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移动开发布局技巧之自定义View流式布局
2017-12-02 10:52:22      个评论    来源:yujie0514的博客  
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移动开发布局技巧之自定义View流式布局。

FlowLayout:
package com.example.a03_flowlayout.flowlayout;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by yujie on 2017/12/1.
 */

public class FlowLayout extends ViewGroup{
    //存储所有子View
    private List<List<View>> mAllChildViews = new ArrayList<>();
    //每一行的高度
    private List<Integer> mLineHeight = new ArrayList<>();

    public FlowLayout(Context context) {
        this(context, null);
        // TODO Auto-generated constructor stub
    }
    public FlowLayout(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
        // TODO Auto-generated constructor stub
    }
    public FlowLayout(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        // TODO Auto-generated constructor stub
    }
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        // TODO Auto-generated method stub

        //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;

        //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) 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;
            }else{//不换行情况
                //叠加行宽
                lineWidth += childWidth;
                //得到最大行高
                lineHeight = Math.max(lineHeight, childHeight);
            }
            //处理最后一个子View的情况
            if(i == childCount -1){
                width = Math.max(width, lineWidth);
                height += lineHeight;
            }
        }
        //wrap_content
        setMeasuredDimension(modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width,
                modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height);
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        // TODO Auto-generated method stub
        mAllChildViews.clear();
        mLineHeight.clear();
        //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 < 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) {
        // TODO Auto-generated method stub

        return new MarginLayoutParams(getContext(), attrs);
    }

}

代码中使用:

 

package com.example.a03_flowlayout;

import android.graphics.Color;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.ViewGroup;
import android.widget.TextView;

import com.example.a03_flowlayout.flowlayout.FlowLayout;

public class MainActivity extends AppCompatActivity {

    private String mNames[] = {
            "welcome","android","TextView",
            "apple","jamy","kobe bryant",
            "jordan","layout","viewgroup",
            "margin","padding","text",
            "name","type","search","logcat"
    };
    private FlowLayout flowLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initChildViews();
    }

    private void initChildViews() {
        // TODO Auto-generated method stub
        flowLayout = findViewById(R.id.flow_layout);
        ViewGroup.MarginLayoutParams lp = new ViewGroup.MarginLayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        lp.leftMargin = 5;
        lp.rightMargin = 5;
        lp.topMargin = 5;
        lp.bottomMargin = 5;
        for(int i = 0; i < mNames.length; i ++){
            TextView view = new TextView(this);
            view.setText(mNames[i]);
            view.setTextColor(Color.WHITE);
            view.setBackgroundDrawable(getResources().getDrawable(R.drawable.textview_bg));
            flowLayout.addView(view,lp);
        }
    }

}
布局:
xml version="1.0" encoding="utf-8"?> <LinearLayout  xmlns:android="https://schemas.android.com/apk/res/android"  xmlns:app="https://schemas.android.com/apk/res-auto"  xmlns:tools="https://schemas.android.com/tools"  android:layout_width="match_parent"  android:layout_height="match_parent"  tools:context="com.example.a03_flowlayout.MainActivity">   <com.example.a03_flowlayout.flowlayout.FlowLayout  android:id="@+id/flow_layout"  android:layout_width="200dp"  android:layout_height="wrap_content">   com.example.a03_flowlayout.flowlayout.FlowLayout>  LinearLayout>
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