Extend Snippet389 to use all GC.drawImage methods

This commit extends Snippet389 to show the results using all drawImage
methods in GC. As not all methods will use all configuration option
(e.g. only one methods supports drawing a cropped part of an image),
changing parameters does not always affect all results.

Author: akoch-yatta

examples/org.eclipse.swt.snippets/previews/Snippet389.png

@@ -19,11 +19,17 @@
 /*
  * Demonstrates cropping and scaling of images using a GC
  *
- * The GC provides two relevant drawImage methods: one that scales an entire
- * image to a destination rectangle, and another that crops a source region and
- * scales it to the destination. The snippet allows to select any source area
- * of an image and draw it to a specific target size. Additionally you can scale
- * it additionally to the selected target size and rotate the image.
+ * The GC provides three drawImage methods: one that draws an image at a target
+ * destination, one that scales an entire image to a destination rectangle, and
+ * another that crops a source region and scales it to the destination. The snippet
+ * allows to select any source area of an image and draw it to a specific target
+ * size. Additionally you can scale it additionally to the selected target size and
+ * rotate the image.
+ *
+ * The snippet will draw the result with all three drawImage methods.
+ * As not all methods will use all configuration option (e.g. only one methods supports
+ * drawing a cropped part of an image), changing parameters does not always affect all
+ * results.
  *
  * This snippet allows experimenting with different source and destination
  * values for the second method. Within the method, the GC receives the
@@ -60,7 +66,7 @@ public static void main(String[] args) {
 		shell.setText("GC#drawImage Interactive");
 
 		new CropImageView(shell, image);
-		shell.setSize(1000, 600);
+		shell.setSize(1000, 800);
 		shell.open();
 
 		while (!shell.isDisposed()) {
@@ -76,15 +82,17 @@ private static class CropImageView extends Composite {
 
 		private Image image;
 		private int srcX, srcY, srcW, srcH;
-		private int dstX, dstY, dstW, dstH;
+		private int dstW, dstH;
 		private float transformationScale;
 		private int transformationRotation;
 		private Text textSrcX, textSrcY, textSrcW, textSrcH;
-		private Text textDstX, textDstY, textDstW, textDstH;
+		private Text textDstW, textDstH;
 		private Text textScale;
 		private Slider rotationSlider;
 		private Canvas srcCanvas;
-		private Canvas dstCanvas;
+		private Canvas dstCanvas1;
+		private Canvas dstCanvas2;
+		private Canvas dstCanvas3;
 
 		public CropImageView(Composite parent, Image image) {
 			super(parent, SWT.None);
@@ -96,16 +104,11 @@ private void init() {
 			setLayout(new GridLayout(2, false));
 
 			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;
 
@@ -122,8 +125,6 @@ private void init() {
 			textSrcW = field(controls, "srcWidth", srcW);
 			textSrcH = field(controls, "srcHeight", srcH);
 
-			textDstX = field(controls, "destX", dstX);
-			textDstY = field(controls, "destY", dstY);
 			textDstW = field(controls, "destWidth", dstW);
 			textDstH = field(controls, "destHeight", dstH);
 
@@ -138,7 +139,13 @@ private void init() {
 			draw.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
 			draw.setLayout(new GridLayout(2, true));
 
-			srcCanvas = new Canvas(draw, SWT.BORDER);
+			Group srcCanvasGroup = new Group(draw, SWT.NONE);
+			srcCanvasGroup.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+			srcCanvasGroup.setLayout(new GridLayout(1, true));
+			Label labelSrcCanvas = new Label(srcCanvasGroup, SWT.NONE);
+			labelSrcCanvas.setText("Source Image");
+			labelSrcCanvas.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));
+			srcCanvas = new Canvas(srcCanvasGroup, SWT.NONE);
 			srcCanvas.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
 			srcCanvas.addListener(SWT.Paint, e -> {
 				try {
@@ -167,61 +174,108 @@ private void init() {
 				}
 			});
 
