Fix GC#drawImage with ImageGcDrawer for Cropping and Scaling

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/graphics/GC.java

@@ -15,16 +15,13 @@
 
 
 import java.util.*;
-import java.util.List;
 import java.util.function.*;
-import java.util.stream.*;
 
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.Image.*;
 import org.eclipse.swt.internal.*;
 import org.eclipse.swt.internal.gdip.*;
 import org.eclipse.swt.internal.win32.*;
-import org.eclipse.swt.widgets.*;
 
 /**
  * Class <code>GC</code> is where all of the drawing capabilities that are
@@ -1178,18 +1175,52 @@ private class DrawScalingImageToImageOperation extends ImageOperation {
 
 	@Override
 	void apply() {
+		draw(getImage(), source.x, source.y, source.width, source.height, destination.x, destination.y, destination.width, destination.height);
+	}
+
+	private void draw(Image image, int srcX, int srcY, int srcWidth, int srcHeight, int destX, int destY, int destWidth, int destHeight) {
 		int gcZoom = getZoom();
-		int srcImageZoom = calculateZoomForImage(gcZoom, source.width, source.height, destination.width, destination.height);
-		drawImage(getImage(), source.x, source.y, source.width, source.height, destination.x, destination.y, destination.width, destination.height, gcZoom, srcImageZoom);
+		int requestedImageZoom = calculateZoomForImage(gcZoom, source.width, source.height, destination.width, destination.height);
+
+		Rectangle src =  new Rectangle(srcX, srcY, srcWidth, srcHeight);
+		Rectangle destPixels = Win32DPIUtils.pointToPixel(drawable, new Rectangle(destX, destY, destWidth, destHeight), gcZoom);
+		Rectangle fullImageBounds = image.getBounds();
+		Rectangle requestedFullImageBoundsPixels = Win32DPIUtils.pointToPixel(drawable, fullImageBounds, requestedImageZoom);
+
+		image.executeOnImageHandleAtBestFittingSize((tempHandle) -> {
+			Rectangle srcPixels = computeSourceRectangle(tempHandle, fullImageBounds, src);
+			drawImage(image, srcPixels.x, srcPixels.y, srcPixels.width, srcPixels.height, destPixels.x, destPixels.y, destPixels.width,
+					destPixels.height, false, tempHandle);
+		}, requestedFullImageBoundsPixels.width, requestedFullImageBoundsPixels.height);
 	}
 
-	private Collection<Integer> getAllCurrentMonitorZooms() {
-		if (device instanceof Display display) {
-			return Arrays.stream(display.getMonitors())
-				.map(Monitor::getZoom)
-				.collect(Collectors.toSet());
+	private Rectangle computeSourceRectangle(ImageHandle imageHandle, Rectangle fullImageBounds, Rectangle src) {
+		/*
+		 * The point values (x, y, width, height) of the source "part" in points will be
+		 * computed to pixels depending on the factor of the full image bounds to the
+		 * actual OS handle size that will be used.
+		 */
+		float scaleFactor = Math.min(1f * imageHandle.width() / fullImageBounds.width, 1f * imageHandle.height() / fullImageBounds.height);
+		int closestZoomOfHandle = Math.round(scaleFactor * 100);
+		Rectangle srcPixels = Win32DPIUtils.pointToPixel(drawable, src, closestZoomOfHandle);
+
+		if (closestZoomOfHandle != 100) {
+			/*
+			 * This is a HACK! Due to rounding errors at fractional scale factors,
+			 * the coordinates may be slightly off. The workaround is to restrict
+			 * coordinates to the allowed bounds.
+			 */
+			int errX = srcPixels.x + srcPixels.width - imageHandle.width();
+			int errY = srcPixels.y + srcPixels.height - imageHandle.height();
+			if (errX != 0 || errY != 0) {
+				if (errX <= closestZoomOfHandle / 100 && errY <= closestZoomOfHandle / 100) {
+					srcPixels.intersect(new Rectangle(0, 0, imageHandle.width(), imageHandle.height()));
+				} else {
+					SWT.error (SWT.ERROR_INVALID_ARGUMENT);
+				}
+			}
 		}
-		return Collections.emptySet();
+		return srcPixels;
 	}
 
 	private int calculateZoomForImage(int gcZoom, int srcWidth, int srcHeight, int destWidth, int destHeight) {
@@ -1205,15 +1236,9 @@ private int calculateZoomForImage(int gcZoom, int srcWidth, int srcHeight, int d
 			return gcZoom;
 		}
 
-		float imageScaleFactor = 1f * destWidth / srcWidth;
+		float imageScaleFactor = Math.max(1f * destWidth / srcWidth, 1f * destHeight / srcHeight);
 		int imageZoom = Math.round(gcZoom * imageScaleFactor);
-		if (getAllCurrentMonitorZooms().contains(imageZoom)) {
-			return imageZoom;
-		}
-		if (imageZoom > 150) {
-			return 200;
-		}
-		return 100;
+		return imageZoom;
 	}
 }
 
@@ -1241,30 +1266,6 @@ private void drawImage(Image image, int destX, int destY, int destWidth, int des
 	}, destPixels.width, destPixels.height);
 }
 
-private void drawImage(Image image, int srcX, int srcY, int srcWidth, int srcHeight, int destX, int destY,
-		int destWidth, int destHeight, int imageZoom, int scaledImageZoom) {
-	Rectangle src = Win32DPIUtils.pointToPixel(drawable, new Rectangle(srcX, srcY, srcWidth, srcHeight), scaledImageZoom);
-	Rectangle dest = Win32DPIUtils.pointToPixel(drawable, new Rectangle(destX, destY, destWidth, destHeight), imageZoom);
-	if (scaledImageZoom != 100) {
-		/*
-		 * This is a HACK! Due to rounding errors at fractional scale factors,
-		 * the coordinates may be slightly off. The workaround is to restrict
-		 * coordinates to the allowed bounds.
-		 */
-		Rectangle b = image.getBounds(scaledImageZoom);
-		int errX = src.x + src.width - b.width;
-		int errY = src.y + src.height - b.height;
-		if (errX != 0 || errY != 0) {
-			if (errX <= scaledImageZoom / 100 && errY <= scaledImageZoom / 100) {
-				src.intersect(b);
-			} else {
-				SWT.error (SWT.ERROR_INVALID_ARGUMENT);
-			}
-		}
-	}
-	drawImage(image, src.x, src.y, src.width, src.height, dest.x, dest.y, dest.width, dest.height, false, image.getHandle(scaledImageZoom, data.nativeZoom));
-}
-
 private class DrawImageToImageOperation extends ImageOperation {
 	private final Rectangle source;
 	private final Rectangle destination;