Snippet for demonstrating Cropping and Scaling of GC#drawImage

examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet389.java

@@ -0,0 +1,177 @@
+/*******************************************************************************
+ * Copyright (c) 2025 IBM Corporation and others.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+
+package org.eclipse.swt.snippets;
+
+import org.eclipse.swt.*;
+import org.eclipse.swt.graphics.*;
+import org.eclipse.swt.layout.*;
+import org.eclipse.swt.widgets.*;
+
+public class Snippet389 {
+
+	private static final String IMAGE_100 = "workset_wiz150.png";
+	private static final String IMAGE_200 = "workset_wiz300.png";
+	private static final String IMAGES_ROOT = "resources/Snippet388/";
+
+	private static final String IMAGE_PATH_100 = IMAGES_ROOT + IMAGE_100;
+	private static final String IMAGE_PATH_200 = IMAGES_ROOT + IMAGE_200;
+
+	static int srcX, srcY, srcW, srcH;
+	static int dstX, dstY, dstW, dstH;
+
+	public static void main(String[] args) {
+
+		ImageFileNameProvider filenameProvider = zoom -> {
+			switch (zoom) {
+				case 100:
+					return IMAGE_PATH_100;
+				case 200:
+					return IMAGE_PATH_200;
+				default:
+					return null;
+			}
+		};
+
+		Display display = new Display();
+		Shell shell = new Shell(display);
+		shell.setText("GC#drawImage Interactive");
+		shell.setLayout(new GridLayout(2, false));
+
+		Image image = new Image(display, filenameProvider);
+		Rectangle imgBounds = image.getBounds();
+
+		final int fixedDstW = imgBounds.width * 2;
+		final int fixedDstH = imgBounds.height * 2;
+		srcX = imgBounds.width / 2;
+		srcY = imgBounds.height / 2;
+		srcW = imgBounds.width / 2;
+		srcH = imgBounds.height / 2;
+
+		dstX = 0;
+		dstY = 0;
+		dstW = imgBounds.width;
+		dstH = imgBounds.height;
+
+		Group controls = new Group(shell, SWT.NONE);
+		controls.setText("GC#drawImage Arguments");
+		controls.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, true));
+		controls.setLayout(new GridLayout(2, false));
+
+		Text tSrcX = field(controls, "srcX", srcX);
+		Text tSrcY = field(controls, "srcY", srcY);
+		Text tSrcW = field(controls, "srcWidth", srcW);
+		Text tSrcH = field(controls, "srcHeight", srcH);
+
+		Text tDstX = field(controls, "destX", dstX);
+		Text tDstY = field(controls, "destY", dstY);
+		Text tDstW = field(controls, "destWidth", dstW);
+		Text tDstH = field(controls, "destHeight", dstH);
+
+		Button apply = new Button(controls, SWT.PUSH);
+		apply.setText("Apply");
+		apply.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false, 2, 1));
+
+		Composite draw = new Composite(shell, SWT.NONE);
+		draw.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+		draw.setLayout(new GridLayout(2, true));
+
+		Canvas srcCanvas = new Canvas(draw, SWT.BORDER);
+		srcCanvas.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+		srcCanvas.addListener(SWT.Paint, e -> {
+			GC gc = e.gc;
+			Rectangle ca = srcCanvas.getClientArea();
+
+			int ix = (ca.width - imgBounds.width) / 2;
+			int iy = (ca.height - imgBounds.height) / 2;
+
+			gc.drawImage(image, ix, iy);
+
+			gc.setLineStyle(SWT.LINE_DASH);
+			gc.setForeground(display.getSystemColor(SWT.COLOR_BLACK));
+			gc.drawRectangle(ix, iy, imgBounds.width, imgBounds.height);
+
+			gc.setForeground(display.getSystemColor(SWT.COLOR_RED));
+			gc.setLineWidth(2);
+			gc.drawRectangle(ix + srcX, iy + srcY, srcW, srcH);
+		});
+
+		Canvas dstCanvas = new Canvas(draw, SWT.BORDER);
+		dstCanvas.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+		dstCanvas.addListener(SWT.Paint, e -> {
+			GC gc = e.gc;
+			Rectangle ca = dstCanvas.getClientArea();
+
+			int px = (ca.width - fixedDstW) / 2;
+			int py = (ca.height - fixedDstH) / 2;
+
+			gc.drawImage(
+				image,
+				srcX, srcY, srcW, srcH,
+				px + dstX, py + dstY,
+				dstW, dstH
+			);
+
+			gc.setLineStyle(SWT.LINE_DASH);
+			gc.setForeground(display.getSystemColor(SWT.COLOR_BLACK));
+			gc.drawRectangle(px, py, fixedDstW, fixedDstH);
+
+			gc.setForeground(display.getSystemColor(SWT.COLOR_RED));
+			gc.setLineWidth(2);
+			gc.drawRectangle(px + dstX, py + dstY, dstW, dstH);
+		});
+
+		Label srcLabel = new Label(draw, SWT.CENTER);
+		srcLabel.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));
+		srcLabel.setText("150 x 150");
+
+		Label dstLabel = new Label(draw, SWT.CENTER);
+		dstLabel.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));
+		dstLabel.setText("300 x 300");
+
+		apply.addListener(SWT.Selection, e -> {
+			srcX = parse(tSrcX);
+			srcY = parse(tSrcY);
+			srcW = parse(tSrcW);
+			srcH = parse(tSrcH);
+
+			dstX = parse(tDstX);
+			dstY = parse(tDstY);
+			dstW = parse(tDstW);
+			dstH = parse(tDstH);
+
+			srcCanvas.redraw();
+			dstCanvas.redraw();
+		});
+
+		shell.setSize(1000, 600);
+		shell.open();
+
+		while (!shell.isDisposed()) {
+			if (!display.readAndDispatch())
+				display.sleep();
+		}
+
+		image.dispose();
+		display.dispose();
+	}
+
+	static Text field(Composite parent, String label, int value) {
+		new Label(parent, SWT.NONE).setText(label);
+		Text t = new Text(parent, SWT.BORDER);
+		t.setText(String.valueOf(value));
+		t.setLayoutData(new GridData(70, SWT.DEFAULT));
+		return t;
+	}
+
+	static int parse(Text t) {
+		try {
+			return Integer.parseInt(t.getText());
+		} catch (NumberFormatException e) {
+			return 0;
+		}
+	}
+}