Java Tutorial/SWT 2D Graphics/Line

Draw a thick line

   <source lang="java">

import org.eclipse.swt.graphics.GC; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Shell; public class ThickLinkDraw {

 public static void main(String[] args) {
   Display display = new Display();
   Shell shell = new Shell(display);
   shell.open();
   GC gc = new GC(shell);
   gc.setLineWidth(4);
   gc.drawRectangle(20, 20, 100, 100);
   gc.dispose();
   while (!shell.isDisposed()) {
     if (!display.readAndDispatch())
       display.sleep();
   }
   display.dispose();
 }

}</source>

Drawing multiple lines

   <source lang="java">

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 DrawMultipleLine {

 public static void main(String[] args) {
   Display display = new Display();
   Shell shell = new Shell(display);
   shell.setText("Canvas Example");
   shell.setLayout(new FillLayout());
   Canvas canvas = new Canvas(shell, SWT.NONE);
   canvas.addPaintListener(new PaintListener() {
     public void paintControl(PaintEvent e) {
       e.gc.setLineWidth(4);
       int[] points = { 0, 0, 100, 0, 0, 100, 100, 100, 0, 200};
       e.gc.drawPolyline(points);
     }
   });
   shell.open();
   while (!shell.isDisposed()) {
     if (!display.readAndDispatch()) {
       display.sleep();
     }
   }
   display.dispose();
 }

}</source>

Drawing Points, Lines and set line width

drawLine() takes four integers that define two Cartesian points, relative to the upper-left corner of the component.

   <source lang="java">

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 DrawPointLineWidth {

 public static void main(String[] args) {
   Display display = new Display();
   Shell shell = new Shell(display);
   shell.setText("Canvas Example");
   shell.setLayout(new FillLayout());
   Canvas canvas = new Canvas(shell, SWT.NONE);
   canvas.addPaintListener(new PaintListener() {
     public void paintControl(PaintEvent e) {
       Canvas canvas = (Canvas) e.widget;
       int maxX = canvas.getSize().x;
       int maxY = canvas.getSize().y;
       int halfX = (int) maxX/2;
       int halfY = (int) maxY/2;
       e.gc.setForeground(e.display.getSystemColor(SWT.COLOR_BLUE));
       e.gc.setLineWidth(10);
       e.gc.drawLine(halfX, 0, halfX, maxY);
       e.gc.drawLine(0, halfY, maxX, halfY);
     }
   });
   shell.open();
   while (!shell.isDisposed()) {
     if (!display.readAndDispatch()) {
       display.sleep();
     }
   }
   display.dispose();
 }

}</source>

Draw line

   <source lang="java">

import org.eclipse.swt.graphics.GC; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Shell; public class DrawLine {

 public static void main(String[] args) {
   Display display = new Display();
   Shell shell = new Shell(display);
   shell.open();
   GC gc = new GC(shell);
   gc.drawLine(0, 0, 19, 19);
   gc.drawLine(19, 0, 0, 19);
   gc.dispose();
   while (!shell.isDisposed()) {
     if (!display.readAndDispatch())
       display.sleep();
   }
   display.dispose();
 }

}</source>

Line Join Style: JOIN_BEVEL, JOIN_MITER, JOIN_ROUND

   <source lang="java">

import org.eclipse.swt.SWT; import org.eclipse.swt.graphics.GC; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Event; import org.eclipse.swt.widgets.Listener; import org.eclipse.swt.widgets.Shell; public class LineJoinStyleBevelMiterRound {

 public static void main(String[] args) {
   final Display display = new Display();
   Shell shell = new Shell(display);
   shell.addListener(SWT.Paint, new Listener() {
     public void handleEvent(Event event) {
       int x = 20, y = 20, w = 120, h = 60;
       GC gc = event.gc;
       gc.setForeground(display.getSystemColor(SWT.COLOR_BLUE));
       gc.setLineWidth(10);
       
       int[] joins = { SWT.JOIN_BEVEL, SWT.JOIN_MITER, SWT.JOIN_ROUND };
       for (int i = 0; i < joins.length; i++) {
         gc.setLineJoin(joins[i]);
         gc.drawPolygon(new int[] { x, y, x + w / 2, y + h, x + w, y });
         y += h + 20;
       }
     }
   });
   shell.open();
   while (!shell.isDisposed()) {
     if (!display.readAndDispatch())
       display.sleep();
   }
   display.dispose();
 }

}</source>

Setting Line caps

   <source lang="java">

import org.eclipse.swt.SWT; import org.eclipse.swt.graphics.GC; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Event; import org.eclipse.swt.widgets.Listener; import org.eclipse.swt.widgets.Shell; public class LineCapsSetting {

 public static void main(String[] args) {
   final Display display = new Display();
   Shell shell = new Shell(display);
   shell.addListener(SWT.Paint, new Listener() {
     public void handleEvent(Event event) {
       int x = 20, y = 20, w = 120, h = 60;
       GC gc = event.gc;
       gc.setForeground(display.getSystemColor(SWT.COLOR_BLUE));
       gc.setLineWidth(10);
       int[] caps = { SWT.CAP_FLAT, SWT.CAP_ROUND, SWT.CAP_SQUARE };
       for (int i = 0; i < caps.length; i++) {
         gc.setLineCap(caps[i]);
         gc.drawLine(x, y, x + w, y);
         y += 20;
       }
     }
   });
   shell.open();
   while (!shell.isDisposed()) {
     if (!display.readAndDispatch())
       display.sleep();
   }
   display.dispose();
 }

}</source>