-			dstCanvas = new Canvas(draw, SWT.BORDER);
+			Group dstCanvas1Group = new Group(draw, SWT.NONE);
+			dstCanvas1Group.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+			dstCanvas1Group.setLayout(new GridLayout(1, true));
+			Label labelDstCanvas1 = new Label(dstCanvas1Group, SWT.WRAP);
+			labelDstCanvas1.setText("GC#drawImage(Image, int, int) - Scale Factor and Rotation (no crop)");
+			labelDstCanvas1.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));
+			dstCanvas1 = initDestinationCanvas(dstCanvas1Group, 1, false);
+
+
+			Group dstCanvas2Group = new Group(draw, SWT.NONE);
+			dstCanvas2Group.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+			dstCanvas2Group.setLayout(new GridLayout(1, true));
+			Label labelDstCanvas2 = new Label(dstCanvas2Group, SWT.WRAP);
+			labelDstCanvas2.setText("GC#drawImage(Image, int, int, int, int) - destWidth, destHeight, Scale Factor and Rotation (no crop)");
+			labelDstCanvas2.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));
+			dstCanvas2 = initDestinationCanvas(dstCanvas2Group, 2, true);
+
+			Group dstCanvas3Group = new Group(draw, SWT.NONE);
+			dstCanvas3Group.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+			dstCanvas3Group.setLayout(new GridLayout(1, true));
+			Label labelDstCanvas3 = new Label(dstCanvas3Group, SWT.WRAP);
+			labelDstCanvas3.setText("GC#drawImage(Image, int, int, int, int, int, int, int, int) - All");
+			labelDstCanvas3.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));
+			dstCanvas3 = initDestinationCanvas(dstCanvas3Group, 3, true);
+
+			apply.addListener(SWT.Selection, e -> refreshView());
+		}
+
+		private Canvas initDestinationCanvas(Composite parent, int drawingMode, boolean scalableAPI) {
+			Canvas dstCanvas = new Canvas(parent, SWT.NONE);
 			dstCanvas.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
 			dstCanvas.addListener(SWT.Paint, e -> {
 				try {
 					GC gc = e.gc;
 					Rectangle ca = dstCanvas.getClientArea();
-
-					int px = (ca.width - fixedDstW) / 2;
-					int py = (ca.height - fixedDstH) / 2;
-					Transform translationTransform = new Transform(getDisplay());
-					translationTransform.translate(px + dstX, py + dstY);
-
-					translationTransform.translate(fixedDstW / 2f, fixedDstH / 2f);
-					if (transformationScale > 1) {
-						translationTransform.scale(transformationScale, transformationScale);
-					}
-					if (transformationRotation != 0) {
-						translationTransform.rotate(transformationRotation);
+					Rectangle imgBounds = image.getBounds();
+					switch (drawingMode) {
+						case 1: {
+							float imageBoundsX = imgBounds.width * transformationScale;
+							float imageBoundsY = imgBounds.height * transformationScale;
+							int px = Math.round((ca.width - imgBounds.width * transformationScale) / 2f);
+							int py = Math.round((ca.height - imgBounds.height * transformationScale) / 2f);
+							prepareTransform(gc, px, py, imageBoundsX, imageBoundsY);
+							gc.drawImage(image, 0, 0);
+							gc.setLineStyle(SWT.LINE_DASH);
+							gc.setForeground(getDisplay().getSystemColor(SWT.COLOR_BLACK));
+							gc.drawRectangle(0, 0, imgBounds.width, imgBounds.height);
+							break;
+						}
+						case 2: {
+							float imageBoundsX = dstW * transformationScale;
+							float imageBoundsY = dstH * transformationScale;
+							int px = Math.round((ca.width - dstW * transformationScale) / 2f);
+							int py = Math.round((ca.height - dstH * transformationScale) / 2f);
+							prepareTransform(gc, px, py, imageBoundsX, imageBoundsY);
+							gc.drawImage(image, 0, 0, dstW, dstH);
+							gc.setLineStyle(SWT.LINE_DASH);
+							gc.setForeground(getDisplay().getSystemColor(SWT.COLOR_BLACK));
+							gc.drawRectangle(0, 0, dstW, dstH);
+							break;
+						}
+						case 3: {
+							float imageBoundsX = dstW * transformationScale;
+							float imageBoundsY = dstH * transformationScale;
+							int px = Math.round((ca.width - dstW * transformationScale) / 2f);
+							int py = Math.round((ca.height - dstH * transformationScale) / 2f);
+							prepareTransform(gc, px, py, imageBoundsX, imageBoundsY);
+							gc.drawImage(image, srcX, srcY, srcW, srcH, 0, 0, dstW, dstH);
+							gc.setLineStyle(SWT.LINE_DASH);
+							gc.setForeground(getDisplay().getSystemColor(SWT.COLOR_BLACK));
+							gc.drawRectangle(0, 0, dstW, dstH);
+							gc.setForeground(getDisplay().getSystemColor(SWT.COLOR_RED));
+							gc.setLineWidth(1);
+							gc.drawRectangle(0, 0, dstW, dstH);
+							break;
+						}
+						default:
+							throw new IllegalArgumentException("Unexpected value: " + drawingMode);
 					}
-					translationTransform.translate(-fixedDstW / 2f, -fixedDstH / 2f);
-					gc.setTransform(translationTransform);
 
