From 7e31cfa6371d18d9f1de02919644a7c26f6b141b Mon Sep 17 00:00:00 2001
From: Manuel Quiñones <manuq@laptop.org>
Date: Thu, 11 Apr 2013 17:28:25 +0000
Subject: Get back preview in downloaded images - SL #1106

This patch from Gonzalo for gtk2 was the main reference:
http://bugs.sugarlabs.org/attachment/ticket/1106/0001-Fix-1106-No-preview-in-Journal-for-downloaded-image.patch

Also borrows from sugar3.activity.Activity.get_preview to make the
preview with cairo.  And uses GdkPixbuf to load any GdkPixbuf
supported format.

Signed-off-by: Manuel Quiñones <manuq@laptop.org>
---
diff --git a/downloadmanager.py b/downloadmanager.py
index 9e630ff..b2a4c35 100644
--- a/downloadmanager.py
+++ b/downloadmanager.py
@@ -20,9 +20,13 @@ import logging
 from gettext import gettext as _
 import tempfile
 import dbus
+import cairo
+import StringIO
 
 from gi.repository import Gtk
+from gi.repository import Gdk
 from gi.repository import WebKit
+from gi.repository import GdkPixbuf
 
 from sugar3.datastore import datastore
 from sugar3 import profile
@@ -186,6 +190,13 @@ class Download(object):
             sniffed_mime_type = mime.get_for_file(self._dest_path)
             self.dl_jobject.metadata['mime_type'] = sniffed_mime_type
 
+            if sniffed_mime_type in ('image/bmp','image/gif','image/jpeg',
+                                     'image/png','image/tiff'):
+                preview = self._get_preview()
+                if preview is not None:
+                    self.dl_jobject.metadata['preview'] = \
+                        dbus.ByteArray(preview)
+
             datastore.write(self.dl_jobject,
                             transfer_ownership=True,
                             reply_handler=self.__internal_save_cb,
@@ -299,6 +310,39 @@ class Download(object):
             'Deleted', self.__datastore_deleted_cb,
             arg0=self.dl_jobject.object_id)
 
+    def _get_preview(self):
+        # This code borrows from sugar3.activity.Activity.get_preview
+        # to make the preview with cairo, and also uses GdkPixbuf to
+        # load any GdkPixbuf supported format.
+        pixbuf = GdkPixbuf.Pixbuf.new_from_file(self._dest_path)
+        image_width = pixbuf.get_width()
+        image_height = pixbuf.get_height()
+
+        preview_width, preview_height = activity.PREVIEW_SIZE
+        preview_surface = cairo.ImageSurface(cairo.FORMAT_ARGB32,
+                                             preview_width, preview_height)
+        cr = cairo.Context(preview_surface)
+
+        scale_w = preview_width * 1.0 / image_width
+        scale_h = preview_height * 1.0 / image_height
+        scale = min(scale_w, scale_h)
+
+        translate_x = int((preview_width - (image_width * scale)) / 2)
+        translate_y = int((preview_height - (image_height * scale)) / 2)
+
+        cr.translate(translate_x, translate_y)
+        cr.scale(scale, scale)
+
+        cr.set_source_rgba(1, 1, 1, 0)
+        cr.set_operator(cairo.OPERATOR_SOURCE)
+        cr.paint()
+        Gdk.cairo_set_source_pixbuf(cr, pixbuf, 0, 0)
+        cr.paint()
+
+        preview_str = StringIO.StringIO()
+        preview_surface.write_to_png(preview_str)
+        return preview_str.getvalue()
+
     def __datastore_deleted_cb(self, uid):
         logging.debug('Downloaded entry has been deleted' \
                           ' from the datastore: %r', uid)
--
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