backend_qt5agg.py
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"""
Render to qt from agg.
"""
import ctypes
from matplotlib.transforms import Bbox
from .. import cbook
from .backend_agg import FigureCanvasAgg
from .backend_qt5 import (
QtCore, QtGui, QtWidgets, _BackendQT5, FigureCanvasQT, FigureManagerQT,
NavigationToolbar2QT, backend_version)
from .qt_compat import QT_API, _setDevicePixelRatioF
class FigureCanvasQTAgg(FigureCanvasAgg, FigureCanvasQT):
def __init__(self, figure):
# Must pass 'figure' as kwarg to Qt base class.
super().__init__(figure=figure)
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
shown onscreen.
"""
if self._update_dpi():
# The dpi update triggered its own paintEvent.
return
self._draw_idle() # Only does something if a draw is pending.
# If the canvas does not have a renderer, then give up and wait for
# FigureCanvasAgg.draw(self) to be called.
if not hasattr(self, 'renderer'):
return
painter = QtGui.QPainter(self)
try:
# See documentation of QRect: bottom() and right() are off
# by 1, so use left() + width() and top() + height().
rect = event.rect()
# scale rect dimensions using the screen dpi ratio to get
# correct values for the Figure coordinates (rather than
# QT5's coords)
width = rect.width() * self._dpi_ratio
height = rect.height() * self._dpi_ratio
left, top = self.mouseEventCoords(rect.topLeft())
# shift the "top" by the height of the image to get the
# correct corner for our coordinate system
bottom = top - height
# same with the right side of the image
right = left + width
# create a buffer using the image bounding box
bbox = Bbox([[left, bottom], [right, top]])
reg = self.copy_from_bbox(bbox)
buf = cbook._unmultiplied_rgba8888_to_premultiplied_argb32(
memoryview(reg))
# clear the widget canvas
painter.eraseRect(rect)
qimage = QtGui.QImage(buf, buf.shape[1], buf.shape[0],
QtGui.QImage.Format_ARGB32_Premultiplied)
_setDevicePixelRatioF(qimage, self._dpi_ratio)
# set origin using original QT coordinates
origin = QtCore.QPoint(rect.left(), rect.top())
painter.drawImage(origin, qimage)
# Adjust the buf reference count to work around a memory
# leak bug in QImage under PySide on Python 3.
if QT_API in ('PySide', 'PySide2'):
ctypes.c_long.from_address(id(buf)).value = 1
self._draw_rect_callback(painter)
finally:
painter.end()
def print_figure(self, *args, **kwargs):
super().print_figure(*args, **kwargs)
self.draw()
@_BackendQT5.export
class _BackendQT5Agg(_BackendQT5):
FigureCanvas = FigureCanvasQTAgg