前言

????在android編碼中有2種方式可以調用到系統的攝像頭,一種是通過Intent調用系統的照相機Activity;另外一種就是通過編碼調用Camera api.

1.??Intent調用系統照相Activity

通過Intent直接調用系統提供的照相機功能,復用它的拍照Activity,這是最簡單和最方便的辦法,不需要考慮手機的兼容性問題,比如預覽拍照圖片大小等,代碼如下:

Intent i =?new?Intent("android.media.action.IMAGE_CAPTURE");

startActivityForResult(i, C.REQUEST_CODE_CAMERA);

?

然后在onActivityResult中獲取返回的數據即可

if(resultCode==RESULT_OK){

??? Bundle extras = data.getExtras();

????if(extras!=null){

?????? Bitmap bitmap = (Bitmap) extras.get(C.CODE_PHOTO_BITMAP_DATA);

?????? … …

??? }

}

但是這樣獲取的圖片是縮小過的,?如果要獲取原始的相片就要在調用的時候就要指定相片生成的路徑,下面的代碼即可.

i.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(new?File(tempPath)));

指定相片的類型,代碼示例.

i.putExtra("outputFormat", Bitmap.CompressFormat.PNG.name());

控制拍照的橫豎屏.

i.putExtra(MediaStore.EXTRA_SCREEN_ORIENTATION, Configuration.ORIENTATION_LANDSCAPE);

2.??Android編碼拍照

直接調用攝像頭的API,自己編寫類似取景框的Activity,這樣靈活度更大,但是你需要考慮比較底層的東西.要知道android有多個版本,攝像頭的分辨率也不一樣,需要先獲取當前相機的分辨率組合,然后再編寫各種屏幕分辨率組合的布局等等.

而且Android提供的SDK(android.hardware.Camera)不能正常的使用豎屏(portrait layout)加載照相機,當用豎屏模式加載照相機時會產生以下情況:1.?照相機成像左傾90度;2.?照相機成像長寬比例不對(失比).原因是:攝像頭對照物的映射是Android底層固定的,以landscape方式為正,并且產生大小為320*480的像,如果換成portrait方式了,攝像頭還是產生320*480的像,但要對應的放入到一個480*320的屏內,此時會失比,并且產生了左傾90度的情況.如圖所示

這種情況可以通過復雜的編碼可以校正.

①???設置Camera的參數來實現轉變圖片預覽角度,但是這種方式并不是對所有的Camera都有效果的.

??? Camera.Parameters parameters =?camera.getParameters();

??? parameters.set("orientation",?"portrait");

??? parameters.set("rotation", 90);

????camera.setParameters(parameters);

?

②???在獲取拍攝相片之后進行旋轉校正,?但這里同時也要如果圖片太大了,會造成內存溢出.

??? Matrix m =?new?Matrix();

??? m.postRotate(90);

??? m.postScale(balance, balance);

??? Bitmap.createBitmap(tempBitmap, 0, 0, tempBitmap.getWidth(), tempBitmap.getHeight(),m,?true);

?

Camera示例代碼:

public?class?CameraDemoActivityextends?Activity?implementsSurfaceHolder.Callback{

????private?Camera??????????????mCamera;

????private?Button??????????????mButton;

????private?SurfaceView?????????mSurfaceView;

????private?SurfaceHolder???????holder;

????private?AutoFocusCallback???mAutoFocusCallback?? =?new?AutoFocusCallback();

?

????@Override

????public?void?onCreate(Bundle?savedInstanceState){

???????super.onCreate(savedInstanceState);

?????? setContentView(R.layout.main);

???????/* SurfaceHolder設置?*/

???????mSurfaceView?= (SurfaceView)findViewById(R.id.mSurfaceView);

???????holder?=?mSurfaceView.getHolder();

???????holder.addCallback(CameraDemoActivity.this);

???????holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

???????/*?設置拍照Button的OnClick事件處理?*/

???????mButton?= (Button)findViewById(R.id.myButton);

???????mButton.setOnClickListener(new?Button.OnClickListener(){

???????????@Override

???????????public?void?onClick(View arg0){

??????????????/*?告動對焦后拍照?*/

??????????????mCamera.autoFocus(mAutoFocusCallback);

?????????? }

?????? });

??? }

?

????@Override

????public?void?surfaceCreated(SurfaceHolder surfaceholder){

???????try{

???????????/*?打開相機, */

???????????mCamera?= Camera.open();

???????????mCamera.setPreviewDisplay(holder);

?????? }catch(IOException exception){

???????????mCamera.release();

???????????mCamera?=?null;

?????? }

??? }

?

????@Override

????public?void?surfaceChanged(SurfaceHolder surfaceholder,?int?format,?int?w,int?h){

???????/*?相機初始化?*/

?????? initCamera();

??? }

?

????@Override

????public?void?surfaceDestroyed(SurfaceHolder surfaceholder){

?????? stopCamera();

???????mCamera.release();

???????mCamera?=?null;

??? }

?

????/*?拍照的method */

????private?void?takePicture(){

???????if(mCamera?!=?null){

???????????mCamera.takePicture(shutterCallback,?rawCallback,?jpegCallback);

?????? }

??? }

?

????private?ShutterCallback??shutterCallback?? =?new?ShutterCallback(){

???????public?void?onShutter(){

???????/*?按下快門瞬間會調用這里的程序?*/

?????? }

??? };

?

????private?PictureCallback??rawCallback?????? =?new?PictureCallback(){

??????????????????????????????????????????public?void?onPictureTaken(byte[] _data, Camera _camera){

???????/*?要處理raw data?寫?否?*/

?????? }

??? };

?

????private?PictureCallback??jpegCallback? =?new?PictureCallback(){

???????public?void?onPictureTaken(byte[] _data, Camera _camera){

?????? ????/*?取得相片?*/

?????? ????try{

?????? ??? ????/*?讓相片顯示3秒后圳重設相機?*/

??? ??? ?????? Thread.sleep(3000);

??? ??? ???????/*?重新設定Camera */

??? ??? ?????? stopCamera();

??? ??? ?????? initCamera();

??? ??? ??? }catch(Exception e){

??? ??? ?????? e.printStackTrace();

??? ??? ??? }

??? ??? }

};

?

????/*?告定義class AutoFocusCallback */

????public?final?class?AutoFocusCallback?implementsandroid.hardware.Camera.AutoFocusCallback{

???????public?void?onAutoFocus(boolean?focused, Camera camera){

???????????/*?對到焦點拍照?*/

???????????if(focused){

????????????? takePicture();

?????????? }

?????? }

??? };

?

????/*?相機初始化的method */

????private?void?initCamera(){

???????if(mCamera?!=?null){

???????????try{

????????????? Camera.Parameters parameters =?mCamera.getParameters();

??????????????/*

????????????? ?*?設定相片大小為1024*768,格式為JPG

????????????? ?*/

????????????? parameters.setPictureFormat(PixelFormat.JPEG);

????????????? parameters.setPictureSize(1024, 768);

??????????????mCamera.setParameters(parameters);

??????????????/*?打開預覽畫面?*/

??????????????mCamera.startPreview();

?????????? }catch(Exception e){

????????????? e.printStackTrace();

?????????? }

?????? }

??? }

?

????/*?停止相機的method */

????private?void?stopCamera(){

???????if(mCamera?!=?null){

???????????try{

??????????????/*?停止預覽?*/

??????????????mCamera.stopPreview();

?????????? }catch(Exception e){

????????????? e.printStackTrace();

?????????? }

?????? }

??? }

}

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