moving trunk for module inkscape

(bzr r1)

1 files changed, 1074 insertions, 0 deletions

diff --git a/src/object-edit.cpp b/src/object-edit.cpp
new file mode 100644
index 000000000..3db0f0a21
--- /dev/null
+++ b/src/object-edit.cpp
@@ -0,0 +1,1074 @@
+#define __SP_OBJECT_EDIT_C__
+
+/*
+ * Node editing extension to objects
+ *
+ * Authors:
+ *   Lauris Kaplinski <lauris@kaplinski.com>
+ *   Mitsuru Oka
+ *
+ * Licensed under GNU GPL
+ */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+
+
+#include "sp-item.h"
+#include "sp-rect.h"
+#include "sp-ellipse.h"
+#include "sp-star.h"
+#include "sp-spiral.h"
+#include "sp-offset.h"
+#include "sp-flowtext.h"
+#include "prefs-utils.h"
+#include "inkscape.h"
+#include "snap.h"
+#include "desktop-affine.h"
+#include <style.h>
+#include "desktop.h"
+
+#include "sp-pattern.h"
+#include "sp-path.h"
+
+#include <glibmm/i18n.h>
+
+#include "object-edit.h"
+
+#include <libnr/nr-scale-ops.h>
+
+
+#include "xml/repr.h"
+
+#include "isnan.h"
+
+#define sp_round(v,m) (((v) < 0.0) ? ((ceil((v) / (m) - 0.5)) * (m)) : ((floor((v) / (m) + 0.5)) * (m)))
+
+static SPKnotHolder *sp_rect_knot_holder(SPItem *item, SPDesktop *desktop);
+static SPKnotHolder *sp_arc_knot_holder(SPItem *item, SPDesktop *desktop);
+static SPKnotHolder *sp_star_knot_holder(SPItem *item, SPDesktop *desktop);
+static SPKnotHolder *sp_spiral_knot_holder(SPItem *item, SPDesktop *desktop);
+static SPKnotHolder *sp_offset_knot_holder(SPItem *item, SPDesktop *desktop);
+static SPKnotHolder *sp_path_knot_holder(SPItem *item, SPDesktop *desktop);
+static SPKnotHolder *sp_flowtext_knot_holder(SPItem *item, SPDesktop *desktop);
+static void sp_pat_knot_holder(SPItem *item, SPKnotHolder *knot_holder);
+
+SPKnotHolder *
+sp_item_knot_holder(SPItem *item, SPDesktop *desktop)
+{
+    if (SP_IS_RECT(item)) {
+        return sp_rect_knot_holder(item, desktop);
+    } else if (SP_IS_ARC(item)) {
+        return sp_arc_knot_holder(item, desktop);
+    } else if (SP_IS_STAR(item)) {
+        return sp_star_knot_holder(item, desktop);
+    } else if (SP_IS_SPIRAL(item)) {
+        return sp_spiral_knot_holder(item, desktop);
+    } else if (SP_IS_OFFSET(item)) {
+        return sp_offset_knot_holder(item, desktop);
+    } else if (SP_IS_PATH(item)) {
+        return sp_path_knot_holder(item, desktop);
+    } else if (SP_IS_FLOWTEXT(item) && SP_FLOWTEXT(item)->has_internal_frame()) {
+        return sp_flowtext_knot_holder(item, desktop);
+    }
+
+    return NULL;
+}
+
+
+/* Pattern manipulation */
+
+static gdouble sp_pattern_extract_theta(SPPattern *pat, gdouble scale)
+{
+    gdouble theta = asin(pat->patternTransform[1] / scale);
+    if (pat->patternTransform[0] < 0) theta = M_PI - theta ;
+    return theta;
+}
+
+static gdouble sp_pattern_extract_scale(SPPattern *pat)
+{
+    gdouble s = pat->patternTransform[1];
+    gdouble c = pat->patternTransform[0];
+    gdouble xscale = sqrt(c * c + s * s);
+    return xscale;
+}
+
+static NR::Point sp_pattern_extract_trans(SPPattern const *pat)
+{
+    return NR::Point(pat->patternTransform[4], pat->patternTransform[5]);
+}
+
+static void
+sp_pattern_xy_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    SPPattern *pat = SP_PATTERN(SP_STYLE_FILL_SERVER(SP_OBJECT(item)->style));
+
+    NR::Point p_snapped = p;
+
+    if ( state & GDK_CONTROL_MASK ) {
+        if (fabs((p - origin)[NR::X]) > fabs((p - origin)[NR::Y])) {
+            p_snapped[NR::Y] = origin[NR::Y];
+        } else {
+            p_snapped[NR::X] = origin[NR::X];
+        }
+    }
+
+    if (state)  {
+        NR::Point const q = p_snapped - sp_pattern_extract_trans(pat);
+        sp_item_adjust_pattern(item, NR::Matrix(NR::translate(q)));
+    }
+
+    item->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+
+static NR::Point sp_pattern_xy_get(SPItem *item)
+{
+    SPPattern const *pat = SP_PATTERN(SP_STYLE_FILL_SERVER(SP_OBJECT(item)->style));
