自定义ViewGroup实现宽度自动换行

自定义ViewGroup实现宽度自动换行

• 自定义ViewGroup

自定义ViewGroup

代码

package com.example.app1;

import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;

public class LiuViewGroup extends ViewGroup {

    int groupWidth,groupHeight;
    private static final String TAG = "LiuViewGroup";

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

    public LiuViewGroup(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
    //onMesure() ——计算childView的测量值以及模式，以及设置自己的宽和高。
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int mode = MeasureSpec.getMode(widthMeasureSpec);
        int size = MeasureSpec.getSize(widthMeasureSpec);
        switch (mode){
            case MeasureSpec.EXACTLY:
                Log.e(TAG, "onMeasure: " );
                groupWidth = size;
                break;
            case MeasureSpec.AT_MOST:
                Log.e(TAG, "onMeasure: " );
                groupWidth = 50;
                break;
        }

        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);
        switch (heightMode){
            case MeasureSpec.EXACTLY: //
                Log.i(TAG, "onMeasure: ");
                groupHeight = heightSize;
                break;
            case MeasureSpec.AT_MOST:
                Log.i(TAG, "onMeasure:111 ");
                groupHeight = 50;
                break;
        }

        setMeasuredDimension(groupWidth,groupHeight);

    }
//通过getChildCount()获取子view数量，
    // getChildAt获取所有子View，
    //那个所有view 的宽的数据 相加
    //如果小于group的宽 横排
    //如果大于group的宽,竖排
    // 分别调用layout(int l, int t, int r, int b)确定每个子View的摆放位置。
    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int childCountWidth = 0;
        int left = 0;
        //定义布局的.
        int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            View childAt = getChildAt(i);

            LinearLayout.LayoutParams layoutParams = (LinearLayout.LayoutParams) childAt.getLayoutParams();
            childCountWidth += layoutParams.width;
            Log.i(TAG, "onLayout: "+layoutParams.width); //px
            Log.i(TAG, "onLayout: "+layoutParams.height);
            //摆放子View 的位置的.

            //父布局的宽和多个子布局的宽度想计算
            int width = getWidth();
            Log.i(TAG, "onLayout: "+width);

            if(width > childCountWidth){
                //横排
                Log.i(TAG, "onLayout: 横排");
                childAt.layout(left,0,layoutParams.width+left,layoutParams.height);
                left += layoutParams.width;
            }else{
                //竖排
                Log.i(TAG, "onLayout: 竖排 ");
                childAt.layout(0,layoutParams.height,layoutParams.width,layoutParams.height*2);
            }
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
    }
    //实现一个布局的属性
    @Override
    public LayoutParams generateLayoutParams(AttributeSet attrs) {
        return new LinearLayout.LayoutParams(getContext(),attrs);
    }
}

xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

        <com.example.app1.LiuViewGroup
            android:id="@+id/group"
            android:layout_width="250dp"
            android:background="@color/colorAccent"
            android:layout_height="match_parent"
            >

            <TextView
                android:layout_width="100dp"
                android:text="哈哈"
                android:background="@color/colorPrimaryDark"
                android:layout_height="100dp"></TextView>

            <TextView
                android:layout_width="100dp"
                android:text="嘿嘿"
                android:background="@color/colorPrimaryDark"
                android:layout_height="100dp"></TextView>

        </com.example.app1.LiuViewGroup>


    </LinearLayout>


</LinearLayout>