[gimp] imagemap: clear preview area background before drawing image

[N/A <ell src gnome org>]

commit f91e2a94a7d0ab41d0c53a8eae480c35b1c11cf7
Author: Ell <ell_se yahoo com>
Date:   Tue Dec 20 13:36:27 2016 -0500

    imagemap: clear preview area background before drawing image
    
    Previously, we neither cleared the preview area's buffer, nor set
    its max size, so if the preview area was bigger than the image, the
    rest of the widget would display garbage.
    
    This is an ad-hoc-ish fix, simply filling the preview area's buffer
    with the background color prior to drawing the image.  Anything
    more sophisticated will have to wait till image maps are cool
    again, I guess :)

 plug-ins/imagemap/imap_preview.c |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)
---
diff --git a/plug-ins/imagemap/imap_preview.c b/plug-ins/imagemap/imap_preview.c
index b0dafe8..cee8c10 100644
--- a/plug-ins/imagemap/imap_preview.c
+++ b/plug-ins/imagemap/imap_preview.c
@@ -75,6 +75,25 @@ preview_get_height(GtkWidget *preview)
 }
 
 static void
+render_background(Preview_t *preview_base)
+{
+   GtkWidget      *preview = preview_base->preview;
+   GtkStyle       *style;
+   const GdkColor *bg_color;
+
+   gtk_widget_ensure_style (preview);
+
+   style    = gtk_widget_get_style (preview);
+   bg_color = &style->bg[GTK_STATE_NORMAL];
+
+   gimp_preview_area_fill (GIMP_PREVIEW_AREA (preview),
+                           0, 0, G_MAXINT, G_MAXINT,
+                           bg_color->red   >> 8,
+                           bg_color->green >> 8,
+                           bg_color->blue  >> 8);
+}
+
+static void
 render_gray_image(Preview_t *preview_base, GimpPixelRgn *srcrgn)
 {
    guchar        *src_row, *dest_buffer, *dest;
@@ -264,6 +283,8 @@ render_rgb_image(Preview_t *preview_base, GimpPixelRgn *srcrgn)
 static void
 render_preview(Preview_t *preview_base, GimpPixelRgn *srcrgn)
 {
+   render_background (preview_base);
+
    switch (gimp_drawable_type(srcrgn->drawable->drawable_id)) {
    case GIMP_RGB_IMAGE:
    case GIMP_RGBA_IMAGE: