[graphics/krita] plugins/filters/colorsfilters: Fix color adjustment curve input controls on open

Git commit a0ffe0dcc3bb923925c59aa0db8e6c3648f49e09 by Dmitry Kazakov, on behalf of Moritz Staudinger.
Committed on 27/07/2026 at 13:56.
Pushed by dkazakov into branch 'master'.

Fix color adjustment curve input controls on open

setActiveChannel() does nothing if the reset channel is
the same as the current one, so we should resync explicitly.

Fixes #117

M  +7    -2    plugins/filters/colorsfilters/kis_multichannel_filter_base.cpp
M  +1    -0    plugins/filters/colorsfilters/kis_multichannel_filter_base.h

https://invent.kde.org/graphics/krita/-/commit/a0ffe0dcc3bb923925c59aa0db8e6c3648f49e09

diff --git a/plugins/filters/colorsfilters/kis_multichannel_filter_base.cpp b/plugins/filters/colorsfilters/kis_multichannel_filter_base.cpp
index 29020ef2045..d967b5608b3 100644
--- a/plugins/filters/colorsfilters/kis_multichannel_filter_base.cpp
+++ b/plugins/filters/colorsfilters/kis_multichannel_filter_base.cpp
@@ -434,12 +434,11 @@ void KisMultiChannelConfigWidget::init() {
         m_histogram = new KisHistogram(m_dev, m_dev->exactBounds(), hpf->generate(), LINEAR);
     }
 
-    m_page->curveWidget->setCurve(m_curves[0]);
     connect(m_page->curveWidget, SIGNAL(modified()), this, SLOT(slotCurveModified()));
 
     {
         KisSignalsBlocker b(m_page->curveWidget);
-        setActiveChannel(0);
+        syncActiveChannelUi();
     }
 }
 
@@ -662,6 +661,12 @@ void KisMultiChannelConfigWidget::setActiveChannel(int ch)
     KIS_SAFE_ASSERT_RECOVER_RETURN(ch < m_curves.size());
 
     m_activeVChannel = ch;
+
+    syncActiveChannelUi();
+}
+
+void KisMultiChannelConfigWidget::syncActiveChannelUi()
+{
     m_page->curveWidget->setCurve(m_curves[m_activeVChannel]);
     m_page->curveWidget->setPixmap(getHistogram());
 
diff --git a/plugins/filters/colorsfilters/kis_multichannel_filter_base.h b/plugins/filters/colorsfilters/kis_multichannel_filter_base.h
index 3ed92844092..ba2be21c55a 100644
--- a/plugins/filters/colorsfilters/kis_multichannel_filter_base.h
+++ b/plugins/filters/colorsfilters/kis_multichannel_filter_base.h
@@ -127,6 +127,7 @@ protected:
     void init();
     void resetCurves();
     void setActiveChannel(int ch);
+    void syncActiveChannelUi();
     virtual int findDefaultVirtualChannelSelection();
 
     virtual void updateChannelControls() = 0;