android自定义view之测量父view和迭代测量子view

最新推荐文章于 2025-05-25 19:13:53 发布

阿杜大

最新推荐文章于 2025-05-25 19:13:53 发布

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分类专栏：自定义view 文章标签： android

本文链接：https://blog.youkuaiyun.com/u010652002/article/details/72475334

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这篇博客介绍了在Android自定义View时如何处理`onMeasure`方法，以确保正确测量父视图和子视图的尺寸。在非精确尺寸模式下，使用了`suggestedMinimumWidth`和`suggestedMinimumHeight`，并提供了默认宽度。而在精确尺寸模式下，选择了宽高中的较小值。此外，博客还详细讲述了如何迭代测量每个子视图，并调整它们的大小以适应父视图。

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@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    int resWidth = 0;
    int resHeight = 0;

    int width = MeasureSpec.getSize(widthMeasureSpec);
    int widthMode = MeasureSpec.getMode(widthMeasureSpec);
    int height = MeasureSpec.getSize(heightMeasureSpec);
    int heightMode = MeasureSpec.getMode(heightMeasureSpec);

    if (widthMode != MeasureSpec.EXACTLY || heightMode != MeasureSpec.EXACTLY) {
        //如果不是精确值对应的处理
        resWidth = getSuggestedMinimumWidth();//取背景图的宽度
        resWidth = resWidth == 0 ? getDefaultWidht() : resWidth;

        resHeight = getSuggestedMinimumHeight();
        resHeight = resHeight == 0 ? getDefaultWidht() : resHeight;
    } else {
        //如果是精确值，则取宽和高中值小的
        resWidth = resHeight = Math.min(width, height);
    }
    setMeasuredDimension(resWidth, resHeight);

    //获得半径
    mRadius = Math.max(getMeasuredWidth(), getMeasuredHeight());

    //menu item个数
    final int childCount = getChildCount();
    //menu item 尺寸
    int childSize = (int) (mRadius * RADIO_DEFAULT_CHILD_DIMENSION);
    int childMode = MeasureSpec.EXACTLY;
    
    //迭代测量
    for (int i = 0; i < childCount; i++) {

        final View child = getChildAt(i);
        if (child.getVisibility() == GONE) {
            continue;
        }

        //测量menu item
        int makeMeasureSpec = -1;
        if (child.getId() == R.id.id_circle_menu_item_center) {
            makeMeasureSpec = MeasureSpec.makeMeasureSpec((int) (mRadius * RADIO_DEFAULT_CENTERITEM_DIMENSION), childMode);
        } else {
            makeMeasureSpec = MeasureSpec.makeMeasureSpec(childSize, childMode);
        }
        child.measure(makeMeasureSpec, makeMeasureSpec);

    }

    mPadding = (int) (RADIO_PADDING_LAYOUT * mRadius);

}