android - fragment 内的 View 坐标始终为空

Question

我需要获取布局中某些 View 的坐标。我尝试这样做(在 onCreateView 内)

TextView[] tv = new TextView[3]
tv[0] = (TextView) view.findViewById(R.id.content0);
tv[1] = (TextView) view.findViewById(R.id.content1);
tv[2] = (TextView) view.findViewById(R.id.content2);
RectF[] positions = new RectF[3];

for (int i = 0; i < tv.length; i++) {
    int top = tv[i].getTop();
    int left = tv[i].getLeft();
    int width = tv[i].getWidth();
    int height = tv[i].getHeight();
    positions[i] = new RectF(left, top, left + width, top + height);

}

但是如果我尝试将位置数组打印到 Logcat 中，我总是获得 0,0,0,0。怎么了？

Answer 1

正如 blackbelt 提到的，您必须等待 View 的布局才能获得维度。使用 ViewTreeObserver。

    getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            for (int i = 0; i < tv.length; i++) {
                int top = tv[i].getTop();
                int left = tv[i].getLeft();
                int width = tv[i].getWidth();
                int height = tv[i].getHeight();
                positions[i] = new RectF(left, top, left + width, top + height);

            }
            getViewTreeObserver().removeOnGlobalLayoutListener(this);

        }
    });