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Merge pull request #1377 from ixjlyons/issue-1353-imageitem-autodownsample

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Consolidate and fix downsample factor computation in ImageItem
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Ogi Moore 2020-09-22 20:18:03 -07:00 committed by GitHub
commit e2dc21e2ca
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1 changed files with 20 additions and 22 deletions
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42
pyqtgraph/graphicsItems/ImageItem.py
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@ -1,3 +1,4 @@
# -*- coding: utf-8 -*-
from __future__ import division
from ..Qt import QtGui, QtCore
@ -370,22 +371,11 @@ class ImageItem(GraphicsObject):
lut = None
if self.autoDownsample:
# reduce dimensions of image based on screen resolution
o = self.mapToDevice(QtCore.QPointF(0,0))
x = self.mapToDevice(QtCore.QPointF(1,0))
y = self.mapToDevice(QtCore.QPointF(0,1))
# Check if graphics view is too small to render anything
if o is None or x is None or y is None:
return
w = Point(x-o).length()
h = Point(y-o).length()
if w == 0 or h == 0:
xds, yds = self._computeDownsampleFactors()
if xds is None:
self.qimage = None
return
xds = max(1, int(1.0 / w))
yds = max(1, int(1.0 / h))
axes = [1, 0] if self.axisOrder == 'row-major' else [0, 1]
image = fn.downsample(self.image, xds, axis=axes[0])
image = fn.downsample(image, yds, axis=axes[1])
@ -552,20 +542,28 @@ class ImageItem(GraphicsObject):
def viewTransformChanged(self):
if self.autoDownsample:
o = self.mapToDevice(QtCore.QPointF(0,0))
x = self.mapToDevice(QtCore.QPointF(1,0))
y = self.mapToDevice(QtCore.QPointF(0,1))
w = Point(x-o).length()
h = Point(y-o).length()
if w == 0 or h == 0:
xds, yds = self._computeDownsampleFactors()
if xds is None:
self.qimage = None
return
xds = max(1, int(1.0 / w))
yds = max(1, int(1.0 / h))
if (xds, yds) != self._lastDownsample:
self.qimage = None
self.update()
def _computeDownsampleFactors(self):
# reduce dimensions of image based on screen resolution
o = self.mapToDevice(QtCore.QPointF(0, 0))
x = self.mapToDevice(QtCore.QPointF(1, 0))
y = self.mapToDevice(QtCore.QPointF(0, 1))
# scene may not be available yet
if o is None:
return None, None
w = Point(x - o).length()
h = Point(y - o).length()
if w == 0 or h == 0:
return None, None
return max(1, int(1.0 / w)), max(1, int(1.0 / h))
def mouseDragEvent(self, ev):
if ev.button() != QtCore.Qt.LeftButton:
ev.ignore()