How to set the size of the camera preview in full screen using the Android API?

Question

I am very new to Android development and I am trying to get a simple app setup for the camera. So far I have a camera application that has the “camera switch” and “snapshot” buttons inside the menu that work fine.

The only problem I am facing is that I am trying to figure out how to get the screen in full screen. Right now, the camera appears only in the very middle of the screen and occupies approximately 1/4 of the screen.

MainActivity Code

package assist.core; import android.app.Activity; import android.app.AlertDialog; import android.hardware.Camera; import android.hardware.Camera.PictureCallback; import android.hardware.Camera.ShutterCallback; import android.hardware.Camera.CameraInfo; import android.os.Bundle; import android.view.Window; import android.view.WindowManager; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.util.Log; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; public class MainActivity extends Activity { private final String TAG = "MainActivity"; private Preview mPreview; Camera mCamera; int numberOfCameras; int cameraCurrentlyLocked; //The first rear facing camera int defaultCameraId; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //Hide the window title. requestWindowFeature(Window.FEATURE_NO_TITLE); getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN); //Create a RelativeLayout container that will hold a SurfaceView, //and set it as the content of our activity. mPreview = new Preview(this); setContentView(mPreview); //Find the total number of cameras available numberOfCameras = Camera.getNumberOfCameras(); //Find the ID of the default camera CameraInfo cameraInfo = new CameraInfo(); for (int i = 0; i < numberOfCameras; i++) { Camera.getCameraInfo(i, cameraInfo); if(cameraInfo.facing == CameraInfo.CAMERA_FACING_BACK) { defaultCameraId = i; } } } @Override protected void onResume() { super.onResume(); //Open the default ie the first rear facing camera. mCamera = Camera.open(); cameraCurrentlyLocked = defaultCameraId; mPreview.setCamera(mCamera); } @Override protected void onPause() { super.onPause(); //Because the Camera object is a shared resource, it very //Important to release it when the activity is paused. if (mCamera != null) { mPreview.setCamera(null); mCamera.release(); mCamera = null; } } @Override public boolean onCreateOptionsMenu(Menu menu) { //Inflate our menu which can gather user input for switching camera MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.camera_menu, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { //Handle item selection switch (item.getItemId()) { case R.id.switchCam: //Check for availability of multiple cameras if (numberOfCameras == 1) { AlertDialog.Builder builder = new AlertDialog.Builder(this); builder.setMessage(this.getString(R.string.camera_alert)).setNeutralButton("Close", null); AlertDialog alert = builder.create(); alert.show(); return true; } //OK, we have multiple cameras. //Release this camera -> cameraCurrentlyLocked if (mCamera != null) { mCamera.stopPreview(); mPreview.setCamera(null); mCamera.release(); mCamera = null; } //Acquire the next camera and request Preview to reconfigure parameters. mCamera = Camera.open((cameraCurrentlyLocked + 1) % numberOfCameras); cameraCurrentlyLocked = (cameraCurrentlyLocked + 1) % numberOfCameras; mPreview.switchCamera(mCamera); //Start the preview mCamera.startPreview(); return true; case R.id.takePicture: mCamera.takePicture(shutterCallback, rawCallback, jpegCallback); return true; default: return super.onOptionsItemSelected(item); } } /** * Called when shutter is opened */ ShutterCallback shutterCallback = new ShutterCallback() { public void onShutter() { } }; /** * Handles data for raw picture when the picture is taken */ PictureCallback rawCallback = new PictureCallback() { public void onPictureTaken(byte[] data, Camera camera) { } }; /** * Handles data for jpeg picture when the picture is taken */ PictureCallback jpegCallback = new PictureCallback() { public void onPictureTaken(byte[] data, Camera camera) { FileOutputStream outStream = null; try { // Write to SD Card outStream = new FileOutputStream(String.format("/sdcard/%d.jpg", System.currentTimeMillis())); outStream.write(data); outStream.close(); } catch (FileNotFoundException e) { Log.e(TAG, "IOException caused by PictureCallback()", e); } catch (IOException e) { Log.e(TAG, "IOException caused by PictureCallback()", e); } } }; } 