+    return sp_pattern_extract_trans(pat);
+}
+
+static NR::Point sp_pattern_angle_get(SPItem *item)
+{
+    SPPattern *pat = SP_PATTERN(SP_STYLE_FILL_SERVER(SP_OBJECT(item)->style));
+
+    gdouble x = (pattern_width(pat)*0.5);
+    gdouble y = 0;
+    NR::Point delta = NR::Point(x,y);
+    gdouble scale = sp_pattern_extract_scale(pat);
+    gdouble theta = sp_pattern_extract_theta(pat, scale);
+    delta = delta * NR::Matrix(NR::rotate(theta))*NR::Matrix(NR::scale(scale,scale));
+    delta = delta + sp_pattern_extract_trans(pat);
+    return delta;
+}
+
+static void
+sp_pattern_angle_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    int const snaps = prefs_get_int_attribute("options.rotationsnapsperpi", "value", 12);
+
+    SPPattern *pat = SP_PATTERN(SP_STYLE_FILL_SERVER(SP_OBJECT(item)->style));
+
+    // get the angle from pattern 0,0 to the cursor pos
+    NR::Point delta = p - sp_pattern_extract_trans(pat);
+    gdouble theta = atan2(delta);
+
+    if ( state & GDK_CONTROL_MASK ) {
+        theta = sp_round(theta, M_PI/snaps);
+    }
+
+    // get the scale from the current transform so we can keep it.
+    gdouble scl = sp_pattern_extract_scale(pat);
+    NR::Matrix rot =  NR::Matrix(NR::rotate(theta)) * NR::Matrix(NR::scale(scl,scl));
+    NR::Point const t = sp_pattern_extract_trans(pat);
+    rot[4] = t[NR::X];
+    rot[5] = t[NR::Y];
+    sp_item_adjust_pattern(item, rot, true);
+    item->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+static void
+sp_pattern_scale_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    SPPattern *pat = SP_PATTERN(SP_STYLE_FILL_SERVER(SP_OBJECT(item)->style));
+
+    // Get the scale from the position of the knotholder,
+    NR::Point d = p - sp_pattern_extract_trans(pat);
+    gdouble s = NR::L2(d);
+    gdouble pat_x = pattern_width(pat) * 0.5;
+    gdouble pat_y = pattern_height(pat) * 0.5;
+    gdouble pat_h = hypot(pat_x, pat_y);
+    gdouble scl = s / pat_h;
+
+    // get angle from current transform, (need get current scale first to calculate angle)
+    gdouble oldscale = sp_pattern_extract_scale(pat);
+    gdouble theta = sp_pattern_extract_theta(pat,oldscale);
+
+    NR::Matrix rot =  NR::Matrix(NR::rotate(theta)) * NR::Matrix(NR::scale(scl,scl));
+    NR::Point const t = sp_pattern_extract_trans(pat);
+    rot[4] = t[NR::X];
+    rot[5] = t[NR::Y];
+    sp_item_adjust_pattern(item, rot, true);
+    item->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+
+static NR::Point sp_pattern_scale_get(SPItem *item)
+{
+    SPPattern *pat = SP_PATTERN(SP_STYLE_FILL_SERVER(SP_OBJECT(item)->style));
+
+    gdouble x = pattern_width(pat)*0.5;
+    gdouble y = pattern_height(pat)*0.5;
+    NR::Point delta = NR::Point(x,y);
+    NR::Matrix a = pat->patternTransform;
+    a[4] = 0;
+    a[5] = 0;
+    delta = delta * a;
+    delta = delta + sp_pattern_extract_trans(pat);
+    return delta;
+}
+
+/* SPRect */
+
+static NR::Point sp_rect_rx_get(SPItem *item)
+{
+    SPRect *rect = SP_RECT(item);
+
+    return NR::Point(rect->x.computed + rect->width.computed - rect->rx.computed, rect->y.computed);
+}
+
+static void sp_rect_rx_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    SPRect *rect = SP_RECT(item);
+
+    if (state & GDK_CONTROL_MASK) {
+        gdouble temp = MIN(rect->height.computed, rect->width.computed) / 2.0;
+        rect->rx.computed = rect->ry.computed = CLAMP(rect->x.computed + rect->width.computed - p[NR::X], 0.0, temp);
+        rect->rx._set = rect->ry._set = true;
+        
+    } else {
+        rect->rx.computed = CLAMP(rect->x.computed + rect->width.computed - p[NR::X], 0.0, rect->width.computed / 2.0);
+        rect->rx._set = true;
+    }
+    
+    ((SPObject*)rect)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+
+static NR::Point sp_rect_ry_get(SPItem *item)
+{
+    SPRect *rect = SP_RECT(item);
+
