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。