Android自定义控件ViewGroup实现标签云（四）

Felicite ·

更新时间:2024-09-21

· 909 次阅读

前言：

前面几篇讲了自定义控件绘制原理Android自定义控件基本原理详解（一），Android自定义控件之自定义属性（二），Android自定义控件之自定义组合控件（三），常言道：“好记性不如烂笔头，光说不练假把式！！！”，作为一名学渣就是因为没有遵循这句名言才沦落于此，所以要谨遵教诲，注重理论与实践相结合，今天通过自定义ViewGroup来实现一下项目中用到的标签云。

需求背景：

公司需要实现一个知识点的标签显示，每个标签的长度未知，如下图所示

基本绘制流程：

绘制原理这里不再介绍大致介绍下绘制流程
•构造函数获取自定义属性
•onMeasure()方法，测量子控件的大小
•onLayout()方法，对子控件进行布局

1.）自定义属性


 <declare-styleable name="TagsLayout">
  <attr name="tagVerticalSpace" format="dimension" />
  <attr name="tagHorizontalSpace" format="dimension" />
</declare-styleable>

2.）构造函数中获取自定义属性值


private int childHorizontalSpace;
 private int childVerticalSpace;
 public TagsLayout(Context context, AttributeSet attrs) {
  super(context, attrs);
  TypedArray attrArray = context.obtainStyledAttributes(attrs, R.styleable.TagsLayout);
  if (attrArray != null) {
   childHorizontalSpace = attrArray.getDimensionPixelSize(R.styleable.TagsLayout_tagHorizontalSpace, 0);
   childVerticalSpace = attrArray.getDimensionPixelSize(R.styleable.TagsLayout_tagVerticalSpace, 0);
   attrArray.recycle();
  }
 }

3.）onMeasure函数测量子控件大小，然后设置当前控件大小


 /**
  * 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) {
  super.onMeasure(widthMeasureSpec, heightMeasureSpec);
  // 获得它的父容器为它设置的测量模式和大小
  int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
  int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
  int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
  int modeHeight = MeasureSpec.getMode(heightMeasureSpec);
  // 如果是warp_content情况下，记录宽和高
  int width = 0;
  int height = 0;
  /**
   * 记录每一行的宽度，width不断取最大宽度
   */
  int lineWidth = 0;
  /**
   * 每一行的高度，累加至height
   */
  int lineHeight = 0;
  int count = getChildCount();
  int left = getPaddingLeft();
  int top = getPaddingTop();
  // 遍历每个子元素
  for (int i = 0; i < count; i++) {
   View child = getChildAt(i);
   if (child.getVisibility() == GONE)
    continue;
   // 测量每一个child的宽和高
   measureChild(child, widthMeasureSpec, heightMeasureSpec);
   // 得到child的lp
   MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
   // 当前子空间实际占据的宽度
   int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin + childHorizontalSpace;
   // 当前子空间实际占据的高度
   int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin + childVerticalSpace;
   /**
    * 如果加入当前child，则超出最大宽度，则的到目前最大宽度给width，类加height 然后开启新行
    */
   if (lineWidth + childWidth > sizeWidth - getPaddingLeft() - getPaddingRight()) {
    width = Math.max(lineWidth, childWidth);// 取最大的
    lineWidth = childWidth; // 重新开启新行，开始记录
    // 叠加当前高度，
    height += lineHeight;
    // 开启记录下一行的高度
    lineHeight = childHeight;
    child.setTag(new Location(left, top + height, childWidth + left - childHorizontalSpace, height + child.getMeasuredHeight() + top));
   } else {// 否则累加值lineWidth,lineHeight取最大高度
    child.setTag(new Location(lineWidth + left, top + height, lineWidth + childWidth - childHorizontalSpace + left, height + child.getMeasuredHeight() + top));
    lineWidth += childWidth;
    lineHeight = Math.max(lineHeight, childHeight);
   }
  }
  width = Math.max(width, lineWidth) + getPaddingLeft() + getPaddingRight();
  height += lineHeight;
  sizeHeight += getPaddingTop() + getPaddingBottom();
  height += getPaddingTop() + getPaddingBottom();
  setMeasuredDimension((modeWidth == MeasureSpec.EXACTLY) ? sizeWidth : width, (modeHeight == MeasureSpec.EXACTLY) ? sizeHeight : height);
 }

通过遍历所有子控件调用measureChild函数获取每个子控件的大小，然后通过宽度叠加判断是否换行，叠加控件的高度，同时记录下当前子控件的坐标，这里记录坐标引用了自己写的一个内部类Location.java


 /**
  * 记录子控件的坐标
  */
 public class Location {
  public Location(int left, int top, int right, int bottom) {
   this.left = left;
   this.top = top;
   this.right = right;
   this.bottom = bottom;
  }
  public int left;
  public int top;
  public int right;
  public int bottom;
 }

4.)onLayout函数对所有子控件重新布局


 @Override
 protected void onLayout(boolean changed, int l, int t, int r, int b) {
  int count = getChildCount();
  for (int i = 0; i < count; i++) {
   View child = getChildAt(i);
   if (child.getVisibility() == GONE)
    continue;
   Location location = (Location) child.getTag();
   child.layout(location.left, location.top, location.right, location.bottom);
  }
 }

