Fix some transformation center regressions, related to the viewbox/units changes

(bzr r13512)

4 files changed, 28 insertions, 20 deletions

diff --git a/src/selection-chemistry.cpp b/src/selection-chemistry.cpp
index f058189d3..868a9d743 100644
--- a/src/selection-chemistry.cpp
+++ b/src/selection-chemistry.cpp
@@ -1621,13 +1621,10 @@ void sp_selection_apply_affine(Inkscape::Selection *selection, Geom::Affine cons
             item->doWriteTransform(item->getRepr(), item->transform, NULL, compensate);
         }
 
-        // if we're transforming the actual object, not just updating the repr, we can transform the
+        // if we're moving the actual object, not just updating the repr, we can transform the
         // center by the same matrix (only necessary for non-translations)
         if (set_i2d && item->isCenterSet() && !(affine.isTranslation() || affine.isIdentity())) {
-            // If there's a viewbox, we might have an affine with a translation component;
-            // we will only apply the scaling/skewing components, not the translations
-            // because otherwise the center will move relative to the item
-            item->setCenter(old_center * affine.withoutTranslation());
+            item->setCenter(old_center * affine);
             item->updateRepr();
         }
     }
diff --git a/src/sp-item-group.cpp b/src/sp-item-group.cpp
index 657aca692..bb52b0c55 100644
--- a/src/sp-item-group.cpp
+++ b/src/sp-item-group.cpp
@@ -660,12 +660,6 @@ void SPGroup::scaleChildItemsRec(Geom::Scale const &sc, Geom::Point const &p)
                         Geom::Translate const s(p);
                         Geom::Affine final = s.inverse() * sc * s;
                         
-                        Geom::Point old_center(0,0);
-                        if (item->isCenterSet()) {
-                            item->scaleCenter(sc.inverse()); // Convert the old relative center position to the new coordinates already now
-                            old_center = item->getCenter(); // because getCenter() will use the bbox midpoint, which is also already in the new coordinates
-                        }
-                        
                         gchar const *conn_type = NULL;
                         if (SP_IS_TEXT_TEXTPATH(item)) {
                             SP_TEXT(item)->optimizeTextpathText();
@@ -710,7 +704,7 @@ void SPGroup::scaleChildItemsRec(Geom::Scale const &sc, Geom::Point const &p)
                         }
                         
                         if (item->isCenterSet() && !(final.isTranslation() || final.isIdentity())) {
-                            item->setCenter(old_center * final);
+                            item->scaleCenter(sc); // All coordinates have been scaled, so also the center must be scaled
                             item->updateRepr();
                         }
                     }
diff --git a/src/sp-item.cpp b/src/sp-item.cpp
index 0cacc86b1..428f9555e 100644
--- a/src/sp-item.cpp
+++ b/src/sp-item.cpp
@@ -228,18 +228,25 @@ void SPItem::setExplicitlyHidden(bool val) {
 }
 
 /**
- * Sets the transform_center_x and transform_center_y properties to retain the rotation centre
- */
+ * Sets the transform_center_x and transform_center_y properties to retain the rotation center
+*/
 void SPItem::setCenter(Geom::Point const &object_centre) {
     document->ensureUpToDate();
 
+    // Copied from DocumentProperties::onDocUnitChange()
+    gdouble viewscale_w = this->document->getWidth().value("px") / this->document->getRoot()->viewBox.width();
+    gdouble viewscale_h = this->document->getHeight().value("px")/ this->document->getRoot()->viewBox.height();
+    gdouble viewscale = std::min(viewscale_h, viewscale_w);
+
     // FIXME this is seriously wrong
     Geom::OptRect bbox = desktopGeometricBounds();
     if (bbox) {
-        transform_center_x = object_centre[Geom::X] - bbox->midpoint()[Geom::X];
+        // object centre is document coordinates (i.e. in pixels), so we need to consider the viewbox
+        // to translate to user units; transform_center_x/y is in user units
+        transform_center_x = (object_centre[Geom::X] - bbox->midpoint()[Geom::X])/viewscale;
         if (Geom::are_near(transform_center_x, 0)) // rounding error
             transform_center_x = 0;
-        transform_center_y = object_centre[Geom::Y] - bbox->midpoint()[Geom::Y];
+        transform_center_y = (object_centre[Geom::Y] - bbox->midpoint()[Geom::Y])/viewscale;
         if (Geom::are_near(transform_center_y, 0)) // rounding error
             transform_center_y = 0;
     }
@@ -255,16 +262,25 @@ bool SPItem::isCenterSet() const {
     return (transform_center_x != 0 || transform_center_y != 0);
 }
 
+// Get the item's transformation center in document coordinates (i.e. in pixels)
 Geom::Point SPItem::getCenter() const {
     document->ensureUpToDate();
 
+    // Copied from DocumentProperties::onDocUnitChange()
+    gdouble viewscale_w = this->document->getWidth().value("px") / this->document->getRoot()->viewBox.width();
+    gdouble viewscale_h = this->document->getHeight().value("px")/ this->document->getRoot()->viewBox.height();
+    gdouble viewscale = std::min(viewscale_h, viewscale_w);
+
     // FIXME this is seriously wrong
     Geom::OptRect bbox = desktopGeometricBounds();
     if (bbox) {
-        return bbox->midpoint() + Geom::Point (transform_center_x, transform_center_y);
+        // transform_center_x/y are stored in user units, so we have to take the viewbox into account to translate to document coordinates
+        return bbox->midpoint() + Geom::Point (transform_center_x*viewscale, transform_center_y*viewscale);
+
     } else {
         return Geom::Point(0, 0); // something's wrong!
     }
+
 }
 
 void
diff --git a/src/ui/dialog/document-properties.cpp b/src/ui/dialog/document-properties.cpp
index 9141b2268..4e4616724 100644
--- a/src/ui/dialog/document-properties.cpp
+++ b/src/ui/dialog/document-properties.cpp
@@ -45,6 +45,7 @@
 #include "widgets/icon.h"
 #include "xml/node-event-vector.h"
 #include "xml/repr.h"
+#include <algorithm>    // std::min
 
 #include "rdf.h"
 #include "ui/widget/entity-entry.h"
@@ -1735,9 +1736,9 @@ void DocumentProperties::onDocUnitChange()
     prefs->setBool("/options/transform/gradient", true);
     {
         ShapeEditor::blockSetItem(true);
-        gdouble viewscale = doc->getWidth().value("px")/doc->getRoot()->viewBox.width();
-        if (doc->getHeight().value("px")/doc->getRoot()->viewBox.height() < viewscale)
-            viewscale = doc->getHeight().value("px")/doc->getRoot()->viewBox.height();
+        gdouble viewscale_w = doc->getWidth().value("px")/doc->getRoot()->viewBox.width();
+        gdouble viewscale_h = doc->getHeight().value("px")/doc->getRoot()->viewBox.height();
+        gdouble viewscale = std::min(viewscale_h, viewscale_w);
         gdouble scale = Inkscape::Util::Quantity::convert(1, old_doc_unit, doc_unit);
         doc->getRoot()->scaleChildItemsRec(Geom::Scale(scale), Geom::Point(-viewscale*doc->getRoot()->viewBox.min()[Geom::X] +
                                                                             (doc->getWidth().value("px") - viewscale*doc->getRoot()->viewBox.width())/2,