Merge branch 'objectchooser_preview-try2' of https://github.com/godiard/sugar-toolkit-gtk3 into godiard-objectchooser_preview-try2

src/sugar3/graphics/objectchooser.py

@@ -20,6 +20,8 @@ STABLE.
 """
 
 import logging
+import StringIO
+import cairo
 
 from gi.repository import GObject
 from gi.repository import Gtk
@@ -27,6 +29,7 @@ from gi.repository import Gdk
 import dbus
 
 from sugar3.datastore import datastore
+from sugar3.activity.activity import PREVIEW_SIZE
 
 
 J_DBUS_SERVICE = 'org.laptop.Journal'
@@ -38,9 +41,67 @@ FILTER_TYPE_GENERIC_MIME = 'generic_mime'
 FILTER_TYPE_ACTIVITY = 'activity'
 
 
+def get_preview_pixbuf(preview_data, width=-1, height=-1):
+    """Retrive a pixbuf with the content of the preview field
+
+    Keyword arguments:
+    metadata -- the metadata dictionary.
+                Can't be None, use metadata.get('preview', '')
+    width -- the pixbuf width, if is not set, the default width will be used
+    height -- the pixbuf width, if is not set, the default height will be used
+
+    Return: a Pixbuf or None if couldn't create it
+
+    """
+    if width == -1:
+        width = PREVIEW_SIZE[0]
+
+    if height == -1:
+        height = PREVIEW_SIZE[1]
+
+    pixbuf = None
+
+    if len(preview_data) > 4:
+        if preview_data[1:4] != 'PNG':
+            # TODO: We are close to be able to drop this.
+            import base64
+            preview_data = base64.b64decode(preview_data)
+
+        png_file = StringIO.StringIO(preview_data)
+        try:
+            # Load image and scale to dimensions
+            surface = cairo.ImageSurface.create_from_png(png_file)
+            png_width = surface.get_width()
+            png_height = surface.get_height()
+
+            preview_surface = cairo.ImageSurface(cairo.FORMAT_ARGB32,
+                                                 width, height)
+            cr = cairo.Context(preview_surface)
+
+            scale_w = width * 1.0 / png_width
+            scale_h = height * 1.0 / png_height
+            scale = min(scale_w, scale_h)
+
+            cr.scale(scale, scale)
+
+            cr.set_source_rgba(1, 1, 1, 0)
+            cr.set_operator(cairo.OPERATOR_SOURCE)
+            cr.paint()
+            cr.set_source_surface(surface)
+            cr.paint()
+
+            pixbuf = Gdk.pixbuf_get_from_surface(preview_surface, 0, 0,
+                                                 width, height)
+        except Exception:
+            logging.exception('Error while loading the preview')
+
+    return pixbuf
+
+
 class ObjectChooser(object):
 
-    def __init__(self, parent=None, what_filter=None, filter_type=None):
+    def __init__(self, parent=None, what_filter=None, filter_type=None,
+                 show_preview=False):
         """Initialise the ObjectChoser
 
         parent -- the widget calling ObjectChooser
@@ -74,6 +135,12 @@ class ObjectChooser(object):
             chooser will filter based on the 'mime_type' metadata
             field and the mime types defined by the activity in the
             activity.info file.
+
+        show_preview -- boolean
+
+            if True will show the preview image asociated with
+            the object in the Journal. This option is only available
+            if filter_type is selected.
         """
 
         if parent is None:
@@ -85,6 +152,7 @@ class ObjectChooser(object):
             parent_xid = parent
 
         self._parent_xid = parent_xid
+        self._show_preview = show_preview
         self._main_loop = None
         self._object_id = None
         self._bus = None
@@ -130,7 +198,8 @@ class ObjectChooser(object):
                 self._parent_xid, what_filter)
         else:
             self._chooser_id = journal.ChooseObjectWithFilter(
-                self._parent_xid, what_filter, self._filter_type)
+                self._parent_xid, what_filter, self._filter_type,
+                self._show_preview)
 
         Gdk.threads_leave()
         try: