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。