Android自定义控件ViewGroup实现标签云（四）

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。