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

<"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。