SPGenericEllipse *>(item);
+    g_assert(ge != NULL);
+
+    if (state & GDK_SHIFT_MASK) {
+        ge->end = ge->start = 0;
+        ge->updateRepr();
+    }
+}
+
+void
+ArcKnotHolderEntityEnd::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    int snaps = Inkscape::Preferences::get()->getInt("/options/rotationsnapsperpi/value", 12);
+
+    SPGenericEllipse *arc = dynamic_cast<SPGenericEllipse *>(item);
+    g_assert(arc != NULL);
+
+    gint side = sp_genericellipse_side(arc, p);
+    if(side != 0) { arc->setArcType( (side == -1) ?
+                                     SP_GENERIC_ELLIPSE_ARC_TYPE_SLICE :
+                                     SP_GENERIC_ELLIPSE_ARC_TYPE_ARC); }
+
+    Geom::Point delta = p - Geom::Point(arc->cx.computed, arc->cy.computed);
+    Geom::Scale sc(arc->rx.computed, arc->ry.computed);
+
+    double offset = arc->end - atan2(delta * sc.inverse());
+    arc->end -= offset;
+
+    if ((state & GDK_CONTROL_MASK) && snaps) {
+        arc->end = sp_round(arc->end, M_PI/snaps);
+    }
+    if (state & GDK_SHIFT_MASK) {
+        arc->start -= offset;
+    }
+
+    arc->normalize();
+    arc->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+Geom::Point
+ArcKnotHolderEntityEnd::knot_get() const
+{
+    SPGenericEllipse const *ge = dynamic_cast<SPGenericEllipse const *>(item);
+    g_assert(ge != NULL);
+
+    return ge->getPointAtAngle(ge->end);
+}
+
+
+void
+ArcKnotHolderEntityEnd::knot_click(unsigned int state)
+{
+    SPGenericEllipse *ge = dynamic_cast<SPGenericEllipse *>(item);
+    g_assert(ge != NULL);
+
+    if (state & GDK_SHIFT_MASK) {
+        ge->end = ge->start = 0;
+        ge->updateRepr();
+    }
+}
+
+
+void
+ArcKnotHolderEntityRX::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    SPGenericEllipse *ge = dynamic_cast<SPGenericEllipse *>(item);
+    g_assert(ge != NULL);
+
+    Geom::Point const s = snap_knot_position(p, state);
+
+    ge->rx = fabs( ge->cx.computed - s[Geom::X] );
+
+    if ( state & GDK_CONTROL_MASK ) {
+        ge->ry = ge->rx.computed;
+    }
+
+    item->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+Geom::Point
+ArcKnotHolderEntityRX::knot_get() const
+{
+    SPGenericEllipse const *ge = dynamic_cast<SPGenericEllipse const *>(item);
+    g_assert(ge != NULL);
+
+    return (Geom::Point(ge->cx.computed, ge->cy.computed) -  Geom::Point(ge->rx.computed, 0));
+}
+
+void
+ArcKnotHolderEntityRX::knot_click(unsigned int state)
+{
+    SPGenericEllipse *ge = dynamic_cast<SPGenericEllipse *>(item);
+    g_assert(ge != NULL);
+
+    if (state & GDK_CONTROL_MASK) {
+        ge->ry = ge->rx.computed;
+        ge->updateRepr();
+    }
+}
+
+void
+ArcKnotHolderEntityRY::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    SPGenericEllipse *ge = dynamic_cast<SPGenericEllipse *>(item);
+    g_assert(ge != NULL);
+
+    Geom::Point const s = snap_knot_position(p, state);
+
+    ge->ry = fabs( ge->cy.computed - s[Geom::Y] );
+
+    if ( state & GDK_CONTROL_MASK ) {
+        ge->rx = ge->ry.computed;
+    }
+
+    item->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+Geom::Point
+ArcKnotHolderEntityRY::knot_get() const
+{
+    SPGenericEllipse const *ge = dynamic_cast<SPGenericEllipse *>(item);
+    g_assert(ge != NULL);
+
+    return (Geom::Point(ge->cx.computed, ge->cy.computed) -  Geom::Point(0, ge->ry.computed));
+}
+
+void
+ArcKnotHolderEntityRY::knot_click(unsigned int state)
+{
+    SPGenericEllipse *ge = dynamic_cast<SPGenericEllipse *>(item);
+    g_assert(ge != NULL);
+
+    if (state & GDK_CONTROL_MASK) {
+        ge->rx = ge->ry.computed;
+        ge->updateRepr();
+    }
+}
+
+void
