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Android透过手势实现的缩放处理

热度：29 发布时间：2016-05-01 19:00:42.0

						
						
					

                  	Android通过手势实现的缩放处理
01 import android.app.Activity; 
02import android.content.Context; 
03import android.graphics.Canvas; 
04import android.graphics.Color; 
05import android.graphics.Paint; 
06import android.os.Bundle; 
07import android.util.DisplayMetrics; 
08import android.view.MotionEvent; 
09import android.view.View; 
10??
11/** 
12?* ... 
13?*? 
14?* @author vlinux 
15?*? 
16?*/
17public class MultiTouchTestActivity extends Activity { 
18????/** Called when the activity is first created. */
19????@Override
20????public void onCreate(Bundle savedInstanceState) { 
21????????super.onCreate(savedInstanceState); 
22????????// setContentView(R.layout.main); 
23????????View view = new MultiTouchView(this); 
24????????setContentView(view); 
25????} 
26??
27????class MultiTouchView extends View { 
28??
29????????private float x1; 
30????????private float y1; 
31????????private float x2; 
32????????private float y2; 
33??
34????????public MultiTouchView(Context context) { 
35????????????super(context); 
36????????????// TODO Auto-generated constructor stub 
37????????} 
38??
39????????@Override
40????????public boolean onTouchEvent(MotionEvent event) { 
41????????????// TODO Auto-generated method stub 
42??
43????????????float size = event.getSize(); 
44??
45????????????int szi = (int) size; 
46????????????int dxi = szi >> 12; 
47????????????int dyit = ((1 << 12) - 1); 
48????????????int dyi = szi & dyit; 
49??
50????????????DisplayMetrics metrics = getResources().getDisplayMetrics(); 
51????????????float dx = metrics.widthPixels * dxi / (float) dyit; 
52????????????float dy = metrics.heightPixels * dyi / (float) dyit; 
53??
54????????????x1 = event.getX(); 
55????????????y1 = event.getY(); 
56??
57????????????x2 = x1 + dx; 
58????????????y2 = y1 + dy; 
59??
60????????????invalidate(); 
61??
62????????????return true; 
63????????} 
64??
65????????@Override
66????????protected void onDraw(Canvas canvas) { 
67????????????// TODO Auto-generated method stub 
68????????????super.onDraw(canvas); 
69??
70????????????float r = (float) Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) 
71????????????????????* (y1 - y2)) / 2; 
72????????????r = 50 >= r ? 50 : r; 
73??
74????????????Paint paint = new Paint(); 
75????????????paint.setColor(Color.BLUE); 
76????????????canvas.drawCircle(x1, y1, r, paint); 
77??
78????????} 
79??
80????} 
81??
82}

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