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Preserve tick pen#2828

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j9ac9k merged 3 commits intopyqtgraph:masterfrom
NilsNemitz:preserve_tick_pen
Oct 4, 2023
Merged

Preserve tick pen#2828
j9ac9k merged 3 commits intopyqtgraph:masterfrom
NilsNemitz:preserve_tick_pen

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@NilsNemitz
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@NilsNemitz NilsNemitz commented Sep 24, 2023

The current handling of tickPen in AxisItem doesn't work for QPens that have more complex brush settings, such as gradients: When the opacity is adjusted for different tick levels (major, minor and extra ticks), resetting the color causes the applied brush settings to be lost.

As a work-around, we can skip the opacity adjustment for any QPen that has a more complex brush setting than Qt.SolidPattern. This lets the ticks be drawn according to the original pen's brush settings, although without the opacity adjustments. This opens up some new drawing options.

While modifying the code, we can also move reconstructing the QPen outside the inner per-tick loop, because it only needs to be done once for major ticks, minor ticks, and extra ticks (if present).

We can also make sure that we are working with copies of QPens and QColors; The current code created problems in earlier PR #1625 by modifying the opacity of the original color.

Here's some code to look at the change:

import numpy as np
import pyqtgraph.pyqtgraph as pg

app = pg.mkQApp("Axes gradient color demo")
y = np.random.normal(size=30)
win = pg.GraphicsLayoutWidget(show=True, title="axes demo")
win.resize(500,500)

p1 = win.addPlot(title="Plain axes", y=y, row=0, col=0)
p1.showAxes(True)
for axis_name in ('top', 'right', 'bottom', 'left'):
    ax = p1.getAxis(axis_name)
    pen = ax.tickPen()
    pen.setWidth(3)
    ax.setTickPen(pen)
    ax.setPen(pen)

p2 = win.addPlot(title="Brushed axes", y=y, row=1, col=0 )
p2.showAxes(True)

cm = pg.colormap.get('CET-L17')
axL = p2.getAxis('left')
penL = cm.getPen( span=(0, axL.rect().height()), width=3, orientation='vertical' )
axL.setTickPen(penL)
axL.setPen(penL)

axT = p2.getAxis('top')
penT = cm.getPen( span=(0.0, axT.rect().width()), width=3, orientation='horizontal' )
axT.setTickPen(penT)
axT.setPen(penT)

axR = p2.getAxis('right')
cm.reverse()
penR = cm.getPen( span=(0.0, axR.rect().height()), width=3, orientation='vertical' )
axR.setTickPen(penR)
axR.setPen(penR)

axB = p2.getAxis('bottom')
penB = cm.getPen( span=(0.0, axB.rect().width()), width=3, orientation='horizontal' )
axB.setTickPen(penB)
axB.setPen(penB)

if __name__ == '__main__':
    pg.exec()

Current code:
gradient axes current

Revised code:
gradient axes update

I'll admit that the use case for this is severly limited. :)

@j9ac9k
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j9ac9k commented Oct 4, 2023

Thanks @NilsNemitz I'm glad you mentioned the other PR as I was reading this, I kept thinking that we saw this being an issue elsewhere.

PR LGTM, merging!

@j9ac9k j9ac9k merged commit c73e50e into pyqtgraph:master Oct 4, 2023
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@NilsNemitz @j9ac9k