package com.fuban.user.views;
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import android.content.Context;
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import android.util.AttributeSet;
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import android.view.View;
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import android.view.ViewGroup;
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import com.fuban.user.views.textbanner.utils.DisplayUtils;
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import java.util.ArrayList;
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import java.util.List;
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public class CenterFlowLayout extends ViewGroup {
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//默认item的spacing
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private static final int DEFAULT_CHILD_SPACING = 0;
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//默认item的topMargin值
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private static final int DEFAULT_ROW_SPACING = 0;
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//子View之间的间距
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private int mChildSpacing = DEFAULT_CHILD_SPACING;
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//子View的marginTop值
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private int mRowSpacing = DEFAULT_ROW_SPACING;
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//用来存储每行item所占用的宽度的总和
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private List<Integer> itemLineWidth = new ArrayList<>();
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//用来存储每行item的个数
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private List<Integer> itemLineNum = new ArrayList<>();
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//用来记录item所占用的总行数
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private int mRowTotalCount = 0;
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public CenterFlowLayout(Context context) {
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this(context, null);
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}
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public CenterFlowLayout(Context context, AttributeSet attrs) {
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this(context, attrs, 0);
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}
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public CenterFlowLayout(Context context, AttributeSet attrs, int defStyleAttr) {
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super(context, attrs, defStyleAttr);
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mChildSpacing = DisplayUtils.dip2px(context,8);
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mRowSpacing = DisplayUtils.dip2px(context,12);
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}
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@Override
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protected void onLayout(boolean changed, int l, int t, int r, int b) {
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//获取父View的paddingLeft值
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int childLeft = getPaddingLeft();
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//获取父View的paddingTop值
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int childTop = getPaddingTop();
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//获取去除paddingRight之后的宽度
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int childRight = getMeasuredWidth() - getPaddingRight();
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//获取实际子View可用的宽度
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int availableWidth = childRight - childLeft;
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//子View初始时left值
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int curLeft;
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//子View初始时的top值
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int curTop = childTop;
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//单行中最大子View的高度
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int maxHeight = 0;
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//子View的高度
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int childHeight;
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//子View宽度
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int childWidth;
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//父View中子View的index
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int childIndex = 0;
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for (int j = 0; j < mRowTotalCount; j++) {
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//获取单行中子View的个数
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Integer childNum = itemLineNum.get(j);
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//初始化子View的left值
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curLeft = childLeft + (availableWidth - itemLineWidth.get(j)) / 2;
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//竖直方向上的margin值
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int verticalMargin = 0;
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for (int i = 0; i < childNum; i++) {
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//获取ViewGroup中的子View
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View child = getChildAt(childIndex++);
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//跳过可见性为GONE的子View
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if (child.getVisibility() == View.GONE) {
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continue;
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}
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//获取子View的宽度
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childWidth = child.getMeasuredWidth();
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//获取子View的高度
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childHeight = child.getMeasuredHeight();
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//获取子View的LayoutParams
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MarginLayoutParams params = (CenterLayoutParams) child.getLayoutParams();
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int marginRight = 0, marginTop = 0, marginBottom;
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if (params instanceof MarginLayoutParams) {
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//获取子View的marginRight值
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marginRight = params.rightMargin;
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//获取子View的marginTop值
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marginTop = params.topMargin;
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//获取子View的marginBottom值
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marginBottom = params.bottomMargin;
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//获取子View上下间距的和
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if (childNum > 1 && i == 0) {
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verticalMargin = marginTop + marginBottom;
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}
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}
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//对子View进行布局
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child.layout(curLeft, curTop, curLeft + childWidth, curTop + childHeight);
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//找到单行中子View的最高高度
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if (maxHeight < childHeight) {
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maxHeight = childHeight;
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}
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//叠加left值，向右一次排列
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curLeft += childWidth + mChildSpacing + marginRight;
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}
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//换行时的高度
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curTop += maxHeight + mRowSpacing + verticalMargin;
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//最大高度重置
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maxHeight = 0;
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}
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}
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@Override
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protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
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super.onMeasure(widthMeasureSpec, heightMeasureSpec);
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//将属性值重置
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itemLineNum.clear();
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itemLineWidth.clear();
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mRowTotalCount = 0;
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//获取ViewGroup的宽度
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int widthSize = MeasureSpec.getSize(widthMeasureSpec);
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//获取ViewGroup的宽度mode
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int widthMode = MeasureSpec.getMode(widthMeasureSpec);
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//获取ViewGroup的高度
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int heightSize = MeasureSpec.getSize(heightMeasureSpec);
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//获取ViewGroup的高度mode
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int heightMode = MeasureSpec.getMode(heightMeasureSpec);
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//获取ViewGroup的可用宽度
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int rowLength = widthSize - getPaddingLeft() - getPaddingRight();
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//测量的宽度
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int measuredWidth = 0;
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//测量的高度
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int measuredHeight = 0;
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//子View最大的宽度
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int maxWidth = 0;
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//子View最大的高度
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int maxHeight = 0;
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//子View的总行数
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int rowCount = 0;
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//子View的个数
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int childCount = getChildCount();
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//单行子View的宽度
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int rowWidth = 0;
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//子View宽度
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int childWidth;
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//子View高度
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int childHeight;
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//单行中子View的个数
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int childNumInRow = 0;
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//最后一行第一个子View的index
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int tempIndex = 0;
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//除最后一行外，其他单行中子View的总和
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int exceptLastRowNum = 0;
