android 实现自动换行的流布局

今天为大家带来一个自定义的ViewGroup自动换行的流布局。原理非常的简单。就是在自定义的ViewGroup的onMeasure中计算每个子View的位置，再在onLayout中画出子View。别的不多说，直接上代码。

package com.ljh.flowviewgroup;

import android.content.Context;
import android.os.Build;
import android.util.ArrayMap;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;

import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

/**
* Created by liujinhua on 15/10/8.
*/
public class FlowViewGroup extends ViewGroup {

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

public FlowViewGroup(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}

public FlowViewGroup(Context context) {
this(context, null);
}

@Override
protected LayoutParams generateDefaultLayoutParams() {
return new MarginLayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
}

private Map<View, ChildViewPosition> map;

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
if (map == null) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
map = new ArrayMap<View, ChildViewPosition>();
} else {
map = new HashMap<View, ChildViewPosition>();
}
} else {
map.clear();
}
//计算所有ziView的大小
measureChildren(widthMeasureSpec, heightMeasureSpec);

int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
int sizeHight = MeasureSpec.getSize(heightMeasureSpec);

int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int hightMode = MeasureSpec.getMode(heightMeasureSpec);

int lineWidth = 0;
int lineHight = 0;

int width = 0;
int hight = 0;

int childCount = getChildCount();

for (int i = 0; i < childCount; i++) {
View childView = getChildAt(i);

MarginLayoutParams lp;
if (childView.getLayoutParams() instanceof MarginLayoutParams) {
lp = (MarginLayoutParams) childView.getLayoutParams();
} else {
lp = new MarginLayoutParams(childView.getLayoutParams());
}

int childWidth = childView.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
int childHight = childView.getMeasuredHeight() + lp.bottomMargin + lp.topMargin;
//判断是非需要换行
if (lineWidth + childWidth > sizeWidth) {
//需要换行

//计算ViewGroup需要的宽高
width = Math.max(width, lineWidth);
hight += lineHight;

//换行重置当前行高度与宽度
lineHight = childHight;
lineWidth = childWidth;
map.put(childView, new ChildViewPosition(0 + lp.leftMargin, hight + lp.topMargin, childWidth - lp.rightMargin, hight + childHight - lp.bottomMargin));

} else {
//不需要换行

map.put(childView, new ChildViewPosition(lineWidth + lp.leftMargin, hight + lp.topMargin, lineWidth + childWidth - lp.rightMargin, hight + childHight - lp.bottomMargin));

//叠加当前行的宽度
lineWidth += childWidth;
//计算当前行最大高度
lineHight = Math.max(lineHight, childHight);

}
//加上最后一行的宽高的计算出ViewGroup需要的宽高
if (i == childCount - 1) {
width = Math.max(width, lineWidth);
hight += lineHight;
}
}

setMeasuredDimension(
widthMode == MeasureSpec.EXACTLY ? sizeWidth : width,
hightMode == MeasureSpec.EXACTLY ? sizeHight : hight
);
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
for (View key : map.keySet()) {
ChildViewPosition position = map.get(key);
key.layout(position.left, position.top, position.right, position.bottom);
}

}

private class ChildViewPosition {
public ChildViewPosition(int left, int top, int right, int bottom) {
this.left = left;
this.right = right;
this.top = top;
this.bottom = bottom;
}

int left;
int right;
int top;
int bottom;
}
}

package com.ljh.flowviewgroup;

import android.graphics.Color;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

FlowViewGroup flowViewGroup;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
flowViewGroup = (FlowViewGroup) findViewById(R.id.flowViewGroup);
for (int i = 0; i < 20; i++) {
TextView text = new TextView(this);
text.setText(" texttext" + i + " ");
text.setBackgroundResource(R.drawable.round);
text.setPadding(10, 10, 10, 10);
flowViewGroup.addView(text);
ViewGroup.MarginLayoutParams lp = (ViewGroup.MarginLayoutParams) text.getLayoutParams();
lp.bottomMargin = 10;
lp.topMargin = 10;
lp.rightMargin = 10;

lp.leftMargin = 10;
text.setLayoutParams(lp);
}
}
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity">

<com.ljh.flowviewgroup.FlowViewGroup
android:id="@+id/flowViewGroup"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</com.ljh.flowviewgroup.FlowViewGroup>
</RelativeLayout>

附上原代码
下载