Android自定义ViewGroup之实现FlowLayout流式布局

前端技术 2023/09/09 Android

整理总结自鸿洋的博客：http://blog.csdn.net/lmj623565791/article/details/38352503/
 一、FlowLayout介绍
 所谓FlowLayout，就是控件根据ViewGroup的宽，自动的往右添加，如果当前行剩余空间不足，则自动添加到下一行。有点像所有的控件都往左飘的感觉，第一行满了，往第二行飘~所以也叫流式布局。Android并没有提供流式布局，但是某些场合中，流式布局还是非常适合使用的，比如关键字标签，搜索热词列表等，比如下图： 

github上已有现成的FlowLayout，本文是从无到有去制作。

二、制作分析 

1、对于FlowLayout，需要指定的LayoutParams，我们目前只需要能够识别margin即可，即使用MarginLayoutParams.
2、onMeasure中计算所有childView的宽和高，然后根据childView的宽和高，计算自己的宽和高。（当然，如果不是wrap_content，直接使用父ViewGroup传入的计算值即可）
3、onLayout中对所有的childView进行布局。 

三、代码 
1、MainActivity.java

 public class MainActivity extends Activity {

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
//  setContentView(R.layout.activity_main2);
//  setContentView(R.layout.activity_main3);
 }
}

 2、CustomViewGroup.java

public class CustomViewGroup extends ViewGroup {

 private final String TAG = getClass().getSimpleName();

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

 public CustomViewGroup(Context context, AttributeSet attrs) {
  super(context, attrs);
 }

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

 /**
  * 一、重写generateLayoutParams，确定该ViewGroup的LayoutParams
  * 返回MarginLayoutParams的实例，这样就为我们的ViewGroup指定了其LayoutParams为MarginLayoutParams
  */
 @Override
 public LayoutParams generateLayoutParams(AttributeSet attrs) {
  return new MarginLayoutParams(getContext(), attrs);
 }

 /**
  * 二、计算所有ChildView的宽度和高度 然后根据ChildView的计算结果，设置自己的宽和高
  */
 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  super.onMeasure(widthMeasureSpec, heightMeasureSpec);
  //1、获得此ViewGroup上级容器为其推荐的宽和高，以及计算模式
  int widthMode = MeasureSpec.getMode(widthMeasureSpec);
  int heightMode = MeasureSpec.getMode(heightMeasureSpec);
  int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
  int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);

  // 2、如果ViewGroup布局是wrap_content时，根据childView的尺寸，计算容器的宽和高
  int width = 0;//ViewGroup的宽度
  int height = 0;//ViewGroup的高度
  int lineWidth = 0;//childView所占据的当前行总宽度
  int lineHeight = 0;//childView所占据的各行总高度
  int cCount = getChildCount();////childView的数量
  for(int i=0; i<cCount; i++){//遍历每个childView
   View childView = getChildAt(i);
   measureChild(childView, widthMeasureSpec, heightMeasureSpec);// 测量当前child的宽和高
   MarginLayoutParams mlp = (MarginLayoutParams) childView.getLayoutParams();
   int cWidth = childView.getMeasuredWidth() + mlp.leftMargin + mlp.rightMargin;
   int cHeight = childView.getMeasuredHeight() + mlp.topMargin + mlp.bottomMargin;
   if(lineWidth + cWidth > sizeWidth){//如果加入当前childView后超出最大宽度，width取最大高度，累加lineHeight，然后开启新行
    width = Math.max(lineWidth, cWidth);
    height += lineHeight;
    lineWidth = cWidth;
   }else{//如果加入当前childView后小于最大宽度，则累加lineWidthheight lineHeight取最大高度
    lineWidth += cWidth;
    height = Math.max(lineHeight, cHeight);
   }
   if(i == cCount-1){// 如果是最后一个childView，则将当前记录的最大宽度和当前lineWidth做比较
    width = Math.max(lineWidth, cWidth);
    height += lineHeight;
   }
  }

  //3、如果是wrap_content设置为我们计算的值;否则直接设置为父容器计算的值
  setMeasuredDimension(
    (widthMode == MeasureSpec.EXACTLY) ? sizeWidth : width,
    (heightMode == MeasureSpec.EXACTLY) ? sizeHeight : height
  );
 }

