http://blog.csdn.net/candycat1992/article/details/21617741

實現

以OpenCV的JavaCameraView為例，首先需要定制自己的Camera，主要代碼如下： [java]?view plaincopy print?

1. import?java.util.ArrayList;??
2. import?java.util.List;??
3. ??
4. import?org.opencv.android.JavaCameraView;??
5. ??
6. import?android.R.integer;??
7. import?android.content.Context;??
8. import?android.graphics.Rect;??
9. import?android.graphics.RectF;??
10. import?android.hardware.Camera;??
11. import?android.hardware.Camera.AutoFocusCallback;??
12. import?android.util.AttributeSet;??
13. import?android.view.MotionEvent;??
14. import?android.widget.Toast;??
15. ??
16. public?class?MTCameraView?extends?JavaCameraView?implements?AutoFocusCallback?{??
17. ??
18. ????public?MTCameraView(Context?context,?int?attrs)?{??
19. ????????super(context,?attrs);??
20. ????????//?TODO?Auto-generated?constructor?stub??
21. ????}??
22. ??
23. ????public?List<Camera.Size>?getResolutionList()?{????????
24. ????????return??mCamera.getParameters().getSupportedPreviewSizes();????????
25. ????}??
26. ??????
27. ????public?Camera.Size?getResolution()?{??
28. ????????Camera.Parameters?params?=?mCamera.getParameters();???
29. ????????Camera.Size?s?=?params.getPreviewSize();??
30. ????????return?s;??
31. ????}??
32. ??????
33. ????public?void?setResolution(Camera.Size?resolution)?{??
34. ????????disconnectCamera();??
35. ????????connectCamera((int)resolution.width,?(int)resolution.height);?????????
36. ????}??
37. ??????
38. ????public?void?focusOnTouch(MotionEvent?event)?{??
39. ????????Rect?focusRect?=?calculateTapArea(event.getRawX(),?event.getRawY(),?1f);??
40. ????????Rect?meteringRect?=?calculateTapArea(event.getRawX(),?event.getRawY(),?1.5f);??
41. ??
42. ????????Camera.Parameters?parameters?=?mCamera.getParameters();??
43. ????????parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);??
44. ??????????
45. ????????if?(parameters.getMaxNumFocusAreas()?>?0)?{??
46. ????????????List<Camera.Area>?focusAreas?=?new?ArrayList<Camera.Area>();??
47. ????????????focusAreas.add(new?Camera.Area(focusRect,?1000));??
48. ??????????
49. ????????????parameters.setFocusAreas(focusAreas);??
50. ????????}??
51. ??
52. ????????if?(parameters.getMaxNumMeteringAreas()?>?0)?{??
53. ????????????List<Camera.Area>?meteringAreas?=?new?ArrayList<Camera.Area>();??
54. ????????????meteringAreas.add(new?Camera.Area(meteringRect,?1000));??
55. ??????????????
56. ????????????parameters.setMeteringAreas(meteringAreas);??
57. ????????}??
58. ??
59. ????????mCamera.setParameters(parameters);??
60. ????????mCamera.autoFocus(this);??
61. ????}??
62. ??????
63. ????/**?
64. ?????*?Convert?touch?position?x:y?to?{@link?Camera.Area}?position?-1000:-1000?to?1000:1000.?
65. ?????*/??
66. ????private?Rect?calculateTapArea(float?x,?float?y,?float?coefficient)?{??
67. ????????float?focusAreaSize?=?300;??
68. ????????int?areaSize?=?Float.valueOf(focusAreaSize?*?coefficient).intValue();??
69. ??
70. ????????int?centerX?=?(int)?(x?/?getResolution().width?*?2000?-?1000);??
71. ????????int?centerY?=?(int)?(y?/?getResolution().height?*?2000?-?1000);??
72. ??
73. ????????int?left?=?clamp(centerX?-?areaSize?/?2,?-1000,?1000);??
74. ????????int?right?=?clamp(left?+?areaSize,?-1000,?1000);??
75. ????????int?top?=?clamp(centerY?-?areaSize?/?2,?-1000,?1000);??
76. ????????int?bottom?=?clamp(top?+?areaSize,?-1000,?1000);??
77. ??
78. ????????return?new?Rect(left,?top,?right,?bottom);??
79. ????????}??
80. ??
81. ????private?int?clamp(int?x,?int?min,?int?max)?{??
82. ????????if?(x?>?max)?{??
83. ????????????return?max;??
84. ????????}??
85. ????????if?(x?<?min)?{??
86. ????????????return?min;??
87. ????????}??
88. ????????return?x;??
89. ????}??
90. ??????
91. ????public?void?setFocusMode?(Context?item,?int?type){??
92. ????????Camera.Parameters?params?=?mCamera.getParameters();???
93. ????????List<String>?FocusModes?=?params.getSupportedFocusModes();??
94. ??
95. ????????switch?(type){??
96. ????????case?0:??
97. ????????????if?(FocusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO))??
98. ????????????????params.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);??