+    return NR::Point(rect->x.computed + rect->width.computed, rect->y.computed + rect->ry.computed);
+}
+
+static void sp_rect_ry_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    SPRect *rect = SP_RECT(item);
+
+    if (state & GDK_CONTROL_MASK) {        
+        gdouble temp = MIN(rect->height.computed, rect->width.computed) / 2.0;
+        rect->rx.computed = rect->ry.computed = CLAMP(p[NR::Y] - rect->y.computed, 0.0, temp);
+        rect->ry._set = rect->rx._set = true;
+    } else {
+        if (!rect->rx._set || rect->rx.computed == 0) {
+            rect->ry.computed = CLAMP(p[NR::Y] - rect->y.computed,
+                                      0.0,
+                                      MIN(rect->height.computed / 2.0, rect->width.computed / 2.0));
+        } else {
+            rect->ry.computed = CLAMP(p[NR::Y] - rect->y.computed,
+                                      0.0,
+                                      rect->height.computed / 2.0);
+        }
+
+        rect->ry._set = true;
+    }
+
+    ((SPObject *)rect)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+/**
+ *  Remove rounding from a rectangle.
+ */
+static void rect_remove_rounding(SPRect *rect)
+{
+    SP_OBJECT_REPR(rect)->setAttribute("rx", NULL);
+    SP_OBJECT_REPR(rect)->setAttribute("ry", NULL);
+}
+
+/**
+ *  Called when the horizontal rounding radius knot is clicked.
+ */
+static void sp_rect_rx_knot_click(SPItem *item, guint state)
+{
+    SPRect *rect = SP_RECT(item);
+
+    if (state & GDK_SHIFT_MASK) {
+        rect_remove_rounding(rect);
+    } else if (state & GDK_CONTROL_MASK) {
+        /* Ctrl-click sets the vertical rounding to be the same as the horizontal */
+        SP_OBJECT_REPR(rect)->setAttribute("ry", SP_OBJECT_REPR(rect)->attribute("rx"));
+    }
+}
+
+/**
+ *  Called when the vertical rounding radius knot is clicked.
+ */
+static void sp_rect_ry_knot_click(SPItem *item, guint state)
+{
+    SPRect *rect = SP_RECT(item);
+
+    if (state & GDK_SHIFT_MASK) {
+        rect_remove_rounding(rect);
+    } else if (state & GDK_CONTROL_MASK) {
+        /* Ctrl-click sets the vertical rounding to be the same as the horizontal */
+        SP_OBJECT_REPR(rect)->setAttribute("rx", SP_OBJECT_REPR(rect)->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.computed = 0.5 * rect->width.computed;
+        rect->rx._set = true;
+    }
+    if (2 * rect->ry.computed > rect->height.computed) {
+        rect->ry.computed = 0.5 * rect->height.computed;
+        rect->ry._set = true;
+    }
+}
+
+static NR::Point sp_rect_wh_get(SPItem *item)
+{
+    SPRect *rect = SP_RECT(item);
+
+    return NR::Point(rect->x.computed + rect->width.computed, rect->y.computed + rect->height.computed);
+}
+
+static NR::Point rect_snap_knot_position(NR::Point const &p)
+{
+    SPDesktop const *desktop = inkscape_active_desktop();
+    NR::Point s = sp_desktop_dt2root_xy_point(desktop, p);
+    SnapManager const m(desktop->namedview);
+    s = m.freeSnap(Inkscape::Snapper::BBOX_POINT | Inkscape::Snapper::SNAP_POINT, s, NULL).getPoint();
+    return sp_desktop_root2dt_xy_point(desktop, s);
+}
+
+static void sp_rect_wh_set_internal(SPRect *rect, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    NR::Point const s = rect_snap_knot_position(p);
+
+    if (state & GDK_CONTROL_MASK) {
+        // original width/height when drag started
+        gdouble const w_orig = (origin[NR::X] - rect->x.computed);
+        gdouble const h_orig = (origin[NR::Y] - rect->y.computed);
+
+        //original ratio
+        gdouble const ratio = (w_orig / h_orig);
+
+        // mouse displacement since drag started
+        gdouble const minx = s[NR::X] - origin[NR::X];
+        gdouble const miny = s[NR::Y] - origin[NR::Y];
+
+        if (fabs(minx) > fabs(miny)) {
+
+            // snap to horizontal or diagonal
+            rect->width.computed = MAX(w_orig + minx, 0);
