Android — Camera聚焦流程
Camera.java
- autoFocus()聚焦回调函数
@Override
public void autoFocus() {
//记录当前聚焦开始时间
mFocusStartTime = System.currentTimeMillis();
//设置Camera的回调聚焦
mCameraDevice.autoFocus(mAutoFocusCallback);
//设置Camera的状态为Focusing
setCameraState(FOCUSING);
}
- 设置相机状态
private void setCameraState(int state) {
mCameraState = state;
switch (state) {
case SNAPSHOT_IN_PROGRESS:
case FOCUSING:
enableCameraControls(false);
break;
case IDLE:
case PREVIEW_STOPPED:
enableCameraControls(true);
break;
}
}
- enableCameraControls，设置enable，是否可以点击
/**
* 设置几个button或者view不可点击
* @param enable
*/
private void enableCameraControls(boolean enable) {
if (mIndicatorControlContainer != null) {
mIndicatorControlContainer.setEnabled(enable);
}
if (mModePicker != null) mModePicker.setEnabled(enable);
if (mZoomControl != null) mZoomControl.setEnabled(enable);
if (mThumbnailView != null) mThumbnailView.setEnabled(enable);
}
- mIndicatorControlContainer的enable的设置
Override
public void setEnabled(boolean enabled) {
super.setEnabled(enabled);
final int count = getChildCount();
for (int i = 0; i < count; i++) {
View v = getChildAt(i);
// Zoom buttons and shutter button are controlled by the activity.
if (v instanceof AbstractIndicatorButton) {
v.setEnabled(enabled);
// Show or hide the indicator buttons during recording.
if (mCurrentMode == MODE_VIDEO) {
v.setVisibility(enabled ? View.VISIBLE : View.INVISIBLE);
}
}
}
if (mCameraPicker != null) {
mCameraPicker.setEnabled(enabled);
if (mCurrentMode == MODE_VIDEO) {
mCameraPicker.setVisibility(enabled ? View.VISIBLE : View.INVISIBLE);
}
}
}
- mAutoFocusCallback中的处理
private final class AutoFocusCallback
implements android.hardware.Camera.AutoFocusCallback {
public void onAutoFocus(
boolean focused, android.hardware.Camera camera) {
//如果是暂停状态，不聚焦
if (mPausing) return;
//算出当前到聚焦开始的时间差
mAutoFocusTime = System.currentTimeMillis() - mFocusStartTime;
Log.v(TAG, "mAutoFocusTime = " + mAutoFocusTime + "ms");
//设置Camera状态为
setCameraState(IDLE);
//调用FocusManager中的AutoFocus
mFocusManager.onAutoFocus(focused);
}
}
FocusManager.java
/**
* 聚焦
* @param focused
*/
public void onAutoFocus(boolean focused) {
Log.i(TAG, "focus used : " + (System.currentTimeMillis() - focusStart));
//正在进行聚焦，拍照动作必须再聚焦完之后
if (mState == STATE_FOCUSING_SNAP_ON_FINISH) {
// 无论聚焦成功还是失败，都会拍照。如果要进行拍照发声，就无需AF发声了
if (focused) {
//聚焦成功
mState = STATE_SUCCESS;
} else {
//聚焦失败
mState = STATE_FAIL;
}
//更新聚焦框UI&&设置人脸识别UI已经各种状态的设置
updateFocusUI();
//拍照，mState的状态变为STATE_IDLE
capture();
} else if (mState == STATE_FOCUSING) {//如果是聚焦中的状态
//此状态的发生分为两种，half-pressing按压聚焦或者触摸聚焦被触发，这个时候不要发生拍照动作
if (focused) {
//聚焦成功
mState = STATE_SUCCESS;
//在连续聚焦状态不要发声，聚焦回调会在拍照前完成，所有状态一直为STATE_FOCUSING
if (!Parameters.FOCUS_MODE_CONTINUOUS_PICTURE.
equals(mFocusMode)) {
mListener.playSound(CameraSound.FOCUS_COMPLETE);
}
} else {
//聚焦失败
mState = STATE_FAIL;
}
//更新聚焦&&人脸UI
updateFocusUI();
// If this is triggered by touch focus, cancel focus after a
// while.
//如果是触摸聚焦，需要延迟一下取消掉聚焦
if (mFocusArea != null) {
mHandler.sendEmptyMessageDelayed(RESET_TOUCH_FOCUS, RESET_TOUCH_FOCUS_DELAY);
}
} else if (mState == STATE_IDLE) {//空闲
// User has released the focus key before focus completes.
// Do nothing.
}
}
- 处理消息
private class MainHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case RESET_TOUCH_FOCUS: {
//取消掉聚焦
cancelAutoFocus();
//开始人脸识别
mListener.startFaceDetection();
break;
}
}
}
}
/**
* 再重置tap area之前调用mListener.cancelAutofocus，否则，聚焦模式将一直是自动&tap聚焦，并且驱动也不会重置
*/
private void cancelAutoFocus() {
//放置聚焦框到屏幕中间
resetTouchFocus();
mListener.cancelAutoFocus();
if (mFaceView != null) mFaceView.resume();
mState = STATE_IDLE;
updateFocusUI();
mHandler.removeMessages(RESET_TOUCH_FOCUS);
}
- 触摸聚焦
/**
* 触摸，，这里会发生触摸聚焦
* @param e
* @return
*/
public boolean onTouch(MotionEvent e) {
//没有初始化或者拍照前的聚焦的状态，直接返回
if (!mInitialized || mState == STATE_FOCUSING_SNAP_ON_FINISH) return false;
//让用户可以取消掉之前未消失的触摸聚焦
if ((mFocusArea != null) && (mState == STATE_FOCUSING ||
mState == STATE_SUCCESS || mState == STATE_FAIL)) {
cancelAutoFocus();
}
// Initialize variables.
int x = Math.round(e.getX());
int y = Math.round(e.getY());
int focusWidth = mFocusIndicatorRotateLayout.getWidth();
int focusHeight = mFocusIndicatorRotateLayout.getHeight();
int previewWidth = mPreviewFrame.getWidth();
int previewHeight = mPreviewFrame.getHeight();
if (mFocusArea == null) {
mFocusArea = new ArrayList<Area>();
mFocusArea.add(new Area(new Rect(), 1));
mMeteringArea = new ArrayList<Area>();
mMeteringArea.add(new Area(new Rect(), 1));
}
//将坐标转换为驱动的格式。AE面积更大,因为曝光会敏感和容易，或者说曝光不足,如果面积太小了。
calculateTapArea(focusWidth, focusHeight, 1f, x, y, previewWidth, previewHeight,
mFocusArea.get(0).rect);
calculateTapArea(focusWidth, focusHeight, 1.5f, x, y, previewWidth, previewHeight,
mMeteringArea.get(0).rect);
// Use margin to set the focus indicator to the touched area.
RelativeLayout.LayoutParams p =
(RelativeLayout.LayoutParams) mFocusIndicatorRotateLayout.getLayoutParams();
int left = Util.clamp(x - focusWidth / 2, 0, previewWidth - focusWidth);
int top = Util.clamp(y - focusHeight / 2, 0, previewHeight - focusHeight);
p.setMargins(left, top, 0, 0);
// Disable "center" rule because we no longer want to put it in the center.
int[] rules = p.getRules();
rules[RelativeLayout.CENTER_IN_PARENT] = 0;
mFocusIndicatorRotateLayout.requestLayout();
//停止人脸识别，因为要进行识别聚焦和测量area
mListener.stopFaceDetection();
//设置聚焦区域&测量区域
mListener.setFocusParameters();
//如果支持触摸聚焦&&手指抬起
if (mFocusAreaSupported && (e.getAction() == MotionEvent.ACTION_UP)) {
autoFocus();
} else { // Just show the indicator in all other cases.
updateFocusUI();
// Reset the metering area in 3 seconds.
mHandler.removeMessages(RESET_TOUCH_FOCUS);
mHandler.sendEmptyMessageDelayed(RESET_TOUCH_FOCUS, RESET_TOUCH_FOCUS_DELAY);
}
return true;
}
聚焦各个状态能做什么事不能做什么事&切换
- STATE_IDLE
doSnap()：空闲状态可以执行拍照
onAutoFocus(boolean focused)：用户再聚焦完成前放掉了聚焦按钮，所以不做任何事。
onPreviewStarted()，onPreviewStopped()：状态都变为空闲
cancelAutoFocus()：取消聚焦，状态变为空闲
updateFocusUI()：如果空闲&有聚焦区域，显示聚焦框框
- STATE_FOCUSING
onShutterUp()：如果是focusmode为自动聚焦，状态为正在聚焦，则取消掉聚焦
doSnap()：如果是正在聚焦状态，将状态改为聚焦完拍照状态
onAutoFocus(boolean focused)：判断focused，为true变为聚焦成功状态，为false变为聚焦失败状态
onTouch(MotionEvent e)：如果正在聚焦&之前有手动聚焦了，则取消掉之前的聚焦
autoFocus()：状态变为聚焦状态
updateFocusUI()：显示聚焦的框框
- STATE_FOCUSING_SNAP_ON_FINISH
onShutterUp()：状态不是聚焦完拍照，可以设置FocusParameters
onAutoFocus(boolean focused)：判断focused，为true变为聚焦成功状态，为false变为聚焦失败状态，更新聚焦框UI
onTouch(MotionEvent e)：直接不继续操作下去
updateFocusUI()：显示聚焦的框框
- STATE_SUCCESS
onShutterDown()：如果是自动聚焦mode，并且不为聚焦成功状态，执行聚焦 onShutterUp()： 如果是自动聚焦mode，并且为聚焦成功状态，执行取消聚焦 doSnap()：拍照 onTouch(MotionEvent e)：让用户可以取消掉之前未消失的触摸聚焦 updateFocusUI()：聚焦框框显示成功
- STATE_FAIL
onShutterDown()：如果是自动聚焦mode，并且不为聚焦失败状态，执行聚焦 onShutterUp()： 如果是自动聚焦mode，并且为聚焦失败状态，执行取消聚焦 doSnap()：拍照 onTouch(MotionEvent e)：让用户可以取消掉之前未消失的触摸聚焦 updateFocusUI()：聚焦框框显示失败
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