Android 實現縮小圖片像素

自定義View類控制焦點以及Android現實縮小圖片的像素和如何通過BitmapFactory讀得圖片資源，做了筆記。以下代碼提供給大伙參考。

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

1. package com.view;
3. import java.util.HashMap;
5. import com.pojo.Constants;
6. import com.test.R;
7. import android.content.Context;
8. import android.graphics.Bitmap;
9. import android.graphics.BitmapFactory;
10. import android.graphics.Canvas;
11. import android.graphics.Color;
12. import android.graphics.Matrix;
13. import android.graphics.Paint;
14. import android.util.Log;
15. import android.view.KeyEvent;
16. import android.view.View;
17. import android.view.ViewGroup;
19. public class ADWView extends View {
20. Context myContext = this.getContext();
21. //讀得String.xml裡面的資源
22. private String a = myContext.getString(R.string.app_a);
23. private String b = myContext.getString(R.string.app_b);
24. private String c = myContext.getString(R.string.app_c);
25. private String d = myContext.getString(R.string.app_d);
26. private String e = myContext.getString(R.string.app_e);
27. private int focusID = 0;
28. private Bitmap focusbmp, progressBar_A,progressBar_B,progressBar_C,progressBar_D,progressBar_E,progressBar;
29. private Bitmap bitmap_A,bitmap_B,bitmap_C,bitmap_D,bitmap_E;
30. HashMap<Integer, Integer> progressBarMap = null;
32. public ADWView(Context context) {
33. super(context);
34. this.setFocusable(true);
35. this.requestFocus();
36. initData();
37. //焦點圖片通過BitmapFactory來得到圖片資源R.drawable.shortcut_bg_sel
38. focusbmp = BitmapFactory.decodeResource(this.getResources(), R.drawable.shortcut_bg_sel);
39. }
43. @Override
44. protected void onDraw(Canvas canvas) {
45. //焦點圖片初始位置
46. if (focusbmp != null) {
47. canvas.drawBitmap(focusbmp, this.getPaddingLeft()-20,
48. this.getPaddingTop() + focusID * 100 + 230, null);
49. }
50. super.onDraw(canvas);
51. Paint paint = new Paint();
52. paint.setColor(Color.WHITE);
53. paint.setTextSize(25);
54. paint.setAntiAlias(true);
55. //獲得圖片的集合progressBarMap.get(Constants.progressBarValueA)
56. progressBar_A = BitmapFactory.decodeResource(this.getResources(),progressBarMap.get(Constants.progressBarValueA));
57. progressBar_B = BitmapFactory.decodeResource(this.getResources(),progressBarMap.get(Constants.progressBarValueB));
58. progressBar_C = BitmapFactory.decodeResource(this.getResources(),progressBarMap.get(Constants.progressBarValueC));
59. progressBar_D = BitmapFactory.decodeResource(this.getResources(),progressBarMap.get(Constants.progressBarValueD));
60. progressBar_E = BitmapFactory.decodeResource(this.getResources(),progressBarMap.get(Constants.progressBarValueE));
61. //獲得圖片的寬和高
62. int w = 22000/progressBar_A.getWidth();
63. int h = 22000/progressBar_A.getHeight();
64. //刷新圖片的像素大小
65. bitmap_A = progressBar.createScaledBitmap(progressBar_A, w, h, true);
66. bitmap_B = progressBar.createScaledBitmap(progressBar_B, w, h, true);
67. bitmap_C = progressBar.createScaledBitmap(progressBar_C, w, h, true);
68. bitmap_D = progressBar.createScaledBitmap(progressBar_D, w, h, true);
69. bitmap_E = progressBar.createScaledBitmap(progressBar_E, w, h, true);
71. //文字放置在屏幕的位置
72. canvas.drawText(a + " " + String.valueOf(Constants.A),
73. getPaddingLeft() + 80, getPaddingTop() + 300, paint);
74. //圖片的放置在屏幕的位置
75. canvas.drawBitmap(bitmap_A,getPaddingLeft()+ 244,
76. getPaddingTop() + 247, null);
78. canvas.drawText(b + " " + String.valueOf(Constants.B),
79. getPaddingLeft() + 80, getPaddingTop() + 400, paint);
80. canvas.drawBitmap(bitmap_B, getPaddingLeft()+ 244,
81. getPaddingTop() + 347, null);
83. canvas.drawText(c + " " + String.valueOf(Constants.C),
84. getPaddingLeft() + 80,getPaddingTop() + 500, paint);
85. canvas.drawBitmap(bitmap_C, getPaddingLeft()+ 244,
86. getPaddingTop() + 447, null);
88. canvas.drawText(d + " " + String.valueOf(Constants.D),
89. getPaddingLeft() + 80,getPaddingTop() + 600, paint);
90. canvas.drawBitmap(bitmap_D, getPaddingLeft()+ 244,
91. getPaddingTop() + 547, null);
93. canvas.drawText(e + " " + String.valueOf(Constants.E),
94. getPaddingLeft() + 80,getPaddingTop() + 700, paint);
95. canvas.drawBitmap(bitmap_E, getPaddingLeft()+ 244,
96. getPaddingTop() + 647, null);
98. }
100. public boolean onKeyDown(int keyCode, KeyEvent event) {
101. super.onKeyDown(keyCode, event);
102. switch (keyCode) {
103. case KeyEvent.KEYCODE_DPAD_UP:
104. if (focusID > 0) {
105. focusID--;
106. } else {
107. focusID = 4;
108. }
109. this.invalidate();
110. break;
111. case KeyEvent.KEYCODE_DPAD_DOWN:
112. if (focusID < 4) {
113. focusID++;
114. } else {
115. focusID = 0;
116. }
117. this.invalidate();
118. break;
119. //左鍵的響應