这里直接遍历所有子控件调用子控件的layout函数进行布局。

如何使用：
1）.布局问自己中直接引用


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:lee="http://schemas.android.com/apk/res-auto"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical">
 <com.whoislcj.views.TagsLayout
  android:id="@+id/image_layout"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:layout_margin="10dp"
  lee:tagHorizontalSpace="10dp"
  lee:tagVerticalSpace="10dp" />
</LinearLayout>

2）.代码添加标签


TagsLayout imageViewGroup = (TagsLayout) findViewById(R.id.image_layout);
 ViewGroup.MarginLayoutParams lp = new ViewGroup.MarginLayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
  String[] string={"从我写代码那天起，我就没有打算写代码","从我写代码那天起","我就没有打算写代码","没打算","写代码"};
  for (int i = 0; i < 5; i++) {
   TextView textView = new TextView(this);
   textView.setText(string[i]);
   textView.setTextColor(Color.WHITE);
   textView.setBackgroundResource(R.drawable.round_square_blue);
   imageViewGroup.addView(textView, lp);
  }

具体效果

3.）最后附上TagsLayout全部代码


public class TagsLayout extends ViewGroup {
 private int childHorizontalSpace;
 private int childVerticalSpace;
 public TagsLayout(Context context, AttributeSet attrs) {
  super(context, attrs);
  TypedArray attrArray = context.obtainStyledAttributes(attrs, R.styleable.TagsLayout);
  if (attrArray != null) {
   childHorizontalSpace = attrArray.getDimensionPixelSize(R.styleable.TagsLayout_tagHorizontalSpace, 0);
   childVerticalSpace = attrArray.getDimensionPixelSize(R.styleable.TagsLayout_tagVerticalSpace, 0);
   attrArray.recycle();
  }
 }
 /**
  * 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) {
  super.onMeasure(widthMeasureSpec, heightMeasureSpec);
  // 获得它的父容器为它设置的测量模式和大小
  int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
  int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
  int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
  int modeHeight = MeasureSpec.getMode(heightMeasureSpec);
  // 如果是warp_content情况下，记录宽和高
  int width = 0;
  int height = 0;
  /**
   * 记录每一行的宽度，width不断取最大宽度
   */
  int lineWidth = 0;
  /**
   * 每一行的高度，累加至height
   */
  int lineHeight = 0;
  int count = getChildCount();
  int left = getPaddingLeft();
  int top = getPaddingTop();
  // 遍历每个子元素
  for (int i = 0; i < count; i++) {
   View child = getChildAt(i);
   if (child.getVisibility() == GONE)
    continue;
   // 测量每一个child的宽和高
   measureChild(child, widthMeasureSpec, heightMeasureSpec);
   // 得到child的lp
   MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
   // 当前子空间实际占据的宽度
   int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin + childHorizontalSpace;
   // 当前子空间实际占据的高度
   int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin + childVerticalSpace;
   /**
    * 如果加入当前child，则超出最大宽度，则的到目前最大宽度给width，类加height 然后开启新行
    */
   if (lineWidth + childWidth > sizeWidth - getPaddingLeft() - getPaddingRight()) {
    width = Math.max(lineWidth, childWidth);// 取最大的
    lineWidth = childWidth; // 重新开启新行，开始记录
    // 叠加当前高度，
    height += lineHeight;
    // 开启记录下一行的高度
    lineHeight = childHeight;
    child.setTag(new Location(left, top + height, childWidth + left - childHorizontalSpace, height + child.getMeasuredHeight() + top));
   } else {// 否则累加值lineWidth,lineHeight取最大高度
    child.setTag(new Location(lineWidth + left, top + height, lineWidth + childWidth - childHorizontalSpace + left, height + child.getMeasuredHeight() + top));
    lineWidth += childWidth;
    lineHeight = Math.max(lineHeight, childHeight);
   }
  }
  width = Math.max(width, lineWidth) + getPaddingLeft() + getPaddingRight();
  height += lineHeight;
  sizeHeight += getPaddingTop() + getPaddingBottom();
  height += getPaddingTop() + getPaddingBottom();
  setMeasuredDimension((modeWidth == MeasureSpec.EXACTLY) ? sizeWidth : width, (modeHeight == MeasureSpec.EXACTLY) ? sizeHeight : height);
 }
 @Override
 protected void onLayout(boolean changed, int l, int t, int r, int b) {
  int count = getChildCount();
  for (int i = 0; i < count; i++) {
   View child = getChildAt(i);
   if (child.getVisibility() == GONE)
    continue;
   Location location = (Location) child.getTag();
   child.layout(location.left, location.top, location.right, location.bottom);
  }
 }
 /**
  * 记录子控件的坐标
  */
 public class Location {
  public Location(int left, int top, int right, int bottom) {
   this.left = left;
   this.top = top;
   this.right = right;
   this.bottom = bottom;
  }
  public int left;
  public int top;
  public int right;
  public int bottom;
 }
}

总结：
至此有关简单的自定义控件已经介绍的差不多了，项目中很复杂的控件现在涉及的比较少，以后用到之后再做记录。

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标签云标签 Android

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