这篇图片拖拽缩放也是我在项目中用到的，今天整理一下，将源码奉献给大家，希望对大家以后碰到相似的问题有帮助。android 大图片拖拽缩放
这篇就不做过多介绍了，直接上源码：
1 public class SpacePageActivity extends Activity {
2
3 private LinearLayout linnerLayout_spacepage;
4 private RelativeLayout relativeLayout_spacepage;
5 private Button btn_spacepage_back;
6 private Button btn_spacepage_save;
7 private static Boolean isTrue=false;
8
9 private static String IMAGE_MIME_TYPE ;
10
11 private ImageView image_spacePage;
12 private ProgressDialog dialog;
13 private Bitmap bitmap;
14 @Override
15 protected void onCreate(Bundle savedInstanceState) {
16 // TODO Auto-generated method stub
17 super.onCreate(savedInstanceState);
18 requestWindowFeature(Window.FEATURE_NO_TITLE);//隐藏标题
19 setContentView(R.layout.spacepage);
20 setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
21 initHead();
22
23 if(isNetworkAvailable()){
24 image_spacePage=(ImageView) findViewById(R.id.image_spacepage);
25 btn_spacepage_save=(Button) findViewById(R.id.btn_spacepage_save);
26 image_spacePage.setOnTouchListener(new MulitPointTouchListener(image_spacePage));
27 image_spacePage.setScaleType(ScaleType.CENTER_INSIDE);
28
29 //加载成功 何问起
30 String urls="http://epaper.yzdsb.com.cn/201201/04/yz2104_7.jpg";
31 bitmap=returnBitMap(urls);
32 if(null!=bitmap){
33 image_spacePage.setImageBitmap(bitmap);
34 }
35
36 }
37 }
38
39
40 public Bitmap returnBitMap(String url) {
41
42 if(null==url || "".equals(url)){
43 return null;
44 }
45 URL myFileUrl = null;
46 Bitmap bitmap = null;
47 try {
48 myFileUrl = new URL(url);
49 } catch (MalformedURLException e) {
50 e.printStackTrace();
51 }
52 try {
53 HttpURLConnection conn = (HttpURLConnection) myFileUrl.openConnection();
54 conn.setConnectTimeout(2000);
55 conn.setDoInput(true);
56 conn.connect();
57 InputStream is = conn.getInputStream();
58 bitmap = BitmapFactory.decodeStream(is);
59 is.close();
60 } catch (IOException e) {
61 e.printStackTrace();
62 }
63
64
65
66 return bitmap;
67 }
68 // hovertree.com
69
70 public class MulitPointTouchListener implements OnTouchListener {
71
72 Matrix matrix = new Matrix();
73 Matrix savedMatrix = new Matrix();
74
75 public ImageView image;
76 static final int NONE = 0;
77 static final int DRAG = 1;
78 static final int ZOOM = 2;
79 int mode = NONE;
80
81 PointF start = new PointF();
82 PointF mid = new PointF();
83 float oldDist = 1f;
84
85
86 public MulitPointTouchListener(ImageView image) {
87 super();
88 this.image = image;
89 }
90
91 @Override
92 public boolean onTouch(View v, MotionEvent event) {
93 this.image.setScaleType(ScaleType.MATRIX);
94
95 ImageView view = (ImageView) v;
96 // dumpEvent(event);
97
98 switch (event.getAction() & MotionEvent.ACTION_MASK) {
99
100 case MotionEvent.ACTION_DOWN:
101
102 Log.w("FLAG", "ACTION_DOWN");
103 matrix.set(view.getImageMatrix());
104 savedMatrix.set(matrix);
105 start.set(event.getX(), event.getY());
106 mode = DRAG;
107 break;
108 case MotionEvent.ACTION_POINTER_DOWN:
109 Log.w("FLAG", "ACTION_POINTER_DOWN");
110 oldDist = spacing(event);
111 if (oldDist > 10f) {
112 savedMatrix.set(matrix);
113 midPoint(mid, event);
114 mode = ZOOM;
115 }
116 break;
117 case MotionEvent.ACTION_UP:
118 Log.w("FLAG", "ACTION_UP");
119 case MotionEvent.ACTION_POINTER_UP:
120 Log.w("FLAG", "ACTION_POINTER_UP");
121 mode = NONE;
122 break;
123 case MotionEvent.ACTION_MOVE:
124 Log.w("FLAG", "ACTION_MOVE");
125 if (mode == DRAG) {
126 matrix.set(savedMatrix);
127 matrix.postTranslate(event.getX() - start.x, event.getY()
128 - start.y);
129 } else if (mode == ZOOM) {
130 float newDist = spacing(event);
131 if (newDist > 10f) {
132 matrix.set(savedMatrix);
133 float scale = newDist / oldDist;
134 matrix.postScale(scale, scale, mid.x, mid.y);
135 }
136 }
137 break;
138 }
139
140 view.setImageMatrix(matrix);
141 return true;
142 }
143
144
145 private float spacing(MotionEvent event) {
146 float x = event.getX(0) - event.getX(1);
147 float y = event.getY(0) - event.getY(1);
148 return FloatMath.sqrt(x * x + y * y);
149 }
150
151 private void midPoint(PointF point, MotionEvent event) {
152 float x = event.getX(0) + event.getX(1);
153 float y = event.getY(0) + event.getY(1);
154 point.set(x / 2, y / 2);
155 }
156 }
157 private void initHead() {
158 linnerLayout_spacepage = (LinearLayout) findViewById(R.id.linnerLayout_spacepage);
159 relativeLayout_spacepage=(RelativeLayout) findViewById(R.id.relativeLayout_spacepage);
160 btn_spacepage_back = (Button) findViewById(R.id.btn_spacepage_back);
161 btn_spacepage_back.setOnClickListener(new OnClickListener() {
162
163 @Override
164 public void onClick(View v) {
165 // TODO Auto-generated method stub
166
167 finish();
168 }
169 });
170 btn_spacepage_save = (Button) findViewById(R.id.btn_spacepage_save);
171
172 }
173 protected boolean isNetworkAvailable() {
174 ConnectivityManager connectivity = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
175 if (connectivity == null) {
176 Log.i("NetWorkState", "Unavailabel");
177 return false;
178 } else {
179 NetworkInfo[] info = connectivity.getAllNetworkInfo();
180 if (info != null) {
181 for (int i = 0; i < info.length; i++) {
182 if (info[i].getState() == NetworkInfo.State.CONNECTED) {
183 Log.i("NetWorkState", "Availabel");
184 return true;
185 }
186 }
187 }
188 }
189 return false;
190 }
191 @Override
192 protected void onStop() {
193 // TODO Auto-generated method stub
194 if(bitmap!=null){
195 if(!bitmap.isRecycled()){
196 bitmap.recycle(); //回收图片所占的内存
197 bitmap=null;
198 System.gc(); //提醒系统及时回收
199 }
200 }
201 super.onStop();
202 }
203 @Override
204 protected void onDestroy() {
205 // TODO Auto-generated method stub
206 super.onDestroy();
207 if(bitmap!=null){
208 if(!bitmap.isRecycled()){
209 bitmap.recycle(); //回收图片所占的内存
210 bitmap=null;
211 System.gc(); //提醒系统及时回收
212 }
213 }
214 }
215 }因为是大图片，在onDestroy的时候要recycle掉，这样系统才会定时回收掉，System.gc();是提醒系统回收，虽然java这种垃圾回收机制不用我们自己关心对象的回收，但是这也给android开发人员带来了不好的一面，如果系统回收不及时很可能就造成了内存溢出了。什么时候手机不担心内存使用了就好了。
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