安卓自定义控件之仅可以显示一行视图的view控件（类似 HorizontalScrollView但不可滑动一行排满不在排）

该控件的功能是显示一行视图，这一行可以无限添加view，以及添加Headview、footview；当本行呗view排列满之后不在排列，如果添加了footview，那么footview肯定会在最后显示。

代码如下：

import android.app.Activity;
import android.content.Context;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.View;
import android.view.ViewGroup;

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

/**
* Created by wangliang on 0022/2016/9/22.
* 功能：显示一行view，水平的，多个view，最多显示一行
* 思路：动态添加view，如果添加了尾view的话，则在绘制onlayout的时候余留除尾view的空间，
* 所有的view取最小view的高度进行压缩显示显示足一整行，显示不足就显示能显示的部分，显示超过，则就显示一行
*/
public class MyHorizontalView extends ViewGroup {
private Context context;
private int windowWidth = 0;
private int nowAllViewWidth = 0;
private boolean whetherAddHeadView = false;
private boolean whetherAddFootView = false;
private String TAG = "MyHorizontalView";
private List<View> allViews = new ArrayList<>();
private int maxHeight = 0;
private View footView;

public MyHorizontalView(Context context) {
super(context);
initSetting(context);
}

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

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

private void initSetting(Context context){
this.context = context;
DisplayMetrics dm = new DisplayMetrics();
//取得窗口属性
((Activity)context).getWindowManager().getDefaultDisplay().getMetrics(dm);
windowWidth = dm.widthPixels;

}

/**
* 添加头view
* @param view
*/
public void addHeadView(View view, ViewGroup.LayoutParams params){
if(!whetherAddHeadView) {
whetherAddHeadView = true;
allViews.add(0,view);
super.addView(view, -1,params);
}
}

/**
* 添加末尾view
* @param view
*/
public void addFootView(View view, ViewGroup.LayoutParams params){
if(!whetherAddFootView) {
whetherAddFootView = true;
footView = view;
super.addView(view, -1,params);
}
}

@Override
public void addView(View child, int index, ViewGroup.LayoutParams params) {
super.addView(child, -1,params);
allViews.add(child);
}

@Override
public void addView(View child) {
addView(child,-1,null);
}

@Override
public void addView(View child, int index) {
addView(child, index,null);
}

@Override
public void addView(View child, LayoutParams params) {
addView(child,-1, params);
}

@Override
protected LayoutParams generateLayoutParams(
LayoutParams p)
{
return new MarginLayoutParams(p);
}

@Override
public LayoutParams generateLayoutParams(AttributeSet attrs)
{
return new MarginLayoutParams(getContext(), attrs);
}

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

/**
* 负责设置子控件的测量模式和大小 根据所有子控件设置自己的宽和高
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
int minHeight = Integer.MAX_VALUE ;

// 遍历每个子元素
for (int i = 0; i < getChildCount(); i++)
{
View child = getChildAt(i);
// 测量每一个child的宽和高
child.measure(0,0);
// 得到child的lp
MarginLayoutParams lp = (MarginLayoutParams) child
.getLayoutParams();

minHeight = Math.min(lp.height  + lp.topMargin
+ lp.bottomMargin,minHeight);

}
setMeasuredDimension(widthMeasureSpec, Math.max(minHeight,heightMeasureSpec));

}

private boolean whetherLayout;
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {

if(whetherLayout){
whetherLayout = false;
}else {
whetherLayout = true;
return;
}

//判断是否有尾视图，如果有则需要计算尾视图，为尾视图预留显示空间
int footViewWidth = 0;
int footViewBc = 0;
int footViewLc = 0;
int footViewTc = 0;
int footViewRc = 0;
if(whetherAddFootView && footView != null){
MarginLayoutParams lp = (MarginLayoutParams) footView.getLayoutParams();
footView.measure(0,0);
double beiShu = getHeight() * 1.0 / (footView.getMeasuredHeight() + lp.topMargin + lp.bottomMargin);
footViewLc = (int) (lp.leftMargin * beiShu);
footViewTc = (int) (lp.topMargin * beiShu);
footViewRc = (int) (footViewLc + (footView.getMeasuredWidth() * beiShu));
footViewBc = (int) (footViewTc + (footView.getMeasuredHeight() * beiShu));
footViewWidth = footViewRc - footViewLc;
}
//判断是否有尾视图，如果有则需要计算尾视图，为尾视图预留显示空间

//绘制尾视图其他部分
int left = 0;
int nowWidth = 0;
for(int i = 0 ; i < allViews.size() ; i++){
View child = allViews.get(i);
child.measure(0,0);
if (child.getVisibility() == View.GONE)
{
continue;
}
MarginLayoutParams lp = (MarginLayoutParams) child
.getLayoutParams();
double beiShu = getMeasuredHeight() * 1.0 / (child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin);
//计算childView的left,top,right,bottom
int lc = (int) (left + lp.leftMargin * beiShu);
int tc = (int) (lp.topMargin * beiShu);
int rc = (int) (lc + child.getMeasuredWidth() * beiShu);
int bc = (int) (tc + child.getMeasuredHeight() * beiShu);
nowWidth += child.getMeasuredWidth() * beiShu + lp.rightMargin * beiShu
+ lp.leftMargin * beiShu;
if(nowWidth + footViewWidth > getMeasuredWidth()){
break;
}

child.layout(lc, tc, rc, bc);
left += child.getMeasuredWidth() * beiShu + lp.rightMargin * beiShu
+ lp.leftMargin * beiShu;
}
//绘制尾视图其他部分

//绘制尾视图
if(whetherAddFootView && footView != null){
footView.layout(left + footViewLc, footViewTc, left + footViewRc, footViewBc);
}

}
}

调用代码（其中RoundRectangleImageView可以更换为其他view）：

ViewGroup.MarginLayoutParams lp = null;
lp = new ViewGroup.MarginLayoutParams(
80, 80);
lp.leftMargin = 10;
lp.rightMargin = 10;
lp.topMargin = 50;
lp.bottomMargin = 50;

RoundRectangleImageView roundRectangleImageView = new RoundRectangleImageView(getContext());
Picasso.with(getContext()).load(R.drawable.people_head)
.placeholder(R.drawable.ic_launcher).error(R.drawable.ic_launcher).resize(500,500).into(roundRectangleImageView);
hv.addHeadView(roundRectangleImageView,lp);
hv.addFootView(roundRectangleImageView,lp);

for(int i = 0; i < 10 ; i++){
roundRectangleImageView = new RoundRectangleImageView(getContext());

Picasso.with(getContext()).load(R.drawable.ic_launcher)
.placeholder(R.drawable.ic_launcher).error(R.drawable.ic_launcher).resize(500,500).into(roundRectangleImageView);
hv.addView(roundRectangleImageView,lp);
}