[dia] [transform] cairo renderer supports affine transformations

[Hans Breuer <hans src gnome org>]

commit ea136600bd4de80a43f4aa871b76922f7d51eddf
Author: Hans Breuer <hans breuer org>
Date:   Sun Sep 12 14:26:25 2010 +0200

    [transform] cairo renderer supports affine transformations
    
     implement CairoRenderer::draw_object() to support affine transformation

 plug-ins/cairo/diacairo-renderer.c |   19 +++++++++++++++++++
 1 files changed, 19 insertions(+), 0 deletions(-)
---
diff --git a/plug-ins/cairo/diacairo-renderer.c b/plug-ins/cairo/diacairo-renderer.c
index 7fbb786..6483a6b 100644
--- a/plug-ins/cairo/diacairo-renderer.c
+++ b/plug-ins/cairo/diacairo-renderer.c
@@ -70,6 +70,7 @@
 #include "diarenderer.h"
 #include "filter.h"
 #include "plug-ins.h"
+#include "object.h" /* only for object->ops->draw */
 
 #include "diacairo.h"
 
@@ -169,10 +170,28 @@ is_capable_to (DiaRenderer *renderer, RenderCapability cap)
     return TRUE;
   else if (RENDER_ALPHA == cap)
     return TRUE;
+  else if (RENDER_AFFINE == cap)
+    return TRUE;
   return FALSE;
 }
 
 static void
+draw_object (DiaRenderer *self, DiaObject *object, DiaMatrix *matrix)
+{
+  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);
+  cairo_matrix_t before;
+  
+  if (matrix) {
+    cairo_get_matrix (renderer->cr, &before);
+    g_assert (sizeof(cairo_matrix_t) == sizeof(DiaMatrix));
+    cairo_transform (renderer->cr, (cairo_matrix_t *)matrix);
+  }
+  object->ops->draw(object, renderer);
+  if (matrix)
+    cairo_set_matrix (renderer->cr, &before);
+}
+
+static void
 ensure_minimum_one_device_unit(DiaCairoRenderer *renderer, real *value)
 {
   double ax = 1., ay = 1.;