BTW, I have written a GraphicsItem, which is basically a "removal" write of
the HistogramLUTItem -- just the Histogram removed, including the ticks (by
setting their size to zero) and without an axis shown.
I dubbed it GradientItem, but it might be better slightly mended to include
the missing elements mentioned. So, here's the code;
"""
Extension to GraphicsWidget displaying a gradient editor, afaiu
"""
import pyqtgraph as pg
from pyqtgraph.Qt import QtGui, QtCore
import pyqtgraph.functions as fn
from pyqtgraph import GraphicsWidget
from pyqtgraph.graphicsItems.ViewBox import *
from pyqtgraph.graphicsItems.GradientEditorItem import *
from pyqtgraph.graphicsItems.AxisItem import *
from pyqtgraph.graphicsItems.GridItem import *
import pyqtgraph.functions as fn
import numpy as np
pg.graphicsItems.GradientEditorItem.Gradients['inverted'] = {'ticks': [(0.0,
(255, 255, 255, 255)), (1.0, (0, 0, 0, 255)),], 'mode': 'rgb'}
pg.graphicsItems.GradientEditorItem.Gradients['highContrast'] = {'ticks': [(
0.0, (0, 0, 0, 255)), (1.0, (255, 255, 0, 255)),], 'mode': 'rgb'}
class GradientItem(GraphicsWidget):
"""
This is a blatant copy/rewrite of the HistogramLUTItem.
Instead of a histogram and stuff it only provides a
Gradient editor to define color lookup table for single-channel images.
In addition, it can set different predefined gradients by function.
"""
sigLookupTableChanged = QtCore.Signal(object)
sigLevelsChanged = QtCore.Signal(object)
sigLevelChangeFinished = QtCore.Signal(object)
def __init__(self, image=None, fillHistogram=True):
"""
If *image* (ImageItem) is provided, then the control will be
automatically linked to the image and changes to the control will be
immediately reflected in the image's appearance.
"""
GraphicsWidget.__init__(self)
self.lut = None
self.imageItem = None
self.layout = QtGui.QGraphicsGridLayout()
self.setLayout(self.layout)
self.layout.setContentsMargins(1,1,1,1)
self.layout.setSpacing(0)
self.vb = ViewBox()
self.vb.setMaximumWidth(152)
self.vb.setMinimumWidth(45)
self.vb.setMouseEnabled(x=False, y=False)
self.gradient = GradientEditorItem()
self.gradient.tickSize = 0 # CR: this is sooooo bad, but there is
no function !?
self.gradient.setOrientation('right')
self.gradient.loadPreset('highContrast')
self.layout.addItem(self.gradient, 0, 0)
self.range = None
self.gradient.setFlag(self.gradient.ItemStacksBehindParent)
self.vb.setFlag(self.gradient.ItemStacksBehindParent)
self.gradient.sigGradientChanged.connect(self.gradientChanged)
if image is not None:
self.setImageItem(image)
def paint(self, p, *args):
pass
def setImageItem(self, img):
self.imageItem = img
img.setLookupTable(self.getLookupTable) ## send function pointer,
not the result
def gradientChanged(self):
if self.imageItem is not None:
if self.gradient.isLookupTrivial():
self.imageItem.setLookupTable(None)
else:
self.imageItem.setLookupTable(self.getLookupTable) ## send
function pointer, not the result
self.lut = None
self.sigLookupTableChanged.emit(self)
def getLookupTable(self, img=None, n=None, alpha=None):
if n is None:
if img.dtype == np.uint8:
n = 256
else:
n = 512
if self.lut is None:
self.lut = self.gradient.getLookupTable(n, alpha=alpha)
return self.lut
def setGradientByName(self, name="highContrast"):
if name in pg.graphicsItems.GradientEditorItem.Gradients:
self.gradient.loadPreset(name)
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