• 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

    我是天王盖地虎的分割线                                                             

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  • 原文地址:https://www.cnblogs.com/yydcdut/p/4133862.html
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