+ArcKnotHolderEntityCenter::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    SPGenericEllipse *ge = dynamic_cast<SPGenericEllipse *>(item);
+    g_assert(ge != NULL);
+
+    Geom::Point const s = snap_knot_position(p, state);
+
+    ge->cx = s[Geom::X];
+    ge->cy = s[Geom::Y];
+
+    item->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+Geom::Point
+ArcKnotHolderEntityCenter::knot_get() const
+{
+    SPGenericEllipse const *ge = dynamic_cast<SPGenericEllipse *>(item);
+    g_assert(ge != NULL);
+
+    return Geom::Point(ge->cx.computed, ge->cy.computed);
+}
+
+
+ArcKnotHolder::ArcKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler) :
+    KnotHolder(desktop, item, relhandler)
+{
+    ArcKnotHolderEntityRX *entity_rx = new ArcKnotHolderEntityRX();
+    ArcKnotHolderEntityRY *entity_ry = new ArcKnotHolderEntityRY();
+    ArcKnotHolderEntityStart *entity_start = new ArcKnotHolderEntityStart();
+    ArcKnotHolderEntityEnd *entity_end = new ArcKnotHolderEntityEnd();
+    ArcKnotHolderEntityCenter *entity_center = new ArcKnotHolderEntityCenter();
+
+    entity_rx->create(desktop, item, this, Inkscape::CTRL_TYPE_SIZER,
+                      _("Adjust ellipse <b>width</b>, with <b>Ctrl</b> to make circle"),
+                      SP_KNOT_SHAPE_SQUARE, SP_KNOT_MODE_XOR);
+
+    entity_ry->create(desktop, item, this, Inkscape::CTRL_TYPE_SIZER,
+                      _("Adjust ellipse <b>height</b>, with <b>Ctrl</b> to make circle"),
+                      SP_KNOT_SHAPE_SQUARE, SP_KNOT_MODE_XOR);
+
+    entity_start->create(desktop, item, this, Inkscape::CTRL_TYPE_ROTATE,
+                         _("Position the <b>start point</b> of the arc or segment; with <b>Shift</b> to move "
+                           "with <b>end point</b>; with <b>Ctrl</b> to snap angle; drag <b>inside</b> the "
+                           "ellipse for arc, <b>outside</b> for segment"),
+                         SP_KNOT_SHAPE_CIRCLE, SP_KNOT_MODE_XOR);
+
+    entity_end->create(desktop, item, this, Inkscape::CTRL_TYPE_ROTATE,
+                       _("Position the <b>end point</b> of the arc or segment; with <b>Shift</b> to move "
+                         "with <b>start point</b>; with <b>Ctrl</b> to snap angle; drag <b>inside</b> the "
+                         "ellipse for arc, <b>outside</b> for segment"),
+                       SP_KNOT_SHAPE_CIRCLE, SP_KNOT_MODE_XOR);
+
+    entity_center->create(desktop, item, this, Inkscape::CTRL_TYPE_POINT,
+                          _("Drag to move the ellipse"),
+                          SP_KNOT_SHAPE_CROSS);
+
+    entity.push_back(entity_rx);
+    entity.push_back(entity_ry);
+    entity.push_back(entity_start);
+    entity.push_back(entity_end);
+    entity.push_back(entity_center);
+
+    add_pattern_knotholder();
+}
+
+/* SPStar */
+
+class StarKnotHolderEntity1 : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+    virtual void knot_click(unsigned int state);
+};
+
+class StarKnotHolderEntity2 : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+    virtual void knot_click(unsigned int state);
+};
+
+class StarKnotHolderEntityCenter : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+void
+StarKnotHolderEntity1::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    SPStar *star = dynamic_cast<SPStar *>(item);
+    g_assert(star != NULL);
+
+    Geom::Point const s = snap_knot_position(p, state);
+
+    Geom::Point d = s - star->center;
+
+    double arg1 = atan2(d);
+    double darg1 = arg1 - star->arg[0];
+
+    if (state & GDK_MOD1_MASK) {
+        star->randomized = darg1/(star->arg[0] - star->arg[1]);
+    } else if (state & GDK_SHIFT_MASK) {
+        star->rounded = darg1/(star->arg[0] - star->arg[1]);
+    } else if (state & GDK_CONTROL_MASK) {
+        star->r[0]    = L2(d);
+    } else {
+        star->r[0]    = L2(d);
+        star->arg[0]  = arg1;
+        star->arg[1] += darg1;
+    }
+    star->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+void
+StarKnotHolderEntity2::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    SPStar *star = dynamic_cast<SPStar *>(item);
+    g_assert(star != NULL);
+
+    Geom::Point const s = snap_knot_position(p, state);
+
+    if (star->flatsided == false) {
+        Geom::Point d = s - star->center;
+
+        double arg1 = atan2(d);
+        double darg1 = arg1 - star->arg[1];
+
+        if (state & GDK_MOD1_MASK) {
+            star->randomized = darg1/(star->arg[0] - star->arg[1]);
+        } else if (state & GDK_SHIFT_MASK) {
+            star->rounded = fabs(darg1/(star->arg[0] - star->arg[1]));
+        } else if (state & GDK_CONTROL_MASK) {
+            star->r[1]   = L2(d);
+            star->arg[1] = star->arg[0] + M_PI / star->sides;
+        }
+        else {
+            star->r[1]   = L2(d);
+            star->arg[1] = atan2(d);
+        }
+        star->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+    }
+}
+
+void
+StarKnotHolderEntityCenter::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    SPStar *star = dynamic_cast<SPStar *>(item);
+    g_assert(star != NULL);
+
+    star->center = snap_knot_position(p, state);
+
+    item->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+Geom::Point
+StarKnotHolderEntity1::knot_get() const
+{
+    g_assert(item != NULL);
+
+    SPStar const *star = dynamic_cast<SPStar const *>(item);
+    g_assert(star != NULL);
+
+    return sp_star_get_xy(star, SP_STAR_POINT_KNOT1, 0);
+
+}
+
+Geom::Point
+StarKnotHolderEntity2::knot_get() const
+{
+    g_assert(item != NULL);
+
+    SPStar const *star = dynamic_cast<SPStar const *>(item);
+    g_assert(star != NULL);
+
+    return sp_star_get_xy(star, SP_STAR_POINT_KNOT2, 0);
+}
+
+Geom::Point
+StarKnotHolderEntityCenter::knot_get() const
+{
+    g_assert(item != NULL);
+
+    SPStar const *star = dynamic_cast<SPStar const *>(item);
+    g_assert(star != NULL);
+
+    return star->center;
+}
+
+static void
+sp_star_knot_click(SPItem *item, unsigned int state)
+{
+    SPStar *star = dynamic_cast<SPStar *>(item);
+    g_assert(star != NULL);
+
+    if (state & GDK_MOD1_MASK) {
+        star->randomized = 0;
+        star->updateRepr();
+    } else if (state & GDK_SHIFT_MASK) {
+        star->rounded = 0;
+        star->updateRepr();
+    } else if (state & GDK_CONTROL_MASK) {
+        star->arg[1] = star->arg[0] + M_PI / star->sides;
+        star->updateRepr();
+    }
+}
+
+void
+StarKnotHolderEntity1::knot_click(unsigned int state)
+{
+    sp_star_knot_click(item, state);
+}
+
+void
+StarKnotHolderEntity2::knot_click(unsigned int state)
+{
+    sp_star_knot_click(item, state);
+}
+
+StarKnotHolder::StarKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler) :
+    KnotHolder(desktop, item, relhandler)
+{
+    SPStar *star = dynamic_cast<SPStar *>(item);
+    g_assert(item != NULL);
+
+    StarKnotHolderEntity1 *entity1 = new StarKnotHolderEntity1();
+    entity1->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                    _("Adjust the <b>tip radius</b> of the star or polygon; "
+                      "with <b>Shift</b> to round; with <b>Alt</b> to randomize"));
+
+    entity.push_back(entity1);
+
+    if (star->flatsided == false) {
+        StarKnotHolderEntity2 *entity2 = new StarKnotHolderEntity2();
+        entity2->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                        _("Adjust the <b>base radius</b> of the star; with <b>Ctrl</b> to keep star rays "
