Android開發中實現多點觸摸的方法 - Android 台灣中文網

package com.ideasandroid.demo;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class MTView extends SurfaceView implements SurfaceHolder.Callback {
private static final int MAX_TOUCHPOINTS = 10;
private static final String START_TEXT = "請隨便觸摸屏幕進行測試";
private Paint textPaint = new Paint();
private Paint touchPaints[] = new Paint[MAX_TOUCHPOINTS];
private int colors[] = new int[MAX_TOUCHPOINTS];
private int width, height;
private float scale = 1.0f;
public MTView(Context context) {
super(context);
SurfaceHolder holder = getHolder();
holder.addCallback(this);
setFocusable(true); // 確保我們的View能獲得輸入焦點
setFocusableInTouchMode(true); // 確保能接收到觸屏事件
init();
}
private void init() {
// 初始化10個不同顏色的畫筆
textPaint.setColor(Color.WHITE);
colors[0] = Color.BLUE;
colors[1] = Color.RED;
colors[2] = Color.GREEN;
colors[3] = Color.YELLOW;
colors[4] = Color.CYAN;
colors[5] = Color.MAGENTA;
colors[6] = Color.DKGRAY;
colors[7] = Color.WHITE;
colors[8] = Color.LTGRAY;
colors[9] = Color.GRAY;
for (int i = 0; i < MAX_TOUCHPOINTS; i++) {
touchPaints[i] = new Paint();
touchPaints[i].setColor(colors[i]);
}
}
/*
* 處理觸屏事件
*/
@Override
public boolean onTouchEvent(MotionEvent event) {
// 獲得屏幕觸點數量
int pointerCount = event.getPointerCount();
if (pointerCount > MAX_TOUCHPOINTS) {
pointerCount = MAX_TOUCHPOINTS;
}
// 鎖定Canvas,開始進行相應的界面處理
Canvas c = getHolder().lockCanvas();
if (c != null) {
c.drawColor(Color.BLACK);
if (event.getAction() == MotionEvent.ACTION_UP) {
// 當手離開屏幕時，清屏
} else {
// 先在屏幕上畫一個十字，然後畫一個圓
for (int i = 0; i < pointerCount; i++) {
// 獲取一個觸點的坐標，然後開始繪製
int id = event.getPointerId(i);
int x = (int) event.getX(i);
int y = (int) event.getY(i);
drawCrosshairsAndText(x, y, touchPaints[id], i, id, c);
}
for (int i = 0; i < pointerCount; i++) {
int id = event.getPointerId(i);
int x = (int) event.getX(i);
int y = (int) event.getY(i);
drawCircle(x, y, touchPaints[id], c);
}
}
// 畫完後，unlock
getHolder().unlockCanvasAndPost(c);
}
return true;
}
/**
* 畫十字及坐標信息
*
* @param x
* @param y
* @param paint
* @param ptr
* @param id
* @param c
*/
private void drawCrosshairsAndText(int x, int y, Paint paint, int ptr,
int id, Canvas c) {
c.drawLine(0, y, width, y, paint);
c.drawLine(x, 0, x, height, paint);
int textY = (int) ((15 + 20 * ptr) * scale);
c.drawText("x" + ptr + "=" + x, 10 * scale, textY,
c.drawText("y" + ptr + "=" + y, 70 * scale, textY,
c.drawText("id" + ptr + "=" + id, width - 55 * sc
}
/**
* 畫圓
*
* @param x
* @param y
* @param paint
* @param c
*/
private void drawCircle(int x, int y, Paint paint, Canvas c
c.drawCircle(x, y, 40 * scale, paint);
}
/*
* 進入程序時背景畫成黑色，然後把「START_TEXT」寫到屏幕
*/
public void surfaceChanged(SurfaceHolder holder, int format, i
int height) {
this.width = width;
this.height = height;
if (width > height) {
this.scale = width / 480f;
} else {
this.scale = height / 480f;
}
textPaint.setTextSize(14 * scale);
Canvas c = getHolder().lockCanvas();
if (c != null) {
// 背景黑色
c.drawColor(Color.BLACK);
float tWidth = textPaint.measureText(START_TEXT);
c.drawText(START_TEXT, width / 2 - tWidth / 2
textPaint);
getHolder().unlockCanvasAndPost(c);
}
}
public void surfaceCreated(SurfaceHolder holder) {
}
public void surfaceDestroyed(SurfaceHolder holder) {
}
}

複製代碼