Android開發中實現多點觸摸的方法

我們曾就《Android手勢識別ViewFlipper觸摸動畫》做過詳細的講解，其實，Android應用程序開發中，多點觸摸（Multitouch）不是那麼遙不可及，實現起來也很簡單。如果您對開發多點觸摸程序感興趣的話，那麼本文將是一個很好的開始，本例只需要兩個類就能實現多點觸摸。
首先來看看我們的視圖類MTView.java:

1. package com.ideasandroid.demo;  
   
2.   
   
3. import android.content.Context;  
   
4. import android.graphics.Canvas;  
   
5. import android.graphics.Color;  
   
6. import android.graphics.Paint;  
   
7. import android.view.MotionEvent;  
   
8. import android.view.SurfaceHolder;  
   
9. import android.view.SurfaceView;  
   
10.   
    
11. public class MTView extends SurfaceView implements SurfaceHolder.Callback {  
    
12.   
    
13.     private static final int MAX_TOUCHPOINTS = 10;  
    
14.     private static final String START_TEXT = "請隨便觸摸屏幕進行測試";  
    
15.     private Paint textPaint = new Paint();  
    
16.     private Paint touchPaints[] = new Paint[MAX_TOUCHPOINTS];  
    
17.     private int colors[] = new int[MAX_TOUCHPOINTS];  
    
18.   
    
19.     private int width, height;  
    
20.     private float scale = 1.0f;  
    
21.   
    
22.     public MTView(Context context) {  
    
23.         super(context);  
    
24.         SurfaceHolder holder = getHolder();  
    
25.         holder.addCallback(this);  
    
26.         setFocusable(true); // 確保我們的View能獲得輸入焦點  
    
27.         setFocusableInTouchMode(true); // 確保能接收到觸屏事件  
    
28.         init();  
    
29.     }  
    
30.   
    
31.     private void init() {  
    
32.         // 初始化10個不同顏色的畫筆  
    
33.         textPaint.setColor(Color.WHITE);  
    
34.         colors[0] = Color.BLUE;  
    
35.         colors[1] = Color.RED;  
    
36.         colors[2] = Color.GREEN;  
    
37.         colors[3] = Color.YELLOW;  
    
38.         colors[4] = Color.CYAN;  
    
39.         colors[5] = Color.MAGENTA;  
    
40.         colors[6] = Color.DKGRAY;  
    
41.         colors[7] = Color.WHITE;  
    
42.         colors[8] = Color.LTGRAY;  
    
43.         colors[9] = Color.GRAY;  
    
44.         for (int i = 0; i < MAX_TOUCHPOINTS; i++) {  
    
45.             touchPaints[i] = new Paint();  
    
46.             touchPaints[i].setColor(colors[i]);  
    
47.         }  
    
48.     }  
    
49.   
    
50.     /*  
    
51.      * 處理觸屏事件  
    
52.      */  
    
53.     @Override  
    
54.     public boolean onTouchEvent(MotionEvent event) {  
    
55.         // 獲得屏幕觸點數量  
    
56.         int pointerCount = event.getPointerCount();  
    
57.         if (pointerCount > MAX_TOUCHPOINTS) {  
    
58.             pointerCount = MAX_TOUCHPOINTS;  
    
59.         }  
    
60.         // 鎖定Canvas,開始進行相應的界面處理  
    
61.         Canvas c = getHolder().lockCanvas();  
    
62.         if (c != null) {  
    
63.             c.drawColor(Color.BLACK);  
    
64.             if (event.getAction() == MotionEvent.ACTION_UP) {  
    
65.                 // 當手離開屏幕時，清屏  
    
66.             } else {  
    
67.                 // 先在屏幕上畫一個十字，然後畫一個圓  
    
68.                 for (int i = 0; i < pointerCount; i++) {  
    
69.                     // 獲取一個觸點的坐標，然後開始繪製  
    
70.                     int id = event.getPointerId(i);  
    
71.                     int x = (int) event.getX(i);  
    
72.                     int y = (int) event.getY(i);  
    
73.                     drawCrosshairsAndText(x, y, touchPaints[id], i, id, c);  
    
74.                 }  
    
75.                 for (int i = 0; i < pointerCount; i++) {  
    
76.                     int id = event.getPointerId(i);  
    
77.                     int x = (int) event.getX(i);  
    
78.                     int y = (int) event.getY(i);  
    
79.                     drawCircle(x, y, touchPaints[id], c);  
    
80.                 }  
    
81.             }  
    
82.             // 畫完後，unlock  
    
83.             getHolder().unlockCanvasAndPost(c);  
    
84.         }  
    
85.         return true;  
    
86.     }  
    
87.   
    
