[dia] [transform] implement SvgRenderer::draw_rotated_image()

[Hans Breuer <hans src gnome org>]

commit 1e9b426539c09a205f009a9a2e45659306dc241a
Author: Hans Breuer <hans breuer org>
Date:   Sun Nov 2 14:44:16 2014 +0100

    [transform] implement SvgRenderer::draw_rotated_image()
    
    ... by just applying a transform to the base class created image node.
    Also fix premature optimization regarding negative offsets. At least
    IE11 did not like the double minus which could result from the offset
    center position being negative already.

 plug-ins/svg/render_svg.c |   56 ++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 50 insertions(+), 6 deletions(-)
---
diff --git a/plug-ins/svg/render_svg.c b/plug-ins/svg/render_svg.c
index a026c0d..519f760 100644
--- a/plug-ins/svg/render_svg.c
+++ b/plug-ins/svg/render_svg.c
@@ -114,6 +114,9 @@ static void draw_text_line    (DiaRenderer *self, TextLine *text_line,
                               Point *pos, Alignment alignment, Color *colour);
 static void draw_text         (DiaRenderer *self, Text *text);
 static void draw_rotated_text (DiaRenderer *self, Text *text, Point *center, real angle);
+static void draw_rotated_image (DiaRenderer *self, Point *point,
+                               real width, real height,
+                               real angle, DiaImage *image);
 
 static void svg_renderer_class_init (SvgRendererClass *klass);
 
@@ -225,6 +228,7 @@ svg_renderer_class_init (SvgRendererClass *klass)
   renderer_class->draw_text  = draw_text;
   renderer_class->draw_text_line  = draw_text_line;
   renderer_class->draw_rotated_text  = draw_rotated_text;
+  renderer_class->draw_rotated_image  = draw_rotated_image;
   renderer_class->is_capable_to = is_capable_to;
 }
 
@@ -547,16 +551,20 @@ draw_rotated_text (DiaRenderer *self, Text *text, Point *center, real angle)
   /* text 'global' properties  */
   node_set_text_style(node_text, renderer, text->font, text->height, text->alignment, &text->color);
   if (angle != 0) {
-     gchar x_buf[G_ASCII_DTOSTR_BUF_SIZE];
-     gchar y_buf[G_ASCII_DTOSTR_BUF_SIZE];
+     gchar x_buf0[G_ASCII_DTOSTR_BUF_SIZE];
+     gchar y_buf0[G_ASCII_DTOSTR_BUF_SIZE];
+     gchar x_buf1[G_ASCII_DTOSTR_BUF_SIZE];
+     gchar y_buf1[G_ASCII_DTOSTR_BUF_SIZE];
      gchar *trans;
      if (center)
        pos = *center;
      g_ascii_formatd (d_buf, sizeof(d_buf), "%g", angle);
-     dia_svg_dtostr(x_buf, pos.x);
-     dia_svg_dtostr(y_buf, pos.y);
-     trans = g_strdup_printf ("translate(%s,%s) rotate(%s) translate(-%s,-%s)",
-                             x_buf, y_buf, d_buf, x_buf, y_buf);
+     dia_svg_dtostr(x_buf0, pos.x);
+     dia_svg_dtostr(y_buf0, pos.y);
+     dia_svg_dtostr(x_buf1, -pos.x);
+     dia_svg_dtostr(y_buf1, -pos.y);
+     trans = g_strdup_printf ("translate(%s,%s) rotate(%s) translate(%s,%s)",
+                             x_buf0, y_buf0, d_buf, x_buf1, y_buf1);
      xmlSetProp(node_text, (const xmlChar *)"transform", (xmlChar *) trans);
      g_free (trans);
   } else {
@@ -581,6 +589,42 @@ draw_rotated_text (DiaRenderer *self, Text *text, Point *center, real angle)
   }
 }
 
+static void
+draw_rotated_image (DiaRenderer *self,
+                   Point *point,
+                   real width, real height,
+                   real angle,
+                   DiaImage *image)
+{
+  DiaSvgRenderer *renderer = DIA_SVG_RENDERER (self);
+
+  /* delegate to base class ... */
+  DIA_RENDERER_CLASS (parent_class)->draw_image (self, point, width, height, image);
+  /* ... and modify the image node to transform */
+  if (angle != 0.0) {
+    xmlNodePtr node = xmlFirstElementChild (renderer->root);
+    gchar d_buf[G_ASCII_DTOSTR_BUF_SIZE];
+    gchar x_buf0[G_ASCII_DTOSTR_BUF_SIZE];
+    gchar y_buf0[G_ASCII_DTOSTR_BUF_SIZE];
+    gchar x_buf1[G_ASCII_DTOSTR_BUF_SIZE];
+    gchar y_buf1[G_ASCII_DTOSTR_BUF_SIZE];
+    gchar *trans;
+    Point pos = { point->x + width/2, point->y + height/2 }; /* center */
+
+    g_return_if_fail (node != NULL && xmlStrcmp (node->name, "image") == 0);
+
+    g_ascii_formatd (d_buf, sizeof(d_buf), "%g", angle);
+    dia_svg_dtostr(x_buf0, pos.x);
+    dia_svg_dtostr(y_buf0, pos.y);
+    dia_svg_dtostr(x_buf1, -pos.x);
+    dia_svg_dtostr(y_buf1, -pos.y);
+    trans = g_strdup_printf ("translate(%s,%s) rotate(%s) translate(%s,%s)",
+                            x_buf0, y_buf0, d_buf, x_buf1, y_buf1);
+    xmlSetProp(node, (const xmlChar *)"transform", (xmlChar *) trans);
+    g_free (trans);
+  }
+}
+
 /*!
  * \brief Callback function registered for export
  * \ingroup SvgExport