+            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
+                rect->height.computed = MAX(h_orig + minx / ratio, 0);
+            } else {
+                // closer to the horizontal, change only width, height is h_orig
+                rect->height.computed = MAX(h_orig, 0);
+            }
+
+        } else {
+            // snap to vertical or diagonal
+            rect->height.computed = MAX(h_orig + miny, 0);
+            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
+                rect->width.computed = MAX(w_orig + miny * ratio, 0);
+            } else {
+                // closer to the vertical, change only height, width is w_orig
+                rect->width.computed = MAX(w_orig, 0);
+            }
+        }
+
+        rect->width._set = rect->height._set = true;
+
+    } else {
+        // move freely
+        rect->width.computed = MAX(s[NR::X] - rect->x.computed, 0);
+        rect->height.computed = MAX(s[NR::Y] - rect->y.computed, 0);
+        rect->width._set = rect->height._set = true;
+    }
+
+    sp_rect_clamp_radii(rect);
+
+    ((SPObject *)rect)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+static void sp_rect_wh_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    SPRect *rect = SP_RECT(item);
+
+    sp_rect_wh_set_internal(rect, p, origin, state);
+}
+
+static NR::Point sp_rect_xy_get(SPItem *item)
+{
+    SPRect *rect = SP_RECT(item);
+
+    return NR::Point(rect->x.computed, rect->y.computed);
+}
+
+static void sp_rect_xy_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    SPRect *rect = SP_RECT(item);
+
+    // 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[NR::X];
+    gdouble h_orig = opposite_y - origin[NR::Y];
+
+    NR::Point const s = rect_snap_knot_position(p);
+
+    // mouse displacement since drag started
+    gdouble minx = s[NR::X] - origin[NR::X];
+    gdouble miny = s[NR::Y] - origin[NR::Y];
+
+    if (state & GDK_CONTROL_MASK) {
+        //original ratio
+        gdouble ratio = (w_orig / h_orig);
+
+        if (fabs(minx) > fabs(miny)) {
+
+            // snap to horizontal or diagonal
+            rect->x.computed = MIN(s[NR::X], opposite_x);
+            rect->width.computed = MAX(w_orig - minx, 0);
+            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
+                rect->y.computed = MIN(origin[NR::Y] + minx / ratio, opposite_y);
+                rect->height.computed = MAX(h_orig - minx / ratio, 0);
+            } else {
+                // closer to the horizontal, change only width, height is h_orig
+                rect->y.computed = MIN(origin[NR::Y], opposite_y);
+                rect->height.computed = MAX(h_orig, 0);
+            }
+
+        } else {
+
+            // snap to vertical or diagonal
+            rect->y.computed = MIN(s[NR::Y], opposite_y);
+            rect->height.computed = MAX(h_orig - miny, 0);
+            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
+                rect->x.computed = MIN(origin[NR::X] + miny * ratio, opposite_x);
+                rect->width.computed = MAX(w_orig - miny * ratio, 0);
+            } else {
+                // closer to the vertical, change only height, width is w_orig
+                rect->x.computed = MIN(origin[NR::X], opposite_x);
+                rect->width.computed = MAX(w_orig, 0);
+            }
+
+        }
+
+        rect->width._set = rect->height._set = rect->x._set = rect->y._set = true;
+
+    } else {
+        // move freely
+        rect->x.computed = MIN(s[NR::X], opposite_x);
+        rect->width.computed = MAX(w_orig - minx, 0);
+        rect->y.computed = MIN(s[NR::Y], opposite_y);
+        rect->height.computed = MAX(h_orig - miny, 0);
+        rect->width._set = rect->height._set = rect->x._set = rect->y._set = true;
+    }
+
+    sp_rect_clamp_radii(rect);
+
+    ((SPObject *)rect)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+static SPKnotHolder *sp_rect_knot_holder(SPItem *item, SPDesktop *desktop)
