直接上效果图
image.png
需求，自定义一个view,一个属性两个参数值，SPREAD代表平均水平分配，并且居中；SPREAD_INSIDE代表优先最左和最右优先分配，其余平均分配，保持居中
直接上手：
1、继承FrameLayout(这个继承没啥要求，看自己个人爱好)，然后关键点就是在于onMeasure()方法和onLayout（）方法
2、在onMeasure()中获取父布局的宽度和高度，并且获取子view的最大宽度和高度，此两个参数于居中处理将会用到
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
viewWidth = this.getMeasuredWidth();
viewHeight = this.getMeasuredWidth();
for (int i = 0;i < getChildCount();i++){
maxChildHeight = Math.max(maxChildHeight,getChildAt(i).getMeasuredHeight());
maxChildWidth = Math.max(maxChildWidth,getChildAt(i).getMeasuredWidth());
}
}
3、在onlayout中重写写子view的布局
在子view数组里面进行逐一布局，并且必要时重新绘制子view,我这边觉得没必要，就全部重写绘制子view了，如果有洁癖的可以通过高度和宽度来判断处理。
SPREAD时：
先获取平均分割的子view的宽度
int childWidth = (right-left) / count;
然后进行布局设置
child.layout(leftNumber, topNumber, leftNumber+childWidth, maxChildHeight-topNumber);
内容的居中处理就是通过判断当前子view的高度是否是小于最高的子view高度，是的话则进行相减除半，sha
最后上源码：
/**
* Created by caisongliang on 2019/7/23 17:52
*/
public class ChainLayout extends LinearLayout {
public static final int SPREAD = 0;//平均分配居中
public static final int SPREAD_INSIDE = 1;//左右优先分配，中间居中
public static final int HORIZONTAL = 0;
public static final int VERTICAL = 1;
private int viewWidth = 0;
private int viewHeight = 0;
private int count = 0;
private int maxChildHeight = 0;//子view最大高度
private int maxChildWidth = 0;//子view最大宽度
private int type = SPREAD;
private int orientation = 0;//布局方向
@Override
public int getOrientation() {
return orientation;
}
@Override
public void setOrientation(int orientation) {
this.orientation = orientation;
}
public ChainLayout(@NonNull Context context) {
super(context);
initView(null);
}
public ChainLayout(@NonNull Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
initView(attrs);
}
public ChainLayout(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initView(attrs);
}
private void initView(AttributeSet attrs) {
TypedArray typedArray = getContext().obtainStyledAttributes(attrs, R.styleable.ChainLayout);
type = typedArray.getInteger(R.styleable.ChainLayout_type,SPREAD);
typedArray.recycle();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
viewWidth = this.getMeasuredWidth();
viewHeight = this.getMeasuredWidth();
for (int i = 0;i < getChildCount();i++){
maxChildHeight = Math.max(maxChildHeight,getChildAt(i).getMeasuredHeight());
maxChildWidth = Math.max(maxChildWidth,getChildAt(i).getMeasuredWidth());
}
}
public int getType() {
return type;
}
public void setType(int type) {
this.type = type;
}
public int getViewWidth() {
return viewWidth;
}
public void setViewWidth(int viewWidth) {
this.viewWidth = viewWidth;
}
public int getViewHeight() {
return viewHeight;
}
public void setViewHeight(int viewHeight) {
this.viewHeight = viewHeight;
}
@Override
protected void onFinishInflate() {
super.onFinishInflate();
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
int count = getChildCount();
int leftNumber = 0;
if (type == SPREAD){
for (int i = 0;i < count;i++){
View child = getChildAt(i);
int childHeight = child.getMeasuredHeight();
int childWidth = (right-left) / count;
int topOffset = 0 ;//上偏移数
int lefOffset = 0 ;//左偏移数
if (childHeight < maxChildHeight){
topOffset = (maxChildHeight-childHeight)/2;
}
if (child.getMeasuredWidth() < childWidth){
lefOffset = (childWidth - child.getMeasuredWidth())/2;
}
child.layout(leftNumber+lefOffset, topOffset, leftNumber+childWidth-lefOffset, maxChildHeight-topOffset);
leftNumber += childWidth;
}
}else if (type == SPREAD_INSIDE){
int centreChildWidth = 0;//中间部分的总有效宽度
for (int j = 1;j < count -1;j++){
centreChildWidth += getChildAt(j).getMeasuredWidth();
}
for (int i = 0;i < count;i++){
View child = getChildAt(i);
int childHeight = child.getMeasuredHeight();
int childWidth = child.getMeasuredWidth();
int topOffset = 0 ;//上偏移数
int lefOffset = 0 ;//左偏移数
int startViewWidth = getChildAt(0).getMeasuredWidth();
int endViewWidth = getChildAt(count-1).getMeasuredWidth();
if (childHeight < maxChildHeight){
topOffset = (maxChildHeight-childHeight)/2;
}
if (centreChildWidth < (viewWidth - startViewWidth - endViewWidth)){
lefOffset = ((viewWidth - startViewWidth - endViewWidth)-centreChildWidth)/(2*(count-2)+2);
}
if (i == 0){
child.measure(makeMeasureSpec(childWidth, EXACTLY),
makeMeasureSpec(childHeight, EXACTLY));
child.layout(leftNumber, topOffset, leftNumber+childWidth, maxChildHeight-topOffset);
leftNumber += childWidth+lefOffset;
}else {
if (count-1 == i){
leftNumber += lefOffset;
child.measure(makeMeasureSpec(endViewWidth, EXACTLY),
makeMeasureSpec(childHeight, EXACTLY));
child.layout(leftNumber, topOffset,viewWidth, maxChildHeight-topOffset);
}else {
startViewWidth = getChildAt(0).getMeasuredWidth();
endViewWidth = getChildAt(count-1).getMeasuredWidth();
childWidth = child.getMeasuredWidth()+lefOffset*2;
if (count-1 == i){
leftNumber+=lefOffset;
child.measure(makeMeasureSpec(endViewWidth, EXACTLY),
makeMeasureSpec(childHeight, EXACTLY));
child.layout(leftNumber, topOffset,viewWidth, maxChildHeight-topOffset);
}else {
child.layout(leftNumber+lefOffset, topOffset, leftNumber+childWidth-lefOffset, maxChildHeight-topOffset);
}
}
leftNumber += childWidth;
}
}
}else {
super.onLayout(changed, left, top, right, bottom);
}
}
}
自定义属性，自己新建一个chain_attrs.xml
<?xml version="1.0" encoding="UTF-8"?>
<resources>
<declare-styleable name="ChainLayout">
<attr name="type" format="enum" >
<enum name="spread" value="0"/>
<enum name="spread_inside" value="1"/>
</attr>
</declare-styleable>
</resources>
然后使用就是和线性布局一样使用就可以了
