使用指针事件在Canvas上绘画 |
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| 作者：j2medev 来源：j2medev.com 发布时间：2006-7-25 8:39:38 | ||
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import javax.microedition.midlet.*; import javax.microedition.lcdui.*; public class Doodle extends MIDlet { private Display display; // The display private DoodleCanvas canvas; // Canvas public Doodle() { display = Display.getDisplay(this); canvas = new DoodleCanvas(this); } protected void startApp() { display.setCurrent( canvas ); } protected void pauseApp() { } protected void destroyApp( boolean unconditional ) { } public void exitMIDlet() { destroyApp(true); notifyDestroyed(); } } /*-------------------------------------------------- * Class DoodleCanvas * * Pointer event handling *-------------------------------------------------*/ class DoodleCanvas extends Canvas implements CommandListener { private Command cmExit; // Exit midlet private Command cmClear; // Clear display private int startx = 0, // Where pointer was clicked starty = 0, currentx = 0, // Current location currenty = 0; private Doodle midlet; private boolean clearDisplay = false; /*-------------------------------------------------- * Constructor *-------------------------------------------------*/ public DoodleCanvas(Doodle midlet) { this.midlet = midlet; // Create exit command & listen for events cmExit = new Command("Exit", Command.EXIT, 1); cmClear = new Command("Clear", Command.SCREEN, 1); addCommand(cmExit); addCommand(cmClear); setCommandListener(this); } /*-------------------------------------------------- * Paint the text representing the key code *-------------------------------------------------*/ protected void paint(Graphics g) { // Clear the background (to white) if (clearDisplay) { g.setColor(255, 255, 255); g.fillRect(0, 0, getWidth(), getHeight()); clearDisplay = false; startx = currentx = starty = currenty = 0; return; } // Draw with black pen g.setColor(0, 0, 0); // Draw line g.drawLine(startx, starty, currentx, currenty); // New starting point is the current position startx = currentx; starty = currenty; } /*-------------------------------------------------- * Command event handling *-------------------------------------------------*/ public void commandAction(Command c, Displayable d) { if (c == cmExit) midlet.exitMIDlet(); else if (c == cmClear) { clearDisplay = true; repaint(); } } /*-------------------------------------------------- * Pointer pressed *-------------------------------------------------*/ protected void pointerPressed(int x, int y) { startx = x; starty = y; } /*-------------------------------------------------- * Pointer moved *-------------------------------------------------*/ protected void pointerDragged(int x, int y) { currentx = x; currenty = y; repaint(); } } |
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