88.     /**  
    
89.      * 畫十字及坐標信息  
    
90.      *  
    
91.      * @param x  
    
92.      * @param y  
    
93.      * @param paint  
    
94.      * @param ptr  
    
95.      * @param id  
    
96.      * @param c  
    
97.      */  
    
98.     private void drawCrosshairsAndText(int x, int y, Paint paint, int ptr,  
    
99.             int id, Canvas c) {  
    
100.         c.drawLine(0, y, width, y, paint);  
     
101.         c.drawLine(x, 0, x, height, paint);  
     
102.         int textY = (int) ((15 + 20 * ptr) * scale);  
     
103.         c.drawText("x" + ptr + "=" + x, 10 * scale, textY,
     
104.         c.drawText("y" + ptr + "=" + y, 70 * scale, textY,
     
105.         c.drawText("id" + ptr + "=" + id, width - 55 * sc
     
106.     }  
     
107.   
     
108.     /**  
     
109.      * 畫圓  
     
110.      *  
     
111.      * @param x  
     
112.      * @param y  
     
113.      * @param paint  
     
114.      * @param c  
     
115.      */  
     
116.     private void drawCircle(int x, int y, Paint paint, Canvas c
     
117.         c.drawCircle(x, y, 40 * scale, paint);  
     
118.     }  
     
119.   
     
120.     /*  
     
121.      * 進入程序時背景畫成黑色，然後把「START_TEXT」寫到屏幕  
     
122.      */  
     
123.     public void surfaceChanged(SurfaceHolder holder, int format, i
     
124.             int height) {  
     
125.         this.width = width;  
     
126.         this.height = height;  
     
127.         if (width > height) {  
     
128.             this.scale = width / 480f;  
     
129.         } else {  
     
130.             this.scale = height / 480f;  
     
131.         }  
     
132.         textPaint.setTextSize(14 * scale);  
     
133.         Canvas c = getHolder().lockCanvas();  
     
134.         if (c != null) {  
     
135.             // 背景黑色  
     
136.             c.drawColor(Color.BLACK);  
     
137.             float tWidth = textPaint.measureText(START_TEXT);
     
138.             c.drawText(START_TEXT, width / 2 - tWidth / 2
     
139.                     textPaint);  
     
140.             getHolder().unlockCanvasAndPost(c);  
     
141.         }  
     
142.     }  
     
143.   
     
144.     public void surfaceCreated(SurfaceHolder holder) {  
     
145.     }  
     
146.   
     
147.     public void surfaceDestroyed(SurfaceHolder holder) {  
     
148.     }  
     
149.   
     
150. }  

複製代碼

接下來看看我們的Activity，MultitouchVisible.java

1. package com.ideasandroid.demo;  
   
2.   
   
3. import android.app.Activity;  
   
4. import android.os.Bundle;  
   
5. import android.view.Window;  
   
6. import android.view.WindowManager;  
   
7.   
   
8. public class MultitouchVisible extends Activity {  
   
9.     @Override  
   
10.     public void onCreate(Bundle savedInstanceState) {  
    
11.         super.onCreate(savedInstanceState);  
    
12.         //隱藏標題欄  
    
13.         requestWindowFeature(Window.FEATURE_NO_TITLE);  
    
14.         //設置成全屏  
    
15.         getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,  
    
16.                 WindowManager.LayoutParams.FLAG_FULLSCREEN);  
    
17.         //設置為上面的MTView  
    
18.         setContentView(new MTView(this));  
    
19.     }  
    
20. }

複製代碼

受教了
真是非常實用的說明
謝謝

太強了~~

厲害喔，受教啦

厲害喔!!

厲害喔，受教啦!

厲害  可是還是看不懂-..-

謝謝分享

so cool!! try it first

good~~~~~~~~~~~~~~