1、利用硬件传感器去实现自动对焦

注册传感器：

SensorManager sm = (SensorManager) getSystemService(SENSOR_SERVICE);

sm.registerListener(this, sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_UI);

传感器接口：

implements SensorEventListener

实现传感器接口方法：

public void onSensorChanged(SensorEvent event) {

float x = event.values[0];

float y = event.values[1];

float z = event.values[2];

if (initFirstSensor) {//初始化默认进入时候的坐标

mLastX = x;

mLastY = y;

mLastZ = z;

initFirstSensor = false;

return;

}

float deltaX = Math.abs(mLastX - x);

float deltaY = Math.abs(mLastY - y);

float deltaZ = Math.abs(mLastZ - z);

if (deltaX > 2.5 || deltaY > 2.5 || deltaZ > 2.5) {//计算坐标偏移值

if (!isPhoto && mCamera != null) {

playFocusAnimal(focusX, focusY);//播放对焦动画

// mCamera.autoFocus(autoFocusCallback);//调用相机对焦

}

}

mLastX = x;

mLastY = y;

mLastZ = z;

}

2、单点触摸对焦

监听touch事件拿到event：

public boolean onTouch(View v, MotionEvent event) {

if (!isPhoto && mCamera != null) {

playFocusAnimal((int) event.getX(), (int) event.getY());

touchFocus(event);

}

return false;

}

根据触摸位置设置对焦点的对焦权值：

(解释一下：每个对焦区域是一个具有特定权值的长方形。方向与重力感应的方向有关。而且不会受到setDisplayOrientation(int)旋转画面设置的影响。矩形的坐标范围指定从-1000到1000 ，(-1000,-1000)是左上角点(1000，1000)是右下角点。对焦权值的取值范围是1-1000，权值为矩形范围像素所平分，这意味着同样的权值对焦区域大的对整体的对焦影响小。

理论结合实际的说就是，假如你的整个屏幕的宽度是width，那么点击某个位置算x，那么要划定对焦区域，就要告诉相机对焦的坐标，根据对焦坐标的范围为-1000到1000，所以要用公式计算对应的对焦坐标实际上是: x/width*2000-1000=对焦x坐标，同样获取到对焦y坐标，然后以x，y为中心，指定对焦区域，设置对焦权值，越大表示优先对焦该位置)

代码：

private void touchFocus(MotionEvent event) {

mCamera.cancelAutoFocus();

Camera.Parameters p = mCamera.getParameters();

float touchX = (event.getRawX() / screenWidth) * 2000 - 1000;

float touchY = (event.getRawY() / screenHeight) * 2000 - 1000;

int left = clamp((int) touchX - AREA_SIZE / 2, -1000, 1000);

int right = clamp(left + AREA_SIZE, -1000, 1000);

int top = clamp((int) touchY - AREA_SIZE / 2, -1000, 1000);

int bottom = clamp(top + AREA_SIZE, -1000, 1000);

Rect rect = new Rect(left, top, right, bottom);

if (p.getMaxNumFocusAreas() > 0) {

List areaList = new ArrayList();

areaList.add(new Camera.Area(rect, 1000));

p.setFocusAreas(areaList);

}

if (p.getMaxNumMeteringAreas() > 0) {

List areaList = new ArrayList();

areaList.add(new Camera.Area(rect, 1000));

p.setMeteringAreas(areaList);

}

p.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);

try {

mCamera.setParameters(p);

} catch (Exception e) {

}

mCamera.autoFocus(autoFocusCallback);

}

private int clamp(int x, int min, int max) {//保证坐标必须在min到max之内，否则异常

if (x > max) {

return max;

}

if (x < min) {

return min;

}

return x;

}

3、小米的坑

miui上的时候如果设置预览分辨率过高，则会导致拍照时候小米假死，无响应

解决方案：预览分辨率设置在屏幕分辨率左右，对miui特殊对待

private void initCameraParameters() {

Camera.Parameters parameters = mCamera.getParameters();

List vSizeList = parameters.getSupportedPictureSizes();

Camera.Size showSize = null;

Camera.Size tempSize;

Camera.Size miuiSize = null;

for (int num = 0; num < vSizeList.size(); num++) {

tempSize = vSizeList.get(num);

try {

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

mCamera.setParameters(parameters);

if (showSize == null || (showSize != null && tempSize.width > showSize.width)) {

showSize = tempSize;//设置最高可以支持的屏幕分辨率

}

if (screenWidth < tempSize.width && (miuiSize == null || miuiSize.width > tempSize.width)) {

miuiSize = tempSize;//设置miui的预览大小在屏幕分辨率左右

}

} catch (Exception e) {

}

try {

parameters.setPictureSize(tempSize.width, tempSize.height);

mCamera.setParameters(parameters);

if (highSize == null || (highSize != null && tempSize.width > highSize.width)) {

highSize = tempSize;//设置相机可支持的最高保存分辨率

}

} catch (Exception e) {

}

if (screenWidth > tempSize.width && (nomalSize == null || nomalSize.width < tempSize.width)) {

nomalSize = tempSize;//设置一般相机保存的分辨率

}

}

if (showSize != null) {

if (android.os.Build.MANUFACTURER.equals("Xiaomi")) {//对待小米特殊设置

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

} else {

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

}

}

if (nomalSize != null) {

parameters.setPictureSize(nomalSize.width, nomalSize.height);

isNomal = true;

if (picQualityButton != null) {

picQualityButton.setImageDrawable(getResources().getDrawable(R.drawable.camera_pic_quality_nomal));

}

}

if (isSupportFlash) {

switch (currentFlashMode % 3) {

case 0:

parameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);

break;

case 1:

parameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);

break;

case 2:

parameters.setFlashMode(Camera.Parameters.FLASH_MODE_AUTO);

break;

}

}

parameters.setPictureFormat(PixelFormat.JPEG);

parameters.setJpegQuality(100);

mCamera.setParameters(parameters);

mCamera.startPreview();

playFocusAnimal(screenWidth / 2, screenHeight / 2);

mCamera.autoFocus(autoFocusCallback);

}

author:iamwsbear@gmail.com

http://blog.csdn.net/iamws/article/details/50401886