自定义 ViewGroup - FlexboxLayout - 弹性流式布局（标签组）

效果

微信图片_20170727104655.png

实现

/**
 * 弹性流式布局
 *
 * @author gavin.xiong 2017/7/26
 */
public class FlexboxLayout extends ViewGroup {

    public FlexboxLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public LayoutParams generateLayoutParams(AttributeSet attrs) {
        return new MarginLayoutParams(getContext(), attrs);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);

        int width = 0, height = 0;
        int lineWidth = 0, lineHeight = 0;

        for (int i = 0; i < getChildCount(); i++) {
            View child = getChildAt(i);

            if (child.getVisibility() == GONE) {
                continue;
            }

            measureChild(child, widthMeasureSpec, heightMeasureSpec);

            MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();

            int childWidth = lp.leftMargin + child.getMeasuredWidth() + lp.rightMargin;
            int childHeight = lp.topMargin + child.getMeasuredHeight() + lp.bottomMargin;

            if (lineWidth + childWidth > widthSize - getPaddingLeft() - getPaddingRight()) {
                width = Math.max(width, lineWidth);
                height += lineHeight;
                lineWidth = childWidth;
                lineHeight = childHeight;
            } else {
                lineWidth += childWidth;
                lineHeight = Math.max(lineHeight, childHeight);
            }

            // 如果是最后一行
            if (i == getChildCount() - 1) {
                width = Math.max(width, lineWidth);
                height += lineHeight;
            }
        }

        setMeasuredDimension(widthMode == MeasureSpec.EXACTLY ? widthSize : width + getPaddingLeft() + getPaddingRight(),
                heightMode == MeasureSpec.EXACTLY ? heightSize : height + getPaddingTop() + getPaddingBottom());
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int left = getPaddingLeft();
        int top = getPaddingTop();

        int lineWidth = 0, lineHeight = 0;

        for (int i = 0; i < getChildCount(); i++) {
            View child = getChildAt(i);

            if (child.getVisibility() == GONE) {
                continue;
            }

            MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();

            int childWidth = lp.leftMargin + child.getMeasuredWidth() + lp.rightMargin;
            int childHeight = lp.topMargin + child.getMeasuredHeight() + lp.bottomMargin;

            if (lineWidth + childWidth > getWidth() - getPaddingLeft() - getPaddingRight()) {
                left = getPaddingLeft();
                top += lineHeight;

                lineWidth = childWidth;
                lineHeight = childHeight;
            } else {
                lineWidth += childWidth;
                lineHeight = Math.max(lineHeight, childHeight);
            }

            int cl = left + lp.leftMargin;
            int ct = top + lp.topMargin;
            int cr = cl + child.getMeasuredWidth();
            int cb = ct + child.getMeasuredHeight();
            child.layout(cl, ct, cr, cb);

            left += lp.leftMargin + child.getMeasuredWidth() + lp.rightMargin;
        }
    }
}