Android Camera相机原理解析(源码)

在应用软件开发中，图片数据，对于一个公司来说是十分重要的，例如：上传图片资料，修改用户头像等，而这其中就离不开相机和相册的使用。对于ios平台来说，直接调用系统相机或相册，就可搞定一切。然而对于Android平台来说，直接调用系统相机或相册，在适配和体验上问题比较多，具体原因，相比大家也知道，安卓品牌太多太杂，性能不一。鉴于此，在开发的过程中，遇到类似问题，建议自己实现相机或相册功能，以保证体验完整。本篇博文将会重点介绍Camera相机的实现。

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首先，推荐两个github项目，可以直接使用的相机和相册；另外，也推荐一个联系人选择器：

相机：CameraDemo(自定义相机)

相册：ImageSelector(仿微信图片选择相册)

联系人：ContactSelector(联系人选择器)

一、打开Camera

        try {                mCamera = Camera.open();//开启相机            } catch (RuntimeException e) {                e.printStackTrace();                LogUtil.d(TAG, "摄像头异常，请检查摄像头权限是否应许");                ToastUtil.getInstance().toast("摄像头异常，请检查摄像头权限是否应许");                return;            }

二、设置Camera参数

默认尺寸可以自由设置，这里取手机的分辨率为默认尺寸。

1.根据指定分辨率查找相机最佳适配分辨率并设置

    private void setCameraParams(int width, int height) {        LogUtil.i(TAG, "setCameraParams  width=" + width + "  height=" + height);        Camera.Parameters parameters = mCamera.getParameters();        List<Camera.Size> pictureSizeList = parameters.getSupportedPictureSizes();        sort(pictureSizeList);//排序        for (Camera.Size size : pictureSizeList) {            LogUtil.i(TAG, "摄像头支持的分辨率：" + " size.width=" + size.width + "  size.height=" + size.height);        }        Camera.Size picSize = getBestSupportedSize(pictureSizeList, ((float) height / width));//从列表中选取合适的分辨率        if (null == picSize) {            picSize = parameters.getPictureSize();        }        LogUtil.e(TAG, "我们选择的摄像头分辨率：" + "picSize.width=" + picSize.width + "  picSize.height=" + picSize.height);        // 根据选出的PictureSize重新设置SurfaceView大小        parameters.setPictureSize(picSize.width, picSize.height);        ....

2.根据指定分辨率查找相机最佳预览分辨率并设置

    private void setCameraParams(int width, int height) {         LogUtil.i(TAG, "setCameraParams  width=" + width + "  height=" + height);        Camera.Parameters parameters = mCamera.getParameters();        /*************************** 获取摄像头支持的PreviewSize列表********************/        List<Camera.Size> previewSizeList = parameters.getSupportedPreviewSizes();        sort(previewSizeList);        for (Camera.Size size : previewSizeList) {            LogUtil.i(TAG, "摄像支持可预览的分辨率：" + " size.width=" + size.width + "  size.height=" + size.height);        }        Camera.Size preSize = getBestSupportedSize(previewSizeList, ((float) height) / width);        if (null != preSize) {            LogUtil.e(TAG, "我们选择的预览分辨率：" + "preSize.width=" + preSize.width + "  preSize.height=" + preSize.height);            parameters.setPreviewSize(preSize.width, preSize.height);        }       ......

3.最佳分辨率适配算法(先排序)

    /**     * 如包含默认尺寸，则选默认尺寸，如没有，则选最大的尺寸     * 规则：在相同比例下，1.优先寻找长宽分辨率相同的->2.找长宽有一个相同的分辨率->3.找最大的分辨率     *     * @param sizes 尺寸集合     * @return 返回合适的尺寸     */    private Camera.Size getBestSupportedSize(List<Camera.Size> sizes, float screenRatio) {        Camera.Size largestSize = null;        int largestArea = 0;        for (Camera.Size size : sizes) {            if ((float) size.height / (float) size.width == screenRatio) {                if (size.width == DEFAULT_PHOTO_WIDTH && size.height == DEFAULT_PHOTO_HEIGHT) {                    // 包含特定的尺寸，直接取该尺寸                    largestSize = size;                    break;                } else if (size.height == DEFAULT_PHOTO_HEIGHT || size.width == DEFAULT_PHOTO_WIDTH) {                    largestSize = size;                    break;                }                int area = size.height + size.width;                if (area > largestArea) {//找出最大的合适尺寸                    largestArea = area;                    largestSize = size;                }            } else if (size.height == DEFAULT_PHOTO_HEIGHT || size.width == DEFAULT_PHOTO_WIDTH) {                largestSize = size;                break;            }        }        if (largestSize == null) {            largestSize = sizes.get(sizes.size() - 1);        }        return largestSize;    }