+{
+    SPKnotHolder *knot_holder = sp_knot_holder_new(desktop, item, NULL);
+
+    sp_knot_holder_add_full(
+      knot_holder, sp_rect_rx_set, sp_rect_rx_get, sp_rect_rx_knot_click,
+      SP_KNOT_SHAPE_CIRCLE, SP_KNOT_MODE_XOR,
+      _("Adjust the <b>horizontal rounding</b> radius; with <b>Ctrl</b> to make the vertical "
+        "radius the same"));
+
+    sp_knot_holder_add_full(
+      knot_holder, sp_rect_ry_set, sp_rect_ry_get, sp_rect_ry_knot_click,
+      SP_KNOT_SHAPE_CIRCLE, SP_KNOT_MODE_XOR,
+      _("Adjust the <b>vertical rounding</b> radius; with <b>Ctrl</b> to make the horizontal "
+        "radius the same")
+      );
+
+    sp_knot_holder_add_full(
+      knot_holder, sp_rect_wh_set, sp_rect_wh_get, NULL,
+      SP_KNOT_SHAPE_SQUARE, SP_KNOT_MODE_XOR,
+      _("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_holder_add_full(
+      knot_holder, sp_rect_xy_set, sp_rect_xy_get, NULL,
+      SP_KNOT_SHAPE_SQUARE, SP_KNOT_MODE_XOR,
+      _("Adjust the <b>width and height</b> of the rectangle; with <b>Ctrl</b> to lock ratio "
+        "or stretch in one dimension only")
+      );
+
+    sp_pat_knot_holder(item, knot_holder);
+    return knot_holder;
+}
+
+/* SPArc */
+
+/*
+ * return values:
+ *   1  : inside
+ *   0  : on the curves
+ *   -1 : outside
+ */
+static gint
+sp_genericellipse_side(SPGenericEllipse *ellipse, NR::Point const &p)
+{
+    gdouble dx = (p[NR::X] - ellipse->cx.computed) / ellipse->rx.computed;
+    gdouble dy = (p[NR::Y] - ellipse->cy.computed) / ellipse->ry.computed;
+
+    gdouble s = dx * dx + dy * dy;
+    if (s < 1.0) return 1;
+    if (s > 1.0) return -1;
+    return 0;
+}
+
+static void
+sp_arc_start_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    int snaps = prefs_get_int_attribute("options.rotationsnapsperpi", "value", 12);
+
+    SPGenericEllipse *ge = SP_GENERICELLIPSE(item);
+    SPArc *arc = SP_ARC(item);
+
+    ge->closed = (sp_genericellipse_side(ge, p) == -1) ? TRUE : FALSE;
+
+    NR::Point delta = p - NR::Point(ge->cx.computed, ge->cy.computed);
+    NR::scale sc(ge->rx.computed, ge->ry.computed);
+    ge->start = atan2(delta * sc.inverse());
+    if ( ( state & GDK_CONTROL_MASK )
+         && snaps )
+    {
+        ge->start = sp_round(ge->start, M_PI/snaps);
+    }
+    sp_genericellipse_normalize(ge);
+    ((SPObject *)arc)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+static NR::Point sp_arc_start_get(SPItem *item)
+{
+    SPGenericEllipse *ge = SP_GENERICELLIPSE(item);
+    SPArc *arc = SP_ARC(item);
+
+    return sp_arc_get_xy(arc, ge->start);
+}
+
+static void
+sp_arc_end_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    int snaps = prefs_get_int_attribute("options.rotationsnapsperpi", "value", 12);
+
+    SPGenericEllipse *ge = SP_GENERICELLIPSE(item);
+    SPArc *arc = SP_ARC(item);
+
+    ge->closed = (sp_genericellipse_side(ge, p) == -1) ? TRUE : FALSE;
+
+    NR::Point delta = p - NR::Point(ge->cx.computed, ge->cy.computed);
+    NR::scale sc(ge->rx.computed, ge->ry.computed);
+    ge->end = atan2(delta * sc.inverse());
+    if ( ( state & GDK_CONTROL_MASK )
+         && snaps )
+    {
+        ge->end = sp_round(ge->end, M_PI/snaps);
+    }
+    sp_genericellipse_normalize(ge);
+    ((SPObject *)arc)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+static NR::Point sp_arc_end_get(SPItem *item)
+{
+    SPGenericEllipse *ge = SP_GENERICELLIPSE(item);
+    SPArc *arc = SP_ARC(item);
+
+    return sp_arc_get_xy(arc, ge->end);
+}
+
+static void
+sp_arc_startend_click(SPItem *item, guint state)
+{
+    SPGenericEllipse *ge = SP_GENERICELLIPSE(item);
+
+    if (state & GDK_SHIFT_MASK) {
+        ge->end = ge->start = 0;
+        ((SPObject *)ge)->updateRepr();
+    }
+}
+
+
+static void
+sp_arc_rx_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    SPGenericEllipse *ge = SP_GENERICELLIPSE(item);
