[dia] cgm: fix image export to CGM

[Hans Breuer <hans src gnome org>]

commit e7c29df252ccf8e625a05ede662336c90226d982
Author: Hans Breuer <hans breuer org>
Date:   Fri May 9 23:14:26 2014 +0200

    cgm: fix image export to CGM
    
    CgmRenderer::draw_image() was creating skewed images during export.
    Now it does works on the already existing pixel data (no RGB data copy)
    and creates the required alignment.

 plug-ins/cgm/cgm.c |   41 +++++++++++++++++++++++++++++------------
 1 files changed, 29 insertions(+), 12 deletions(-)
---
diff --git a/plug-ins/cgm/cgm.c b/plug-ins/cgm/cgm.c
index 1e5d566..84f43a4 100644
--- a/plug-ins/cgm/cgm.c
+++ b/plug-ins/cgm/cgm.c
@@ -1058,10 +1058,15 @@ draw_image(DiaRenderer *self,
     const gint maxlen = 32767 - 6 * REALSIZE - 4 * 2;
     double x1 = point->x, y1 = swap_y(renderer, point->y), 
            x2 = x1+width, y2 = y1-height;
-    gint rowlen = dia_image_width(image) * 3, lines = dia_image_height(image);
+    gint rowlen = dia_image_width(image) * 3;
+    gint x, y, columns = dia_image_width(image);
+    gint lines = dia_image_height(image);
     double linesize = (y1 - y2) / lines;
     gint chunk, clines;
-    guint8 *pImg, *ptr;
+    const guint8 *pixels;
+    const GdkPixbuf* pixbuf;
+    int rowstride = dia_image_rowstride(image);
+    gboolean has_alpha;
 
     if (rowlen > maxlen) {
        dia_context_add_message(renderer->ctx, 
@@ -1070,14 +1075,14 @@ draw_image(DiaRenderer *self,
        return;
     }
 
-    ptr = pImg = dia_image_rgb_data(image);
-    if (!pImg) {
-      dia_context_add_message(renderer->ctx, _("Not enough memory for image drawing."));
-      return;
-    }
+    /* don't copy the data, work on pixbuf  */
+    pixbuf = dia_image_pixbuf (image);
+    g_return_if_fail (pixbuf != NULL); /* very sick DiaImage */
+    pixels = gdk_pixbuf_get_pixels (pixbuf);
+    has_alpha = gdk_pixbuf_get_has_alpha (pixbuf);
 
     while (lines > 0) {
-       chunk = MIN(rowlen * lines, maxlen);
+       chunk = (MIN(rowlen * lines, maxlen) / 2) * 2; /* CELL ARRAY is WORD aligned */
        clines = chunk / rowlen;
        chunk = clines * rowlen;
 
@@ -1090,19 +1095,31 @@ draw_image(DiaRenderer *self,
        write_real(renderer->file, y1);
 
        /* write image size */
-       write_int16(renderer->file, dia_image_width(image));
+       write_int16(renderer->file, columns);
        write_int16(renderer->file, clines);
 
        write_int16(renderer->file, 8); /* color precision */
        write_int16(renderer->file, 1); /* packed encoding */
 
-       fwrite(ptr, sizeof(guint8), chunk, renderer->file);
+       /* fwrite(ptr, sizeof(guint8), chunk, renderer->file);
+        * ... would only work for RGB with columns%3==0 and columns%4==0
+        */
+       for (y = 0; y < clines; ++y) {
+           const guint8 *ptr = pixels + (dia_image_height(image) - lines + y) * rowstride;
+           for (x = 0; x < columns; ++x) {
+               fwrite(ptr, sizeof(guint8), 3, renderer->file);
+               if (has_alpha)
+                   ptr += 4;
+               else
+                   ptr += 3;
+           }
+           if (rowlen%2) /* padding */
+               fwrite(ptr, sizeof(guint8), 1, renderer->file);
+       }
 
        lines -= clines;
-       ptr += chunk;
        y1 -= clines * linesize;
     }
-    g_free (pImg);
 }
 
 static gboolean