4.对焦模式选择
由于部分智能手机，前置摄像头无对焦模式，对焦参数设置应区分前置摄像头

   //对焦模式的选择         if(cameraId == Camera.CameraInfo.CAMERA_FACING_BACK){            parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);//手动区域自动对焦        }

5.图片质量
PixelFormat中有多种模式，源码有解。

        //图片质量        parameters.setJpegQuality(100); // 设置照片质量        parameters.setPreviewFormat(PixelFormat.YCbCr_420_SP); // 预览格式        parameters.setPictureFormat(PixelFormat.JPEG); // 相片格式为JPEG，默认为NV21

6.闪关灯及横竖屏镜头调整

        // 关闪光灯        parameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);        // 横竖屏镜头自动调整        if (mContext.getResources().getConfiguration().orientation != Configuration.ORIENTATION_LANDSCAPE) {            mCamera.setDisplayOrientation(90);        } else {            mCamera.setDisplayOrientation(0);        }

7.相机异常监听

        //相机异常监听        mCamera.setErrorCallback(new Camera.ErrorCallback() {            @Override            public void onError(int error, Camera camera) {                String error_str;                switch (error) {                    case Camera.CAMERA_ERROR_SERVER_DIED: // 摄像头已损坏                        error_str = "摄像头已损坏";                        break;                    case Camera.CAMERA_ERROR_UNKNOWN:                        error_str = "摄像头异常，请检查摄像头权限是否应许";                        break;                    default:                        error_str = "摄像头异常，请检查摄像头权限是否应许";                        break;                }                ToastUtil.getInstance().toast(error_str);                Log.i(TAG, error_str);            }        });

完整参数设置代码：

  /**     * 设置分辨率等参数     *     * @param width  宽     * @param height 高     */    private void setCameraParams(int width, int height) {        LogUtil.i(TAG, "setCameraParams  width=" + width + "  height=" + height);        Camera.Parameters parameters = mCamera.getParameters();        /*************************** 获取摄像头支持的PictureSize列表********************/        List<Camera.Size> pictureSizeList = parameters.getSupportedPictureSizes();        sort(pictureSizeList);//排序        for (Camera.Size size : pictureSizeList) {            LogUtil.i(TAG, "摄像头支持的分辨率：" + " size.width=" + size.width + "  size.height=" + size.height);        }        Camera.Size picSize = getBestSupportedSize(pictureSizeList, ((float) height / width));//从列表中选取合适的分辨率        if (null == picSize) {            picSize = parameters.getPictureSize();        }        LogUtil.e(TAG, "我们选择的摄像头分辨率：" + "picSize.width=" + picSize.width + "  picSize.height=" + picSize.height);        // 根据选出的PictureSize重新设置SurfaceView大小        parameters.setPictureSize(picSize.width, picSize.height);        /*************************** 获取摄像头支持的PreviewSize列表********************/        List<Camera.Size> previewSizeList = parameters.getSupportedPreviewSizes();        sort(previewSizeList);        for (Camera.Size size : previewSizeList) {            LogUtil.i(TAG, "摄像支持可预览的分辨率：" + " size.width=" + size.width + "  size.height=" + size.height);        }        Camera.Size preSize = getBestSupportedSize(previewSizeList, ((float) height) / width);        if (null != preSize) {            LogUtil.e(TAG, "我们选择的预览分辨率：" + "preSize.width=" + preSize.width + "  preSize.height=" + preSize.height);            parameters.setPreviewSize(preSize.width, preSize.height);        }        /*************************** 对焦模式的选择 ********************/        if(cameraId == Camera.CameraInfo.CAMERA_FACING_BACK){            parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);//手动区域自动对焦        }        //图片质量        parameters.setJpegQuality(100); // 设置照片质量        parameters.setPreviewFormat(PixelFormat.YCbCr_420_SP); // 预览格式        parameters.setPictureFormat(PixelFormat.JPEG); // 相片格式为JPEG，默认为NV21        // 关闪光灯        parameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);        // 横竖屏镜头自动调整        if (mContext.getResources().getConfiguration().orientation != Configuration.ORIENTATION_LANDSCAPE) {            mCamera.setDisplayOrientation(90);        } else {            mCamera.setDisplayOrientation(0);        }        //相机异常监听        mCamera.setErrorCallback(new Camera.ErrorCallback() {            @Override            public void onError(int error, Camera camera) {                String error_str;                switch (error) {                    case Camera.CAMERA_ERROR_SERVER_DIED: // 摄像头已损坏                        error_str = "摄像头已损坏";                        break;                    case Camera.CAMERA_ERROR_UNKNOWN:                        error_str = "摄像头异常，请检查摄像头权限是否应许";                        break;                    default:                        error_str = "摄像头异常，请检查摄像头权限是否应许";                        break;                }                ToastUtil.getInstance().toast(error_str);                Log.i(TAG, error_str);            }        });        mCamera.cancelAutoFocus();        mCamera.setParameters(parameters);    }

