自定义ViewGroup控件（四）----->流式布局进阶（四）

onMeasure()函数由ViewGroup调用子类的方法，因此值也是从这个ViewGroup中传入的

1、当我们设置自定义控件width或height为fill_parent时，容器在布局时调用子view的measure方法传入的模式是EXACTLY

2、当设置自定义控件为 wrap_content时，容器传进去的是AT_MOST,表示子view的大小最多是多少

3、当设置自定义控件的大小设置为精确值时，容器传入的是EXACTLY

activity_main.xml

<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" >

    <com.imooc.view.FlowLayout
        android:id="@+id/id_flowlayout"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:background="#E5E5F5"
        android:padding="20dp" >
    </com.imooc.view.FlowLayout>

</RelativeLayout>

tv.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_margin="5dp"
    android:background="@drawable/tv_bg"
    android:textColor="#5BC4ED"
    android:text="Helloworld" >

</TextView>

MainActivity

package com.imooc.flowlayout;

import android.app.Activity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.widget.TextView;

import com.imooc.view.FlowLayout;

public class MainActivity extends Activity {
private String[] mVals = new String[] { "Hello", "Android", "Weclome Hi ",
"Button", "TextView", "Hello", "Android", "Weclome",
"Button ImageView", "TextView", "Helloworld", "Android",
"Weclome Hello", "Button Text", "TextView" };

private FlowLayout mFlowLayout;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//加载布局
setContentView(R.layout.activity_main);
//获取视图id
mFlowLayout = (FlowLayout) findViewById(R.id.id_flowlayout);
//初始化数据
initData();
}

public void initData() {
LayoutInflater mInflater = LayoutInflater.from(this);
for (int i = 0; i < mVals.length; i++) {
TextView tv = (TextView) mInflater.inflate(R.layout.tv,
mFlowLayout, false);
tv.setText(mVals[i]);
mFlowLayout.addView(tv);
}

}

}

FlowLayout

package com.imooc.view;

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

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

public class FlowLayout extends ViewGroup {

/**
 * 构造方法
 */
public FlowLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}

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

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

/**
 * ViewGroup指定了其LayoutParams为MarginLayoutParams。 子类可以获取
 */
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs) {
return new MarginLayoutParams(getContext(), attrs);
}

/**
 * 自定义控件
 * android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       heightMeasureSpec 是自定义控件的父类传给自定义控件的，里面包含父类约束子类的模式、高宽值
 */
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
/**容器的宽和高*/
int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
int modeHeight = MeasureSpec.getMode(heightMeasureSpec);

// wrap_content需要计算高度、宽度--容器的行高、行宽
int width = 0;
int height = 0;

// 记录每一行的宽度与高度
int lineWidth = 0;
int lineHeight = 0;

// 得到内部元素的个数
int cCount = getChildCount();
for (int i = 0; i < cCount; i++) {
View child = getChildAt(i);
// 测量子View的宽和高，调用viewGroup的测量子view的方法
measureChild(child, widthMeasureSpec, heightMeasureSpec);
// 得到子类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;

// 当前的行宽+子view的宽度>容器的宽度 --就换行
if (lineWidth + childWidth > sizeWidth - getPaddingLeft()
- getPaddingRight()) {
// 对比得到最大的宽度
width = Math.max(width, lineWidth);
// 重置lineWidth--换行之后就是子view的宽度
lineWidth = childWidth;
// 记录行高
height += lineHeight;
//重置每一行的行高
lineHeight = childHeight;
} else
// 未换行
{
// 叠加行宽
lineWidth += childWidth;
// 得到当前行最大的高度
lineHeight = Math.max(lineHeight, childHeight);
}
// 最后一个控件
if (i == cCount - 1) {
width = Math.max(lineWidth, width);
height += lineHeight;
}
}

/**
 * MeasureSpec.EXACTLY说明自定义控件是fill_parent
 * MeasureSpec.AT_MOST说明是wrap_content
 */
setMeasuredDimension(
//
modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width
+ getPaddingLeft() + getPaddingRight(),
modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height
+ getPaddingTop() + getPaddingBottom()//
);

}

/**
 * 存储所有的View
 */
private List<List<View>> mAllViews = new ArrayList<List<View>>();
/**
 * 每一行的高度
 */
private List<Integer> mLineHeight = new ArrayList<Integer>();

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
mAllViews.clear();
mLineHeight.clear();

// 当前ViewGroup的宽度
int width = getWidth();

int lineWidth = 0;
int lineHeight = 0;

/*
 * 每一行的子View集合
 */
List<View> lineViews = new ArrayList<View>();

int cCount = getChildCount();

for (int i = 0; i < cCount; i++) {
View child = getChildAt(i);
//拿到子类的
MarginLayoutParams lp = (MarginLayoutParams) child
.getLayoutParams();
//获取子类的宽度高度
int childWidth = child.getMeasuredWidth();
int childHeight = child.getMeasuredHeight();

// 如果需要换行
if (childWidth + lineWidth + lp.leftMargin + lp.rightMargin > width
- getPaddingLeft() - getPaddingRight()) {
// 记录LineHeight
mLineHeight.add(lineHeight);
// 记录当前行的Views
mAllViews.add(lineViews);

// 重置我们的行宽和行高
lineWidth = 0;
lineHeight = childHeight + lp.topMargin + lp.bottomMargin;
// 重置我们的View集合
lineViews = new ArrayList<View>();
}
lineWidth += childWidth + lp.leftMargin + lp.rightMargin;
lineHeight = Math.max(lineHeight, childHeight + lp.topMargin
+ lp.bottomMargin);
//每一行添加子view
lineViews.add(child);

}// for end
// 处理最后一行
mLineHeight.add(lineHeight);
mAllViews.add(lineViews);

// 设置子View的位置

int left = getPaddingLeft();
int top = getPaddingTop();

// 行数
int lineNum = mAllViews.size();

for (int i = 0; i < lineNum; i++) {
// 当前行的所有的View
lineViews = mAllViews.get(i);
lineHeight = mLineHeight.get(i);

for (int j = 0; j < lineViews.size(); j++) {
View child = lineViews.get(j);
// 判断child的状态
if (child.getVisibility() == View.GONE) {
continue;
}

MarginLayoutParams lp = (MarginLayoutParams) child
.getLayoutParams();

int lc = left + lp.leftMargin;
int tc = top + lp.topMargin;
int rc = lc + child.getMeasuredWidth();
int bc = tc + child.getMeasuredHeight();

// 为子View进行布局
child.layout(lc, tc, rc, bc);

left += child.getMeasuredWidth() + lp.leftMargin
+ lp.rightMargin;
}
left = getPaddingLeft();
top += lineHeight;
}

}

}