[graphics/krita] libs/ui/tool: Use KisDisplayColorConverter::convertImageToDisplayColorSpace() for accurate color profile

Git commit 3a41164483b0bbae20aaa16479d425fa32cdb522 by Emmet O'Neill, on behalf of Dat Le.
Committed on 13/08/2026 at 23:16.
Pushed by emmetoneill into branch 'master'.

Use KisDisplayColorConverter::convertImageToDisplayColorSpace() for accurate color profile

TODO: Remove caching cause it's getting too slow

M  +11   -5    libs/ui/tool/KisAsyncColorSamplerHelper.cpp
M  +8    -2    libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp
M  +6    -4    libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.h

https://invent.kde.org/graphics/krita/-/commit/3a41164483b0bbae20aaa16479d425fa32cdb522

diff --git a/libs/ui/tool/KisAsyncColorSamplerHelper.cpp b/libs/ui/tool/KisAsyncColorSamplerHelper.cpp
index a38004d4048..24a970e82bd 100644
--- a/libs/ui/tool/KisAsyncColorSamplerHelper.cpp
+++ b/libs/ui/tool/KisAsyncColorSamplerHelper.cpp
@@ -676,10 +676,11 @@ void KisAsyncColorSamplerHelper::paintCircle(QPainter &gc,
         zoomDocRectF.setSize(zoomDocRectF.size() / m_d->circleZoomPreviewScale);
         zoomDocRectF.moveCenter(m_d->sampleDocPoint);
 
+        // Returns true if painted or not needed, returns false if painting was deferred
         bool canvasPainted = paintCircleCanvasPreview(cachePainter, cacheRect, zoomDocRectF, tf.map(m_d->cacheCircleInnerClip));
 
-        // canvasPainted is false when canvas preview is not yet available, leave the center hollow for better visual
-        // When draging from the outside (or from ref image only) to canvas, canvasPainted can also be false, causing flickering on the already painted zoom preview
+        // If canvasPainted is false (deferred), leave the center hollow to avoid gray flickering from fill
+        // When draging from the outside to canvas, canvasPainted can go from true (not needed) to false (deferred), causing flickering on the already painted zoom preview
         // So if preview was ever successfully render, don't hide these and cause flickering
         if (canvasPainted || m_d->zoomPreviewHasPainted) {
             paintCircleReferenceImagePreview(cachePainter, cacheRect, zoomDocRectF, tf.map(m_d->cacheCircleInnerClip));
@@ -709,10 +710,15 @@ void KisAsyncColorSamplerHelper::paintCircleCrosshair(QPainter &gc, const QRectF
     qreal luminance = KisPaintingTweaks::luminosityCoarse(currentColor);
     if (luminance < 0.5) crosshairColor = Qt::white;
 
+    qreal dpr = gc.device()->devicePixelRatioF();
+    qreal penWidth = 1.0 * dpr;
+    QPen pen = QPen(crosshairColor, penWidth);
+
     gc.save();
 
+    gc.setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
     gc.setCompositionMode(QPainter::CompositionMode_SourceOver);
-    gc.setPen(crosshairColor);
+    gc.setPen(pen);
 
     QTransform tf;
     tf.translate(viewRectF.center().x(), viewRectF.center().y());
@@ -738,7 +744,7 @@ QImage KisAsyncColorSamplerHelper::cacheCanvasImage(QRect &canvasPixelRect) {
     if (m_d->cacheCanvasPreviewRect.isEmpty() || !m_d->cacheCanvasPreviewRect.contains(canvasPixelRect)) {
         // Cache an area larger than the needed preview area to avoid rapid small dynamic allocations
         // And also avoid frequent preview delay from repeatedly fetching canvas image asynchronously
-        qreal cacheScale = 4;
+        qreal cacheScale = 1;
 