三、对焦

要实现点击对焦，并有对焦环，需要自定义实现对焦环View.

1.自定义对焦环View-CameraFocusView

核心功能，就是对焦环缩小，并变绿。利用动画改变对焦环半径即可。

     @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        if(isShow){            if(radius == GREEN_RADIUS){                mPaint.setColor(Color.GREEN);            }            if(centerPoint!=null){                canvas.drawCircle(centerPoint.x, centerPoint.y, radius, mPaint);            }        }    }    private void showAnimView() {        isShow = true;        if (lineAnimator == null) {            lineAnimator = ValueAnimator.ofInt(0, 20);            lineAnimator.setDuration(DURATION_TIME);            lineAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {                @Override                public void onAnimationUpdate(ValueAnimator animation) {                    int animationValue = (Integer) animation                            .getAnimatedValue();                    if(lastValue!=animationValue&&radius>=(int) ((mScreenWidth * 0.1)-20)){                        radius = radius - animationValue;                        lastValue = animationValue;                    }                    isShow = true;                    invalidate();                }            });            lineAnimator.addListener(new AnimatorListenerAdapter() {                @Override                public void onAnimationEnd(Animator animation) {                    super.onAnimationEnd(animation);                    isShow = false;                    lastValue = 0;                    mPaint.setColor(Color.WHITE);                    radius = (int) (mScreenWidth * 0.1);                    invalidate();                }            });        }else{            lineAnimator.end();            lineAnimator.cancel();            lineAnimator.setInterpolator(new AccelerateDecelerateInterpolator());            lineAnimator.start();        }    }

2.布局界面

让对焦环自定义View获取整个界面的触摸事件

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent">    <com.awen.camera.widget.CameraSurfaceView        android:id="@+id/cameraSurfaceView"        android:layout_width="match_parent"        android:layout_height="match_parent" />    <com.awen.camera.widget.CameraFocusView        android:id="@+id/cameraFocusView"        android:layout_width="match_parent"        android:layout_height="match_parent" />    ......

3.定义对焦接口

i.定义接口

    /**     * 聚焦的回调接口     */    public interface IAutoFocus {        void autoFocus(float x,float y);    }

ii.对焦环View触摸事件中触发接口：

    @Override    public boolean onTouchEvent(MotionEvent event) {        switch (event.getAction()) {            case MotionEvent.ACTION_UP:                int x = (int) event.getX();                int y = (int) event.getY();                lastValue = 0;                mPaint.setColor(Color.WHITE);                radius = (int) (mScreenWidth * 0.1);                centerPoint = null;                if(y>TOP_CONTROL_HEIGHT&&y<ScreenSizeUtil.getScreenHeight()-BETTOM_CONTROL_HEIGHT){//状态栏和底部禁止点击获取焦点（显示体验不好）                    centerPoint = new Point(x, y);                    showAnimView();                    //开始对焦                    if (mIAutoFocus != null) {                        mIAutoFocus.autoFocus(event.getX(),event.getY());                    }                }                break;        }        return true;    }

