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Let QPaintEvent tell us what region to repaint. #8951

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Merged
merged 1 commit into from
Jul 20, 2018
Merged

Let QPaintEvent tell us what region to repaint. #8951

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2 changes: 2 additions & 0 deletions lib/matplotlib/backends/backend_qt5.py
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Original file line number Diff line number Diff line change
Expand Up @@ -241,6 +241,7 @@ def __init__(self, figure):
self._dpi_ratio_prev = None

self._draw_pending = False
self._erase_before_paint = False
self._is_drawing = False
self._draw_rect_callback = lambda painter: None

Expand Down Expand Up @@ -494,6 +495,7 @@ def draw(self):
return
with cbook._setattr_cm(self, _is_drawing=True):
super().draw()
self._erase_before_paint = True
self.update()

def draw_idle(self):
Expand Down
54 changes: 25 additions & 29 deletions lib/matplotlib/backends/backend_qt5agg.py
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Original file line number Diff line number Diff line change
Expand Up @@ -15,11 +15,7 @@

class FigureCanvasQTAgg(FigureCanvasAgg, FigureCanvasQT):

def __init__(self, figure):
super().__init__(figure=figure)
self._bbox_queue = []

def paintEvent(self, e):
def paintEvent(self, event):
"""Copy the image from the Agg canvas to the qt.drawable.

In Qt, all drawing should be done inside of here when a widget is
Expand All @@ -37,29 +33,31 @@ def paintEvent(self, e):

painter = QtGui.QPainter(self)

if self._bbox_queue:
bbox_queue = self._bbox_queue
else:
if self._erase_before_paint:
painter.eraseRect(self.rect())
bbox_queue = [
Bbox([[0, 0], [self.renderer.width, self.renderer.height]])]
self._bbox_queue = []
for bbox in bbox_queue:
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One concern is that Qt drops some paint events, but that would be surprising.

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If Qt pulls the rug under us, we're cooked anyways, no?

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)
# Adjust the buf reference count to work around a memory leak bug
# in QImage under PySide on Python 3.
if QT_API == 'PySide':
ctypes.c_long.from_address(id(buf)).value = 1
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)
self._erase_before_paint = False

rect = event.rect()
left = rect.left()
top = rect.top()
width = rect.width()
height = rect.height()
# See documentation of QRect: bottom() and right() are off by 1, so use
# left() + width() and top() + height().
bbox = Bbox([[left, self.renderer.height - (top + height)],
[left + width, self.renderer.height - top]])
reg = self.copy_from_bbox(bbox)
buf = reg.to_string_argb()
qimage = QtGui.QImage(buf, width, height, QtGui.QImage.Format_ARGB32)
if hasattr(qimage, 'setDevicePixelRatio'):
# Not available on Qt4 or some older Qt5.
qimage.setDevicePixelRatio(self._dpi_ratio)
origin = QtCore.QPoint(left, top)
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':
ctypes.c_long.from_address(id(buf)).value = 1

self._draw_rect_callback(painter)

Expand All @@ -73,8 +71,6 @@ def blit(self, bbox=None):
if bbox is None and self.figure:
bbox = self.figure.bbox

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]
t = b + h
Expand Down
3 changes: 3 additions & 0 deletions lib/matplotlib/backends/backend_qt5cairo.py
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,9 @@ def paintEvent(self, event):
# Not available on Qt4 or some older Qt5.
qimage.setDevicePixelRatio(dpi_ratio)
painter = QtGui.QPainter(self)
if self._erase_before_paint:
painter.eraseRect(self.rect())
self._erase_before_paint = False
painter.drawImage(0, 0, qimage)
self._draw_rect_callback(painter)
painter.end()
Expand Down