-					Rectangle imageBounds = image.getBounds();
-					if (imageBounds.equals(new Rectangle(srcX, srcY, srcW, srcH))) {
-						gc.drawImage(image, 0, 0, dstW, dstH);
-					} else {
-						gc.drawImage(image, srcX, srcY, srcW, srcH, 0, 0, dstW, dstH);
-					}
 
-					gc.setLineStyle(SWT.LINE_DASH);
-					gc.setForeground(getDisplay().getSystemColor(SWT.COLOR_BLACK));
-					gc.drawRectangle(0, 0, fixedDstW, fixedDstH);
-
-					gc.setForeground(getDisplay().getSystemColor(SWT.COLOR_RED));
-					gc.setLineWidth(2);
-					gc.drawRectangle(0, 0, dstW, dstH);
 				} catch (Exception ex) {
 					MessageBox box = new MessageBox(getShell());
 					box.setText("Invalid values");
 					box.setMessage("There seem to be invalid value, the images cannot be drawn.");
 					box.open();
 				}
 			});
+			return dstCanvas;
+		}
 
-			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 -> {
-				refreshView();
-			});
+		private void prepareTransform(GC gc,  int offestX, int offsetY, float imageBoundsX, float imageBoundsY) {
+			Transform translationTransform = new Transform(getDisplay());
+			translationTransform.translate(offestX + imageBoundsX/2, offsetY + imageBoundsY/2);
+			if (transformationScale > 1) {
+				translationTransform.scale(transformationScale, transformationScale);
+			}
+			if (transformationRotation != 0) {
+				translationTransform.rotate(transformationRotation);
+			}
+			translationTransform.translate(-imageBoundsX/2/transformationScale, -imageBoundsY/2/transformationScale);
+			gc.setTransform(translationTransform);
 		}
 
 		private void refreshView() {
@@ -230,16 +284,16 @@ private void refreshView() {
 			srcW = parseInt(textSrcW);
 			srcH = parseInt(textSrcH);
 
-			dstX = parseInt(textDstX);
-			dstY = parseInt(textDstY);
 			dstW = parseInt(textDstW);
 			dstH = parseInt(textDstH);
 
 			transformationScale = parseFloat(textScale);
 			transformationRotation = rotationSlider.getSelection();
 
 			srcCanvas.redraw();
-			dstCanvas.redraw();
+			dstCanvas1.redraw();
+			dstCanvas2.redraw();
+			dstCanvas3.redraw();
 		}
 
 		Text field(Composite parent, String label, Number value) {