[graphics/krita] libs/ui/tool/strokes: Clean up the preview stroke job data API a bit

Git commit 516d8e0ed65429e10fa7568ce86b61e2ff23a2db by Emmet O'Neill, on behalf of Dat Le.
Committed on 13/08/2026 at 23:16.
Pushed by emmetoneill into branch 'master'.

Clean up the preview stroke job data API a bit

M  +3    -6    libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp
M  +6    -8    libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.h

https://invent.kde.org/graphics/krita/-/commit/516d8e0ed65429e10fa7568ce86b61e2ff23a2db

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 095b25b0708..f711aa6988a 100644
--- a/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp
+++ b/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp
@@ -69,13 +69,10 @@ void KisColorSamplerStrokeStrategy::doStrokeCallback(KisStrokeJobData *data)
 
         QImage image = previewData->colorConverter->convertImageToDisplayColorSpace(tmpDev, effectiveRect, true);
 
-        // In case of instant preview, scale the sample back up to fit the original requested rect
-        if (previewData->levelOfDetail > 0) {
-            if (!previewData->originalRect.isValid()) return;
+        if (previewData->outputSize.isValid()) {
+            image = image.scaled(previewData->outputSize);
 
-            image = image.scaled(previewData->originalRect.size());
-
-            effectiveRect = QRect(QPoint(0,0), previewData->originalRect.size());
+            effectiveRect = QRect(QPoint(0,0), previewData->outputSize);
         }
 
         Q_EMIT sigCanvasZoomPreviewUpdated(image, effectiveRect);
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 4990ed8c0e9..d329ae03d83 100644
--- a/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.h
+++ b/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.h
@@ -50,14 +50,13 @@ public:
     class GenerateCanvasZoomPreviewData : public KisStrokeJobData {
     public:
         GenerateCanvasZoomPreviewData(KisPaintDeviceSP _canvasDev, const QRect &_canvasPixelRect, KisDisplayColorConverter *_colorConverter,
-                                      int _levelOfDetail = 0, QSharedPointer<boost::none_t> _cookie = nullptr)
+                                      QSize _outputSize = QSize(), QSharedPointer<boost::none_t> _cookie = nullptr)
             : canvasDev(_canvasDev), canvasPixelRect(_canvasPixelRect), colorConverter(_colorConverter),
-            levelOfDetail(_levelOfDetail), strokeCookie(_cookie), originalRect()
+            outputSize(_outputSize), strokeCookie(_cookie)
         {}
 
         KisStrokeJobData* createLodClone(int levelOfDetail) override {
             KisLodTransform transform(levelOfDetail);
-
             QRect lodPixelRect = transform.map(canvasPixelRect);
 
             // The LOD pixel rect size should be odd so that the pixel sampled is in the center
@@ -69,15 +68,15 @@ public:
             }
             lodPixelRect.moveCenter(transform.map(canvasPixelRect.center()));
 
+            // When instant preview mode is on, canvas is scaled down. Therefore, sample the canvas with the scaled LOD rect
+            // But the data returned needs to be the original requested size
             GenerateCanvasZoomPreviewData *newData =
-                new GenerateCanvasZoomPreviewData(canvasDev, lodPixelRect, colorConverter, levelOfDetail);
+                new GenerateCanvasZoomPreviewData(canvasDev, lodPixelRect, colorConverter, canvasPixelRect.size());
 
             // When Lod is involved, swap the cookie to the new Lod clone to track execution
             // The original object seems to leaks
             newData->swapCookie(strokeCookie);
 
-            newData->originalRect = canvasPixelRect;
-
             return newData;
         }
 
@@ -93,9 +92,8 @@ public:
         KisPaintDeviceSP canvasDev;
         QRect canvasPixelRect;
         KisDisplayColorConverter *colorConverter;
-        int levelOfDetail;
+        QSize outputSize; // Useful for LOD
         QSharedPointer<boost::none_t> strokeCookie;
-        QRect originalRect;
     };
 public:
     KisColorSamplerStrokeStrategy(int radius, int blend, int lod = 0);