Android获取View的边界矩形

Question

我正在为Android应用程序实现拖放操作.为了知道drop是否发生在drop target中,我需要知道drop target视图的边界矩形.然后,getRawX/Y()当我得到ACTION_UP动作时,我会看到MotionEvent中是否属于这个矩形.

我意识到我可以调用getLeft/Right/Top/Bottom()放置目标视图,但这些是相对于父容器的.我似乎需要知道"真实"或原始值,以便我可以将它们与MotionEvent中的原始x,y进行比较.

Answer 1

回答我自己的问题......是的,View.getLocationOnScreen()做了诀窍.例如,

private boolean isViewContains(View view, int rx, int ry) {
    int[] l = new int[2];
    view.getLocationOnScreen(l);
    int x = l[0];
    int y = l[1];
    int w = view.getWidth();
    int h = view.getHeight();

    if (rx < x || rx > x + w || ry < y || ry > y + h) {
        return false;
    }
    return true;
}

Answer 2

你也可以在这里使用一个Rect:

private boolean isViewContains(...) {
    int[] l = new int[2];
    imageView.getLocationOnScreen(l);
    Rect rect = new Rect(l[0], l[1], l[0] + imageView.getWidth(), l[1] + imageView.getHeight());
    return rect.contains(rx, ry);
}

不那么罗嗦,可能更快,但肯定(IMO)更具可读性.

Answer 3

此代码考虑了所Views涉及的周长,并且仅true当拖动View完全位于放置区域内时才返回.

public boolean containsView(View dropZone, View draggedView){
     // Create the Rect for the view where items will be dropped
     int[] pointA = new int[2];
     dropZone.getLocationOnScreen(pointA);
     Rect rectA = new Rect(pointA[0], pointA[1], pointA[0] + dropZone.getWidth(), pointA[1] + dropZone.getHeight());

     // Create the Rect for the view been dragged
     int[] pointB = new int[2];
     draggedView.getLocationOnScreen(pointB);
     Rect rectB = new Rect(pointB[0], pointB[1], pointB[0] + draggedView.getWidth(), pointB[1] + draggedView.getHeight());

     // Check if the dropzone currently contains the dragged view
     return rectA.contains(rectB);
}