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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.example.android.apis.graphics;
     18 
     19 import android.app.Activity;
     20 import android.content.Context;
     21 import android.hardware.Camera;
     22 import android.hardware.Camera.Size;
     23 import android.os.Bundle;
     24 import android.view.SurfaceHolder;
     25 import android.view.SurfaceView;
     26 import android.view.Window;
     27 
     28 import java.io.IOException;
     29 import java.util.List;
     30 
     31 // ----------------------------------------------------------------------
     32 
     33 public class CameraPreview extends Activity {
     34     private Preview mPreview;
     35 
     36     @Override
     37 	protected void onCreate(Bundle savedInstanceState) {
     38         super.onCreate(savedInstanceState);
     39 
     40         // Hide the window title.
     41         requestWindowFeature(Window.FEATURE_NO_TITLE);
     42 
     43         // Create our Preview view and set it as the content of our activity.
     44         mPreview = new Preview(this);
     45         setContentView(mPreview);
     46     }
     47 
     48 }
     49 
     50 // ----------------------------------------------------------------------
     51 
     52 class Preview extends SurfaceView implements SurfaceHolder.Callback {
     53     SurfaceHolder mHolder;
     54     Camera mCamera;
     55 
     56     Preview(Context context) {
     57         super(context);
     58 
     59         // Install a SurfaceHolder.Callback so we get notified when the
     60         // underlying surface is created and destroyed.
     61         mHolder = getHolder();
     62         mHolder.addCallback(this);
     63         mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
     64     }
     65 
     66     public void surfaceCreated(SurfaceHolder holder) {
     67         // The Surface has been created, acquire the camera and tell it where
     68         // to draw.
     69         mCamera = Camera.open();
     70         try {
     71            mCamera.setPreviewDisplay(holder);
     72         } catch (IOException exception) {
     73             mCamera.release();
     74             mCamera = null;
     75             // TODO: add more exception handling logic here
     76         }
     77     }
     78 
     79     public void surfaceDestroyed(SurfaceHolder holder) {
     80         // Surface will be destroyed when we return, so stop the preview.
     81         // Because the CameraDevice object is not a shared resource, it's very
     82         // important to release it when the activity is paused.
     83         mCamera.stopPreview();
     84         mCamera.release();
     85         mCamera = null;
     86     }
     87 
     88 
     89     private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
     90         final double ASPECT_TOLERANCE = 0.05;
     91         double targetRatio = (double) w / h;
     92         if (sizes == null) return null;
     93 
     94         Size optimalSize = null;
     95         double minDiff = Double.MAX_VALUE;
     96 
     97         int targetHeight = h;
     98 
     99         // Try to find an size match aspect ratio and size
    100         for (Size size : sizes) {
    101             double ratio = (double) size.width / size.height;
    102             if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
    103             if (Math.abs(size.height - targetHeight) < minDiff) {
    104                 optimalSize = size;
    105                 minDiff = Math.abs(size.height - targetHeight);
    106             }
    107         }
    108 
    109         // Cannot find the one match the aspect ratio, ignore the requirement
    110         if (optimalSize == null) {
    111             minDiff = Double.MAX_VALUE;
    112             for (Size size : sizes) {
    113                 if (Math.abs(size.height - targetHeight) < minDiff) {
    114                     optimalSize = size;
    115                     minDiff = Math.abs(size.height - targetHeight);
    116                 }
    117             }
    118         }
    119         return optimalSize;
    120     }
    121 
    122     public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
    123         // Now that the size is known, set up the camera parameters and begin
    124         // the preview.
    125         Camera.Parameters parameters = mCamera.getParameters();
    126 
    127         List<Size> sizes = parameters.getSupportedPreviewSizes();
    128         Size optimalSize = getOptimalPreviewSize(sizes, w, h);
    129         parameters.setPreviewSize(optimalSize.width, optimalSize.height);
    130 
    131         mCamera.setParameters(parameters);
    132         mCamera.startPreview();
    133     }
    134 
    135 }
    136