PopupWindow计算弹出位置

1.首先自定义PopupWindow

   popWindowView= LinearLayout.inflate(context, R.layout.popupWindow,null);

   popupWindow = new PopupWindow(popWindowView, LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT, true);

   popupWindow.setOutsideTouchable(true);//点击弹窗以外的地方消失

   popupWindow.setBackgroundDrawable(new BitmapDrawable());//响应返回键

2.一般我们会让弹出框在我们指定控件的某个位置展示，那么就有如下计算

             /**

     * @param anchorView  弹窗时作为参照物的view
     * @param contentView   内容布局（可以直接放popupWindow）
     * @return 左上角的x,y坐标
     */
    private static int[] PopViewPos(final View anchorView, final View contentView) {
        final int windowPos[] = new int[2];
        final int anchorLoc[] = new int[2];
　　　　 // 获取锚点View在屏幕上的左上角坐标位置,赋值给anchorLoc数组
        anchorView.getLocationOnScreen(anchorLoc);
        //获取参照view的高度
        final int anchorHeight = anchorView.getHeight();
        // 获取屏幕的高宽
        final int screenHeight = ScreenUtils.getScreenHeight(anchorView.getContext());
        final int screenWidth = ScreenUtils.getScreenWidth(anchorView.getContext());
        //设置测量模式，让父容器不影响view的测量
        contentView.measure(View.MeasureSpec.UNSPECIFIED, View.MeasureSpec.UNSPECIFIED);
        // 计算contentView的高宽
        final int windowHeight = contentView.getMeasuredHeight();
        final int windowWidth = contentView.getMeasuredWidth();
        // 判断需要向上弹出还是向下弹出显示
        final boolean isNeedShowUp = (screenHeight - anchorLoc[1] - anchorHeight < windowHeight);
        if (isNeedShowUp) {
            windowPos[0] = screenWidth - windowWidth;
            windowPos[1] = anchorLoc[1] - windowHeight;
        } else {
            windowPos[0] = screenWidth - windowWidth;
            windowPos[1] = anchorLoc[1] + anchorHeight;
        }
        return viewPos;
    }

3.显示showAtLoaction
int viewPos[] = calculatePopWindowPos(view, contentView);

popupwindow.showAtLocation(view, Gravity.TOP | Gravity.START, viewPos[0], viewPos[1]);

/**
     * 获取屏幕高度(px)
     */
    public static int getScreenHeight(Context context) {
        return context.getResources().getDisplayMetrics().heightPixels;
    }
    /**
     * 获取屏幕宽度(px)
     */
    public static int getScreenWidth(Context context) {
        return context.getResources().getDisplayMetrics().widthPixels;
    }