"""

Render to qt from agg.

"""

import ctypes

from matplotlib.transforms import Bbox

from .qt_compat import QT_API, QtCore, QtGui

from .backend_agg import FigureCanvasAgg

from .backend_qt import _BackendQT, FigureCanvasQT

from .backend_qt import ( # noqa: F401 # pylint: disable=W0611

FigureManagerQT, NavigationToolbar2QT)

class FigureCanvasQTAgg(FigureCanvasAgg, FigureCanvasQT):

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.

"""

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.device_pixel_ratio

height = rect.height() * self.device_pixel_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]])

buf = memoryview(self.copy_from_bbox(bbox))

if QT_API == "PyQt6":

from PyQt6 import sip

ptr = int(sip.voidptr(buf))

else:

ptr = buf

painter.eraseRect(rect) # clear the widget canvas

qimage = QtGui.QImage(ptr, buf.shape[1], buf.shape[0],

QtGui.QImage.Format.Format_RGBA8888)

qimage.setDevicePixelRatio(self.device_pixel_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.

if QT_API == "PySide2" and QtCore.__version_info__ < (5, 12):

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)

# In some cases, Qt will itself trigger a paint event after closing the file

# save dialog. When that happens, we need to be sure that the internal canvas is

# re-drawn. However, if the user is using an automatically-chosen Qt backend but

# saving with a different backend (such as pgf), we do not want to trigger a

# full draw in Qt, so just set the flag for next time.

self._draw_pending = True

@_BackendQT.export

class _BackendQTAgg(_BackendQT):

FigureCanvas = FigureCanvasQTAgg