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Smooth Scaling Rounding error fix for win32 #62 #1913

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Merged
merged 1 commit into from
Mar 21, 2025
Merged

Smooth Scaling Rounding error fix for win32 #62 #1913

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10 changes: 9 additions & 1 deletion bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/DPIUtil.java
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Original file line number Diff line number Diff line change
Expand Up @@ -292,7 +292,7 @@ private static ImageData autoScaleImageData (Device device, final ImageData imag
int height = imageData.height;
int scaledWidth = Math.round (width * scaleFactor);
int scaledHeight = Math.round (height * scaleFactor);
boolean useSmoothScaling = autoScaleMethod == AutoScaleMethod.SMOOTH && imageData.getTransparencyType() != SWT.TRANSPARENCY_MASK;
boolean useSmoothScaling = isSmoothScalingEnabled() && imageData.getTransparencyType() != SWT.TRANSPARENCY_MASK;
if (useSmoothScaling) {
Image original = new Image (device, (ImageDataProvider) zoom -> imageData);
/* Create a 24 bit image data with alpha channel */
Expand All @@ -316,6 +316,10 @@ private static ImageData autoScaleImageData (Device device, final ImageData imag
}
}

public static boolean isSmoothScalingEnabled() {
return autoScaleMethod == AutoScaleMethod.SMOOTH;
}

/**
* Returns a new rectangle as per the scaleFactor.
*/
Expand Down Expand Up @@ -628,6 +632,10 @@ public static boolean useCairoAutoScale() {
}

public static int getZoomForAutoscaleProperty (int nativeDeviceZoom) {
return getZoomForAutoscaleProperty(nativeDeviceZoom, autoScaleValue);
}

private static int getZoomForAutoscaleProperty (int nativeDeviceZoom, String autoScaleValue) {
int zoom = 0;
if (autoScaleValue != null) {
if ("false".equalsIgnoreCase (autoScaleValue)) {
Expand Down
54 changes: 45 additions & 9 deletions bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/graphics/Image.java
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Original file line number Diff line number Diff line change
Expand Up @@ -361,7 +361,7 @@ public Image(Device device, ImageData data) {
if (data == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
initialNativeZoom = DPIUtil.getNativeDeviceZoom();
int deviceZoom = getZoom();
data = DPIUtil.scaleImageData(device, new ElementAtZoom<>(data, 100), deviceZoom);
data = scaleImageData(data, deviceZoom, 100);
init(data, deviceZoom);
init();
this.device.registerResourceWithZoomSupport(this);
Expand Down Expand Up @@ -405,8 +405,8 @@ public Image(Device device, ImageData source, ImageData mask) {
SWT.error(SWT.ERROR_INVALID_ARGUMENT);
}
initialNativeZoom = DPIUtil.getNativeDeviceZoom();
source = DPIUtil.autoScaleUp(device, source);
mask = DPIUtil.autoScaleUp(device, mask);
source = scaleImageData(source, getZoom(), 100);
mask = scaleImageData(mask, getZoom(), 100);
mask = ImageData.convertMask(mask);
initIconHandle(this.device, source, mask, getZoom());
init();
Expand Down Expand Up @@ -470,7 +470,8 @@ public Image (Device device, InputStream stream) {
super(device);
initialNativeZoom = DPIUtil.getNativeDeviceZoom();
int deviceZoom = getZoom();
ImageData data = DPIUtil.scaleImageData(device, ImageDataLoader.load(stream, FileFormat.DEFAULT_ZOOM, deviceZoom), deviceZoom);
ElementAtZoom<ImageData> imageCandidate = ImageDataLoader.load(stream, FileFormat.DEFAULT_ZOOM, deviceZoom);
ImageData data = scaleImageData(imageCandidate.element(), deviceZoom, imageCandidate.zoom());
init(data, deviceZoom);
init();
this.device.registerResourceWithZoomSupport(this);
Expand Down Expand Up @@ -513,7 +514,8 @@ public Image (Device device, String filename) {
if (filename == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
initialNativeZoom = DPIUtil.getNativeDeviceZoom();
int deviceZoom = getZoom();
ImageData data = DPIUtil.scaleImageData(device, ImageDataLoader.load(filename, FileFormat.DEFAULT_ZOOM, deviceZoom), deviceZoom);
ElementAtZoom<ImageData> imageCandidate = ImageDataLoader.load(filename, FileFormat.DEFAULT_ZOOM, deviceZoom);
ImageData data = scaleImageData(imageCandidate.element(), deviceZoom, imageCandidate.zoom());
init(data, deviceZoom);
init();
this.device.registerResourceWithZoomSupport(this);
Expand Down Expand Up @@ -1237,7 +1239,7 @@ private ImageData getScaledImageData (int zoom) {
}
TreeSet<Integer> availableZooms = new TreeSet<>(zoomLevelToImageHandle.keySet());
int closestZoom = Optional.ofNullable(availableZooms.higher(zoom)).orElse(availableZooms.lower(zoom));
return DPIUtil.scaleImageData (device, getImageMetadata(closestZoom).getImageData(), zoom, closestZoom);
return scaleImageData(getImageMetadata(closestZoom).getImageData(), zoom, closestZoom);
}


