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Add tests for drawing scaled image with GC#drawImage() #2623

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Oct 15, 2025
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Add tests for drawing scaled image with GC#drawImage() #2623

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156 changes: 156 additions & 0 deletions ...e.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_graphics_GC.java
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@
*******************************************************************************/
package org.eclipse.swt.tests.junit;

import static org.eclipse.swt.internal.DPIUtil.pointToPixel;
import static org.eclipse.swt.tests.junit.SwtTestUtil.assertSWTProblem;
import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import static org.junit.jupiter.api.Assertions.assertEquals;
Expand All @@ -37,6 +38,8 @@
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.ImageDataAtSizeProvider;
import org.eclipse.swt.graphics.ImageDataProvider;
import org.eclipse.swt.graphics.ImageGcDrawer;
import org.eclipse.swt.graphics.LineAttributes;
import org.eclipse.swt.graphics.PaletteData;
Expand All @@ -51,6 +54,10 @@
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.condition.EnabledOnOs;
import org.junit.jupiter.api.condition.OS;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.ValueSource;

/**
* Automated Test Suite for class org.eclipse.swt.graphics.GC
Expand Down Expand Up @@ -390,6 +397,155 @@ public void test_drawImageLorg_eclipse_swt_graphics_ImageIIII() {
images.dispose();
}

@Test
public void test_drawImageLorg_eclipse_swt_graphics_ImageIIII_ImageDataProvider() {
int width = 32;
int height = 48;
Image drawToImage = new Image(display, width, height);
GC gc = new GC(drawToImage);
gc.setAntialias(SWT.OFF);
RGB drawnRgb = new RGB(255, 255, 255);
RGB undrawnRgb = new RGB(0, 0, 0);
ImageDataProvider imageDataProvider = zoom -> {
if (zoom != 100) {
return null;
}
PaletteData palette = new PaletteData(0xFF0000, 0xFF00, 0xFF);
ImageData imageData = new ImageData(16, 16, 32, palette);
int drawnPixel = palette.getPixel(drawnRgb);
for (int i = 0; i < 16; i++) {
imageData.setPixel(i, 0, drawnPixel);
imageData.setPixel(i, 15, drawnPixel);
imageData.setPixel(0, i, drawnPixel);
imageData.setPixel(15, i, drawnPixel);
}
return imageData;
};
Image image = new Image(display, imageDataProvider);
try {
gc.drawImage(image, 0, 0, width, height);
int zoom = DPIUtil.getDeviceZoom();
ImageData printedImageData = drawToImage.getImageData(zoom);
PaletteData printedPalette = printedImageData.palette;
// Expect that image is blurry scaled to the desired extents
assertEquals(drawnRgb, printedPalette.getRGB(printedImageData.getPixel(0, 0)));
assertNotEquals(undrawnRgb, printedPalette.getRGB(printedImageData.getPixel(1, 1)));
assertNotEquals(undrawnRgb, printedPalette.getRGB(printedImageData.getPixel(1, 2)));
assertEquals(undrawnRgb, printedPalette.getRGB(printedImageData.getPixel(pointToPixel(width, zoom) / 2, pointToPixel(height, zoom) / 2)));
assertNotEquals(undrawnRgb, printedPalette.getRGB(printedImageData.getPixel(pointToPixel(width, zoom) - 2, pointToPixel(height, zoom) - 3)));
assertNotEquals(undrawnRgb, printedPalette.getRGB(printedImageData.getPixel(pointToPixel(width, zoom) - 2, pointToPixel(height, zoom) - 2)));
assertEquals(drawnRgb, printedPalette.getRGB(printedImageData.getPixel(pointToPixel(width, zoom) - 1, pointToPixel(height, zoom) - 1)));
} finally {
image.dispose();
drawToImage.dispose();
}
}

@Test
@EnabledOnOs(value = OS.WINDOWS)
public void test_drawImageLorg_eclipse_swt_graphics_ImageIIII_ImageDataAtSizeProvider_invalid() {
ImageDataAtSizeProvider provider = new ImageDataAtSizeProvider() {
@Override
public ImageData getImageData(int zoom) {
return new ImageData(1, 1, 32, new PaletteData(0xFF0000, 0xFF00, 0xFF));
}

