Fix painting with colorsmudge brush when a selection is active

Selection crops destination rect, not the source one

BUG:394439
CCBUG:423851

libs/image/kis_painter.cc

@@ -493,7 +493,8 @@ inline bool KisPainter::Private::tryReduceSourceRect(const KisPaintDevice *srcDe
          * We should also crop the blitted area by the selected region,
          * because we cannot paint outside the selection.
          */
-        *srcRect &= selection->selectedRect();
+        *srcRect &= selection->selectedRect().translated(*srcX - *dstX,
+                                                         *srcY - *dstY);
 
         if (srcRect->isEmpty()) return true;
         needsReadjustParams = true;
@@ -541,12 +542,10 @@ void KisPainter::bitBltWithFixedSelection(qint32 dstX, qint32 dstY,
     Q_ASSERT(selection->colorSpace() == KoColorSpaceRegistry::instance()->alpha8());
 
     QRect srcRect = QRect(srcX, srcY, srcWidth, srcHeight);
-    QRect selRect = QRect(selX, selY, srcWidth, srcHeight);
 
-    /* Trying to read outside a KisFixedPaintDevice is inherently wrong and shouldn't be done,
-    so crash if someone attempts to do this. Don't resize YET as it would obfuscate the mistake. */
-    Q_ASSERT(selection->bounds().contains(selRect));
-    Q_UNUSED(selRect); // only used by the above Q_ASSERT
+    // save selection offset in case tryReduceSourceRect() will change rects
+    const int xSelectionOffset = selX - srcX;
+    const int ySelectionOffset = selY - srcY;
 
     /**
      * An optimization, which crops the source rect by the bounds of
@@ -557,6 +556,16 @@ void KisPainter::bitBltWithFixedSelection(qint32 dstX, qint32 dstY,
                                &srcWidth, &srcHeight,
                                &dstX, &dstY)) return;
 
+    const QRect selRect = QRect(srcX + xSelectionOffset,
+                                srcY + ySelectionOffset,
+                                srcWidth, srcHeight);
+
+    /* Trying to read outside a KisFixedPaintDevice is inherently wrong and shouldn't be done,
+    so crash if someone attempts to do this. Don't resize YET as it would obfuscate the mistake. */
+    KIS_SAFE_ASSERT_RECOVER_RETURN(selection->bounds().contains(selRect));
+    Q_UNUSED(selRect); // only used by the above Q_ASSERT
+
+
     /* Create an intermediate byte array to hold information before it is written
     to the current paint device (d->device) */
     quint8* dstBytes = 0;
@@ -580,9 +589,9 @@ void KisPainter::bitBltWithFixedSelection(qint32 dstX, qint32 dstY,
 
     srcDev->readBytes(srcBytes, srcX, srcY, srcWidth, srcHeight);
 
-    QRect selBounds = selection->bounds();
+    const QRect selBounds = selection->bounds();
     const quint8 *selRowStart = selection->data() +
-        (selBounds.width() * (selY - selBounds.top()) + (selX - selBounds.left())) * selection->pixelSize();
+        (selBounds.width() * (selRect.y() - selBounds.top()) + (selRect.x() - selBounds.left())) * selection->pixelSize();
 
     /*
      * This checks whether there is nothing selected.