+    SPArc *arc = SP_ARC(item);
+
+    ge->rx.computed = fabs( ge->cx.computed - p[NR::X] );
+
+    if ( state & GDK_CONTROL_MASK ) {
+        ge->ry.computed = ge->rx.computed;
+    }
+
+    ((SPObject *)arc)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+static NR::Point sp_arc_rx_get(SPItem *item)
+{
+    SPGenericEllipse *ge = SP_GENERICELLIPSE(item);
+
+    return (NR::Point(ge->cx.computed, ge->cy.computed) -  NR::Point(ge->rx.computed, 0));
+}
+
+static void
+sp_arc_ry_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    SPGenericEllipse *ge = SP_GENERICELLIPSE(item);
+    SPArc *arc = SP_ARC(item);
+
+    ge->ry.computed = fabs( ge->cy.computed - p[NR::Y] );
+
+    if ( state & GDK_CONTROL_MASK ) {
+        ge->rx.computed = ge->ry.computed;
+    }
+
+    ((SPObject *)arc)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+static NR::Point sp_arc_ry_get(SPItem *item)
+{
+    SPGenericEllipse *ge = SP_GENERICELLIPSE(item);
+
+    return (NR::Point(ge->cx.computed, ge->cy.computed) -  NR::Point(0, ge->ry.computed));
+}
+
+static void
+sp_arc_rx_click(SPItem *item, guint state)
+{
+    SPGenericEllipse *ge = SP_GENERICELLIPSE(item);
+
+    if (state & GDK_CONTROL_MASK) {
+        ge->ry.computed = ge->rx.computed;
+        ((SPObject *)ge)->updateRepr();
+    }
+}
+
+static void
+sp_arc_ry_click(SPItem *item, guint state)
+{
+    SPGenericEllipse *ge = SP_GENERICELLIPSE(item);
+
+    if (state & GDK_CONTROL_MASK) {
+        ge->rx.computed = ge->ry.computed;
+        ((SPObject *)ge)->updateRepr();
+    }
+}
+
+static SPKnotHolder *
+sp_arc_knot_holder(SPItem *item, SPDesktop *desktop)
+{
+    SPKnotHolder *knot_holder = sp_knot_holder_new(desktop, item, NULL);
+
+    sp_knot_holder_add_full(knot_holder, sp_arc_rx_set, sp_arc_rx_get, sp_arc_rx_click,
+                            SP_KNOT_SHAPE_SQUARE, SP_KNOT_MODE_XOR,
+                            _("Adjust ellipse <b>width</b>, with <b>Ctrl</b> to make circle"));
+    sp_knot_holder_add_full(knot_holder, sp_arc_ry_set, sp_arc_ry_get, sp_arc_ry_click,
+                            SP_KNOT_SHAPE_SQUARE, SP_KNOT_MODE_XOR,
+                            _("Adjust ellipse <b>height</b>, with <b>Ctrl</b> to make circle"));
+    sp_knot_holder_add_full(knot_holder, sp_arc_start_set, sp_arc_start_get, sp_arc_startend_click,
+                            SP_KNOT_SHAPE_CIRCLE, SP_KNOT_MODE_XOR,
+                            _("Position the <b>start point</b> of the arc or segment; with <b>Ctrl</b> to snap angle; drag <b>inside</b> the ellipse for arc, <b>outside</b> for segment"));
+    sp_knot_holder_add_full(knot_holder, sp_arc_end_set, sp_arc_end_get, sp_arc_startend_click,
+                            SP_KNOT_SHAPE_CIRCLE, SP_KNOT_MODE_XOR,
+                            _("Position the <b>end point</b> of the arc or segment; with <b>Ctrl</b> to snap angle; drag <b>inside</b> the ellipse for arc, <b>outside</b> for segment"));
+
+    sp_pat_knot_holder(item, knot_holder);
+
+    return knot_holder;
+}
+
+/* SPStar */
+
+static void
+sp_star_knot1_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    SPStar *star = SP_STAR(item);
+
+    NR::Point d = p - 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;
+    }
+    ((SPObject *)star)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+static void
+sp_star_knot2_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    SPStar *star = SP_STAR(item);
+    if (star->flatsided == false) {
+        NR::Point d = p - 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);
+        }
+        ((SPObject *)star)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+    }
+}
+
+static NR::Point sp_star_knot1_get(SPItem *item)
+{
+    g_assert(item != NULL);
+
+    SPStar *star = SP_STAR(item);
+
+    return sp_star_get_xy(star, SP_STAR_POINT_KNOT1, 0);
+
+}
+
+static NR::Point sp_star_knot2_get(SPItem *item)
+{
+    g_assert(item != NULL);
+
+    SPStar *star = SP_STAR(item);
+
+    return sp_star_get_xy(star, SP_STAR_POINT_KNOT2, 0);
+}
+
+static void
+sp_star_knot_click(SPItem *item, guint state)
+{
+    SPStar *star = SP_STAR(item);
+
+    if (state & GDK_MOD1_MASK) {
+        star->randomized = 0;
+        ((SPObject *)star)->updateRepr();
+    } else if (state & GDK_SHIFT_MASK) {
+        star->rounded = 0;
+        ((SPObject *)star)->updateRepr();
+    } else if (state & GDK_CONTROL_MASK) {
+        star->arg[1] = star->arg[0] + M_PI / star->sides;
+        ((SPObject *)star)->updateRepr();
+    }
+}
+
+static SPKnotHolder *
+sp_star_knot_holder(SPItem *item, SPDesktop *desktop)
+{
+    /* we don't need to get parent knot_holder */
+    SPKnotHolder *knot_holder = sp_knot_holder_new(desktop, item, NULL);
+    g_assert(item != NULL);
+
+    SPStar *star = SP_STAR(item);
+
+    sp_knot_holder_add(knot_holder, sp_star_knot1_set, sp_star_knot1_get, sp_star_knot_click,
+                       _("Adjust the <b>tip radius</b> of the star or polygon; with <b>Shift</b> to round; with <b>Alt</b> to randomize"));
+    if (star->flatsided == false)
+        sp_knot_holder_add(knot_holder, sp_star_knot2_set, sp_star_knot2_get, sp_star_knot_click,
+                           _("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"));
+
+    sp_pat_knot_holder(item, knot_holder);
+
+    return knot_holder;
+}
+
+/* SPSpiral */
+
+/*
+ * 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
+ */
+static void
+sp_spiral_inner_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    int snaps = prefs_get_int_attribute("options.rotationsnapsperpi", "value", 12);
+
+    SPSpiral *spiral = SP_SPIRAL(item);
+
+    gdouble   dx = p[NR::X] - spiral->cx;
+    gdouble   dy = p[NR::Y] - spiral->cy;
+
+    if (state & GDK_MOD1_MASK) {
+        // adjust divergence by vertical drag, relative to rad
+        double new_exp = (spiral->rad + dy)/(spiral->rad);
+        spiral->exp = new_exp > 0? new_exp : 0;
+    } else {
+        // roll/unroll from inside
+        gdouble   arg_t0;
+        sp_spiral_get_polar(spiral, 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);
+    }
+
+    ((SPObject *)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
+ */
+static void
+sp_spiral_outer_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    int snaps = prefs_get_int_attribute("options.rotationsnapsperpi", "value", 12);
+
+    SPSpiral *spiral = SP_SPIRAL(item);
+
+    gdouble  dx = p[NR::X] - spiral->cx;
+    gdouble  dy = p[NR::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;
+        sp_spiral_get_polar(spiral, 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)
+            sp_spiral_get_polar(spiral, 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;
+            sp_spiral_get_polar(spiral, spiral->t0, &r0, NULL);
+            spiral->rad = rad_new;
+            spiral->t0 = pow(r0 / spiral->rad, 1.0/spiral->exp);
+        }
+        if (!isFinite(spiral->t0)) spiral->t0 = 0.0;
+        spiral->t0 = CLAMP(spiral->t0, 0.0, 0.999);
+    }
+
+    ((SPObject *)spiral)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+static NR::Point sp_spiral_inner_get(SPItem *item)
+{
+    SPSpiral *spiral = SP_SPIRAL(item);
+
+    return sp_spiral_get_xy(spiral, spiral->t0);
+}
+
+static NR::Point sp_spiral_outer_get(SPItem *item)
+{
+    SPSpiral *spiral = SP_SPIRAL(item);
+
+    return sp_spiral_get_xy(spiral, 1.0);
+}
+
+static void
+sp_spiral_inner_click(SPItem *item, guint state)
+{
+    SPSpiral *spiral = SP_SPIRAL(item);
+
+    if (state & GDK_MOD1_MASK) {
+        spiral->exp = 1;
+        ((SPObject *)spiral)->updateRepr();
+    } else if (state & GDK_SHIFT_MASK) {
+        spiral->t0 = 0;
+        ((SPObject *)spiral)->updateRepr();
+    }
+}
+
+static SPKnotHolder *
+sp_spiral_knot_holder(SPItem *item, SPDesktop *desktop)
+{
