[graphics/krita] libs/ui/tool: LOD support WIP

Git commit c1dce6e425a56e902fb9f2aea0f974e86578e9d3 by Emmet O'Neill, on behalf of Dat Le.
Committed on 13/08/2026 at 23:16.
Pushed by emmetoneill into branch 'master'.

LOD support WIP

M  +7    -0    libs/ui/tool/KisAsyncColorSamplerHelper.cpp
M  +17   -2    libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp
M  +7    -4    libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.h

https://invent.kde.org/graphics/krita/-/commit/c1dce6e425a56e902fb9f2aea0f974e86578e9d3

diff --git a/libs/ui/tool/KisAsyncColorSamplerHelper.cpp b/libs/ui/tool/KisAsyncColorSamplerHelper.cpp
index 71ce4bc522b..1d3cdffc675 100644
--- a/libs/ui/tool/KisAsyncColorSamplerHelper.cpp
+++ b/libs/ui/tool/KisAsyncColorSamplerHelper.cpp
@@ -727,7 +727,10 @@ 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());
 
@@ -736,6 +739,8 @@ 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());
 
@@ -835,6 +840,8 @@ 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 d29b24534e7..97dc2191f09 100644
--- a/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp
+++ b/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.cpp
@@ -58,12 +58,27 @@ void KisColorSamplerStrokeStrategy::doStrokeCallback(KisStrokeJobData *data)
         }
     } else if (previewData) {
         KisPaintDeviceSP tmpDev = new KisPaintDevice(previewData->canvasDev->colorSpace());
-
         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(image, previewData->canvasPixelRect);
+        Q_EMIT sigCanvasZoomPreviewUpdated(QImage(), QRect());
     }
 }
 
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 811dcca8d48..0681b580482 100644
--- a/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.h
+++ b/libs/ui/tool/strokes/kis_color_sampler_stroke_strategy.h
@@ -49,13 +49,15 @@ public:
 
     class GenerateCanvasZoomPreviewData : public KisStrokeJobData {
     public:
-        GenerateCanvasZoomPreviewData(KisPaintDeviceSP _canvasDev, const QRect &_canvasPixelRect, KisDisplayColorConverter *_colorConverter)
-            : canvasDev(_canvasDev), canvasPixelRect(_canvasPixelRect), colorConverter(_colorConverter)
+        GenerateCanvasZoomPreviewData(KisPaintDeviceSP _canvasDev, const QRect &_canvasPixelRect, KisDisplayColorConverter *_colorConverter,
+                                      int _levelOfDetail = -1, QSharedPointer<boost::none_t> _cookie = nullptr)
+            : canvasDev(_canvasDev), canvasPixelRect(_canvasPixelRect), colorConverter(_colorConverter), levelOfDetail(_levelOfDetail), fetchingCookie(_cookie)
         {}
 
         KisStrokeJobData* createLodClone(int levelOfDetail) override {
-            Q_UNUSED(levelOfDetail);
-            return new GenerateCanvasZoomPreviewData(canvasDev, canvasPixelRect, colorConverter);
+            KisLodTransform transform(levelOfDetail);
+            QRect lodPixelRect = transform.map(canvasPixelRect);
+            return new GenerateCanvasZoomPreviewData(canvasDev, lodPixelRect, colorConverter, levelOfDetail, fetchingCookie);
         }
 
         QWeakPointer<boost::none_t> cookie() {
@@ -66,6 +68,7 @@ public:
         KisPaintDeviceSP canvasDev;
         QRect canvasPixelRect;
         KisDisplayColorConverter *colorConverter;
+        int levelOfDetail;
         QSharedPointer<boost::none_t> fetchingCookie;
     };
 public: