SWT(JFace)体验之Canvas（画布）

最新推荐文章于 2021-03-06 23:55:14 发布

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本文通过多个示例介绍如何使用Eclipse SWT进行图形绘制，包括基本形状、图像处理、文字渲染及高级绘图技巧。

说道画图，我们首先要介绍一下SWT的GC类。

package swt_jface.demo10; import org.eclipse.swt.SWT; import org.eclipse.swt.custom.CLabel; import org.eclipse.swt.graphics.GC; import org.eclipse.swt.graphics.Image; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Shell; public class GCCreation { Display display = new Display(); Shell shell = new Shell(display); public GCCreation() { Image image = new Image(display, "C:/icons/eclipse.gif"); Image image2 = new Image(display, image.getImageData()); GC gc = new GC(image2); gc.setForeground(display.getSystemColor(SWT.COLOR_WHITE)); gc.drawOval(10, 10, 90, 40); gc.dispose(); CLabel label = new CLabel(shell, SWT.NULL); label.setImage(image); label.setBounds(10, 10, 130, 130); CLabel label2 = new CLabel(shell, SWT.NULL); label2.setImage(image2); label2.setBounds(150, 10, 130, 130); shell.pack(); shell.open(); while (!shell.isDisposed()) { if (!display.readAndDispatch()) { display.sleep(); } } display.dispose(); } public static void main(String[] args) { new GCCreation(); } }

接下来请参看以下示例：

演示代码1：

package swt_jface.demo10; import org.eclipse.swt.SWT; import org.eclipse.swt.events.PaintEvent; import org.eclipse.swt.events.PaintListener; import org.eclipse.swt.widgets.Canvas; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Shell; public class CanvasExample { Display display = new Display(); Shell shell = new Shell(display); public CanvasExample() { Canvas canvas = new Canvas(shell, SWT.NULL); canvas.setBounds(10, 10, 200, 100); canvas.addPaintListener(new PaintListener() { public void paintControl(PaintEvent e) { e.gc.drawRoundRectangle(10, 10, 180, 80, 10, 10); } }); shell.pack(); shell.open(); while (!shell.isDisposed()) { if (!display.readAndDispatch()) { display.sleep(); } } display.dispose(); } public static void main(String[] args) { new CanvasExample(); } }

演示代码2：(三角)

演示代码3：（动态画布）

package swt_jface.demo10; import org.eclipse.swt.SWT; import org.eclipse.swt.events.PaintEvent; import org.eclipse.swt.events.PaintListener; import org.eclipse.swt.graphics.GC; import org.eclipse.swt.graphics.Image; import org.eclipse.swt.graphics.Point; import org.eclipse.swt.graphics.Rectangle; import org.eclipse.swt.layout.FillLayout; import org.eclipse.swt.widgets.Canvas; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Shell; public class DoubleBuffer { Display display = new Display(); Shell shell = new Shell(display); public DoubleBuffer() { shell.setLayout(new FillLayout()); final Canvas canvas = new Canvas(shell, SWT.NULL); canvas.addPaintListener(new PaintListener() { public void paintControl(PaintEvent e) { Point size = canvas.getSize(); int x1 = (int) (Math.random() * size.x); int y1 = (int) (Math.random() * size.y); int x2 = Math.max(canvas.getBounds().width - x1 - 10, 50); int y2 = Math.max(canvas.getBounds().height - y1 - 10, 50); e.gc.drawRoundRectangle(x1, y1, x2, y2, 5, 5); display.timerExec(100, new Runnable() { public void run() { canvas.redraw(); } }); } }); final Canvas doubleBufferedCanvas = new Canvas(shell, SWT.NO_BACKGROUND); doubleBufferedCanvas.addPaintListener(new PaintListener() { public void paintControl(PaintEvent e) { Image image = (Image) doubleBufferedCanvas.getData("double-buffer-image"); if (image == null || image.getBounds().width != doubleBufferedCanvas.getSize().x || image.getBounds().height != doubleBufferedCanvas.getSize().y) { image = new Image( display, doubleBufferedCanvas.getSize().x, doubleBufferedCanvas.getSize().y); doubleBufferedCanvas.setData("double-buffer-image", image); } GC imageGC = new GC(image); imageGC.setBackground(e.gc.getBackground()); imageGC.setForeground(e.gc.getForeground()); imageGC.setFont(e.gc.getFont()); Rectangle imageSize = image.getBounds(); imageGC.fillRectangle(0, 0, imageSize.width + 1, imageSize.height + 1); Point size = doubleBufferedCanvas.getSize(); int x1 = (int) (Math.random() * size.x); int y1 = (int) (Math.random() * size.y); int x2 = Math.max(doubleBufferedCanvas.getBounds().width - x1 - 10, 50); int y2 = Math.max(doubleBufferedCanvas.getBounds().height - y1 - 10, 50); imageGC.drawRoundRectangle(x1, y1, x2, y2, 5, 5); e.gc.drawImage(image, 0, 0); imageGC.dispose(); display.timerExec(100, new Runnable() { public void run() { doubleBufferedCanvas.redraw(); } }); } }); shell.setSize(300, 200); shell.open(); while (!shell.isDisposed()) { if (!display.readAndDispatch()) { display.sleep(); } } display.dispose(); } public static void main(String[] args) { new DoubleBuffer(); } }

演示代码4：（图片）

演示代码5：（画线）

package swt_jface.demo10; import org.eclipse.swt.SWT; import org.eclipse.swt.events.PaintEvent; import org.eclipse.swt.events.PaintListener; import org.eclipse.swt.layout.FillLayout; import org.eclipse.swt.widgets.Canvas; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Shell; public class Drawings { Display display = new Display(); Shell shell = new Shell(display); public Drawings() { shell.setLayout(new FillLayout()); Canvas canvas = new Canvas(shell, SWT.BORDER); canvas.setBackground(display.getSystemColor(SWT.COLOR_WHITE)); canvas.addPaintListener(new PaintListener() { public void paintControl(PaintEvent e) { e.gc.drawString("SWT.LINE_SOLID (default)", 10, 10); e.gc.drawString("SWT.LINE_DASH", 10, 30); e.gc.drawString("SWT.LINE_DOT", 10, 50); e.gc.drawString("SWT.LINE_DASHDOT", 10, 70); e.gc.drawString("SWT.LINE_DASHDOTDOT", 10, 90); e.gc.drawString("Line width = 1 (default)", 10, 120); e.gc.drawString("Line width = 3", 10, 140); int start = 150; e.gc.setLineWidth(1); e.gc.setLineStyle(SWT.LINE_SOLID); e.gc.drawLine(start, 15, start + 200, 15); e.gc.setLineStyle(SWT.LINE_DASH); e.gc.drawLine(start, 35, start + 200, 35); e.gc.setLineStyle(SWT.LINE_DOT); e.gc.drawLine(start, 55, start + 200, 55); e.gc.setLineStyle(SWT.LINE_DASHDOT); e.gc.drawLine(start, 75, start + 200, 75); e.gc.setLineStyle(SWT.LINE_DASHDOTDOT); e.gc.drawLine(start, 95, start + 200, 95); e.gc.setLineStyle(SWT.LINE_SOLID); e.gc.drawLine(start, 125, start + 200, 125); e.gc.setLineWidth(3); e.gc.drawLine(start, 145, start + 200, 145); int[] points = new int[3 * 2]; points[0] = 10; points[1] = 10; points[2] = 10; points[3] = 100; points[4] = 100; points[5] = 100; e.gc.drawPolyline(points); e.gc.setLineStyle(SWT.LINE_SOLID); e.gc.setBackground(display.getSystemColor(SWT.COLOR_DARK_GREEN)); e.gc.fillArc(10, 10, 200, 100, 0, -90); e.gc.setLineStyle(SWT.LINE_DOT); e.gc.drawLine(0, 60, 220, 60); e.gc.drawLine(110, 0, 110, 120); } }); shell.pack(); shell.open(); while (!shell.isDisposed()) { if (!display.readAndDispatch()) { display.sleep(); } } display.dispose(); } public static void main(String[] args) { new Drawings(); } }

演示代码6：（文本效果）

演示代码7：（T型）

package swt_jface.demo10; import org.eclipse.swt.SWT; import org.eclipse.swt.events.PaintEvent; import org.eclipse.swt.events.PaintListener; import org.eclipse.swt.graphics.Image; import org.eclipse.swt.graphics.ImageData; import org.eclipse.swt.graphics.PaletteData; import org.eclipse.swt.graphics.RGB; import org.eclipse.swt.layout.FillLayout; import org.eclipse.swt.widgets.Canvas; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Shell; public class Palettes { Display display = new Display(); Shell shell = new Shell(display); public Palettes() { shell.setLayout(new FillLayout()); PaletteData paletteData = new PaletteData(0xFF0000, 0x00FF00, 0x0000FF); ImageData imageData = new ImageData(100, 100, 24, paletteData); for (int i = 0; i < 100; i++) { // each column. for (int j = 0; j < 100; j++) { // each row. if (j < 30 || (i > 35 && i < 65)) imageData.setPixel(i, j, 0xFF); else imageData.setPixel(i, j, 0xFFFF00); } } // int pixelValue = imageData.getPixel(50, 50); // int redComponent = pixelValue & imageData.palette.redMask; // int greenComponent = pixelValue & imageData.palette.greenMask; // int blueComponent = pixelValue & imageData.palette.blueMask; PaletteData paletteData2 = new PaletteData(new RGB[] { new RGB(0, 0, 255), // blue new RGB(255, 255, 0) // yellow }); ImageData imageData2 = new ImageData(100, 100, 1, paletteData2); for (int i = 0; i < 100; i++) { // each column. for (int j = 0; j < 100; j++) { // each row. if (j < 30 || (i > 35 && i < 65)) imageData2.setPixel(i, j, 0); else imageData2.setPixel(i, j, 1); } } System.out.println(imageData.palette.getRGB(imageData.getPixel(50, 50))); final Image image2 = new Image(display, imageData2); //final Image image = new Image(display, imageData); final Canvas canvas = new Canvas(shell, SWT.NULL); canvas.setBackground(display.getSystemColor(SWT.COLOR_WHITE)); canvas.addPaintListener(new PaintListener() { public void paintControl(PaintEvent e) { e.gc.drawImage(image2, 0, 0); } }); shell.pack(); shell.open(); while (!shell.isDisposed()) { if (!display.readAndDispatch()) { display.sleep(); } } display.dispose(); } public static void main(String[] args) { new Palettes(); } }

演示代码8：（三环）

演示代码9：（Transparency）