4.在CameraSurfaceView实现对焦

i.计算对焦区域

   private Rect caculateFocusPoint(int x, int y) {        Rect rect = new Rect(x - 100, y - 100, x + 100, y + 100);        int left = rect.left * 2000 / getWidth() - 1000;        int top = rect.top * 2000 / getHeight() - 1000;        int right = rect.right * 2000 / getWidth() - 1000;        int bottom = rect.bottom * 2000 / getHeight() - 1000;        // 如果超出了(-1000,1000)到(1000, 1000)的范围，则会导致相机崩溃        left = left < -1000 ? -1000 : left;        top = top < -1000 ? -1000 : top;        right = right > 1000 ? 1000 : right;        bottom = bottom > 1000 ? 1000 : bottom;        return new Rect(left, top, right, bottom);    }

ii.设置参数进行对焦

      private void camerFocus(Rect rect) {        if (mCamera != null) {            Camera.Parameters parameters = mCamera.getParameters();            if(cameraId == Camera.CameraInfo.CAMERA_FACING_BACK){                parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);//手动区域自动对焦            }            if (parameters.getMaxNumFocusAreas() > 0) {                List<Camera.Area> focusAreas = new ArrayList<Camera.Area>();                focusAreas.add(new Camera.Area(rect, 1000));                parameters.setFocusAreas(focusAreas);            }            mCamera.cancelAutoFocus(); // 先要取消掉进程中所有的聚焦功能            mCamera.setParameters(parameters);            mCamera.autoFocus(this);        }

四、拍照

为了图片方便预览，需要对图片进行处理，所以需要知道相机的拍照时的方向，故在拍照应先设置照片的方向参数

1.CameraOrientationDetector(Camera方向监听器)

/** * 方向变化监听器，监听传感器方向的改变 * Created by AwenZeng on 2017/2/21. */public class CameraOrientationDetector extends OrientationEventListener {    int mOrientation;    public CameraOrientationDetector(Context context, int rate) {        super(context, rate);    }    @Override    public void onOrientationChanged(int orientation) {        this.mOrientation = orientation;        if (orientation == OrientationEventListener.ORIENTATION_UNKNOWN) {            return;        }        //保证只返回四个方向,分别为0°、90°、180°和270°中的一个        int newOrientation = ((orientation + 45) / 90 * 90) % 360;        if (newOrientation != mOrientation) {            mOrientation = newOrientation;        }    }    public int getOrientation() {        return mOrientation;    }}

2.设置照片方向参数

    /**     * 拍照     *     * @param callback     */    public void takePicture(Camera.PictureCallback callback) {        if (mCamera != null) {            int orientation = mCameraOrientation.getOrientation();            Camera.Parameters cameraParameter = mCamera.getParameters();            if (orientation == 90) {                cameraParameter.setRotation(90);                cameraParameter.set("rotation", 90);            } else if (orientation == 180) {                cameraParameter.setRotation(180);                cameraParameter.set("rotation", 180);            } else if (orientation == 270) {                cameraParameter.setRotation(270);                cameraParameter.set("rotation", 270);            } else {                cameraParameter.setRotation(0);                cameraParameter.set("rotation", 0);            }            mCamera.setParameters(cameraParameter);        }        mCamera.takePicture(null, null, callback);    }