99. ????????????else???
100. ????????????????Toast.makeText(item,?"Auto?Mode?not?supported",?Toast.LENGTH_SHORT).show();??
101. ????????????break;??
102. ????????case?1:???????????
103. ????????????if?(FocusModes.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO))??
104. ????????????????params.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);??
105. ????????????else??
106. ????????????????Toast.makeText(item,?"Continuous?Mode?not?supported",?Toast.LENGTH_SHORT).show();??
107. ????????????break;??
108. ????????case?2:???????????
109. ????????????if?(FocusModes.contains(Camera.Parameters.FOCUS_MODE_EDOF))??
110. ????????????????params.setFocusMode(Camera.Parameters.FOCUS_MODE_EDOF);??
111. ????????????else??
112. ????????????????Toast.makeText(item,?"EDOF?Mode?not?supported",?Toast.LENGTH_SHORT).show();??
113. ????????????break;??
114. ????????case?3:??
115. ????????????if?(FocusModes.contains(Camera.Parameters.FOCUS_MODE_FIXED))??
116. ????????????????params.setFocusMode(Camera.Parameters.FOCUS_MODE_FIXED);??
117. ????????????else??
118. ????????????????Toast.makeText(item,?"Fixed?Mode?not?supported",?Toast.LENGTH_SHORT).show();??
119. ????????????break;??
120. ????????case?4:??
121. ????????????if?(FocusModes.contains(Camera.Parameters.FOCUS_MODE_INFINITY))??
122. ????????????????params.setFocusMode(Camera.Parameters.FOCUS_MODE_INFINITY);??
123. ????????????else??
124. ????????????????Toast.makeText(item,?"Infinity?Mode?not?supported",?Toast.LENGTH_SHORT).show();??
125. ????????????break;??
126. ????????case?5:??
127. ????????????if?(FocusModes.contains(Camera.Parameters.FOCUS_MODE_MACRO))??
128. ????????????????params.setFocusMode(Camera.Parameters.FOCUS_MODE_MACRO);??
129. ????????????else??
130. ????????????????Toast.makeText(item,?"Macro?Mode?not?supported",?Toast.LENGTH_SHORT).show();??
131. ????????????break;????????
132. ????????}??
133. ??
134. ????????mCamera.setParameters(params);??
135. ????}??
136. ??????
137. ????public?void?setFlashMode?(Context?item,?int?type){??
138. ????????Camera.Parameters?params?=?mCamera.getParameters();??
139. ????????List<String>?FlashModes?=?params.getSupportedFlashModes();??
140. ??
141. ????????switch?(type){??
142. ????????case?0:??
143. ????????????if?(FlashModes.contains(Camera.Parameters.FLASH_MODE_AUTO))??
144. ????????????????params.setFlashMode(Camera.Parameters.FLASH_MODE_AUTO);??
145. ????????????else??
146. ????????????????Toast.makeText(item,?"Auto?Mode?not?supported",?Toast.LENGTH_SHORT).show();??
147. ????????????break;??
148. ????????case?1:??
149. ????????????if?(FlashModes.contains(Camera.Parameters.FLASH_MODE_OFF))??
150. ????????????????params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);??
151. ????????????else??
152. ????????????????Toast.makeText(item,?"Off?Mode?not?supported",?Toast.LENGTH_SHORT).show();????????????
153. ????????????break;??
154. ????????case?2:??
155. ????????????if?(FlashModes.contains(Camera.Parameters.FLASH_MODE_ON))??
156. ????????????????params.setFlashMode(Camera.Parameters.FLASH_MODE_ON);??
157. ????????????else??
158. ????????????????Toast.makeText(item,?"On?Mode?not?supported",?Toast.LENGTH_SHORT).show();?????????
159. ????????????break;??
160. ????????case?3:??
161. ????????????if?(FlashModes.contains(Camera.Parameters.FLASH_MODE_RED_EYE))??
162. ????????????????params.setFlashMode(Camera.Parameters.FLASH_MODE_RED_EYE);??
163. ????????????else??
164. ????????????????Toast.makeText(item,?"Red?Eye?Mode?not?supported",?Toast.LENGTH_SHORT).show();????????????
165. ????????????break;??
166. ????????case?4:??
167. ????????????if?(FlashModes.contains(Camera.Parameters.FLASH_MODE_TORCH))??
168. ????????????????params.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);??
169. ????????????else??
170. ????????????????Toast.makeText(item,?"Torch?Mode?not?supported",?Toast.LENGTH_SHORT).show();??????????
171. ????????????break;??
172. ????????}??
173. ??
174. ????????mCamera.setParameters(params);??
175. ????}??
176. ??
177. ????@Override??
178. ????public?void?onAutoFocus(boolean?arg0,?Camera?arg1)?{??
179. ???????????
180. ????}??
181. }??

在MainActivity中需要初始化MTCamera，并且實現OnTouchListener接口，以便在觸摸屏幕時可以調用onTouch函數。其中主要代碼如下： [java]?view plaincopy print?

1. private?MTCameraView?mOpenCvCameraView;??
2. ??
3. public?void?init()?{??
4. ????mOpenCvCameraView?=?new?MTCameraView(this,?-1);??
5. ????mOpenCvCameraView.setCvCameraViewListener(this);??
6. ????mOpenCvCameraView.setFocusable(true);??
7. ????mOpenCvCameraView.setOnTouchListener(MainActivity.this);??
8. ????mOpenCvCameraView.enableView();??
9. ??????
10. ????FrameLayout?frame?=?new?FrameLayout(this);??
11. ????frame.addView(mOpenCvCameraView);??
12. ??????
13. ????setContentView(frame);??
14. ?????}??
15. ??
16. @Override??
17. public?boolean?onTouch(View?arg0,?MotionEvent?arg1)?{??
18. ????//?TODO?Auto-generated?method?stub??
19. ????mOpenCvCameraView.focusOnTouch(arg1);??
20. ????return?true;??
21. }??

init()函數是自定義的初始化函數，可以在onCreate時使用。由于這里需要使用OpenCV庫，所以本項目是在加載完OpenCV庫并判斷成功后才調用init()函數的。

解釋

在發生觸摸事件時，MainActivity由于實現了OnTouchListener接口，因此會調用重寫的onTouch函數，并把它的第二個參數MotionEvent傳遞給MTCamera，以便定位觸摸位置。 MTCamera的focusOnTouch函數繼續工作。它首先根據觸摸位置計算對焦和測光（metering）區域的大小（通過calculateTapArea函數），然后創建新的Camera.Parameters，并設置攝像機的對焦模式為Auto。 然后，它分別判斷該設備的相機是否支持設置對焦區域和測光區域，如果支持就分別為parameters設置之前計算好的聚焦和測光區域。 最后，讓Camera自動對焦。

• calculateTapArea函數
  
  這個函數主要實現從屏幕坐標系到對焦坐標系的轉換。由MotionEvent.getRowX()得到的是以屏幕坐標系（即屏幕左上角為原點，右下角為你的當前屏幕分辨率，單位是一個像素）為準的坐標，而setFocusAreas接受的List<Area>中的每一個Area的范圍是（-1000，-1000）到（1000， 1000），也就是說屏幕中心為原點，左上角為（-1000，-1000），右下角為（1000，1000）。注意，如果超出這個范圍的話，會報setParemeters failed的錯誤哦！除此之外，我們還提前定義了一個對焦框（測光框）的大小，并且接受一個參數（第三個參數coefficient）作為百分比進行調節。
  
  
  

至此完成了觸摸對焦的功能。 但是，可以發現MTCamera里還有很大部分代碼，主要是兩個函數setFocusMode和setFlashMode。這兩個函數，主要是因為在項目中我的圖像經常是模糊的，但不知道系統支持那么對焦模式。這時，就可以使用這兩個函數進行測試。這還需要在MainActivity中添加菜單欄的代碼，以便進行選擇。代碼如下： [java]?view plaincopy print?