Class Code Preliminary Code

 package assist.core; import android.content.Context; import android.hardware.Camera; import android.hardware.Camera.Size; import android.util.Log; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.view.View; import android.view.ViewGroup; import java.util.List; import java.io.IOException; /** * * @author cmetrolis */ class Preview extends ViewGroup implements SurfaceHolder.Callback { private final String TAG = "Preview"; SurfaceView mSurfaceView; SurfaceHolder mHolder; Size mPreviewSize; List<Size> mSupportedPreviewSizes; Camera mCamera; Preview(Context context) { super(context); mSurfaceView = new SurfaceView(context); addView(mSurfaceView); //Install a SurfaceHolder.Callback so we get notified when the //underlying surface is created and destroyed. mHolder = mSurfaceView.getHolder(); mHolder.addCallback(this); mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); } public void setCamera(Camera camera) { mCamera = camera; if(mCamera != null) { mSupportedPreviewSizes = mCamera.getParameters().getSupportedPreviewSizes(); requestLayout(); } } public void switchCamera(Camera camera) { setCamera(camera); try { camera.setPreviewDisplay(mHolder); } catch (IOException exception) { Log.e(TAG, "IOException caused by setPreviewDisplay()", exception); } Camera.Parameters parameters = camera.getParameters(); parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height); requestLayout(); camera.setParameters(parameters); } /** * Called to determine the size requirements for this view and all of its children. * @param widthMeasureSpec * @param heightMeasureSpec */ @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { //We purposely disregard child measurements because act as a //Wrapper to a SurfaceView that centers the camera preview instead of stretching it. final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec); final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec); setMeasuredDimension(width, height); if(mSupportedPreviewSizes != null) { mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width, height); } } /** * Called when this view should assign a size and position to all of its children. * @param changed * @param l * @param t * @param r * @param b */ @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { if(changed && getChildCount() > 0) { final View child = getChildAt(0); final int width = r - l; final int height = b - t; int previewWidth = width; int previewHeight = height; if(mPreviewSize != null) { previewWidth = mPreviewSize.width; previewHeight = mPreviewSize.height; } // Center the child SurfaceView within the parent. if(width * previewHeight > height * previewWidth) { final int scaledChildWidth = previewWidth * height / previewHeight; child.layout((width - scaledChildWidth) / 2, 0, (width + scaledChildWidth) / 2, height); } else { final int scaledChildHeight = previewHeight * width / previewWidth; child.layout(0, (height - scaledChildHeight) / 2, width, (height + scaledChildHeight) / 2); } } } /** * This is called immediately after the surface is first created * @param holder */ public void surfaceCreated(SurfaceHolder holder) { try { if(mCamera != null) { mCamera.setPreviewDisplay(holder); } } catch (IOException e) { Log.e(TAG, "IOException caused by setPreviewDisplay()", e); } } /** * This is called immediately before a surface is being destroyed * @param holder */ public void surfaceDestroyed(SurfaceHolder holder) { //Surface will be destroyed when we return, so stop the preview. if(mCamera != null) { mCamera.stopPreview(); mCamera.release(); } } /** * This is called immediately after any structural changes (format or size) have been made to the surface * @param holder * @param format * @param w * @param h */ public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { Camera.Parameters parameters = mCamera.getParameters(); parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height); mCamera.setDisplayOrientation(90); requestLayout(); mCamera.setParameters(parameters); mCamera.startPreview(); } /** * Returns the best preview size * @param sizes * @param w * @param h * @return Size */ private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) { final double ASPECT_TOLERANCE = 0.1; double targetRatio = (double) w / h; if (sizes == null) return null; Size optimalSize = null; double minDiff = Double.MAX_VALUE; int targetHeight = h; // Try to find an size match aspect ratio and size for(Size size : sizes) { double ratio = (double) size.width / size.height; if(Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue; if(Math.abs(size.height - targetHeight) < minDiff) { optimalSize = size; minDiff = Math.abs(size.height - targetHeight); } } // Cannot find the one match the aspect ratio, ignore the requirement if(optimalSize == null) { minDiff = Double.MAX_VALUE; for (Size size : sizes) { if(Math.abs(size.height - targetHeight) < minDiff) { optimalSize = size; minDiff = Math.abs(size.height - targetHeight); } } } return optimalSize; } } 

camer_menu.xml code

 <?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <item android:id="@+id/switchCam" android:title="@string/switch_cam" /> <item android:id="@+id/takePicture" android:title="@string/take_picture" android:onClick="snapPicture" android:layout_gravity="center" /> </menu> 

UPDATE

I tried changing the code in the Preview constructor to the following.

 ViewGroup.LayoutParams lp = new ViewGroup.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT); this.setLayoutParams(lp); mSurfaceView = new SurfaceView(context); mSurfaceView.setLayoutParams(lp); addView(mSurfaceView); 

This did not work, but also did not make the camera full screen.

Answer 1

I fixed it by removing the following code from the Preview class,

 if(mPreviewSize != null) { previewWidth = mPreviewSize.width; previewHeight = mPreviewSize.height; } 

Answer 2

Since you are using setContentView with your custom Preview class, which comes from ViewGroup, just pass ViewGroup.LayoutParams so that it populates it with the parent.

Something like that:

 ViewGroup.LayoutParams lp = new ViewGroup.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT); Preview.setLayoutParams(lp);