2.0 Touch Screen Games — Java Midp

protected void pointerDragged(int x, int y) touchX = x; touchY = y; onTouchDrag(x, y);

private int startX, startY; public void pointerPressed(int x, int y) startX = x; startY = y; public void pointerReleased(int x, int y) int dx = x - startX, dy = y - startY; if (Math.abs(dx) > Math.abs(dy) && Math.abs(dx) > 20) if (dx > 0) swipeRight(); else swipeLeft(); else if (Math.abs(dy) > 20) if (dy > 0) swipeDown(); else swipeUp();

protected void pointerPressed(int x, int y) touching = true; touchX = x; touchY = y; onTouchDown(x, y);

protected void paint(Graphics g) // Draw game, e.g. draw button if touching if (touching) g.setColor(0xFF0000); g.fillRect(touchX-10, touchY-10, 20, 20); java midp 2.0 touch screen games

Handle touch input by converting screen → virtual coordinates before game logic. | Problem | Cause | Fix | |--------|-------|-----| | Touch not detected | No pointer events supported | Add vendor API fallback or emulate via keypad | | Slow drag | Full repaint on every move | Only repaint affected area or use repaint(x,y,w,h) | | Sticky touch | No pointerReleased called | Add timeout reset after 500ms | | Accidental taps | Too sensitive | Require min drag distance of 5px before action | | Overlapping UI | Fingers cover screen | Place UI at bottom/edges, use haptic feedback (if supported via DeviceControl – rare) | 8. Example: Simple Touch Arcade Shooter import javax.microedition.lcdui.*; import javax.microedition.midlet.*; public class TouchShooter extends MIDlet implements CommandListener { private Display display; private GameCanvas canvas; private Command exitCommand;

// Or via TouchEvent listener: TouchDevice.addListener(touchListener); They support standard pointerPressed reliably. No extra JAR needed. Defensive detection pattern: public boolean isTouchSupported() { try Class.forName("com.nokia.mid.ui.TouchEvent"); return true; catch (ClassNotFoundException e) {} // Also test if pointerPressed works: return getClass().getMethod("pointerPressed", int.class, int.class) != null; // rough } Better: check touch capability via Canvas.hasPointerEvents() (midp 2.0) – but that returns false if not supported.

int dpadCenterX = 40, dpadCenterY = screenHeight - 40; if (Math.hypot(touchX - dpadCenterX, touchY - dpadCenterY) < 35) int dx = touchX - dpadCenterX; int dy = touchY - dpadCenterY; if (Math.abs(dx) > Math.abs(dy)) moveHorizontal(dx); else moveVertical(dy); protected void pointerDragged(int x, int y) touchX =

class GameCanvas extends Canvas implements Runnable { private int playerX, playerY; private boolean shootRequested; private boolean running;

private void updateGame() // Use touchX, touchY, touching for game logic

public void run() { while (running) { updateGame(); repaint(); try Thread.sleep(30); catch (InterruptedException e) {} } } Example: Simple Touch Arcade Shooter import javax

protected void pointerPressed(int x, int y) playerX = Math.min(Math.max(x, 10), getWidth() - 10); shootRequested = true;

protected void paint(Graphics g) offGfx.setColor(0x000000); offGfx.fillRect(0, 0, getWidth(), getHeight()); drawGame(offGfx); g.drawImage(offscreen, 0, 0, Graphics.TOP

protected void pointerDragged(int x, int y) playerX = Math.min(Math.max(x, 10), getWidth() - 10);

protected void paint(Graphics g) g.setColor(0); g.fillRect(0, 0, getWidth(), getHeight()); g.setColor(0x00FF00); g.fillRect(playerX - 10, playerY - 10, 20, 20); drawBullets(g); // ... bullet management methods }

public void startApp() canvas = new GameCanvas(); display = Display.getDisplay(this); display.setCurrent(canvas); canvas.start();