[graphics/krita] libs/ui/tool: Instant preview now working

Git commit 356243d61cdb6f80669dd63ddb0a39b8ca7f8e27 by Emmet O'Neill, on behalf of Dat Le.
Committed on 13/08/2026 at 23:16.
Pushed by emmetoneill into branch 'master'.

Instant preview now working

M  +0    -5    libs/ui/tool/KisAsyncColorSamplerHelper.cpp
M  +6    -8    libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp
M  +6    -2    libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.h

https://invent.kde.org/graphics/krita/-/commit/356243d61cdb6f80669dd63ddb0a39b8ca7f8e27

diff --git a/libs/ui/tool/KisAsyncColorSamplerHelper.cpp b/libs/ui/tool/KisAsyncColorSamplerHelper.cpp
index 1d3cdffc675..70e33d193d4 100644
--- a/libs/ui/tool/KisAsyncColorSamplerHelper.cpp
+++ b/libs/ui/tool/KisAsyncColorSamplerHelper.cpp
@@ -729,7 +729,6 @@ QImage KisAsyncColorSamplerHelper::fetchCanvasPreview(QRect &canvasPixelRect, Ki
     // If not already have a job fetching canvas image, then do it
     // TODO: If LOD is involved, the cookie seems leaked. Also, Q_EMIT never trigger the slot?
     if (!m_d->canvasPreviewFetchingCookie && m_d->cacheCanvasPreviewRect != canvasPixelRect) {
-        qDebug() << "Original rect:" << canvasPixelRect;
 
         KisColorSamplerStrokeStrategy::GenerateCanvasZoomPreviewData *data =
             new KisColorSamplerStrokeStrategy::GenerateCanvasZoomPreviewData(canvasImage->projection(), canvasPixelRect, m_d->canvas->displayColorConverter());
@@ -739,8 +738,6 @@ QImage KisAsyncColorSamplerHelper::fetchCanvasPreview(QRect &canvasPixelRect, Ki
         m_d->strokesFacade()->addJob(m_d->strokeId, data);
     }
 
-    // qDebug() << "Has fetching finished: " << m_d->canvasPreviewFetchingCookie.isNull();
-
     // Render the last frame if available
     if (!m_d->cacheCanvasPreviewRect.isNull()) canvasPixelRect = QRect(QPoint(0,0), m_d->cacheCanvasPreviewRect.size());
 
@@ -840,8 +837,6 @@ void KisAsyncColorSamplerHelper::slotCanvasZoomPreviewUpdated(const QImage &canv
     m_d->cacheCanvasPreviewRect = canvasRect;
     m_d->cacheCanvasPreviewImage = canvasImage;
 
-    qDebug() << "Canvas fetching finished";
-
     Q_EMIT sigRequestUpdateOutline();
 }
 
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 97dc2191f09..f846bcdcb9a 100644
--- a/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp
+++ b/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp
@@ -19,6 +19,8 @@ struct KisColorSamplerStrokeStrategy::Private
     int blend = 100;
 
     boost::optional<KoColor> lastSelectedColor;
+
+    QSharedPointer<boost::none_t> strokeCookie = nullptr;
 };
 
 KisColorSamplerStrokeStrategy::KisColorSamplerStrokeStrategy(int radius, int blend, int lod)
@@ -61,24 +63,17 @@ void KisColorSamplerStrokeStrategy::doStrokeCallback(KisStrokeJobData *data)
         tmpDev->makeCloneFrom(previewData->canvasDev, previewData->canvasPixelRect);
 
         QImage image = previewData->colorConverter->convertImageToDisplayColorSpace(tmpDev, previewData->canvasPixelRect, true);
-        qDebug() << "Scaled image rect: " << image.rect();
 
         if (previewData->levelOfDetail > 0) {
-            qDebug() << previewData->levelOfDetail;
-            qDebug() << "Modified rect" << previewData->canvasPixelRect;
             KisLodTransform transform(previewData->levelOfDetail);
-
             qreal scale = transform.lodToInvScale(previewData->levelOfDetail);
-            qDebug() << "Lod to scale" << scale;
 
             image = image.scaled(QSize(scale * image.width(), scale * image.height()));
-            qDebug() << "Restored image rect: " << image.rect();
 
             previewData->canvasPixelRect = transform.mapInverted(previewData->canvasPixelRect);
-            qDebug() << "Restored rect: " << previewData->canvasPixelRect;
         }
 
-        Q_EMIT sigCanvasZoomPreviewUpdated(QImage(), QRect());
+        Q_EMIT sigCanvasZoomPreviewUpdated(image, previewData->canvasPixelRect);
     }
 }
 
@@ -90,5 +85,8 @@ KisStrokeStrategy* KisColorSamplerStrokeStrategy::createLodClone(int levelOfDeta
     connect(lodStrategy, &KisColorSamplerStrokeStrategy::sigColorUpdated,
             this, &KisColorSamplerStrokeStrategy::sigColorUpdated,
             Qt::DirectConnection);
+    connect(lodStrategy, &KisColorSamplerStrokeStrategy::sigCanvasZoomPreviewUpdated,
+            this, &KisColorSamplerStrokeStrategy::sigCanvasZoomPreviewUpdated,
+            Qt::DirectConnection);
     return lodStrategy;
 }
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 0681b580482..90280926a72 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 +50,18 @@ public:
     class GenerateCanvasZoomPreviewData : public KisStrokeJobData {
     public:
         GenerateCanvasZoomPreviewData(KisPaintDeviceSP _canvasDev, const QRect &_canvasPixelRect, KisDisplayColorConverter *_colorConverter,
-                                      int _levelOfDetail = -1, QSharedPointer<boost::none_t> _cookie = nullptr)
+                                      int _levelOfDetail = 0, QSharedPointer<boost::none_t> _cookie = nullptr)
             : canvasDev(_canvasDev), canvasPixelRect(_canvasPixelRect), colorConverter(_colorConverter), levelOfDetail(_levelOfDetail), fetchingCookie(_cookie)
         {}
 
         KisStrokeJobData* createLodClone(int levelOfDetail) override {
             KisLodTransform transform(levelOfDetail);
             QRect lodPixelRect = transform.map(canvasPixelRect);
-            return new GenerateCanvasZoomPreviewData(canvasDev, lodPixelRect, colorConverter, levelOfDetail, fetchingCookie);
+            GenerateCanvasZoomPreviewData *newData = new GenerateCanvasZoomPreviewData(canvasDev, lodPixelRect, colorConverter, levelOfDetail);
+            // When Lod is involved, swap the cookie to the new Lod clone to track execution, the original object seems to leaks
+            newData->fetchingCookie.swap(fetchingCookie);
+
+            return newData;
         }
 
         QWeakPointer<boost::none_t> cookie() {