Add gdk-pixbuf as a libpurple dependency and move helpers from pidgin to purple

Adding gdk-pixbuf as a dependency to libpurple is kind of questionable, but it's dependencies are really just libpng, libjpeg, and libtiff. In other words, nothing UI specific. Which means we can remove a bunch of API with this change which is awesome.

This is the first step in replacing `PurpleImage` with `GdkPixbuf`. Which will also eventually include `PurpleBuddyIcon` and remove the need for `PurpleBuddyIconSpec` as protocol plugins will just be able to scale and format images themselves.

* Move `pidgingdkpixbuf.[ch]` to `purplegdkpixbuf.[ch]`
* Renamed all function from `purplegdkpixbuf.[ch]` to be in the purple_gdk_pixbuf namespace
* Removed all unused function from `purplegdkpixbuf.[ch]`

I also did some research on how much disk space adding gdkpixbuf would add.

The base is a base debian container and this is against libpurple2 which is obviously going to be different. But the question was how much additional disk space will be used by adding gdkpixbuf.

```
base:                       157680
bitlbee:                    216452
bitlbee+gdkpixbuf:          222388
bitlbee-purple *:           363860
bitlbee-purple+gdkpixbuf *: 369796

* --no-install-recommends
```

We can see that for gdkpixbuf will about about 6MB of of disk usage which I would hope would be acceptable when libpurple adds 141MB by itself.

Testing Done:
Ran and verified that an animated buddy icon was still displayed properly in the infopane and the buddy list.

Reviewed at https://reviews.imfreedom.org/r/1224/

1 files changed, 235 insertions, 0 deletions

diff --git a/libpurple/purplegdkpixbuf.c b/libpurple/purplegdkpixbuf.c
new file mode 100644
index 0000000000..570563df11
--- /dev/null
+++ b/libpurple/purplegdkpixbuf.c
@@ -0,0 +1,235 @@
+/*
+ * Purple - Internet Messaging Library
+ * Copyright (C) Pidgin Developers <devel@pidgin.im>
+ *
+ * Purple is the legal property of its developers, whose names are too numerous
+ * to list here.  Please refer to the COPYRIGHT file distributed with this
+ * source distribution.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "libpurple/purplegdkpixbuf.h"
+
+#include "debug.h"
+
+void purple_gdk_pixbuf_make_round(GdkPixbuf *pixbuf) {
+	gint width, height, rowstride;
+	guchar *pixels;
+
+	if (!gdk_pixbuf_get_has_alpha(pixbuf)) {
+		return;
+	}
+
+	width = gdk_pixbuf_get_width(pixbuf);
+	height = gdk_pixbuf_get_height(pixbuf);
+	rowstride = gdk_pixbuf_get_rowstride(pixbuf);
+	pixels = gdk_pixbuf_get_pixels(pixbuf);
+
+	if (width < 6 || height < 6) {
+		return;
+	}
+
+	/* The following code will convert the alpha of the pixel data in all
+	 * corners to look something like the following diagram.
+	 *
+	 * 00 80 c0 FF FF c0 80 00
+	 * 80 FF FF FF FF FF FF 80
+	 * c0 FF FF FF FF FF FF c0
+	 * FF FF FF FF FF FF FF FF
+	 * FF FF FF FF FF FF FF FF
+	 * c0 FF FF FF FF FF FF c0
+	 * 80 FF FF FF FF FF FF 80
+	 * 00 80 c0 FF FF c0 80 00
+	 */
+
+	/* Top left */
+	pixels[3] = 0;
+	pixels[7] = 0x80;
+	pixels[11] = 0xC0;
+	pixels[rowstride + 3] = 0x80;
+	pixels[rowstride * 2 + 3] = 0xC0;
+
+	/* Top right */
+	pixels[width * 4 - 1] = 0;
+	pixels[width * 4 - 5] = 0x80;
+	pixels[width * 4 - 9] = 0xC0;
+	pixels[rowstride + (width * 4) - 1] = 0x80;
+	pixels[(2 * rowstride) + (width * 4) - 1] = 0xC0;
+
+	/* Bottom left */
+	pixels[(height - 1) * rowstride + 3] = 0;
+	pixels[(height - 1) * rowstride + 7] = 0x80;
+	pixels[(height - 1) * rowstride + 11] = 0xC0;
+	pixels[(height - 2) * rowstride + 3] = 0x80;
+	pixels[(height - 3) * rowstride + 3] = 0xC0;
+
+	/* Bottom right */
+	pixels[height * rowstride - 1] = 0;
+	pixels[(height - 1) * rowstride - 1] = 0x80;
+	pixels[(height - 2) * rowstride - 1] = 0xC0;
+	pixels[height * rowstride - 5] = 0x80;
+	pixels[height * rowstride - 9] = 0xC0;
+}
+
+gboolean
+purple_gdk_pixbuf_is_opaque(GdkPixbuf *pixbuf) {
+	gint height, rowstride, i;
+	guchar *pixels;
+	guchar *row;
+
+	if (!gdk_pixbuf_get_has_alpha(pixbuf)) {
+		return TRUE;
+	}
+
+	height = gdk_pixbuf_get_height (pixbuf);
+	rowstride = gdk_pixbuf_get_rowstride (pixbuf);
+	pixels = gdk_pixbuf_get_pixels (pixbuf);
+
+	/* check the top row */
+	row = pixels;
+	for (i = 3; i < rowstride; i+=4) {
+		if (row[i] < 0xfe) {
+			return FALSE;
+		}
+	}
+
+	/* check the left and right sides */
+	for (i = 1; i < height - 1; i++) {
+		row = pixels + (i * rowstride);
+		if (row[3] < 0xfe || row[rowstride - 1] < 0xfe) {
+			return FALSE;
+		}
+	}
+
+	/* check the bottom */
+	row = pixels + ((height - 1) * rowstride);
+	for (i = 3; i < rowstride; i += 4) {
+		if (row[i] < 0xfe) {
+			return FALSE;
+		}
+	}
+
+	return TRUE;
+}
+
+static GObject *purple_gdk_pixbuf_from_data_helper(const guchar *buf, gsize count, gboolean animated)
+{
+	GObject *pixbuf;
+	GdkPixbufLoader *loader;
+	GError *error = NULL;
+
+	loader = gdk_pixbuf_loader_new();
+
+	if (!gdk_pixbuf_loader_write(loader, buf, count, &error) || error) {
+		purple_debug_warning("gtkutils", "gdk_pixbuf_loader_write() "
+				"failed with size=%" G_GSIZE_FORMAT ": %s\n", count,
+				error ? error->message : "(no error message)");
+		if (error)
+			g_error_free(error);
+		g_object_unref(G_OBJECT(loader));
+		return NULL;
+	}
+
+	if (!gdk_pixbuf_loader_close(loader, &error) || error) {
+		purple_debug_warning("gtkutils", "gdk_pixbuf_loader_close() "
+				"failed for image of size %" G_GSIZE_FORMAT ": %s\n", count,
+				error ? error->message : "(no error message)");
+		if (error)
+			g_error_free(error);
+		g_object_unref(G_OBJECT(loader));
+		return NULL;
+	}
+
+	if (animated)
+		pixbuf = G_OBJECT(gdk_pixbuf_loader_get_animation(loader));
+	else
+		pixbuf = G_OBJECT(gdk_pixbuf_loader_get_pixbuf(loader));
+	if (!pixbuf) {
+		purple_debug_warning("gtkutils", "%s() returned NULL for image "
+				"of size %" G_GSIZE_FORMAT "\n",
+				animated ? "gdk_pixbuf_loader_get_animation"
+					: "gdk_pixbuf_loader_get_pixbuf", count);
+		g_object_unref(G_OBJECT(loader));
+		return NULL;
+	}
+
+	g_object_ref(pixbuf);
+	g_object_unref(G_OBJECT(loader));
+
+	return pixbuf;
+}
+
+GdkPixbuf *purple_gdk_pixbuf_from_data(const guchar *buf, gsize count)
+{
+	return GDK_PIXBUF(purple_gdk_pixbuf_from_data_helper(buf, count, FALSE));
+}
+
+GdkPixbuf *
+purple_gdk_pixbuf_from_image(PurpleImage *image)
+{
+	return purple_gdk_pixbuf_from_data(purple_image_get_data(image),
+		purple_image_get_data_size(image));
+}
+
+GdkPixbuf *purple_gdk_pixbuf_new_from_file(const gchar *filename)
+{
+	GdkPixbuf *pixbuf;
+	GError *error = NULL;
+
+	g_return_val_if_fail(filename != NULL, NULL);
+	g_return_val_if_fail(filename[0] != '\0', NULL);
+
+	pixbuf = gdk_pixbuf_new_from_file(filename, &error);
+	if (!pixbuf || error) {
+		purple_debug_warning("gtkutils", "gdk_pixbuf_new_from_file() "
+				"returned %s for file %s: %s\n",
+				pixbuf ? "something" : "nothing",
+				filename,
+				error ? error->message : "(no error message)");
+		if (error)
+			g_error_free(error);
+		if (pixbuf)
+			g_object_unref(G_OBJECT(pixbuf));
+		return NULL;
+	}
+
+	return pixbuf;
+}
+
+GdkPixbuf *purple_gdk_pixbuf_new_from_file_at_size(const char *filename, int width, int height)
+{
+	GdkPixbuf *pixbuf;
+	GError *error = NULL;
+
+	g_return_val_if_fail(filename != NULL, NULL);
+	g_return_val_if_fail(filename[0] != '\0', NULL);
+
+	pixbuf = gdk_pixbuf_new_from_file_at_size(filename,
+			width, height, &error);
+	if (!pixbuf || error) {
+		purple_debug_warning("gtkutils", "gdk_pixbuf_new_from_file_at_size() "
+				"returned %s for file %s: %s\n",
+				pixbuf ? "something" : "nothing",
+				filename,
+				error ? error->message : "(no error message)");
+		if (error)
+			g_error_free(error);
+		if (pixbuf)
+			g_object_unref(G_OBJECT(pixbuf));
+		return NULL;
+	}
+
+	return pixbuf;
+}