Qt: On draw(), request a full repaint.

anntzer · anntzer · commit c2af4f2e9506 · 2017-07-27T22:32:35.000-07:00
(instead of just updating the blitboxes.)
diff --git a/lib/matplotlib/backends/backend_qt5agg.py b/lib/matplotlib/backends/backend_qt5agg.py
@@ -7,6 +7,7 @@
 import six
 
 import ctypes
+from threading import Lock
 import traceback
 
 from matplotlib import cbook
@@ -34,9 +35,14 @@ class FigureCanvasQTAggBase(FigureCanvasAgg):
     def __init__(self, figure):
         super(FigureCanvasQTAggBase, self).__init__(figure=figure)
         self.setAttribute(QtCore.Qt.WA_OpaquePaintEvent)
+        self._drawRect = None
         self._agg_draw_pending = False
+        # A list of Bboxes that will be repainted in the next paintEvent.  As a
+        # special case, an entry set to None requests the canvas to be fully
+        # erased.
         self._bbox_queue = []
-        self._drawRect = None
+        # A mutex to protect all changes to _bbox_queue.
+        self._bbox_queue_lock = Lock()
 
     def drawRectangle(self, rect):
         if rect is not None:
@@ -48,7 +54,7 @@ def drawRectangle(self, rect):
     @property
     @cbook.deprecated("2.1")
     def blitbox(self):
-        return self._bbox_queue
+        return [bbox for bbox in self._bbox_queue if bbox is not None]
 
     def paintEvent(self, e):
         """Copy the image from the Agg canvas to the qt.drawable.
@@ -62,30 +68,30 @@ def paintEvent(self, e):
             return
 
         painter = QtGui.QPainter(self)
-
-        if self._bbox_queue:
+        with self._bbox_queue_lock:
             bbox_queue = self._bbox_queue
-        else:
-            painter.eraseRect(self.rect())
-            bbox_queue = [
-                Bbox([[0, 0], [self.renderer.width, self.renderer.height]])]
+            self._bbox_queue = []
+
         self._bbox_queue = []
         for bbox in bbox_queue:
-            l, b, r, t = map(int, bbox.extents)
-            w = r - l
-            h = t - b
-            reg = self.copy_from_bbox(bbox)
-            buf = reg.to_string_argb()
-            qimage = QtGui.QImage(buf, w, h, QtGui.QImage.Format_ARGB32)
-            if hasattr(qimage, 'setDevicePixelRatio'):
-                # Not available on Qt4 or some older Qt5.
-                qimage.setDevicePixelRatio(self._dpi_ratio)
-            origin = QtCore.QPoint(l, self.renderer.height - t)
-            painter.drawImage(origin / self._dpi_ratio, qimage)
-            # Adjust the buf reference count to work around a memory
-            # leak bug in QImage under PySide on Python 3.
-            if QT_API == 'PySide' and six.PY3:
-                ctypes.c_long.from_address(id(buf)).value = 1
+            if bbox is None:
+                painter.eraseRect(self.rect())
+            else:
+                l, b, r, t = map(int, bbox.extents)
+                w = r - l
+                h = t - b
+                reg = self.copy_from_bbox(bbox)
+                buf = reg.to_string_argb()
+                qimage = QtGui.QImage(buf, w, h, QtGui.QImage.Format_ARGB32)
+                if hasattr(qimage, 'setDevicePixelRatio'):
+                    # Not available on Qt4 or some older Qt5.
+                    qimage.setDevicePixelRatio(self._dpi_ratio)
+                origin = QtCore.QPoint(l, self.renderer.height - t)
+                painter.drawImage(origin / self._dpi_ratio, qimage)
+                # Adjust the buf reference count to work around a memory
+                # leak bug in QImage under PySide on Python 3.
+                if QT_API == 'PySide' and six.PY3:
+                    ctypes.c_long.from_address(id(buf)).value = 1
 
         # draw the zoom rectangle to the QPainter
         if self._drawRect is not None:
@@ -103,6 +109,11 @@ def draw(self):
         # The Agg draw is done here; delaying causes problems with code that
         # uses the result of the draw() to update plot elements.
         super(FigureCanvasQTAggBase, self).draw()
+        with self._bbox_queue_lock:
+            # Erase the canvas and repaint everything.
+            self._bbox_queue = [
+                None,
+                Bbox([[0, 0], [self.renderer.width, self.renderer.height]])]
         self.update()
 
     def draw_idle(self):
@@ -137,7 +148,8 @@ def blit(self, bbox=None):
         if bbox is None and self.figure:
             bbox = self.figure.bbox
 
-        self._bbox_queue.append(bbox)
+        with self._bbox_queue_lock:
+            self._bbox_queue.append(bbox)
 
         # repaint uses logical pixels, not physical pixels like the renderer.
         l, b, w, h = [pt / self._dpi_ratio for pt in bbox.bounds]
