Android 大圖片拖拽縮放

這篇Android圖片拖拽縮放也是我在項目中用到的，今天整理一下，將源碼奉獻給大家，希望對大家以後碰到相似的問題有幫助。

這篇就不做過多介紹了，直接上源碼：

1. public class SpacePageActivity extends Activity {
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;
9. private static String IMAGE_MIME_TYPE ;
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);//隱藏標題
19. setContentView(R.layout.spacepage);
20. setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
21. initHead();
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);
29. //加載成功
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. }
36. }
37. }
40. public Bitmap returnBitMap(String url) {
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. }
66. return bitmap;
67. }
68. public class MulitPointTouchListener implements OnTouchListener {
70. Matrix matrix = new Matrix();
71. Matrix savedMatrix = new Matrix();
73. public ImageView image;
74. static final int NONE = 0;
75. static final int DRAG = 1;
76. static final int ZOOM = 2;
77. int mode = NONE;
79. PointF start = new PointF();
80. PointF mid = new PointF();
81. float oldDist = 1f;
84. public MulitPointTouchListener(ImageView image) {
85. super();
86. this.image = image;
87. }
89. @Override
90. public boolean onTouch(View v, MotionEvent event) {
91. this.image.setScaleType(ScaleType.MATRIX);
93. ImageView view = (ImageView) v;
94. // dumpEvent(event);
96. switch (event.getAction() & MotionEvent.ACTION_MASK) {
98. case MotionEvent.ACTION_DOWN:
100. Log.w("FLAG", "ACTION_DOWN");
101. matrix.set(view.getImageMatrix());
102. savedMatrix.set(matrix);
103. start.set(event.getX(), event.getY());
104. mode = DRAG;
105. break;
106. case MotionEvent.ACTION_POINTER_DOWN:
107. Log.w("FLAG", "ACTION_POINTER_DOWN");
108. oldDist = spacing(event);
109. if (oldDist > 10f) {
110. savedMatrix.set(matrix);
111. midPoint(mid, event);
112. mode = ZOOM;
113. }
114. break;
115. case MotionEvent.ACTION_UP:
116. Log.w("FLAG", "ACTION_UP");
117. case MotionEvent.ACTION_POINTER_UP:
118. Log.w("FLAG", "ACTION_POINTER_UP");
119. mode = NONE;
120. break;
121. case MotionEvent.ACTION_MOVE:
122. Log.w("FLAG", "ACTION_MOVE");
123. if (mode == DRAG) {
124. matrix.set(savedMatrix);
125. matrix.postTranslate(event.getX() - start.x, event.getY()
126. - start.y);
127. } else if (mode == ZOOM) {
128. float newDist = spacing(event);
129. if (newDist > 10f) {
130. matrix.set(savedMatrix);
131. float scale = newDist / oldDist;
132. matrix.postScale(scale, scale, mid.x, mid.y);
133. }
134. }
135. break;
136. }
138. view.setImageMatrix(matrix);
139. return true;
140. }
143. private float spacing(MotionEvent event) {
144. float x = event.getX(0) - event.getX(1);
145. float y = event.getY(0) - event.getY(1);
146. return FloatMath.sqrt(x * x + y * y);
147. }
149. private void midPoint(PointF point, MotionEvent event) {
150. float x = event.getX(0) + event.getX(1);
151. float y = event.getY(0) + event.getY(1);
152. point.set(x / 2, y / 2);
153. }
154. }
155. private void initHead() {
156. linnerLayout_spacepage = (LinearLayout) findViewById(R.id.linnerLayout_spacepage);
157. relativeLayout_spacepage=(RelativeLayout) findViewById(R.id.relativeLayout_spacepage);
158. btn_spacepage_back = (Button) findViewById(R.id.btn_spacepage_back);
159. btn_spacepage_back.setOnClickListener(new OnClickListener() {
161. @Override
162. public void onClick(View v) {
163. // TODO Auto-generated method stub
165. finish();
166. }
167. });
168. btn_spacepage_save = (Button) findViewById(R.id.btn_spacepage_save);
170. }
171. protected boolean isNetworkAvailable() {
172. ConnectivityManager connectivity = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
173. if (connectivity == null) {
174. Log.i("NetWorkState", "Unavailabel");
175. return false;
176. } else {
177. NetworkInfo[] info = connectivity.getAllNetworkInfo();
178. if (info != null) {
179. for (int i = 0; i < info.length; i++) {
180. if (info[i].getState() == NetworkInfo.State.CONNECTED) {
181. Log.i("NetWorkState", "Availabel");
182. return true;
183. }
184. }
185. }
186. }
187. return false;
188. }
189. @Override
190. protected void onStop() {
191. // TODO Auto-generated method stub
192. if(bitmap!=null){
193. if(!bitmap.isRecycled()){
194. bitmap.recycle(); //回收圖片所占的內存
195. bitmap=null;
196. System.gc(); //提醒系統及時回收
197. }
198. }
199. super.onStop();
200. }
201. @Override
202. protected void onDestroy() {
203. // TODO Auto-generated method stub
204. super.onDestroy();
205. if(bitmap!=null){
206. if(!bitmap.isRecycled()){
207. bitmap.recycle(); //回收圖片所占的內存
208. bitmap=null;
209. System.gc(); //提醒系統及時回收
210. }
211. }
212. }
213. }

因為是大圖片，在onDestroy的時候要recycle掉，這樣系統才會定時回收掉，System.gc();是提醒系統回收，雖然java這種垃圾回收機制不用我們自己關心對象的回收，但是這也給android開發人員帶來了不好的一面，如果系統回收不及時很可能就造成了內存溢出了。什麼時候手機不擔心內存使用了就好了。

運行一下看看效果：

更多Android相關信息見Android 專題頁面 http://www.linuxidc.com/topicnews.aspx?tid=11