Expand Down Expand Up @@ -1850,6 +1852,40 @@ private void setBackground(Color color, long handle) {
device.internal_dispose_GC(hDC, null);
}

private ImageData scaleImageData(final ImageData imageData, int targetZoom, int currentZoom) {
if (imageData == null || targetZoom == currentZoom || (device != null && !device.isAutoScalable())) return imageData;
float scaleFactor = (float) targetZoom / (float) currentZoom;
int width = imageData.width;
int height = imageData.height;
int scaledWidth = Math.round (width * scaleFactor);
int scaledHeight = Math.round (height * scaleFactor);
boolean useSmoothScaling = DPIUtil.isSmoothScalingEnabled() && imageData.getTransparencyType() != SWT.TRANSPARENCY_MASK;
if (useSmoothScaling) {
return scaleToUsingSmoothScaling(scaledWidth, scaledHeight, imageData);
}
return imageData.scaledTo (scaledWidth, scaledHeight);
}

private ImageData scaleToUsingSmoothScaling(int width, int height, ImageData imageData) {
Image original = new Image (device, (ImageDataProvider) zoom -> imageData);
/* Create a 24 bit image data with alpha channel */
final ImageData resultData = new ImageData (width, height, 24, new PaletteData (0xFF, 0xFF00, 0xFF0000));
resultData.alphaData = new byte [width * height];
Image resultImage = new Image (device, (ImageDataProvider) zoom -> resultData);
GC gc = new GC (resultImage);
gc.setAntialias (SWT.ON);
gc.drawImage (original, 0, 0, imageData.width, imageData.height,
/* E.g. destWidth here is effectively DPIUtil.autoScaleDown (scaledWidth), but avoiding rounding errors.
* Nevertheless, we still have some rounding errors due to the point-based API GC#drawImage(..).
*/
0, 0, width, height, false);
gc.dispose ();
original.dispose ();
ImageData result = resultImage.getImageData (resultImage.getZoom());
resultImage.dispose ();
return result;
}

private int getZoom() {
return DPIUtil.getZoomForAutoscaleProperty(initialNativeZoom);
}
Expand Down Expand Up @@ -2059,7 +2095,7 @@ ImageData getImageData(int zoom) {

private ImageData scaleIfNecessary(ElementAtZoom<ImageData> imageDataAtZoom, int zoom) {
if (imageDataAtZoom.zoom() != zoom) {
return DPIUtil.scaleImageData(device, imageDataAtZoom, zoom);
return scaleImageData(imageDataAtZoom.element(), zoom, imageDataAtZoom.zoom());
} else {
return imageDataAtZoom.element();
}
Expand Down Expand Up @@ -2308,13 +2344,13 @@ protected Rectangle getBounds(int zoom) {
@Override
ImageData getImageData(int zoom) {
ElementAtZoom<ImageData> data = DPIUtil.validateAndGetImageDataAtZoom (provider, zoom);
return DPIUtil.scaleImageData (device, data.element(), zoom, data.zoom());
return scaleImageData(data.element(), zoom, data.zoom());
}

@Override
ImageHandle getImageMetadata(int zoom) {
ElementAtZoom<ImageData> imageCandidate = DPIUtil.validateAndGetImageDataAtZoom (provider, zoom);
ImageData resizedData = DPIUtil.scaleImageData (device, imageCandidate.element(), zoom, imageCandidate.zoom());
ImageData resizedData = scaleImageData(imageCandidate.element(), zoom, imageCandidate.zoom());
ImageData newData = adaptImageDataIfDisabledOrGray(resizedData);
init(newData, zoom);
return zoomLevelToImageHandle.get(zoom);
Expand Down
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