+    SPKnotHolder *knot_holder = sp_knot_holder_new(desktop, item, NULL);
+
+    sp_knot_holder_add(knot_holder, sp_spiral_inner_set, sp_spiral_inner_get, sp_spiral_inner_click,
+                       _("Roll/unroll the spiral from <b>inside</b>; with <b>Ctrl</b> to snap angle; with <b>Alt</b> to converge/diverge"));
+    sp_knot_holder_add(knot_holder, sp_spiral_outer_set, sp_spiral_outer_get, NULL,
+                       _("Roll/unroll the spiral from <b>outside</b>; with <b>Ctrl</b> to snap angle; with <b>Shift</b> to scale/rotate"));
+
+    sp_pat_knot_holder(item, knot_holder);
+
+    return knot_holder;
+}
+
+/* SPOffset */
+
+static void
+sp_offset_offset_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    SPOffset *offset = SP_OFFSET(item);
+
+    offset->rad = sp_offset_distance_to_original(offset, p);
+    offset->knot = p;
+    offset->knotSet = true;
+
+    ((SPObject *)offset)->requestDisplayUpdate(SP_OBJECT_MODIFIED_FLAG);
+}
+
+
+static NR::Point sp_offset_offset_get(SPItem *item)
+{
+    SPOffset *offset = SP_OFFSET(item);
+
+    NR::Point np;
+    sp_offset_top_point(offset,&np);
+    return np;
+}
+
+static SPKnotHolder *
+sp_offset_knot_holder(SPItem *item, SPDesktop *desktop)
+{
+    SPKnotHolder *knot_holder = sp_knot_holder_new(desktop, item, NULL);
+
+    sp_knot_holder_add(knot_holder, sp_offset_offset_set, sp_offset_offset_get, NULL,
+                       _("Adjust the <b>offset distance</b>"));
+
+    sp_pat_knot_holder(item, knot_holder);
+
+    return knot_holder;
+}
+
+static SPKnotHolder *
+sp_path_knot_holder(SPItem *item, SPDesktop *desktop) // FIXME: eliminate, instead make a pattern-drag similar to gradient-drag
+{
+    if ((SP_OBJECT(item)->style->fill.type == SP_PAINT_TYPE_PAINTSERVER)
+        && SP_IS_PATTERN(SP_STYLE_FILL_SERVER(SP_OBJECT(item)->style)))
+    {
+        SPKnotHolder *knot_holder = sp_knot_holder_new(desktop, item, NULL);
+
+        sp_pat_knot_holder(item, knot_holder);
+
+        return knot_holder;
+    }
+    return NULL;
+}
+
+static void
+sp_pat_knot_holder(SPItem *item, SPKnotHolder *knot_holder)
+{
+    if ((SP_OBJECT(item)->style->fill.type == SP_PAINT_TYPE_PAINTSERVER)
+        && SP_IS_PATTERN(SP_STYLE_FILL_SERVER(SP_OBJECT(item)->style)))
+    {
+        sp_knot_holder_add_full(knot_holder, sp_pattern_xy_set, sp_pattern_xy_get, NULL, SP_KNOT_SHAPE_CROSS, SP_KNOT_MODE_XOR,
+                                // TRANSLATORS: This refers to the pattern that's inside the object
+                                _("<b>Move</b> the pattern fill inside the object"));
+        sp_knot_holder_add_full(knot_holder, sp_pattern_scale_set, sp_pattern_scale_get, NULL, SP_KNOT_SHAPE_SQUARE, SP_KNOT_MODE_XOR,
+                                _("<b>Scale</b> the pattern fill uniformly"));
+        sp_knot_holder_add_full(knot_holder, sp_pattern_angle_set, sp_pattern_angle_get, NULL, SP_KNOT_SHAPE_CIRCLE, SP_KNOT_MODE_XOR,
+                                _("<b>Rotate</b> the pattern fill; with <b>Ctrl</b> to snap angle"));
+    }
+}
+
+static NR::Point sp_flowtext_corner_get(SPItem *item)
+{
+    SPRect *rect = SP_RECT(item);
+
+    return NR::Point(rect->x.computed + rect->width.computed, rect->y.computed + rect->height.computed);
+}
+
+static void
+sp_flowtext_corner_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state)
+{
+    SPRect *rect = SP_RECT(item);
+
+    sp_rect_wh_set_internal(rect, p, origin, state);
+}
+
+static SPKnotHolder *
+sp_flowtext_knot_holder(SPItem *item, SPDesktop *desktop)
+{
+    SPKnotHolder *knot_holder = sp_knot_holder_new(desktop, SP_FLOWTEXT(item)->get_frame(NULL), NULL);
+
+    sp_knot_holder_add(knot_holder, sp_flowtext_corner_set, sp_flowtext_corner_get, NULL,
+                       _("Drag to resize the <b>flowed text frame</b>"));
+
+    return knot_holder;
+}
+
+
+/*
+  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:encoding=utf-8:textwidth=99 :