照相机技术（二）

//定制拍照：
public class MainActivity extends Activity {
    private Camera mCamera;
    private Preview mPreview;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // setContentView(R.layout.fragment_main);
        // 隐藏标题
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        // 设置为全屏
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
        mPreview = new Preview(this);
        setContentView(mPreview);
    }

    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();
        // 第一步：打开照相机
        mCamera = Camera.open(0);
        mPreview.setCamera(mCamera);
    }

    // 释放焦点
    @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();
        if (mCamera != null) {
            mCamera.release();
            mCamera = null;
            mPreview.setCamera(null);
        }
    }

    // 第三步：添加回调事件监听器SurfaceHolder.addCallback
    class Preview extends ViewGroup implements SurfaceHolder.Callback,
            OnClickListener {
        SurfaceView mSurfaceView;
        SurfaceHolder mHolder;
        Size mPreviewSize;
        List<Size> msupportedPreviewSizes;
        Camera mCamera;
        Context mContext;

        public Preview(Context context) {
            super(context);
            // TODO Auto-generated constructor stub
            mContext = context;
            mSurfaceView = new SurfaceView(context);
            addView(mSurfaceView);
            mHolder = mSurfaceView.getHolder();
            mHolder.addCallback(this);
        }

        public void setCamera(Camera camera) {
            mCamera = camera;
            if (mCamera != null) {
                // 获得所有预览尺寸
                msupportedPreviewSizes = mCamera.getParameters()
                        .getSupportedPictureSizes();
                requestLayout();

            }
        }

        @Override
        public void surfaceCreated(SurfaceHolder holder) {
            // TODO Auto-generated method stub
            try {
                if (mCamera != null) {
                    // 将Camera和SurfaceView关联
                    mCamera.setPreviewDisplay(holder);
                }
            } catch (Exception e) {
                // TODO: handle exception
            }
        }

        private PictureCallback mpPictureCallback = new PictureCallback() {

            @Override
            public void onPictureTaken(byte[] data, Camera camera) {
                mCamera.startPreview();
                File pictureFile = new File("/sdcard/image.jpg");
                try {
                    FileOutputStream fos = new FileOutputStream(pictureFile);
                    fos.write(data);
                    fos.close();
                } catch (Exception e) {
                    // TODO: handle exception
                }
            }
        };

        @Override
        public void surfaceChanged(SurfaceHolder holder, int format, int width,
                int height) {

            // 设置最佳预览尺寸
            Camera.Parameters parameters = mCamera.getParameters();

            parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);

            mCamera.setParameters(parameters);
            mCamera.startPreview();
        }

        @Override
        public void surfaceDestroyed(SurfaceHolder holder) {
            // TODO Auto-generated method stub
            if (mCamera != null) {
                mCamera.stopPreview();
            }
        }

        @Override
        protected void onLayout(boolean changed, int l, int t, int r, int b) {
            // 使预览和实际窗口大小一致
            if (changed && getChildCount() > 0) {
                final View child = getChildAt(0);
                int width = r - l;
                int height = b - t;
                int previewWidth = width;
                int previewHeight = height;
                if (mPreviewSize != null) {
                    previewWidth = mPreviewSize.width;
                    previewHeight = mPreviewSize.height;

                }
                // 手机屏幕的宽高比大于采集图像的宽高比
                if (width * previewHeight > height * previewWidth) {
                    final int scaledChildWidth = previewWidth * height
                            / previewHeight;
                    // child.layout((width - scaledChildWidth) / 2, 0,
                    // (width + scaledChildWidth) / 2, height);
                    child.layout(100, 100, 340, 240);// 设置照相框位置
                } else {
                    final int scaledChildHeight = previewWidth * width
                            / previewWidth;
                    child.layout(0, (height - scaledChildHeight) / 2, width,
                            (height + scaledChildHeight) / 2);
                }
            }

        }

        private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {

            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;
            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);
                }

            }
            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;

        }

        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            // TODO Auto-generated method stub
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            int width = resolveSize(getSuggestedMinimumWidth(),
                    widthMeasureSpec);
            int height = resolveSize(getSuggestedMinimumHeight(),
                    heightMeasureSpec);
            setMeasuredDimension(width, height);
            if (msupportedPreviewSizes != null) {
                mPreviewSize = getOptimalPreviewSize(msupportedPreviewSizes,
                        width, height);
            }

        }

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            mCamera.takePicture(null, null, mpPictureCallback);
        }

    }

}