Replace rectangle based zooming by affine based zooming.

This allows a rotation to be included in the drawing to window mapping.
General code cleanup.
Added documentation.
Any change to zooming behavior is probably a bug.

(bzr r15592)

3 files changed, 12 insertions, 4 deletions

diff --git a/src/display/canvas-grid.cpp b/src/display/canvas-grid.cpp
index cf7d04555..2dadde336 100644
--- a/src/display/canvas-grid.cpp
+++ b/src/display/canvas-grid.cpp
@@ -841,7 +841,9 @@ void
 CanvasXYGrid::Update (Geom::Affine const &affine, unsigned int /*flags*/)
 {
     ow = origin * affine;
-    sw = spacing * affine;
+    // Temp hack to insure grid doesn't collapse with rotation.
+    sw[0] = spacing[0] * sqrt(affine[0]*affine[0] + affine[1]*affine[1]);
+    sw[1] = spacing[1] * sqrt(affine[2]*affine[2] + affine[3]*affine[3]);
     sw -= Geom::Point(affine[4], affine[5]);
 
     for(int dim = 0; dim < 2; dim++) {
diff --git a/src/display/sp-canvas.cpp b/src/display/sp-canvas.cpp
index 9cc9e51a2..61602e880 100644
--- a/src/display/sp-canvas.cpp
+++ b/src/display/sp-canvas.cpp
@@ -1937,10 +1937,16 @@ double start_angle = 0;
 bool started = false;
 bool rotated = false;
 
-void SPCanvas::scrollTo(double cx, double cy, unsigned int clear, bool is_scrolling)
+/**
+ * Scroll screen to point 'c'. 'c' is measured in screen pixels.
+ */
+void SPCanvas::scrollTo( Geom::Point const &c, unsigned int clear, bool is_scrolling)
 {
     GtkAllocation allocation;
 
+    double cx = c[Geom::X];
+    double cy = c[Geom::Y];
+
     int ix = (int) round(cx); // ix and iy are the new canvas coordinates (integer screen pixels)
     int iy = (int) round(cy); // cx might be negative, so (int)(cx + 0.5) will not do!
     int dx = ix - _x0; // dx and dy specify the displacement (scroll) of the
diff --git a/src/display/sp-canvas.h b/src/display/sp-canvas.h
index 21b6760f2..708653bdf 100644
--- a/src/display/sp-canvas.h
+++ b/src/display/sp-canvas.h
@@ -70,8 +70,8 @@ GType sp_canvas_get_type() G_GNUC_CONST;
  * Port of GnomeCanvas for inkscape needs.
  */
 struct SPCanvas {
-    /// Scrolls canvas to specific position (cx and cy are measured in screen pixels).
-    void scrollTo(double cx, double cy, unsigned int clear, bool is_scrolling = false);
+    /// Scrolls canvas to specific position (c is measured in screen pixels).
+    void scrollTo(Geom::Point const &c, unsigned int clear, bool is_scrolling = false);
     void startRotateTo(double angle);
     void rotateTo(double angle);
     bool endRotateTo();