如何在Android 12 aosp系统源码中添加三指下滑截图功能

如何在Android 12 aosp系统源码中添加三指下滑截图功能

系统中截图api非常简单：

private static ScreenshotHelper sScreenshotHelper;

sScreenshotHelper = new ScreenshotHelper(mContext);


//调用
sScreenshotHelper.takeScreenshot(WindowManager.TAKE_SCREENSHOT_FULLSCREEN, true, true, mScreenShotHandler, null);

如果在系统中添加三指下滑监听了：

首先找到：

我们这里基于Android12 源码

首先找到：SystemGesturesPointerEventListener类，这里面有监听系统滑动手势的地方：

找到下面代码添加手势判断：

    private int detectSwipe(int i, long time, float x, float y) {
        final float fromX = mDownX[i];
        final float fromY = mDownY[i];
        final long elapsed = time - mDownTime[i];
        if (DEBUG) Slog.d(TAG, "pointer " + mDownPointerId[i]
                + " moved (" + fromX + "->" + x + "," + fromY + "->" + y + ") in " + elapsed);
        //添加三指下滑判断
        float xDistance = Math.abs(x - fromX);
        float yDistance = Math.abs(y - fromY);
        if (fromY >= mSwipeStartThreshold * 2
                && yDistance > xDistance
                && y > fromY + mSwipeDistanceThreshold
                && elapsed < SWIPE_TIMEOUT_MS) {
            return SWIPE_FROM_CENTER_TO_DOWN;
        }
        if (fromY <= mSwipeStartThreshold
                && y > fromY + mSwipeDistanceThreshold
                && elapsed < SWIPE_TIMEOUT_MS) {
            return SWIPE_FROM_TOP;
        }
        if (fromY >= screenHeight - mSwipeStartThreshold
                && y < fromY - mSwipeDistanceThreshold
                && elapsed < SWIPE_TIMEOUT_MS) {
            return SWIPE_FROM_BOTTOM;
        }
        if (fromX >= screenWidth - mSwipeStartThreshold
                && x < fromX - mSwipeDistanceThreshold
                && elapsed < SWIPE_TIMEOUT_MS) {
            return SWIPE_FROM_RIGHT;
        }
        if (fromX <= mSwipeStartThreshold
                && x > fromX + mSwipeDistanceThreshold
                && elapsed < SWIPE_TIMEOUT_MS) {
            return SWIPE_FROM_LEFT;
        }
        return SWIPE_NONE;
    }

再找到这个方法：

public void onPointerEvent(MotionEvent event)

在里面添加代码：

            case MotionEvent.ACTION_MOVE:
                if (mSwipeFireable) {
                    final int swipe = detectSwipe(event);
                    mSwipeFireable = swipe == SWIPE_NONE;
                    if (swipe == SWIPE_FROM_TOP) {
                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromTop");
                        mCallbacks.onSwipeFromTop();
                    } else if (swipe == SWIPE_FROM_BOTTOM) {
                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromBottom");
                        mCallbacks.onSwipeFromBottom();
                    } else if (swipe == SWIPE_FROM_RIGHT) {
                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromRight");
                        mCallbacks.onSwipeFromRight();
                    } else if (swipe == SWIPE_FROM_LEFT) {
                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromLeft");
                        mCallbacks.onSwipeFromLeft();
                    } else if (swipe == SWIPE_FROM_CENTER_TO_DOWN) {
                        if (DEBUG) Slog.d(TAG, "Firing onSwipeFromCenterToDown:" + event.getPointerCount());
                        //判断三指开始截图
                        if (event.getPointerCount() == 3) {
                            sScreenshotHelper.takeScreenshot(WindowManager.TAKE_SCREENSHOT_FULLSCREEN, true, true, mScreenShotHandler, null);
                        }
                    }
                }
                break;

那么三指截图就完成了！！！！

是不是很干，没有水分，有用记得点赞收藏。

补充：

private static final int SWIPE_FROM_CENTER_TO_DOWN = 5;