import android.content.Context;
import android.text.Layout;
import android.text.StaticLayout;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

/**
 * TextView + View 动态布局
 * 该布局目前仅支持TextView + View 组合。
 * 来源:https://www.loongwind.com/archives/217.html
 */
public class CustomLayout extends ViewGroup {
    //单行显示
    private static final int SINGLE_LINE = 0x01;
    //多行显示
    private static final int MULTI_LINE = 0x02;
    //显示到下一行
    private static final int NEXT_LINE = 0x03;
    //显示样式
    private int type;
    //绘制文字最后一行的顶部坐标
    private int lastLineTop;
    //绘制文字最后一行的右边坐标
    private float lastLineRight;

    public CustomLayout(Context context) {
        super(context);
    }

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

    public CustomLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }


    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int childCount = getChildCount();
        int w = MeasureSpec.getSize(widthMeasureSpec);
        if (childCount == 2) {
            TextView tv = null;
            if(getChildAt(0) instanceof  TextView){
                tv = (TextView) getChildAt(0);
                initTextParams(tv.getText(), tv.getMeasuredWidth(), tv.getPaint());
            }else{
                throw new RuntimeException("CustomLayout first child view not a TextView");
            }

            View sencodView = getChildAt(1);

            //测量子view的宽高
            measureChildren(widthMeasureSpec, heightMeasureSpec);

            //两个子view宽度相加小于该控件宽度的时候
            if (tv.getMeasuredWidth() + sencodView.getMeasuredWidth() <= w) {
                int width = tv.getMeasuredWidth()+sencodView.getMeasuredWidth();
                //计算高度
                int height = Math.max(tv.getMeasuredHeight(), sencodView.getMeasuredHeight());
                //设置该viewgroup的宽高
                setMeasuredDimension(width, height);
                type = SINGLE_LINE;
                return;
            }
            if (getChildAt(0) instanceof TextView) {
                //最后一行文字的宽度加上第二个view的宽度大于viewgroup宽度时第二个控件换行显示
                if (lastLineRight + sencodView.getMeasuredWidth() > w) {
                    setMeasuredDimension(tv.getMeasuredWidth(), tv.getMeasuredHeight() + sencodView.getMeasuredHeight());
                    type = NEXT_LINE;
                    return;
                }

                int height = Math.max(tv.getMeasuredHeight(), lastLineTop + sencodView.getMeasuredHeight());
                setMeasuredDimension(tv.getMeasuredWidth(), height);
                type = MULTI_LINE;
            }
        } else {
            throw new RuntimeException("CustomLayout child count must is 2");
        }

    }


    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        if (type == SINGLE_LINE || type == MULTI_LINE) {
            TextView tv = (TextView) getChildAt(0);
            View v1 = getChildAt(1);
            //设置第二个view在Textview文字末尾位置
            tv.layout(0, 0, tv.getMeasuredWidth(), tv.getMeasuredHeight());
            int left = (int) lastLineRight;
            int top  = lastLineTop;
            //最后一行的高度 注:通过staticLayout得到的行高不准确故采用这种方式
            int lastLineHeight = tv.getBottom()-tv.getPaddingBottom() -lastLineTop;
            //当第二view高度小于单行文字高度时竖直居中显示
            if(v1.getMeasuredHeight() < lastLineHeight){
                top = lastLineTop + (lastLineHeight - v1.getMeasuredHeight())/2;
            }
            v1.layout(left, top, left + v1.getMeasuredWidth(), top+v1.getMeasuredHeight());
        } else if (type == NEXT_LINE) {
            View v0 = getChildAt(0);
            View v1 = getChildAt(1);
            //设置第二个view换行显示
            v0.layout(0, 0, v0.getMeasuredWidth(), v0.getMeasuredHeight());
            v1.layout(0, v0.getMeasuredHeight(), v1.getMeasuredWidth(), v0.getMeasuredHeight() + v1.getMeasuredHeight());
        }
    }

    /**
     * 得到Textview绘制文字的基本信息
     * @param text Textview的文字内容
     * @param maxWidth Textview的宽度
     * @param paint 绘制文字的paint
     */
    private void initTextParams(CharSequence text, int maxWidth, TextPaint paint) {
        StaticLayout staticLayout = new StaticLayout(text, paint, maxWidth, Layout.Alignment.ALIGN_NORMAL, 1.0f, 0.0f, false);
        int lineCount = staticLayout.getLineCount();
        lastLineTop = staticLayout.getLineTop(lineCount - 1);
        lastLineRight = staticLayout.getLineRight(lineCount - 1);
    }

}