1. private?List<Camera.Size>?mResolutionList;??
2. ??
3. private?MenuItem[]?mResolutionMenuItems;??
4. private?MenuItem[]?mFocusListItems;??
5. private?MenuItem[]?mFlashListItems;??
6. ??
7. private?SubMenu?mResolutionMenu;??
8. private?SubMenu?mFocusMenu;??
9. private?SubMenu?mFlashMenu;??
10. ??
11. @Override??
12. public?boolean?onCreateOptionsMenu(Menu?menu)?{??
13. ????Log.i(TAG,?"called?onCreateOptionsMenu");??
14. ??????
15. ????List<String>?mFocusList?=?new?LinkedList<String>();??
16. ?int?idx?=0;??
17. ??
18. ?mFocusMenu?=?menu.addSubMenu("Focus");??
19. ??
20. ?mFocusList.add("Auto");??
21. ?mFocusList.add("Continuous?Video");??
22. ?mFocusList.add("EDOF");??
23. ?mFocusList.add("Fixed");??
24. ?mFocusList.add("Infinity");??
25. ?mFocusList.add("Makro");??
26. ?mFocusList.add("Continuous?Picture");??
27. ??
28. ?mFocusListItems?=?new?MenuItem[mFocusList.size()];??
29. ??
30. ?ListIterator<String>?FocusItr?=?mFocusList.listIterator();??
31. ?while(FocusItr.hasNext()){??
32. ?????//?add?the?element?to?the?mDetectorMenu?submenu??
33. ?????String?element?=?FocusItr.next();??
34. ?????mFocusListItems[idx]?=?mFocusMenu.add(2,idx,Menu.NONE,element);??
35. ?????idx++;??
36. ?}??
37. ??
38. ?List<String>?mFlashList?=?new?LinkedList<String>();??
39. ?idx?=?0;??
40. ??
41. ?mFlashMenu?=?menu.addSubMenu("Flash");??
42. ??
43. ?mFlashList.add("Auto");??
44. ?mFlashList.add("Off");??
45. ?mFlashList.add("On");??
46. ?mFlashList.add("Red-Eye");??
47. ?mFlashList.add("Torch");??
48. ??
49. ?mFlashListItems?=?new?MenuItem[mFlashList.size()];??
50. ??
51. ?ListIterator<String>?FlashItr?=?mFlashList.listIterator();??
52. ?while(FlashItr.hasNext()){??
53. ?????//?add?the?element?to?the?mDetectorMenu?submenu??
54. ?????String?element?=?FlashItr.next();??
55. ?????mFlashListItems[idx]?=?mFlashMenu.add(3,idx,Menu.NONE,element);??
56. ?????idx++;??
57. ?}??
58. ??
59. ?mResolutionMenu?=?menu.addSubMenu("Resolution");??
60. ?mResolutionList?=?mOpenCvCameraView.getResolutionList();??
61. ?mResolutionMenuItems?=?new?MenuItem[mResolutionList.size()];??
62. ??
63. ?ListIterator<Camera.Size>?resolutionItr?=?mResolutionList.listIterator();??
64. ?idx?=?0;??
65. ?while(resolutionItr.hasNext())?{??
66. ?????Camera.Size?element?=?resolutionItr.next();??
67. ?????mResolutionMenuItems[idx]?=?mResolutionMenu.add(1,?idx,?Menu.NONE,??
68. ?????????????Integer.valueOf((int)?element.width).toString()?+?"x"?+?Integer.valueOf((int)?element.height).toString());??
69. ?????idx++;??
70. ??}??
71. ??
72. ?return?true;??
73. }??
74. ??
75. public?boolean?onOptionsItemSelected(MenuItem?item)?{??
76. ????Log.i(TAG,?"called?onOptionsItemSelected;?selected?item:?"?+?item);??
77. ??
78. ????if?(item.getGroupId()?==?1)??
79. ?{??
80. ?????int?id?=?item.getItemId();??
81. ?????Camera.Size?resolution?=?mResolutionList.get(id);??
82. ?????mOpenCvCameraView.setResolution(resolution);??
83. ?????resolution?=?mOpenCvCameraView.getResolution();??
84. ?????String?caption?=?Integer.valueOf((int)?resolution.width).toString()?+?"x"?+?Integer.valueOf((int)?resolution.height).toString();??
85. ?????Toast.makeText(this,?caption,?Toast.LENGTH_SHORT).show();??
86. ?}???
87. ?else?if?(item.getGroupId()==2){??
88. ??
89. ????int?focusType?=?item.getItemId();??
90. ??
91. ????mOpenCvCameraView.setFocusMode(this,?focusType);??
92. ?}??
93. ?else?if?(item.getGroupId()==3){??
94. ??
95. ????int?flashType?=?item.getItemId();??
96. ??
97. ????mOpenCvCameraView.setFlashMode(this,?flashType);??
98. ?}??
99. ??
100. ????return?true;??
101. }??

這樣運行后，點擊菜單就可以看見有三個菜籃列表：Focus（對焦模式），Flash（視頻模式），Resolution（支持的分辨率）。對焦模式和視頻模式中提供了幾種常見的模式供選擇，代碼會判斷當前設備是否支持該模式。而分辨率菜單欄會顯示出當前設備支持的所有分辨率種類。

參考

• StackOverFlow上關于觸摸對焦的討論
• Android多媒體和相機講解十
• 解讀Android 4.0 Camera原生應用程序的設計思路
• OpenCV上的提問：ANDROID: Use autofocus with CameraBridgeViewBase?

轉載于:https://www.cnblogs.com/jukan/p/6857881.html

總結

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