Deprecate mate_desktop_thumbnail_scale_down_pixbuf()

As scaling down by huge factors is now fixed in gdk-pixbuf. Require the
newer gdk-pixbuf as well, to avoid running into a pre-fix version.

https://bugzilla.gnome.org/show_bug.cgi?id=775991

origin commit:
https://gitlab.gnome.org/GNOME/gnome-desktop/commit/cb64228

3 files changed, 18 insertions, 122 deletions

diff --git a/configure.ac b/configure.ac
index 5e17d20..9bc5c2d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -98,7 +98,7 @@ else
         EXTERNAL_PNP_IDS="$with_pnp_ids_path"
 fi
 
-GDK_PIXBUF_REQUIRED=2.36.1
+GDK_PIXBUF_REQUIRED=2.36.5
 GLIB_REQUIRED=2.50.0
 GIO_REQUIRED=2.26.0
 GTK_REQUIRED=3.22.0
diff --git a/libmate-desktop/mate-desktop-thumbnail.h b/libmate-desktop/mate-desktop-thumbnail.h
index 1decb4a..9f26dab 100644
--- a/libmate-desktop/mate-desktop-thumbnail.h
+++ b/libmate-desktop/mate-desktop-thumbnail.h
@@ -101,6 +101,13 @@ char *     mate_desktop_thumbnail_path_for_uri      (const char         *uri,
 
 /* Pixbuf utils */
 
+#ifndef __GTK_DOC_IGNORE__
+#define MATE_DESKTOP_DEPRECATED_IN_1_24_FOR(f) G_DEPRECATED_FOR(f) extern
+#else
+#define MATE_DESKTOP_DEPRECATED_IN_1_24_FOR(f) extern
+#endif
+
+MATE_DESKTOP_DEPRECATED_IN_1_24_FOR(gdk_pixbuf_scale_simple)
 GdkPixbuf *mate_desktop_thumbnail_scale_down_pixbuf (GdkPixbuf          *pixbuf,
 						      int                 dest_width,
 						      int                 dest_height);
diff --git a/libmate-desktop/mate-thumbnail-pixbuf-utils.c b/libmate-desktop/mate-thumbnail-pixbuf-utils.c
index d005913..ee00655 100644
--- a/libmate-desktop/mate-thumbnail-pixbuf-utils.c
+++ b/libmate-desktop/mate-thumbnail-pixbuf-utils.c
@@ -39,8 +39,11 @@
  * @dest_height: the desired new height
  *
  * Scales the pixbuf to the desired size. This function
- * is a lot faster than gdk-pixbuf when scaling down by
- * large amounts.
+ * used to be a lot faster than gdk-pixbuf when scaling
+ * down by large amounts. This is not true anymore since
+ * gdk-pixbuf UNRELEASED. You should use
+ * gdk_pixbuf_scale_simple() instead, which this function
+ * now does internally.
  *
  * Return value: (transfer full): a scaled pixbuf
  *
@@ -51,126 +54,12 @@ mate_desktop_thumbnail_scale_down_pixbuf (GdkPixbuf *pixbuf,
 					   int dest_width,
 					   int dest_height)
 {
-	int source_width, source_height;
-	int s_x1, s_y1, s_x2, s_y2;
-	int s_xfrac, s_yfrac;
-	int dx, dx_frac, dy, dy_frac;
-	div_t ddx, ddy;
-	int x, y;
-	int r, g, b, a;
-	int n_pixels;
-	gboolean has_alpha;
-	guchar *dest, *src, *xsrc, *src_pixels;
-	GdkPixbuf *dest_pixbuf;
-	int pixel_stride;
-	int source_rowstride, dest_rowstride;
+	g_return_val_if_fail (GDK_IS_PIXBUF (pixbuf), NULL);
+	g_return_val_if_fail (gdk_pixbuf_get_width (pixbuf) >= dest_width, NULL);
+	g_return_val_if_fail (gdk_pixbuf_get_height (pixbuf) >= dest_height, NULL);
 