+                          "radial (no skew); with <b>Shift</b> to round; with <b>Alt</b> to randomize"));
+        entity.push_back(entity2);
+    }
+
+    StarKnotHolderEntityCenter *entity_center = new StarKnotHolderEntityCenter();
+    entity_center->create(desktop, item, this, Inkscape::CTRL_TYPE_POINT,
+                          _("Drag to move the star"),
+                          SP_KNOT_SHAPE_CROSS);
+    entity.push_back(entity_center);
+
+    add_pattern_knotholder();
+}
+
+/* SPSpiral */
+
+class SpiralKnotHolderEntityInner : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+    virtual void knot_click(unsigned int state);
+};
+
+class SpiralKnotHolderEntityOuter : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+class SpiralKnotHolderEntityCenter : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+
+/*
+ * set attributes via inner (t=t0) knot point:
+ *   [default] increase/decrease inner point
+ *   [shift]   increase/decrease inner and outer arg synchronizely
+ *   [control] constrain inner arg to round per PI/4
+ */
+void
+SpiralKnotHolderEntityInner::knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state)
+{
+    Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+    int snaps = prefs->getInt("/options/rotationsnapsperpi/value", 12);
+
+    SPSpiral *spiral = dynamic_cast<SPSpiral *>(item);
+    g_assert(spiral != NULL);
+
+    gdouble   dx = p[Geom::X] - spiral->cx;
+    gdouble   dy = p[Geom::Y] - spiral->cy;
+
+    gdouble   moved_y = p[Geom::Y] - origin[Geom::Y];
+
+    if (state & GDK_MOD1_MASK) {
+        // adjust divergence by vertical drag, relative to rad
+        if (spiral->rad > 0) {
+            double exp_delta = 0.1*moved_y/(spiral->rad); // arbitrary multiplier to slow it down
+            spiral->exp += exp_delta;
+            if (spiral->exp < 1e-3)
+                spiral->exp = 1e-3;
+        }
+    } else {
+        // roll/unroll from inside
+        gdouble   arg_t0;
+        spiral->getPolar(spiral->t0, NULL, &arg_t0);
+
+        gdouble   arg_tmp = atan2(dy, dx) - arg_t0;
+        gdouble   arg_t0_new = arg_tmp - floor((arg_tmp+M_PI)/(2.0*M_PI))*2.0*M_PI + arg_t0;
+        spiral->t0 = (arg_t0_new - spiral->arg) / (2.0*M_PI*spiral->revo);
+
+        /* round inner arg per PI/snaps, if CTRL is pressed */
+        if ( ( state & GDK_CONTROL_MASK )
+             && ( fabs(spiral->revo) > SP_EPSILON_2 )
+             && ( snaps != 0 ) ) {
+            gdouble arg = 2.0*M_PI*spiral->revo*spiral->t0 + spiral->arg;
+            spiral->t0 = (sp_round(arg, M_PI/snaps) - spiral->arg)/(2.0*M_PI*spiral->revo);
+        }
+
+        spiral->t0 = CLAMP(spiral->t0, 0.0, 0.999);
+    }
+
+    spiral->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+/*
+ * set attributes via outer (t=1) knot point:
+ *   [default] increase/decrease revolution factor
+ *   [control] constrain inner arg to round per PI/4
+ */
+void
+SpiralKnotHolderEntityOuter::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+    int snaps = prefs->getInt("/options/rotationsnapsperpi/value", 12);
+
+    SPSpiral *spiral = dynamic_cast<SPSpiral *>(item);
+    g_assert(spiral != NULL);
+
+    gdouble  dx = p[Geom::X] - spiral->cx;
+    gdouble  dy = p[Geom::Y] - spiral->cy;
+
+    if (state & GDK_SHIFT_MASK) { // rotate without roll/unroll
+        spiral->arg = atan2(dy, dx) - 2.0*M_PI*spiral->revo;
+        if (!(state & GDK_MOD1_MASK)) {
+            // if alt not pressed, change also rad; otherwise it is locked
+            spiral->rad = MAX(hypot(dx, dy), 0.001);
+        }
+        if ( ( state & GDK_CONTROL_MASK )
+             && snaps ) {
+            spiral->arg = sp_round(spiral->arg, M_PI/snaps);
+        }
+    } else { // roll/unroll
