+ * This example provides a graphical user interface that allows users to select + * from several different {@link org.eclipse.swt.graphics.Cursor} constructors, + * showing the resulting cursor in real time on the application shell. It also + * dynamically updates to reflect changes in system DPI scaling (zoom), + * displaying the expected cursor size and drawing a set of reference ticks to + * help visualize scaling. + *
+ * Features of this snippet include: + *
+ * For a list of all SWT example snippets see + * http://www.eclipse.org/swt/snippets/ + *
+ */ +public class Snippet386 { + + private static final int IMAGE_SIZE_IN_POINTS = 16; + + public static void main(String[] args) { + Display display = new Display(); + Shell shell = createShell(display); + + Combo combo = createConstructorCombo(shell); + Label zoomLabel = createZoomLabel(shell); + + addZoomChangedListener(shell, zoomLabel); + Group section = new Group(shell, SWT.NONE); + section.setText("Scale"); + section.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true)); + section.setLayout(new FillLayout()); + addPaintTicks(section); + + CursorManager cursorManager = new CursorManager(display, shell, combo); + combo.addListener(SWT.Selection, e -> cursorManager.updateCursor()); + cursorManager.updateCursor(); + + shell.setSize(400, 400); + shell.open(); + + eventLoop(display, shell); + display.dispose(); + } + + private static Shell createShell(Display display) { + Shell shell = new Shell(display); + shell.setText("Snippet 386"); + shell.setLayout(new GridLayout(1, false)); + return shell; + } + + private static Combo createConstructorCombo(Composite parent) { + Label label = new Label(parent, SWT.NONE); + label.setText("Choose Cursor Constructor:"); + + Combo combo = new Combo(parent, SWT.READ_ONLY); + combo.setItems("Cursor(Device, int)", "Cursor(Device, ImageData, ImageData, int, int)", + "Cursor(Device, ImageData, int, int)", "Cursor(Device, ImageDataProvider, int, int)"); + combo.select(0); + return combo; + } + + private static Label createZoomLabel(Shell parent) { + Label zoomLabel = new Label(parent, SWT.NONE); + zoomLabel.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false)); + setZoomLabelText(parent, zoomLabel); + return zoomLabel; + } + + private static void setZoomLabelText(Shell shell, Label label) { + int zoom = shell.getMonitor().getZoom(); + int expectedCursorSize = Math.round(IMAGE_SIZE_IN_POINTS * (zoom / 100f)); + label.setText("Current zoom: " + zoom + "% \nExpected Cursor Size = " + expectedCursorSize); + } + + private static void addZoomChangedListener(Shell shell, Label zoomLabel) { + shell.addListener(SWT.Resize, event -> { + setZoomLabelText(shell, zoomLabel); + shell.layout(); + }); + } + + private static void addPaintTicks(Composite composite) { + composite.addPaintListener(event -> { + drawTicks(composite, event.gc); + }); + } + + private static void drawTicks(Composite shell, GC gc) { + int deviceZoom = shell.getMonitor().getZoom(); + float devScale = deviceZoom / 100f; + Point client = shell.getSize(); + int xPos = (int) ((client.x / 2) - (6 * (IMAGE_SIZE_IN_POINTS / devScale))); + int tickHeight = 10; + int yPos = 20; + + for (int tickIndex = 0; tickIndex < 6; tickIndex++) { + xPos += (IMAGE_SIZE_IN_POINTS / devScale); + int yOffset = (tickIndex % 3 == 1) ? 20 : (tickIndex % 3 == 2) ? 40 : 0; + + gc.drawLine(xPos, yPos, xPos, yPos + tickHeight); + gc.drawText(Integer.toString(tickIndex * IMAGE_SIZE_IN_POINTS), xPos - 5, yPos + 12 + yOffset); + } + } + + private static void eventLoop(Display display, Shell shell) { + while (!shell.isDisposed()) { + if (!display.readAndDispatch()) + display.sleep(); + } + } + + public static ImageData createSolidColorImageData(int size, RGB color) { + PaletteData palette = new PaletteData(0xFF0000, 0x00FF00, 0x0000FF); + ImageData imageData = new ImageData(size, size, 24, palette); + + int pixel = palette.getPixel(color); + for (int y = 0; y < size; y++) { + for (int x = 0; x < size; x++) { + imageData.setPixel(x, y, pixel); + } + } + return imageData; + } + + private static class CursorManager { + private final Display display; + private final Shell shell; + private final Combo combo; + + CursorManager(Display display, Shell shell, Combo combo) { + this.display = display; + this.shell = shell; + this.combo = combo; + } + + void updateCursor() { + int selection = combo.getSelectionIndex(); + Cursor oldCursor = shell.getCursor(); + if (oldCursor != null && !oldCursor.isDisposed()) { + oldCursor.dispose(); + } + Cursor cursor = createCursor(selection); + if (cursor != null) { + shell.setCursor(cursor); + } + } + + private Cursor createCursor(int selection) { + switch (selection) { + case 0: + return new Cursor(display, SWT.CURSOR_HAND); + case 1: { + PaletteData rgbPalette = new PaletteData(0xFF0000, 0x00FF00, 0x0000FF); + int bluePixel = rgbPalette.getPixel(new RGB(0, 0, 255)); + ImageData source = new ImageData(IMAGE_SIZE_IN_POINTS, IMAGE_SIZE_IN_POINTS, 24, + new PaletteData(0xFF0000, 0x00FF00, 0x0000FF)); + + for (int x = 0; x < IMAGE_SIZE_IN_POINTS; x++) { + for (int y = 0; y < IMAGE_SIZE_IN_POINTS; y++) { + source.setPixel(x, y, bluePixel); + } + } + + ImageData mask = new ImageData(IMAGE_SIZE_IN_POINTS, IMAGE_SIZE_IN_POINTS, 1, + new PaletteData(new RGB[] { new RGB(0, 0, 0), new RGB(255, 255, 255) })); + for (int x = 0; x < IMAGE_SIZE_IN_POINTS; x++) { + for (int y = 0; y < IMAGE_SIZE_IN_POINTS; y++) { + mask.setPixel(x, y, x % 2); + } + } + + return new Cursor(display, source, mask, IMAGE_SIZE_IN_POINTS / 2, IMAGE_SIZE_IN_POINTS / 2); + } + case 2: + RGB red = new RGB(255, 0, 0); + return new Cursor(display, createSolidColorImageData(IMAGE_SIZE_IN_POINTS, red), 0, 0); + + case 3: { + RGB green = new RGB(0, 255, 0); + ImageDataProvider provider = zoom -> { + return createSolidColorImageData(IMAGE_SIZE_IN_POINTS * zoom / 100, green); + }; + return new Cursor(display, provider, 0, 0); + } + default: + return null; + } + } + } +} \ No newline at end of file