         QRect cacheCanvasRect = canvasPixelRect;
         cacheCanvasRect.setSize(canvasPixelRect.size() * cacheScale);
@@ -754,7 +760,7 @@ QImage KisAsyncColorSamplerHelper::cacheCanvasImage(QRect &canvasPixelRect) {
         if (!m_d->canvasPreviewFetchingStarted) {
             m_d->canvasPreviewFetchingStarted = true;
             m_d->strokesFacade()->addJob(m_d->strokeId,
-                new KisColorSamplerStrokeStrategy::GenerateCanvasZoomPreviewData(canvasImage, cacheCanvasRect, canvasImage->colorSpace()->profile()));
+                new KisColorSamplerStrokeStrategy::GenerateCanvasZoomPreviewData(m_d->canvas, cacheCanvasRect, canvasImage->colorSpace()->profile()));
         }
 
         // Return the last valid canvas preview while we wait to fetch new canvas cache async
diff --git a/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp b/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp
index 31946545e4e..b3719928b7a 100644
--- a/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp
+++ b/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp
@@ -6,9 +6,10 @@
 
 #include "kis_color_sampler_stroke_strategy.h"
 
+#include "kis_canvas2.h"
+#include "kis_display_color_converter.h"
 #include "kis_tool_utils.h"
 #include "kis_paint_device.h"
-#include "kis_image.h"
 
 struct KisColorSamplerStrokeStrategy::Private
 {
@@ -57,7 +58,12 @@ void KisColorSamplerStrokeStrategy::doStrokeCallback(KisStrokeJobData *data)
             Q_EMIT sigFinalColorSelected(*m_d->lastSelectedColor);
         }
     } else if (previewData) {
-        QImage image = previewData->canvasImage->convertToQImage(previewData->canvasPixelRect, previewData->colorProfile);
+        KisPaintDeviceSP dev = previewData->canvas->image()->projection();
+        KisPaintDeviceSP tmp = new KisPaintDevice(dev->colorSpace());
+
+        tmp->makeCloneFromRough(dev, previewData->canvasPixelRect);
+
+        QImage image = previewData->canvas->displayColorConverter()->convertImageToDisplayColorSpace(tmp, previewData->canvasPixelRect, true);
 
         Q_EMIT sigCanvasZoomPreviewUpdated(image, previewData->canvasPixelRect);
     }
diff --git a/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.h b/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.h
index 2de6217b603..bdf761473a1 100644
--- a/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.h
+++ b/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.h
@@ -12,6 +12,8 @@
 #include "kis_lod_transform.h"
 #include "KoColor.h"
 
+class KisCanvas2;
+
 class KisColorSamplerStrokeStrategy : public QObject, public KisSimpleStrokeStrategy
 {
     Q_OBJECT
@@ -47,16 +49,16 @@ public:
 
     class GenerateCanvasZoomPreviewData : public KisStrokeJobData {
     public:
-        GenerateCanvasZoomPreviewData(KisImageWSP _image, const QRect &_canvasPixelRect, const KoColorProfile *_colorProfile)
-            : canvasImage(_image), canvasPixelRect(_canvasPixelRect), colorProfile(_colorProfile)
+        GenerateCanvasZoomPreviewData(KisCanvas2* _canvas, const QRect &_canvasPixelRect, const KoColorProfile *_colorProfile)
+            : canvas(_canvas), canvasPixelRect(_canvasPixelRect), colorProfile(_colorProfile)
         {}
 
         KisStrokeJobData* createLodClone(int levelOfDetail) override {
             Q_UNUSED(levelOfDetail);
-            return new GenerateCanvasZoomPreviewData(canvasImage, canvasPixelRect, colorProfile);
+            return new GenerateCanvasZoomPreviewData(canvas, canvasPixelRect, colorProfile);
         }
 
-        KisImageWSP canvasImage;
+        KisCanvas2 *canvas;
         QRect canvasPixelRect;
         const KoColorProfile *colorProfile;
     };