+        // arg of the spiral outer end
+        double arg_1;
+        spiral->getPolar(1, NULL, &arg_1);
+
+        // its fractional part after the whole turns are subtracted
+        double arg_r = arg_1 - sp_round(arg_1, 2.0*M_PI);
+
+        // arg of the mouse point relative to spiral center
+        double mouse_angle = atan2(dy, dx);
+        if (mouse_angle < 0)
+            mouse_angle += 2*M_PI;
+
+        // snap if ctrl
+        if ( ( state & GDK_CONTROL_MASK ) && snaps ) {
+            mouse_angle = sp_round(mouse_angle, M_PI/snaps);
+        }
+
+        // by how much we want to rotate the outer point
+        double diff = mouse_angle - arg_r;
+        if (diff > M_PI)
+            diff -= 2*M_PI;
+        else if (diff < -M_PI)
+            diff += 2*M_PI;
+
+        // calculate the new rad;
+        // the value of t corresponding to the angle arg_1 + diff:
+        double t_temp = ((arg_1 + diff) - spiral->arg)/(2*M_PI*spiral->revo);
+        // the rad at that t:
+        double rad_new = 0;
+        if (t_temp > spiral->t0)
+            spiral->getPolar(t_temp, &rad_new, NULL);
+
+        // change the revo (converting diff from radians to the number of turns)
+        spiral->revo += diff/(2*M_PI);
+        if (spiral->revo < 1e-3)
+            spiral->revo = 1e-3;
+
+        // if alt not pressed and the values are sane, change the rad
+        if (!(state & GDK_MOD1_MASK) && rad_new > 1e-3 && rad_new/spiral->rad < 2) {
+            // adjust t0 too so that the inner point stays unmoved
+            double r0;
+            spiral->getPolar(spiral->t0, &r0, NULL);
+            spiral->rad = rad_new;
+            spiral->t0 = pow(r0 / spiral->rad, 1.0/spiral->exp);
+        }
+        if (!IS_FINITE(spiral->t0)) spiral->t0 = 0.0;
+        spiral->t0 = CLAMP(spiral->t0, 0.0, 0.999);
+    }
+
+    spiral->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+void
+SpiralKnotHolderEntityCenter::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    SPSpiral *spiral = dynamic_cast<SPSpiral *>(item);
+    g_assert(spiral != NULL);
+
+    Geom::Point const s = snap_knot_position(p, state);
+
+    spiral->cx = s[Geom::X];
+    spiral->cy = s[Geom::Y];
+
+    spiral->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+Geom::Point
+SpiralKnotHolderEntityInner::knot_get() const
+{
+    SPSpiral const *spiral = dynamic_cast<SPSpiral const *>(item);
+    g_assert(spiral != NULL);
+
+    return spiral->getXY(spiral->t0);
+}
+
+Geom::Point
+SpiralKnotHolderEntityOuter::knot_get() const
+{
+    SPSpiral const *spiral = dynamic_cast<SPSpiral const *>(item);
+    g_assert(spiral != NULL);
+
+    return spiral->getXY(1.0);
+}
+
+Geom::Point
+SpiralKnotHolderEntityCenter::knot_get() const
+{
+    SPSpiral const *spiral = dynamic_cast<SPSpiral const *>(item);
+    g_assert(spiral != NULL);
+
+    return Geom::Point(spiral->cx, spiral->cy);
+}
+
+void
+SpiralKnotHolderEntityInner::knot_click(unsigned int state)
+{
+    SPSpiral *spiral = dynamic_cast<SPSpiral *>(item);
+    g_assert(spiral != NULL);
+
+    if (state & GDK_MOD1_MASK) {
+        spiral->exp = 1;
+        spiral->updateRepr();
+    } else if (state & GDK_SHIFT_MASK) {
+        spiral->t0 = 0;
+        spiral->updateRepr();
+    }
+}
+
+SpiralKnotHolder::SpiralKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler) :
+    KnotHolder(desktop, item, relhandler)
+{
+    SpiralKnotHolderEntityCenter *entity_center = new SpiralKnotHolderEntityCenter();
+    SpiralKnotHolderEntityInner *entity_inner = new SpiralKnotHolderEntityInner();
+    SpiralKnotHolderEntityOuter *entity_outer = new SpiralKnotHolderEntityOuter();
+
+    // NOTE: entity_central and entity_inner can overlap.
