自动换行的流式布局代码,Java代码库,德仔网

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【Java】自动换行的流式布局
作者:智瑞 / 发布于2016/5/10/ 754
package com.robert;
 
import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import java.util.ArrayList;
import java.util.List;
 
/**
 * 自由布局
 * 
 */
public class FixGridLayout extends ViewGroup {
 
    /**
     * 布局最大行数
     */
    private int maxLine = 3;
 
    public FixGridLayout(Context context) {
        this(context, null);
    }
 
    public FixGridLayout(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }
 
    public FixGridLayout(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }
 
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 
        //父控件传进来的宽度和高度以及对应的测量模式
        int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
        int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
        int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
        int modeHeight = MeasureSpec.getMode(heightMeasureSpec);
 
        //如果当前ViewGroup的宽高为wrap_content的情况
        int width = 0;//自己测量的 宽度
        int height = 0;//自己测量的高度
        //记录每一行的宽度和高度
        int lineWidth = 0;
        int lineHeight = 0;
 
        int line = 1;
        //获取子view的个数
        int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = getChildAt(i);
            //测量子View的宽和高
            measureChild(child, widthMeasureSpec, heightMeasureSpec);
            //得到LayoutParams
            MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
            //子View占据的宽度
            int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
            //子View占据的高度
            int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;
            //换行时候
            if (lineWidth + childWidth > sizeWidth) {
                //对比得到最大的宽度
                width = Math.max(width, lineWidth);
                //重置lineWidth
                lineWidth = childWidth;
                //记录行高
                height += lineHeight;
                lineHeight = childHeight;
                line++;
            } else {//不换行情况
                //叠加行宽
                lineWidth += childWidth;
                //得到最大行高
                lineHeight = Math.max(lineHeight, childHeight);
            }
 
            if (line > maxLine) {
                break;
            } else if (i == childCount - 1) {
                width = Math.max(width, lineWidth);
                height += lineHeight;
            }
        }
        //wrap_content
        setMeasuredDimension(modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width,
                modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height);
    }
 
    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        List<List<View>> mAllChildViews = new ArrayList<>();
        List<Integer> mLineHeight = new ArrayList<>();
        //获取当前ViewGroup的宽度
        int width = getWidth();
 
        int lineWidth = 0;
        int lineHeight = 0;
        //记录当前行的view
        List<View> lineViews = new ArrayList<View>();
        int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = getChildAt(i);
            MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
            int childWidth = child.getMeasuredWidth();
            int childHeight = child.getMeasuredHeight();
 
            //如果需要换行
            if (childWidth + lineWidth + lp.leftMargin + lp.rightMargin > width) {
                //记录LineHeight
                mLineHeight.add(lineHeight);
                //记录当前行的Views
                mAllChildViews.add(lineViews);
                //重置行的宽高
                lineWidth = 0;
                lineHeight = childHeight + lp.topMargin + lp.bottomMargin;
                //重置view的集合
                lineViews = new ArrayList();
            }
            lineWidth += childWidth + lp.leftMargin + lp.rightMargin;
            lineHeight = Math.max(lineHeight, childHeight + lp.topMargin + lp.bottomMargin);
            lineViews.add(child);
        }
        //处理最后一行
        mLineHeight.add(lineHeight);
        mAllChildViews.add(lineViews);
 
        //设置子View的位置
        int left = 0;
        int top = 0;
        //获取行数
        int lineCount = mAllChildViews.size();
        for (int i = 0; i < Math.min(maxLine, lineCount); i++) {
            //当前行的views和高度
            lineViews = mAllChildViews.get(i);
            lineHeight = mLineHeight.get(i);
            for (int j = 0; j < lineViews.size(); j++) {
                View child = lineViews.get(j);
                //判断是否显示
                if (child.getVisibility() == View.GONE) {
                    continue;
                }
                MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
                int cLeft = left + lp.leftMargin;
                int cTop = top + lp.topMargin;
                int cRight = cLeft + child.getMeasuredWidth();
                int cBottom = cTop + child.getMeasuredHeight();
                //进行子View进行布局
                child.layout(cLeft, cTop, cRight, cBottom);
                left += child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
            }
            left = 0;
            top += lineHeight;
        }
 
    }
 
    /**
     * 与当前ViewGroup对应的LayoutParams
     */
    @Override
    public LayoutParams generateLayoutParams(AttributeSet attrs) {
 
        return new MarginLayoutParams(getContext(), attrs);
    }
}
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