 /**
  * 三、重写onLayout，对其所有childView进行定位（设置childView的绘制区域）
  */
 private List<List<View>> allChildViews = new ArrayList<List<View>>();//存储所有的childView，按行记录
 private List<Integer> maxLineHeight = new ArrayList<Integer>();//存储每行的最大高度值
 @Override
 protected void onLayout(boolean changed, int l, int t, int r, int b) {
  allChildViews.clear();
  maxLineHeight.clear();

  int width = getWidth();//每行的最大宽度
  int lineWidth = 0;//每行的即时宽度
  int lineHeight = 0;//每行的即时高度

  List<View> lineChildViews = new ArrayList<View>();//存储每行所有的childView

  int cCount = getChildCount();
  for(int i=0; i<cCount; i++){//遍历所有childView
   View childView = getChildAt(i);
   MarginLayoutParams mlp = (MarginLayoutParams) childView.getLayoutParams();
   int cWidth = childView.getMeasuredWidth();
   int cHeight = childView.getMeasuredHeight();
   if(lineWidth + cWidth + mlp.leftMargin + mlp.rightMargin > width){//如果需要换行
    maxLineHeight.add(lineHeight);// 存储这一行最大高度
    allChildViews.add(lineChildViews);// 将当前行的childView保存，然后开启新的ArrayList保存下一行的childView
    lineChildViews = new ArrayList<View>();
    lineWidth = 0;// 重置行宽
   }else{//如果不需要换行
    lineWidth += cWidth + mlp.leftMargin + mlp.rightMargin;//即时宽度累加
    lineHeight = Math.max(lineHeight,cHeight + mlp.topMargin + mlp.bottomMargin );//即时高度取最大值
    lineChildViews.add(childView);//把当前childView存入这一行的集合
   }
  }
  // 记录最后一行
  maxLineHeight.add(lineHeight);
  allChildViews.add(lineChildViews);

  int left = 0;//左坐标
  int top = 0;//上坐标
  int lineNums = allChildViews.size();// 得到总行数
  for (int i = 0; i < lineNums; i++) {
   lineChildViews = allChildViews.get(i);// 取得每一行的所有的views
   lineHeight = maxLineHeight.get(i);// 取得当前行的最大高度

   Log.e(TAG, \"第\" + i + \"行 ：\" + lineChildViews.size() + \" , \" + lineChildViews);
   Log.e(TAG, \"第\" + i + \"行， ：\" + lineHeight);

   // 遍历当前行所有的View 
   for (int j = 0; j < lineChildViews.size(); j++) {
    View childView = lineChildViews.get(j);//取得childView
    if (childView.getVisibility() == View.GONE) {
     continue;
    }
    MarginLayoutParams mlp = (MarginLayoutParams) childView.getLayoutParams();
    //计算childView的left,top,right,bottom
    int lc = left + mlp.leftMargin;
    int tc = top + mlp.topMargin;
    int rc = lc + childView.getMeasuredWidth();
    int bc = tc + childView.getMeasuredHeight();

    Log.e(TAG, childView + \" , l = \" + lc + \" , t = \" + t + \" , r =\" + rc + \" , b = \" + bc);

    childView.layout(lc, tc, rc, bc);//设置这个childView的位置
    left += childView.getMeasuredWidth() + mlp.rightMargin + mlp.leftMargin;//左坐标累加
   }
   left = 0;//开始新的一行，左坐标重置
   top += lineHeight;//开始新的一行，上坐标累加
  }
 }
}

 3、activity_main.xml

<LinearLayout xmlns:android=\"http://schemas.android.com/apk/res/android\"
 xmlns:tools=\"http://schemas.android.com/tools\"
 android:layout_width=\"fill_parent\"
 android:layout_height=\"fill_parent\"
 android:background=\"#E1E6F6\"
 android:orientation=\"vertical\">

 <com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup
  android:layout_width=\"fill_parent\"
  android:layout_height=\"wrap_content\">

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"Welcome\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"IT工程师\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"学习ing\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"恋爱ing\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"挣钱ing\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"努力ing\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"I thick i can\" />
 </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup>

</LinearLayout>

 4、activity_main2.xml

<LinearLayout xmlns:android=\"http://schemas.android.com/apk/res/android\"
 xmlns:tools=\"http://schemas.android.com/tools\"
 android:layout_width=\"fill_parent\"
 android:layout_height=\"fill_parent\"
 android:background=\"#E1E6F6\"
 android:orientation=\"vertical\">

 <com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup
  android:layout_width=\"fill_parent\"
  android:layout_height=\"wrap_content\">

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"Welcome\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"IT工程师\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"学习ing\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"恋爱ing\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"挣钱ing\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"努力ing\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:text=\"I thick i can\" />
 </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup>


 <com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup
  android:layout_width=\"fill_parent\"
  android:layout_height=\"wrap_content\"
  android:layout_marginTop=\"20dp\">

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_02\"
   android:text=\"Welcome\"
   android:textColor=\"#888888\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_02\"
   android:text=\"IT工程师\"
   android:textColor=\"#888888\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_02\"
   android:text=\"学习ing\"
   android:textColor=\"#888888\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_02\"
   android:text=\"恋爱ing\"
   android:textColor=\"#888888\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_02\"
   android:text=\"挣钱ing\"
   android:textColor=\"#888888\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_02\"
   android:text=\"努力ing\"
   android:textColor=\"#888888\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_02\"
   android:text=\"I thick i can\"
   android:textColor=\"#888888\" />
 </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup>

 <com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup
  android:layout_width=\"fill_parent\"
  android:layout_height=\"wrap_content\"
  android:layout_marginTop=\"20dp\">

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_03\"
   android:text=\"Welcome\"
   android:textColor=\"#43BBE7\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_03\"
   android:text=\"IT工程师\"
   android:textColor=\"#43BBE7\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_03\"
   android:text=\"学习ing\"
   android:textColor=\"#43BBE7\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_03\"
   android:text=\"恋爱ing\"
   android:textColor=\"#43BBE7\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_03\"
   android:text=\"挣钱ing\"
   android:textColor=\"#43BBE7\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_03\"
   android:text=\"努力ing\"
   android:textColor=\"#43BBE7\" />

  <TextView
   style=\"@style/text_flag_01\"
   android:background=\"@drawable/flag_03\"
   android:text=\"I thick i can\"
   android:textColor=\"#43BBE7\" />
 </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup>

</LinearLayout>

 5、activity_main3.xml

<com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup xmlns:android=\"http://schemas.android.com/apk/res/android\"
 xmlns:tools=\"http://schemas.android.com/tools\"
 android:layout_width=\"200dp\"
 android:layout_height=\"wrap_content\"
 android:background=\"#FFFFFF\">

 <TextView
  style=\"@style/text_flag_01\"
  android:background=\"@drawable/flag_04\"
  android:text=\"Welcome\"
  android:textColor=\"#323232\" />

 <TextView
  style=\"@style/text_flag_01\"
  android:background=\"@drawable/flag_04\"
  android:text=\"IT工程师\"
  android:textColor=\"#323232\" />

 <TextView
  style=\"@style/text_flag_01\"
  android:background=\"@drawable/flag_04\"
  android:text=\"学习ing\"
  android:textColor=\"#323232\" />

 <TextView
  style=\"@style/text_flag_01\"
  android:background=\"@drawable/flag_04\"
  android:text=\"恋爱ing\"
  android:textColor=\"#323232\" />

 <TextView
  style=\"@style/text_flag_01\"
  android:background=\"@drawable/flag_04\"
  android:text=\"挣钱ing\"
  android:textColor=\"#323232\" />

 <TextView
  style=\"@style/text_flag_01\"
  android:background=\"@drawable/flag_04\"
  android:text=\"努力ing\"
  android:textColor=\"#323232\" />

 <TextView
  style=\"@style/text_flag_01\"
  android:background=\"@drawable/flag_04\"
  android:text=\"I thick i can\"
  android:textColor=\"#323232\" />

</com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup>

 以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持phpstudy。

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