120. case KeyEvent.KEYCODE_DPAD_LEFT:
121. if (focusID == 0) {
122. if (Constants.A >-10) {
123. Constants.A--;
124. Constants.progressBarValueA--;
125. } else {
126. Constants.A = -10;
127. Constants.progressBarValueA=6;
128. }
129. this.invalidate();
130. } else if (focusID == 1) {
131. if (Constants.B > -10) {
132. Constants.B--;
133. Constants.progressBarValueB--;
134. } else {
135. Constants.B = -10;
136. Constants.progressBarValueB=6;
137. }
138. this.invalidate();
139. }else if (focusID == 2) {
140. if (Constants.C > -10) {
141. Constants.C--;
142. Constants.progressBarValueC--;
143. } else {
144. Constants.C = -10;
145. Constants.progressBarValueC=6;
146. }
147. this.invalidate();
148. }else if (focusID == 3) {
149. if (Constants.D > -10) {
150. Constants.D--;
151. Constants.progressBarValueD--;
152. } else {
153. Constants.D = -10;
154. Constants.progressBarValueD=6;
155. }
156. this.invalidate();
157. }else if (focusID == 4) {
158. if (Constants.E > -10) {
159. Constants.E--;
160. Constants.progressBarValueE--;
161. } else {
162. Constants.E = -10;
163. Constants.progressBarValueE=6;
164. }
165. this.invalidate();
166. }
167. break;
168. //右鍵的響應
169. case KeyEvent.KEYCODE_DPAD_RIGHT:
170. if (focusID == 0) {
171. if (Constants.A < (10-1)) {
172. Constants.A++;
173. Constants.progressBarValueA++;
174. } else {
175. Constants.A = 10;
176. Constants.progressBarValueA = 26;
177. }
178. this.invalidate();
179. } else if (focusID == 1) {
180. if (Constants.B < (10 - 1)) {
181. Constants.B++;
182. Constants.progressBarValueB++;
183. } else {
184. Constants.B = 10;
185. Constants.progressBarValueB = 26;
186. }
187. this.invalidate();
188. }else if (focusID == 2) {
189. if (Constants.C < (10 - 1)) {
190. Constants.C++;
191. Constants.progressBarValueC++;
192. } else {
193. Constants.C = 10;
194. Constants.progressBarValueC = 26;
195. }
196. this.invalidate();
197. }else if (focusID == 3) {
198. if (Constants.D < (10 - 1)) {
199. Constants.D++;
200. Constants.progressBarValueD++;
201. } else {
202. Constants.D = 10;
203. Constants.progressBarValueD = 26;
204. }
205. this.invalidate();
206. }else if (focusID == 4) {
207. if (Constants.E < (10 - 1)) {
208. Constants.E++;
209. Constants.progressBarValueE++;
210. } else {
211. Constants.E = 10;
212. Constants.progressBarValueE = 26;
213. }
214. this.invalidate();
215. }
216. break;
218. //焦點的控制
219. case KeyEvent.KEYCODE_ENTER:
220. switch (focusID) {
221. case 0:
222. focusID = 1;
223. break;
224. case 1:
225. focusID = 2;
226. break;
227. case 2:
228. focusID = 3;
229. break;
230. case 3:
231. focusID = 4;
232. break;
233. case 4:
234. focusID = 0;
235. break;
236. default:
237. break;
238. }
239. this.invalidate();
240. break;
241. //退出按鍵的響應
242. case KeyEvent.KEYCODE_BACK:
243. ((ViewGroup) (this.getParent())).removeView(this);
244. break;
245. default:
246. break;
247. }
248. return true;
249. }
251. //做一個圖片資源的集合
252. public void initData() {
253. progressBarMap = new HashMap<Integer, Integer>();
254. progressBarMap.put(1, R.drawable.sound_1);
255. progressBarMap.put(2, R.drawable.sound_2);
256. progressBarMap.put(3, R.drawable.sound_3);
257. progressBarMap.put(4, R.drawable.sound_4);
258. progressBarMap.put(5, R.drawable.sound_5);
259. progressBarMap.put(6, R.drawable.sound_6);
260. progressBarMap.put(7, R.drawable.sound_7);
261. progressBarMap.put(8, R.drawable.sound_8);
262. progressBarMap.put(9, R.drawable.sound_9);
263. progressBarMap.put(10, R.drawable.sound_10);
264. progressBarMap.put(11, R.drawable.sound_11);
265. progressBarMap.put(12, R.drawable.sound_12);
266. progressBarMap.put(13, R.drawable.sound_13);
267. progressBarMap.put(14, R.drawable.sound_14);
268. progressBarMap.put(15, R.drawable.sound_15);
269. progressBarMap.put(16, R.drawable.sound_16);
270. progressBarMap.put(17, R.drawable.sound_17);
271. progressBarMap.put(18, R.drawable.sound_18);
272. progressBarMap.put(19, R.drawable.sound_19);
273. progressBarMap.put(20, R.drawable.sound_20);
274. progressBarMap.put(21, R.drawable.sound_21);
275. progressBarMap.put(22, R.drawable.sound_22);
276. progressBarMap.put(23, R.drawable.sound_23);
277. progressBarMap.put(24, R.drawable.sound_24);
278. progressBarMap.put(25, R.drawable.sound_25);
279. progressBarMap.put(26, R.drawable.sound_26);
280. progressBarMap.put(27, R.drawable.sound_27);
281. progressBarMap.put(28, R.drawable.sound_28);
282. progressBarMap.put(29, R.drawable.sound_29);
283. progressBarMap.put(30, R.drawable.sound_30);
284. progressBarMap.put(31, R.drawable.sound_31);
285. progressBarMap.put(32, R.drawable.sound_32);
286. }
288. }