@Override
public ImageData getImageData(int width, int height) {
return null;
}
};
Image image = new Image(display, provider);
Image drawToImage = new Image(display, 1, 1);
try {
GC gc = new GC(drawToImage);
Exception e = assertThrows(IllegalArgumentException.class, () -> gc.drawImage(image, 0, 0, 1, 1));
assertSWTProblem("Incorrect exception thrown for provider == null", SWT.ERROR_INVALID_ARGUMENT, e);
} finally {
image.dispose();
drawToImage.dispose();
}
}

@ParameterizedTest
@ValueSource(ints = {SWT.IMAGE_COPY, SWT.IMAGE_DISABLE, SWT.IMAGE_GRAY, -1})
@EnabledOnOs(value = OS.WINDOWS)
public void test_drawImageLorg_eclipse_swt_graphics_ImageIIII_ImageDataAtSizeProvider(int styleFlag) {
int width = 50;
int height = 70;
Image drawToImage = new Image(display, width, height);
GC gc = new GC(drawToImage);
gc.setAntialias(SWT.OFF);
RGB drawnRgb = new RGB(255, 255, 255);
RGB undrawnRgb = new RGB(0, 0, 0);
ImageDataAtSizeProvider imageDataAtSizeProvider = new ImageDataAtSizeProvider() {
@Override
public ImageData getImageData(int width, int height) {
PaletteData palette = new PaletteData(0xFF0000, 0xFF00, 0xFF);
int drawnPixel = palette.getPixel(drawnRgb);
ImageData imageData = new ImageData(width, height, 32, palette);
for (int i = 0; i < width; i++) {
imageData.setPixel(i, 0, drawnPixel);
imageData.setPixel(i, height - 1, drawnPixel);
}
for (int i = 0; i < height; i++) {
imageData.setPixel(0, i, drawnPixel);
imageData.setPixel(width - 1, i, drawnPixel);
}
return imageData;
}
@Override
public ImageData getImageData(int zoom) {
return new ImageData(1, 1, 32, new PaletteData(0xFF0000, 0xFF00, 0xFF));
}
};
Image image = styleImage(new Image(display, imageDataAtSizeProvider), styleFlag);

try {
gc.drawImage(image, 0, 0, width, height);
int zoom = DPIUtil.getDeviceZoom();
ImageData printedImageData = drawToImage.getImageData(zoom);
PaletteData printedPalette = printedImageData.palette;
RGB styledDrawnRgb = getStyledRgb(drawnRgb, styleFlag);
RGB styledUndrawnRgb = getStyledRgb(undrawnRgb, styleFlag);
assertEquals(styledDrawnRgb, printedPalette.getRGB(printedImageData.getPixel(0, 0)));
assertEquals(styledUndrawnRgb, printedPalette.getRGB(printedImageData.getPixel(1, 1)));
assertEquals(styledUndrawnRgb, printedPalette.getRGB(printedImageData.getPixel(pointToPixel(width, zoom) / 2, pointToPixel(height, zoom) / 2)));
assertEquals(styledUndrawnRgb, printedPalette.getRGB(printedImageData.getPixel(pointToPixel(width, zoom) - 2, pointToPixel(height, zoom) - 2)));
assertEquals(styledDrawnRgb, printedPalette.getRGB(printedImageData.getPixel(pointToPixel(width, zoom) - 4, pointToPixel(height, zoom) - 1)));
} finally {
image.dispose();
drawToImage.dispose();
}
}

private Image styleImage(Image image, int styleFlag) {
if (styleFlag == -1) {
return image;
}
Image styledImage = new Image(display, image, styleFlag);
image.dispose();
return styledImage;
}

private RGB getStyledRgb(RGB rgb, int styleFlag) {
if (styleFlag == -1) {
return rgb;
}
PaletteData palette = new PaletteData(0xFF0000, 0xFF00, 0xFF);
ImageData referenceData = new ImageData(1, 1, 32, palette);
referenceData.setPixel(0, 0, palette.getPixel(rgb));
Image referenceImage = new Image(display, referenceData);
Image styledReferenceImage = new Image(display, referenceImage, styleFlag);
try {
ImageData styledmageData = styledReferenceImage.getImageData();
return styledmageData.palette.getRGB(styledmageData.getPixel(0, 0));
} finally {
styledReferenceImage.dispose();
referenceImage.dispose();
}
}

@Test
public void test_drawLineIIII() {
gc.drawLine(0,0,0,20);
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