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for (int i = 0; i < childCount; i++) {
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View child = getChildAt(i);
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if (child.getVisibility() == View.GONE) {
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continue;
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}
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CenterLayoutParams params = (CenterLayoutParams) child.getLayoutParams();
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int marginRight = 0, marginTop = 0, marginBottom = 0;
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if (params instanceof MarginLayoutParams) {
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measureChildWithMargins(child, widthMeasureSpec, 0, heightMeasureSpec, measuredHeight);
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marginRight = params.rightMargin;
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marginTop = params.topMargin;
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marginBottom = params.bottomMargin;
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} else {
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measureChild(child, widthMeasureSpec, heightMeasureSpec);
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}
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//子View本身的宽度+子View之间的间距+子View的marginRight值（我这么写偷懒了，mChildSpacing和marginRight不用同时设置值）
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childWidth = child.getMeasuredWidth() + mChildSpacing + marginRight;
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//子View本身的高度+子View的marginTop值+子View的marginBottom+marginTop值（我这么写偷懒了，mRowSpacing和marginBottom + marginTop不用同时设置值）
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childHeight = child.getMeasuredHeight() + mRowSpacing + marginBottom + marginTop;
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//叠加子View的宽度
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rowWidth += childWidth;
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//取出最大的宽度
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maxWidth += Math.max(maxWidth, childWidth);
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//判断是否需要换行
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if (measuredWidth + childWidth > rowLength) {
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//循环后，就可获取，最后一行中第一个子View的index
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tempIndex = i;
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//获取单行的宽度
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rowWidth = rowWidth - childWidth - mChildSpacing - marginRight;
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//存储单行的宽度
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itemLineWidth.add(rowWidth);
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//设置下一行宽度为第一个子View的宽度
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rowWidth = childWidth;
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//行数自增
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++rowCount;
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//保存测量的宽度
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measuredWidth = childWidth;
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//叠加子View的高度
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maxHeight += childHeight;
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//存储单行中子View的个数
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itemLineNum.add(childNumInRow);
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//叠加获取除了最后一行外，其他行子View的个数的总和
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exceptLastRowNum += childNumInRow;
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//重置子View的个数，因为已经要换行了
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childNumInRow = 1;
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} else {
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//叠加宽度
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measuredWidth += childWidth;
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//叠加单行中的子View个数
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++childNumInRow;
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//计算出最大的高度
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maxHeight = Math.max(maxHeight, childHeight);
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}
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}
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//最后一行的宽度
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int lastRowWidth = 0;
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int singleHorizalMargin = 0;
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for (int i = tempIndex; i < childCount; i++) {
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View child = getChildAt(i);
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int horizalMargin = 0;
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CenterLayoutParams params = (CenterLayoutParams) child.getLayoutParams();
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if (params instanceof MarginLayoutParams) {
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//获取子View的marginRight
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singleHorizalMargin = horizalMargin = params.rightMargin;
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}
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//叠加最后一行中所有子View的宽度
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lastRowWidth += child.getMeasuredWidth() + mChildSpacing + horizalMargin;
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}
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//获取最后一行子View的个数
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int lastChildCount = childCount - exceptLastRowNum;
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//减去多余的marginRight或mChildSpacing，得到最终的宽度
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lastRowWidth -= mChildSpacing == 0 ? singleHorizalMargin : mChildSpacing;
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//保存最后一行的宽度值
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itemLineWidth.add(lastRowWidth);
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//保存最后一行子View的个数
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itemLineNum.add(lastChildCount);
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//子View的总行数
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mRowTotalCount = rowCount + 1;
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//子View的最大宽度+ViewGroup中的paddingLeft和paddingRight值
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maxWidth = Math.max(maxWidth, getSuggestedMinimumWidth()) + getPaddingRight() + getPaddingLeft();
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//子View的最大高度+ViewGroup中的paddingTop和paddingBottom值
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maxHeight = Math.max(maxHeight, getSuggestedMinimumHeight()) + getPaddingTop() + getPaddingBottom();
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//根据widthMode设置width值
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measuredWidth=widthMode==MeasureSpec.EXACTLY?widthSize:maxWidth;
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//根据heightMode设置height值
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measuredHeight=heightMode==MeasureSpec.EXACTLY?heightSize:maxHeight;
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//设置ViewGroup的宽高
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setMeasuredDimension(resolveSize(measuredWidth, widthMeasureSpec),
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resolveSize(measuredHeight, heightMeasureSpec));
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}
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/**
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* 设置子View的间距
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* @param childSpacing
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*/
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public void setChildSpacing(int childSpacing){
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mChildSpacing=childSpacing;
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requestLayout();
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}
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/**
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* 设置子View的marginTop值
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* @param rowSpacing
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*/
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public void setRowSpacing(int rowSpacing){
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mRowSpacing=rowSpacing;
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requestLayout();
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}
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@Override
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protected LayoutParams generateLayoutParams(LayoutParams p) {
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return new CenterLayoutParams(p);
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}
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@Override
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public LayoutParams generateLayoutParams(AttributeSet attrs) {
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return new CenterLayoutParams(getContext(), attrs);
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}
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/**
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* @param p
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* @return
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*/
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@Override
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protected boolean checkLayoutParams(LayoutParams p) {
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return p instanceof CenterLayoutParams;
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}
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/**
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* 因为需要获取子View的margin值，所以这里需要重写一下该方法
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*/
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public static class CenterLayoutParams extends MarginLayoutParams {
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public CenterLayoutParams(MarginLayoutParams source) {
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super(source);
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}
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public CenterLayoutParams(LayoutParams source) {
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super(source);
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}
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public CenterLayoutParams(Context c, AttributeSet attrs) {
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super(c, attrs);
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}
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public CenterLayoutParams(int width, int height) {
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super(width, height);
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}
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}
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}
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