3.保存图片

为了方便预览，对不同方向的图片，需要做正向处理。

  public String handlePhoto(byte[] data, int cameraId) {        String filePath = FileUtil.saveFile(data, "/DCIM");        if (!TextUtils.isEmpty(filePath)) {            int degree = BitmapUtil.getPhotoDegree(filePath);            Log.i(TAG, degree + "");            Bitmap bitmap = BitmapFactory.decodeFile(filePath);            Bitmap tBitmap = null;            try {                Log.i(TAG, "保存图片大小："+"width = " + bitmap.getWidth() + "   ------ height = " + bitmap.getHeight());                if (cameraId == Camera.CameraInfo.CAMERA_FACING_BACK) {                    switch (degree) {                        case 0:                            tBitmap = BitmapUtil.rotateBitmap(bitmap, 90);                            filePath = BitmapUtil.saveBitmap(tBitmap == null ? bitmap : tBitmap, filePath);                            break;                        case 90:                            tBitmap = BitmapUtil.rotateBitmap(bitmap, 180);                            filePath = BitmapUtil.saveBitmap(tBitmap == null ? bitmap : tBitmap, filePath);                            break;                        case 180:                            tBitmap = BitmapUtil.rotateBitmap(bitmap, 270);                            filePath = BitmapUtil.saveBitmap(tBitmap == null ? bitmap : tBitmap, filePath);                            break;                        case 270:                            tBitmap = BitmapUtil.rotateBitmap(bitmap, 360);                            filePath = BitmapUtil.saveBitmap(tBitmap == null ? bitmap : tBitmap, filePath);                            break;                    }                } else if (cameraId == Camera.CameraInfo.CAMERA_FACING_FRONT) {                    switch (degree) {                        case 0:                            tBitmap = BitmapUtil.rotateBitmap(bitmap, 270);                            filePath = BitmapUtil.saveBitmap(tBitmap == null ? bitmap : tBitmap, filePath);                            break;                        case 90:                            tBitmap = BitmapUtil.rotateBitmap(bitmap, 180);                            filePath = BitmapUtil.saveBitmap(tBitmap == null ? bitmap : tBitmap, filePath);                            break;                        case 180:                            tBitmap = BitmapUtil.rotateBitmap(bitmap, 90);                            filePath = BitmapUtil.saveBitmap(tBitmap == null ? bitmap : tBitmap, filePath);                            break;                        case 270:                            tBitmap = BitmapUtil.rotateBitmap(bitmap, 360);                            filePath = BitmapUtil.saveBitmap(tBitmap == null ? bitmap : tBitmap, filePath);                            break;                    }                }            } catch (Exception e) {                e.printStackTrace();                // 重新拍照                return "";            } finally {                if (bitmap != null) {                    bitmap.recycle();                    bitmap = null;                }                if (tBitmap != null) {                    tBitmap.recycle();                    tBitmap = null;                }                ScannerByReceiver(mContext, filePath);//图库扫描            }            return filePath;        }        return null;    }

五、切换摄像头

   /**     * 切换摄像头     */    public void changeCamera(int camera_id) {        mCamera.stopPreview();        mCamera.release();        try {            openCamera(camera_id);            mCamera.setPreviewDisplay(holder);            setCameraParams(DEFAULT_PHOTO_WIDTH, DEFAULT_PHOTO_HEIGHT);            mCamera.startPreview();        } catch (Exception e) {            e.printStackTrace();        }    }    public boolean openCamera(int camera_id) {        LogUtil.i(TAG, "openCamera id = " + camera_id);        try {            mCamera = Camera.open(camera_id); // 打开摄像头            cameraId = camera_id;        } catch (Exception e) {            e.printStackTrace();            ToastUtil.getInstance().toast("请先开启摄像头权限");            LogUtil.i(TAG, "请先开启摄像头权限");            return false;        }        return true;    }

六、打开或关闭闪光灯

    /**     * 设置闪光灯     *     * @param isOpen     */    public void changeFlashMode(boolean isOpen, Camera mCamera, int cameraId) {        if (cameraId == Camera.CameraInfo.CAMERA_FACING_BACK) { // 后摄像头才有闪光灯            Camera.Parameters parameters = mCamera.getParameters();            PackageManager pm = mContext.getPackageManager();            FeatureInfo[] features = pm.getSystemAvailableFeatures();            for (FeatureInfo f : features) {                if (PackageManager.FEATURE_CAMERA_FLASH.equals(f.name)) { // 判断设备是否支持闪光灯                    if (isOpen) {                        parameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH); // 开闪光灯                    } else {                        parameters                                .setFlashMode(Camera.Parameters.FLASH_MODE_OFF); // 关闪光灯                    }                }            }            mCamera.setParameters(parameters);        }    }

注意事项

• Android6.0以上权限收紧，所以在使用相机前，请用PermissionsModel做好权限判断。具体Android6.0权限
• 部分智能手机，前置摄像头无对焦模式，对焦参数设置应区分前置摄像头
• Android5.0以后，官方推荐使用Camera2,本例子未使用新版本。