-	if (dest_width == 0 || dest_height == 0) {
+	if (dest_width == 0 || dest_height == 0)
 		return NULL;
-	}
 
-	source_width = gdk_pixbuf_get_width (pixbuf);
-	source_height = gdk_pixbuf_get_height (pixbuf);
-
-	g_assert (source_width >= dest_width);
-	g_assert (source_height >= dest_height);
-
-	ddx = div (source_width, dest_width);
-	dx = ddx.quot;
-	dx_frac = ddx.rem;
-
-	ddy = div (source_height, dest_height);
-	dy = ddy.quot;
-	dy_frac = ddy.rem;
-
-	has_alpha = gdk_pixbuf_get_has_alpha (pixbuf);
-	source_rowstride = gdk_pixbuf_get_rowstride (pixbuf);
-	src_pixels = gdk_pixbuf_get_pixels (pixbuf);
-
-	dest_pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, has_alpha, 8,
-				      dest_width, dest_height);
-	dest = gdk_pixbuf_get_pixels (dest_pixbuf);
-	dest_rowstride = gdk_pixbuf_get_rowstride (dest_pixbuf);
-
-	pixel_stride = (has_alpha)?4:3;
-
-	s_y1 = 0;
-	s_yfrac = -dest_height/2;
-	while (s_y1 < source_height) {
-		s_y2 = s_y1 + dy;
-		s_yfrac += dy_frac;
-		if (s_yfrac > 0) {
-			s_y2++;
-			s_yfrac -= dest_height;
-		}
-
-		s_x1 = 0;
-		s_xfrac = -dest_width/2;
-		while (s_x1 < source_width) {
-			s_x2 = s_x1 + dx;
-			s_xfrac += dx_frac;
-			if (s_xfrac > 0) {
-				s_x2++;
-				s_xfrac -= dest_width;
-			}
-
-			/* Average block of [x1,x2[ x [y1,y2[ and store in dest */
-			r = g = b = a = 0;
-			n_pixels = 0;
-
-			src = src_pixels + s_y1 * source_rowstride + s_x1 * pixel_stride;
-			for (y = s_y1; y < s_y2; y++) {
-				xsrc = src;
-				if (has_alpha) {
-					for (x = 0; x < s_x2-s_x1; x++) {
-						n_pixels++;
-
-						r += xsrc[3] * xsrc[0];
-						g += xsrc[3] * xsrc[1];
-						b += xsrc[3] * xsrc[2];
-						a += xsrc[3];
-						xsrc += 4;
-					}
-				} else {
-					for (x = 0; x < s_x2-s_x1; x++) {
-						n_pixels++;
-						r += *xsrc++;
-						g += *xsrc++;
-						b += *xsrc++;
-					}
-				}
-				src += source_rowstride;
-			}
-
-			if (has_alpha) {
-				if (a != 0) {
-					*dest++ = r / a;
-					*dest++ = g / a;
-					*dest++ = b / a;
-					*dest++ = a / n_pixels;
-				} else {
-					*dest++ = 0;
-					*dest++ = 0;
-					*dest++ = 0;
-					*dest++ = 0;
-				}
-			} else {
-				if (n_pixels != 0) {
-					*dest++ = r / n_pixels;
-					*dest++ = g / n_pixels;
-					*dest++ = b / n_pixels;
-				} else {
-					*dest++ = 0;
-					*dest++ = 0;
-					*dest++ = 0;
-				}
-			}
-
-			s_x1 = s_x2;
-		}
-		s_y1 = s_y2;
-		dest += dest_rowstride - dest_width * pixel_stride;
-	}
-
-	return dest_pixbuf;
+	return gdk_pixbuf_scale_simple (pixbuf, dest_width, dest_height, GDK_INTERP_HYPER);
 }