[pitivi] Save resources by only drawing the visible thumbs

[Jean-François Fortin Tam <jfft src gnome org>]

commit aa64ac94b0cffa4aa1756d7d619f2ea248f42956
Author: Daniel Thul <daniel thul gmail com>
Date:   Wed Apr 17 19:03:01 2013 +0200

    Save resources by only drawing the visible thumbs

 pitivi/timeline/previewers.py |   59 ++++++++++++----------------------------
 1 files changed, 18 insertions(+), 41 deletions(-)
---
diff --git a/pitivi/timeline/previewers.py b/pitivi/timeline/previewers.py
index 275bcbb..ea6a3f0 100644
--- a/pitivi/timeline/previewers.py
+++ b/pitivi/timeline/previewers.py
@@ -61,18 +61,20 @@ class VideoPreviewer(Clutter.ScrollActor, Zoomable):
 
         self.callback_id = None
 
+        self.counter = 0
+
     # Internal API
 
     def _scroll_changed(self, unused):
-        self._updateWishlist()
+        self._update()
 
     def start_changed(self, unused_bElement, unused_value):
-        self._updateWishlist()
+        self._update()
 
     def _update(self, unused_msg_source=None):
         if self.callback_id:
             GLib.source_remove(self.callback_id)
-        self.callback_id = GLib.idle_add(self._addAllThumbnails, priority=GLib.PRIORITY_LOW)
+        self.callback_id = GLib.idle_add(self._addVisibleThumbnails, priority=GLib.PRIORITY_LOW)
 
     def _setupPipeline(self):
         """
@@ -155,9 +157,10 @@ class VideoPreviewer(Clutter.ScrollActor, Zoomable):
             Gst.SeekType.SET, time,
             Gst.SeekType.NONE, -1)
 
-    def _addAllThumbnails(self):
+    def _addVisibleThumbnails(self):
         self.remove_all_children()
         self.thumbs = {}
+        self.wishlist = []
 
         thumb_duration_tmp = Zoomable.pixelToNs(self.thumb_width + self.thumb_margin)
 
@@ -171,8 +174,12 @@ class VideoPreviewer(Clutter.ScrollActor, Zoomable):
         # make sure that we don't show thumbnails more often than thumb_period
         thumb_duration = max(thumb_duration, self.thumb_period)
 
-        current_time = 0
-        while current_time < self.duration:
+        element_left, element_right = self._get_visible_range()
+        # TODO: replace with a call to utils.misc.quantize:
+        element_left = (element_left // thumb_duration) * thumb_duration
+
+        current_time = element_left
+        while current_time < element_right:
             thumb = Thumbnail(self.thumb_width, self.thumb_height)
             thumb.set_position(Zoomable.nsToPixel(current_time), self.thumb_margin)
             self.add_child(thumb)
@@ -180,47 +187,17 @@ class VideoPreviewer(Clutter.ScrollActor, Zoomable):
             if current_time in self.thumb_cache:
                 gdkpixbuf = self.thumb_cache[current_time]
                 self.thumbs[current_time].set_from_gdkpixbuf(gdkpixbuf)
+            else:
+                self.wishlist.append(current_time)
             current_time += thumb_duration
-
-        self._updateWishlist()
+        self.counter += 1
+        print(self.counter)
 
     def _inpoint_changed_cb(self, unused_bElement, unused_value):
         position = Clutter.Point()
         position.x = Zoomable.nsToPixel(self.bElement.props.in_point)
         self.scroll_to_point(position)
-        self._updateWishlist()
-
-    def _updateWishlist(self):
-        """
-        Adds thumbnails for the whole clip.
-
-        Takes the zoom setting into account and removes potentially
-        existing thumbnails prior to adding the new ones.
-        """
-        self.wishlist = []
-
-        # calculate unquantized length of a thumb in nano seconds
-        thumb_duration_tmp = Zoomable.pixelToNs(self.thumb_width + self.thumb_margin)
-
-        # quantize thumb length to thumb_period
-        # TODO: replace with a call to utils.misc.quantize:
-        thumb_duration = (thumb_duration_tmp // self.thumb_period) * self.thumb_period
-        # make sure that the thumb duration after the quantization isn't smaller than before
-        if thumb_duration < thumb_duration_tmp:
-            thumb_duration += self.thumb_period
-
-        # make sure that we don't show thumbnails more often than thumb_period
-        thumb_duration = max(thumb_duration, self.thumb_period)
-
-        element_left, element_right = self._get_visible_range()
-        # TODO: replace with a call to utils.misc.quantize:
-        element_left = (element_left // thumb_duration) * thumb_duration
-
-        current_time = element_left
-        while current_time < element_right:
-            if current_time not in self.thumb_cache:
-                self.wishlist.append(current_time)
-            current_time += thumb_duration
+        self._update()
 
     def _get_wish(self):
         """Returns a wish that is also in the queue or None