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

Android自定义控件ViewGroup实现标签云(四)_第1张图片 

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

 
  
  
 

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 




 



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

 Android自定义控件ViewGroup实现标签云(四)_第2张图片

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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