+    //
+    // In that case it would be a problem if the center control point was ON
+    // TOP because it would steal the mouse focus and the user would loose the
+    // ability to access the inner control point using only the mouse.
+    //
+    // However if the inner control point is ON TOP, taking focus, the
+    // situation is a lot better: the user can still move the inner control
+    // point with the mouse to regain access to the center control point.
+    //
+    // So, create entity_inner AFTER entity_center; this ensures that
+    // entity_inner gets rendered ON TOP.
+    entity_center->create(desktop, item, this, Inkscape::CTRL_TYPE_POINT,
+                          _("Drag to move the spiral"),
+                          SP_KNOT_SHAPE_CROSS);
+
+    entity_inner->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                         _("Roll/unroll the spiral from <b>inside</b>; with <b>Ctrl</b> to snap angle; "
+                           "with <b>Alt</b> to converge/diverge"));
+
+    entity_outer->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                         _("Roll/unroll the spiral from <b>outside</b>; with <b>Ctrl</b> to snap angle; "
+                           "with <b>Shift</b> to scale/rotate; with <b>Alt</b> to lock radius"));
+
+    entity.push_back(entity_center);
+    entity.push_back(entity_inner);
+    entity.push_back(entity_outer);
+
+    add_pattern_knotholder();
+}
+
+/* SPOffset */
+
+class OffsetKnotHolderEntity : public KnotHolderEntity {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+void
+OffsetKnotHolderEntity::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, unsigned int state)
+{
+    SPOffset *offset = dynamic_cast<SPOffset *>(item);
+    g_assert(offset != NULL);
+
+    Geom::Point const p_snapped = snap_knot_position(p, state);
+
+    offset->rad = sp_offset_distance_to_original(offset, p_snapped);
+    offset->knot = p_snapped;
+    offset->knotSet = true;
+
+    offset->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+
+Geom::Point
+OffsetKnotHolderEntity::knot_get() const
+{
+    SPOffset const *offset = dynamic_cast<SPOffset const *>(item);
+    g_assert(offset != NULL);
+
+    Geom::Point np;
+    sp_offset_top_point(offset,&np);
+    return np;
+}
+
+OffsetKnotHolder::OffsetKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler) :
+    KnotHolder(desktop, item, relhandler)
+{
+    OffsetKnotHolderEntity *entity_offset = new OffsetKnotHolderEntity();
+    entity_offset->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                          _("Adjust the <b>offset distance</b>"));
+    entity.push_back(entity_offset);
+
+    add_pattern_knotholder();
+}
+
+// TODO: this is derived from RectKnotHolderEntityWH because it used the same static function
+// set_internal as the latter before KnotHolderEntity was C++ified. Check whether this also makes
+// sense logically.
+class FlowtextKnotHolderEntity : public RectKnotHolderEntityWH {
+public:
+    virtual Geom::Point knot_get() const;
+    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state);
+};
+
+Geom::Point
+FlowtextKnotHolderEntity::knot_get() const
+{
+    SPRect const *rect = dynamic_cast<SPRect const *>(item);
+    g_assert(rect != NULL);
+
+    return Geom::Point(rect->x.computed + rect->width.computed, rect->y.computed + rect->height.computed);
+}
+
+void
+FlowtextKnotHolderEntity::knot_set(Geom::Point const &p, Geom::Point const &origin, unsigned int state)
+{
+    set_internal(p, origin, state);
+}
+
+FlowtextKnotHolder::FlowtextKnotHolder(SPDesktop *desktop, SPItem *item, SPKnotHolderReleasedFunc relhandler) :
+    KnotHolder(desktop, item, relhandler)
+{
+    g_assert(item != NULL);
+
+    FlowtextKnotHolderEntity *entity_flowtext = new FlowtextKnotHolderEntity();
+    entity_flowtext->create(desktop, item, this, Inkscape::CTRL_TYPE_SHAPER,
+                            _("Drag to resize the <b>flowed text frame</b>"));
+    entity.push_back(entity_flowtext);
+}
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :