<uses-permission android:name="android.permission.CAMERA"/> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <uses-feature android:name="android.hardware.camera" /> <uses-feature android:name="android.hardware.camera.autofocus" />
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="horizontal" tools:context="mirror.android.cameratest.CameraTest" > <!-- 4.Palcing preview in a layout --> <FrameLayout android:id="@+id/camera_preview" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_weight="1" /> <Button android:id="@+id/button_capture" android:text="Capture" android:layout_width="wrap_content" android:layout_height="wrap_content" android:gravity="center"/> </LinearLayout>
package mirror.android.cameratest; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import android.app.Activity; import android.content.Context; import android.content.pm.PackageManager; import android.hardware.Camera; import android.hardware.Camera.CameraInfo; import android.hardware.Camera.Parameters; import android.hardware.Camera.PictureCallback; import android.net.Uri; import android.os.Bundle; import android.os.Environment; import android.util.Log; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.FrameLayout; public class CameraTest extends Activity { private Camera camera; private CameraPreview mPreview; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_camera_test); if(checkCameraHardware(getApplication())){ camera = getCameraInstance(); Parameters p = camera.getParameters(); //Log.d("Camera--->getParameters",p.toString());//--->android.hardware.Camera$Parameters@41757e0 // get camera information of the device int cameraCount = Camera.getNumberOfCameras(); CameraInfo cameraInfo = new CameraInfo(); for(int i = 0; i < cameraCount ; i++){ Camera.getCameraInfo(i, cameraInfo); //get information from cameraInfo object //such as cameraInfo.orientation } //Create our Preview view and set it as the content of our activity. mPreview = new CameraPreview(getApplication(), camera); FrameLayout preview = (FrameLayout)findViewById(R.id.camera_preview); preview.addView(mPreview); } Button captureButton = (Button)findViewById(R.id.button_capture); captureButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { camera.takePicture(null, null, mPicture); } }); } //1.check if the device has a camera private boolean checkCameraHardware(Context context){ if(context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) // this device has a camera return true; else // no camera on this device return false; } //2.A safe way to get an instance of the Camera object public static Camera getCameraInstance(){ Camera c = null; try { c = Camera.open(); // attempt to get a Camera instance } catch (Exception e) { // Camera is not available (in use or does not exist) e.printStackTrace(); } return c; // returns null if camera is unavailable } //5. implements a PictureCallback to save image private PictureCallback mPicture = new PictureCallback() { @Override public void onPictureTaken(final byte[] data, Camera camera) { camera.stopPreview(); new Thread( new Runnable(){ @Override public void run() { File pictureFile = new File(Environment.getExternalStorageDirectory(), System.currentTimeMillis() + ".jpg"); try{ FileOutputStream fos = new FileOutputStream(pictureFile); fos.write(data); fos.close(); }catch (FileNotFoundException e) { Log.d("Camera Error","File not found: " + e.getMessage()); }catch (IOException e) { Log.d("Camera Error","Error accessing file: " + e.getMessage()); } } } ).start(); camera.startPreview(); } }; //6. realese the camera obkect @Override protected void onDestroy() { if(camera != null){ camera.stopPreview(); camera.release(); camera = null; } super.onDestroy(); } }
package mirror.android.cameratest; import java.io.IOException; import android.content.Context; import android.hardware.Camera; import android.util.Log; import android.view.SurfaceHolder; import android.view.SurfaceView; //3. Creating a preview class public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback{ private SurfaceHolder mHolder; private Camera mCamera; public CameraPreview(Context context, Camera camera) { super(context); mCamera = camera; mHolder = getHolder(); //Install a SurfaceHolder.Callback so we get notified when the underlying surface is created and destroyed. mHolder.addCallback(this); } @Override public void surfaceCreated(SurfaceHolder holder) { // The Surface has been created, now tell the camera where to draw the preview. try { mCamera.setPreviewDisplay(holder); mCamera.startPreview(); } catch (IOException e) { Log.d("Camera Error", "Error setting camera preview: " + e.getMessage()); } } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { // If your preview can change or rotate, take care of those events here. // Make sure to stop the preview before resizing or reformatting it. if(mHolder.getSurface() == null){ // preview surface does not exist return; } // stop preview before making changes mCamera.stopPreview(); // set preview size and make any resize, rotate or // reformatting changes here try { mCamera.setPreviewDisplay(mHolder); mCamera.startPreview(); } catch (IOException e) { Log.d("Camera Error", "Error setting camera preview: " + e.getMessage()); } } @Override public void surfaceDestroyed(SurfaceHolder holder) { // empty. Take care of releasing the Camera preview in your activity. } }
1. Manifest Declarations
<uses-permission android:name="android.permission.CAMERA" /> permission to use a device camera
<uses-feature android:name="android.hardware.camera" /> declare use of camera features
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> saves images to the external storage (SD Card),
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> tags images with GPS location information
2. Detecting camera hardware
Check for the existence of cameras and request access.
private boolean checkCameraHardware(Context context) { if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)){ // this device has a camera return true; } else { // no camera on this device return false; } }
get an instance of Camera by open() method
public static Camera getCameraInstance(){ Camera c = null; try { c = Camera.open(); // attempt to get a Camera instance } catch (Exception e){ // Camera is not available (in use or does not exist) } return c; // returns null if camera is unavailable }
3. Checking camera features
get further information about its capabilities using the getParameters() method and checking the returned Parameters object for supported
capabilities.
use getcameraInfo() to determine if a camera is on the front or back of the device, and the orientation of the image.
4. Creating a preview class
A camera preview class is a SurfaceView that can display the live image data coming from a camera
implements SurfaceHolder.Calback to captrue the callback events for creating and destroying the view
/** A basic Camera preview class */ public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback { private SurfaceHolder mHolder; private Camera mCamera; public CameraPreview(Context context, Camera camera) { super(context); mCamera = camera; // Install a SurfaceHolder.Callback so we get notified when the // underlying surface is created and destroyed. mHolder = getHolder(); mHolder.addCallback(this); } public void surfaceCreated(SurfaceHolder holder) { // The Surface has been created, now tell the camera where to draw the preview. try { mCamera.setPreviewDisplay(holder); mCamera.startPreview(); } catch (IOException e) { Log.d(TAG, "Error setting camera preview: " + e.getMessage()); } } public void surfaceDestroyed(SurfaceHolder holder) { // empty. Take care of releasing the Camera preview in your activity. } public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { // If your preview can change or rotate, take care of those events here. // Make sure to stop the preview before resizing or reformatting it. if (mHolder.getSurface() == null){ // preview surface does not exist return; } // stop preview before making changes try { mCamera.stopPreview(); } catch (Exception e){ // ignore: tried to stop a non-existent preview } // set preview size and make any resize, rotate or // reformatting changes here // start preview with new settings try { mCamera.setPreviewDisplay(mHolder); mCamera.startPreview(); } catch (Exception e){ Log.d(TAG, "Error starting camera preview: " + e.getMessage()); } } }
5. Placing preview in a layput
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="fill_parent" > <FrameLayout android:id="@+id/camera_preview" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_weight="1" /> <Button android:id="@+id/button_capture" android:text="Capture" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" /> </LinearLayout>
activity android:name=".CameraActivity" android:label="@string/app_name" android:screenOrientation="landscape"> <!-- configure this activity to use landscape orientation --> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity>
6. Capturing pictures
In order to retrieve a picture, use the takePicture() method.
This method takes three parameters which receive data from the camera.
<1>
<2>
<3>
In order to receive data in a JPEG format, you must implement an PictureCallback interface to receive the image data and write it to a file.
// Add a listener to the Capture button Button captureButton = (Button) findViewById(id.button_capture); captureButton.setOnClickListener( new View.OnClickListener() { @Override public void onClick(View v) { // get an image from the camera mCamera.takePicture(null, null, mPicture); } } );
private PictureCallback mPicture = new PictureCallback() { @Override public void onPictureTaken(byte[] data, Camera camera) { File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE); //参照上面的总例程修改 if (pictureFile == null){ Log.d(TAG, "Error creating media file, check storage permissions: " + e.getMessage()); return; } try { FileOutputStream fos = new FileOutputStream(pictureFile); fos.write(data); fos.close(); } catch (FileNotFoundException e) { Log.d(TAG, "File not found: " + e.getMessage()); } catch (IOException e) { Log.d(TAG, "Error accessing file: " + e.getMessage()); } } };
7. Releasing the camera
release the camera object when your application stops using it, and as soon as your application is paused
protected void onPause() { super.onPause(); if (mCamera != null){ mCamera.release(); // release the camera for other applications mCamera = null; } }
8. Saving Media Files
pictures and videos should be saved to a device's external storage directory (SD Card) to conserve system space and to allow users
to access these files without their device
<1>Enviroment.getExternalStoragePublicDirectory(Evironment.DIRECTORY_PICTURE)
This method returns the standard, shared and recommended location for saving pictures and videos.
This directory is shared (public), so other applications can easily discover, read, change and delete files saved in this location.
If your application is uninstalled by the user, media files saved to this location will not be removed.
<2>Context.getExternalFileDir(Environment.DIRECTORY_PICTURE)
standard location for saving pictures and videos which are associated with your application
If your application is uninstalled, any files saved in this location are removed.
9. Camera Features
9.1 Checking feature availabity
Check the availabilty of camera features by getting an instance of a camera’s parameters object, and checking the relevant methods.
// get Camera parameters Camera.Parameters params = mCamera.getParameters(); List<String> focusModes = params.getSupportedFocusModes(); if (focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) { // Autofocus mode is supported }
9.2 Using camera features
// get Camera parameters Camera.Parameters params = mCamera.getParameters(); // set the focus mode params.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO); // set Camera parameters mCamera.setParameters(params);
9.2.1 Metering and focus areas
http://my.oschina.net/madmatrix/blog/204333