這裡整理了一些關於在Android寫相機App會產生的一些疑問，並且把自己寫好的程式整理出來放在Github上面．
這裡產生的相機功能主要如下:
-
利用 Camera class產生相機的控制部分
-
預覽的視窗
-
拍照後可以讓Android系統預設的相簿觀看
讓相機產生preview
1.將需要授權的相關部分放在”AndroidManifest.xml”
<uses-permissionandroid:name=”android.permission.CAMERA”/>
<uses-featureandroid:name=”android.hardware.camera.autofocus”/>
<uses-featureandroid:name=”android.hardware.camera”android:required=”false”/>
<uses-permissionandroid:name=”android.permission.WRITE_EXTERNAL_STORAGE”/>
- 把需要的元件畫出來，需要一個SurfaceView跟一個Button，修改reslayoutactivity_main.xml
<SurfaceView
android:id=”@+id/surfaceView1”
android:layout_width=”fill_parent”
android:layout_height=”fill_parent”
android:layout_alignParentBottom=”true”
android:layout_alignParentLeft=”true”
android:layout_alignParentRight=”true”>
</SurfaceView>
<Button
android:id=”@+id/btn_capture”
android:layout_width=”wrap_content”
android:layout_height=”wrap_content”
android:layout_alignRight=”@+id/surfaceView1”
android:layout_below=”@+id/textView1”
android:layout_marginRight=”18dp”
android:layout_marginTop=”144dp”
android:text=”Capture”/>
- 讓preview可以動作，這裡的code比較多，儘量寫清楚點
3.1 建立 相關原件
//Camera object
Camera mCamera;
//Preview surface
SurfaceView surfaceView;
//Preview surface handle for callback
SurfaceHolder surfaceHolder;
//Camera button
Button btnCapture;
//Note if preview windows is on.
booleanpreviewing;
3.2 連接原件修改原來的 OnCreate
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnCapture = (Button) findViewById(R.id.btn_capture);
surfaceView = (SurfaceView) findViewById(R.id.surfaceView1);
surfaceHolder = surfaceView.getHolder();
surfaceHolder.addCallback(new SurfaceViewCallback());
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
3.3 增加surface callback class讓surface自己來處理相關預覽的部分
private final class SurfaceViewCallback implements android.view.SurfaceHolder.Callback {
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3)
{
if (previewing) {
mCamera.stopPreview();
previewing = false;
}
try {
mCamera.setPreviewDisplay(arg0);
mCamera.startPreview();
previewing = true;
} catch (Exception e) {}
}
public void surfaceCreated(SurfaceHolder holder) {
mCamera = Camera.open();
// get Camera parameters
Camera.Parameters params = mCamera.getParameters();
List
if (focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
// Autofocus mode is supported
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
mCamera.stopPreview();
mCamera.release();
mCamera = null;
previewing = false;
}
}
- 這樣就可以看到完整的camera preview，接下來就要implement 拍照後的一些處理
4.1 實作出拍照的功能
btnCapture.setOnClickListener(new Button.OnClickListener() {
public void onClick(View arg0) {
if (previewing)
mCamera.takePicture(shutterCallback, rawPictureCallback,jpegPictureCallback);
}
});
4.2 實作camera.takePicutre 的callback function
先接起來button click listener
btnCapture.setOnClickListener(new Button.OnClickListener() {
public void onClick(View arg0) {
if (previewing)
mCamera.takePicture(shutterCallback, rawPictureCallback, jpegPictureCallback);
}
});
要把相關的 shutterCallback, rawPictureCallback加進去，最後記得要把jpegPictureCallback 弄好
ShutterCallback shutterCallback = new ShutterCallback() {
@Override
public void onShutter() {
}
};
PictureCallback rawPictureCallback = new PictureCallback() {
@Override
public void onPictureTaken(byte[] arg0, Camera arg1) {
}
};
這裡要注意，在jpegPictureCallback 中有幾件重要的事情
-
將抓下來的部分存成檔案
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檔案目錄與檔名的選取，記得使用Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM)
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在檔案的存取方面，使用的是BufferedOutputStream來寫檔案～這裡大部分網路例子會先轉成 Bitmap 然後再轉成JPG，這裡要改
-
-
利用 MediaScannerConnection 去連接MediaStore 來把你拍下來的照片通知給系統，讓系統的相簿可以抓到你的相片
這部分的code 如下
PictureCallback jpegPictureCallback = new PictureCallback() {
@Override
public void onPictureTaken(byte[] arg0, Camera arg1) {
String fileName = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).toString()
+ File.separator
+ “PicTest_” + System.currentTimeMillis() + “.jpg”;
File file = new File(fileName);
if (!file.getParentFile().exists()) {
file.getParentFile().mkdir();
}
try {
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file));
bos.write(arg0);
bos.flush();
bos.close();
scanFileToPhotoAlbum(file.getAbsolutePath());
Toast.makeText(MainActivity.this, “[Test] Photo take and store in” + file.toString(),Toast.LENGTH_LONG).show();
} catch (Exception e) {
Toast.makeText(MainActivity.this, “Picture Failed” + e.toString(),Toast.LENGTH_LONG).show();
}
};
};
public void scanFileToPhotoAlbum(String path) {
MediaScannerConnection.scanFile(MainActivity.this,
new String[] { path }, null,
new MediaScannerConnection.OnScanCompletedListener() {
public void onScanCompleted(String path, Uri uri) {
Log.i(“TAG”, “Finished scanning “ + path);
}
});
這樣就完成了，完整的程式放在Github
