[dia] pstricks: fix PstricksRenderer::draw_image() to not skew the image

[Hans Breuer <hans src gnome org>]

commit d75573aa879dffcd2bceac084ff7c39aa3cb7fbe
Author: Hans Breuer <hans breuer org>
Date:   Fri May 2 17:32:14 2014 +0200

    pstricks: fix PstricksRenderer::draw_image() to not skew the image

 plug-ins/pstricks/render_pstricks.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/plug-ins/pstricks/render_pstricks.c b/plug-ins/pstricks/render_pstricks.c
index 455912f..b85cb3b 100644
--- a/plug-ins/pstricks/render_pstricks.c
+++ b/plug-ins/pstricks/render_pstricks.c
@@ -822,9 +822,9 @@ draw_image(DiaRenderer *self,
        fprintf(renderer->file, "{currentfile pix readhexstring pop}\n");
        fprintf(renderer->file, "false 3 colorimage\n");
        /*    fprintf(renderer->file, "\n"); */
-       ptr = rgb_data;
-       for (y = 0; y < img_width; y++) {
-           for (x = 0; x < img_height; x++) {
+       for (y = 0; y < img_height; y++) {
+           ptr = rgb_data + y * dia_image_rowstride(image);
+           for (x = 0; x < img_width; x++) {
                fprintf(renderer->file, "%02x", (int)(*ptr++));
                fprintf(renderer->file, "%02x", (int)(*ptr++));
                fprintf(renderer->file, "%02x", (int)(*ptr++));