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Fix GC#drawImage + ImageGcDrawer for Cropping and Scaling #2913

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Fix GC#drawImage + ImageGcDrawer for Cropping and Scaling #2913

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52 changes: 28 additions & 24 deletions bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/graphics/GC.java
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -1183,15 +1180,6 @@ void apply() {
drawImage(getImage(), source.x, source.y, source.width, source.height, destination.x, destination.y, destination.width, destination.height, gcZoom, srcImageZoom);
}

private Collection<Integer> getAllCurrentMonitorZooms() {
if (device instanceof Display display) {
return Arrays.stream(display.getMonitors())
.map(Monitor::getZoom)
.collect(Collectors.toSet());
}
return Collections.emptySet();
}

private int calculateZoomForImage(int gcZoom, int srcWidth, int srcHeight, int destWidth, int destHeight) {
if (srcWidth == 1 && srcHeight == 1) {
// One pixel images can use the GC zoom
Expand All @@ -1207,13 +1195,7 @@ private int calculateZoomForImage(int gcZoom, int srcWidth, int srcHeight, int d

float imageScaleFactor = 1f * destWidth / srcWidth;
int imageZoom = Math.round(gcZoom * imageScaleFactor);
if (getAllCurrentMonitorZooms().contains(imageZoom)) {
return imageZoom;
}
if (imageZoom > 150) {
return 200;
}
return 100;
return imageZoom;
}
}

Expand Down Expand Up @@ -1245,24 +1227,46 @@ private void drawImage(Image image, int srcX, int srcY, int srcWidth, int srcHei
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);
Rectangle fullImageBounds = image.getBounds();
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@arunjose696 arunjose696 Dec 31, 2025

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Can see image.getBounds is called above in case the zoom!=100 can you see if the hack still makes sense, It would make sense to consider if we can stream line these calls

Rectangle fullImageBoundsScaled = Win32DPIUtils.pointToPixel(drawable, fullImageBounds, scaledImageZoom);
Rectangle unscaledSrc = new Rectangle(srcX, srcY, srcWidth, srcHeight);
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;
int errX = src.x + src.width - fullImageBoundsScaled.width;
int errY = src.y + src.height - fullImageBoundsScaled.height;
if (errX != 0 || errY != 0) {
if (errX <= scaledImageZoom / 100 && errY <= scaledImageZoom / 100) {
src.intersect(b);
src.intersect(fullImageBoundsScaled);
} 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));
image.executeOnImageHandleAtBestFittingSize((tempHandle) -> {
Rectangle newSrc = computeSourceRectangle(tempHandle, fullImageBounds, fullImageBoundsScaled, unscaledSrc, src);
drawImage(image, newSrc.x, newSrc.y, newSrc.width, newSrc.height, dest.x, dest.y, dest.width,
dest.height, false, tempHandle);
}, fullImageBoundsScaled.width, fullImageBoundsScaled.height);
}

private Rectangle computeSourceRectangle(ImageHandle imageHandle, Rectangle fullImageBounds, Rectangle fullImageBoundsScaled, Rectangle unscaledSrc, Rectangle src) {
if (new Rectangle(0, 0, imageHandle.getWidth(), imageHandle.getHeight()).equals(fullImageBoundsScaled)) {
return src;
} else {
/*
* the achieved handle with its drawings has not the required size, thus we calculate the zoom of the handle
*
* with respect to the full 100% image. The point values (x,y,width,height) of the source "part" of the full image will
* be computed to pixels by this zoom.
*/
float scaleFactor = 1f * imageHandle.getWidth() / fullImageBounds.width;
int closestZoomOfHandle = Math.round(scaleFactor * 100);
return Win32DPIUtils.pointToPixel(drawable, unscaledSrc, closestZoomOfHandle);
}
}

private class DrawImageToImageOperation extends ImageOperation {
Expand Down
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