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Android 流式布局

作者:小小Code
  • 2022 年 5 月 10 日
  • 本文字数:1829 字

    阅读完需:约 6 分钟

public class XFlowLayout extends ViewGroup {


private int childHorizontalSpace;


private int childVerticalSpace;


private Map<Object, Location> mLocationMap;


public XFlowLayout(Context context, AttributeSet attrs) {


super(context, attrs);


TypedArray attrArray = context.obtainStyledAttributes(attrs, R.styleable.XLFlowLayout);


mLocationMap = new HashMap<>();


if (attrArray != null) {


childHorizontalSpace = attrArray.getDimensionPixelSize(R.styleable.XLFlowLayout_childHorizontalSpace, 0);


childVerticalSpace = attrArray.getDimensionPixelSize(R.styleable.XLFlowLayout_childVerticalSpace, 0);


attrArray.recycle();


}


}


@Override


protected LayoutParams generateLayoutParams(LayoutParams p) {


return new MarginLayoutParams(p);


}


@Override


public LayoutParams generateLayoutParams(AttributeSet attrs) {


return new MarginLayoutParams(getContext(), attrs);


}


@Override


protected LayoutParams generateDefaultLayoutParams() {


return new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);


}


/**


  • 负责设置子控件的测量模式和大小 根据所有子控件设置自己的宽和高


*/


@Override


protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {


super.onMeasure(widthMeasureSpec, heightMeasureSpec);


if (mLocationMap != null && !mLocationMap.isEmpty()) {


mLocationMap.clear();


}


// 获得它的父容器为它设置的测量模式和大小


int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);


int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);


int modeWidth = MeasureSpec.getMode(widthMeasureSpec);


int modeHeight = MeasureSpec.getMode(heightMeasureSpec);


// 如果是 warp_content 情况下,记录宽和高


int width = 0;


int height = 0;


/**


  • 记录每一行的宽度,width 不断取最大宽度


*/


int lineWidth = 0;


/**


  • 每一行的高度,累加至 height


*/


int lineHeight = 0;


int count = getChildCount();


int left = getPaddingLeft();


int top = getPaddingTop();


// 遍历每个子元素


for (int i = 0; i < count; i++) {


View child = getChildAt(i);


if (child.getVisibility() == GONE)


continue;


// 测量每一个 child 的宽和高


measureChild(child, widthMeasureSpec, heightMeasureSpec);


// 得到 child 的 lp


LayoutParams lp = child.getLayoutParams();


// 当前子空间实际占据的宽度


int childWidth = child.getMeasuredWidth() + childHorizontalSpace;


// 当前子空间实际占据的高度


int childHeight = child.getMeasuredHeight() + childVerticalSpace;


if (lp != null && lp instanceof MarginLayoutParams) {


MarginLayoutParams params = (MarginLayoutParams) lp;


childWidth += params.leftMargin + params.rightMargin;


chi 《Android 学习笔记总结+最新移动架构视频+大厂安卓面试真题+项目实战源码讲义》无偿开源 徽信搜索公众号【编程进阶路】 ldHeight += params.topMargin + params.bottomMargin;


}


/**


  • 如果加入当前 child 的宽度,超出了最大宽度,则的到目前最大宽度给 width,累加 height 然后开启新行


*/


if (lineWidth + childWidth > sizeWidth - getPaddingLeft() - getPaddingRight()) {


width = Math.max(lineWidth, childWidth);// 取最大的


lineWidth = childWidth; // 重新开启新行,开始记录


// 叠加当前高度,


height += lineHeight;


// 开启记录下一行的高度


lineHeight = childHeight;


mLocationMap.put(child, new Location(left, top + height, childWidth + left - childHorizontalSpace, height +


child.getMeasuredHeight() + top));


} else {// 否则累加值 lineWidth,lineHeight 取最大高度


mLocationMap.put(child, new Location(lineWidth + left, top + height, lineWidth + childWidth -


childHorizontalSpace + left, height + child.getMeasuredHeight() + top));


lineWidth += childWidth;


lineHeight = Math.max(lineHeight, childHeight);


}


}


width = Math.max(width, lineWidth) + getPaddingLeft() + getPaddingRight();


height += lineHeight;


sizeHeight += getPaddingTop() + getPaddingBottom();


height += getPaddingTop() + getPaddingBottom();


setMeasuredDimension((modeWidth == MeasureSpec.EXACTLY) ? sizeWidth : width, (modeHeight == MeasureSpec.EXACTLY) ?


sizeHeight : height);


}

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