自定义可设置每行最多显示数目，每个子View宽度等分的FlowView
// 存储所有子View
private List<List<View>> mAllChildViews = new ArrayList<List<View>>();
// 每一行的高度
private List<Integer> mLineHeight = new ArrayList<Integer>();
// 最多的列数 默认设置为4，可以自己另行设置
private int lineMaxColumn = 4;
public FlowView(Context context) {
this(context, null);
}
public FlowView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public FlowView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}设置最大的列数，最大列数的取值范围为大于1
public void setLineMaxColumn(int count) {
if (count < 1) {
this.lineMaxColumn = 1;
} else {
this.lineMaxColumn = count;
}
}首先得到其父容器传入的测量模式和宽高的计算值，然后遍历所有的childView，使用measureChild方法对所有的childView进行测量。然后根据所有childView的测量得出的宽和高得到该ViewGroup如果设置为wrap_content时的宽和高。最后根据模式，如果是MeasureSpec.EXACTLY则直接使用父ViewGroup传入的宽和高，否则设置为自己计算的宽和高。
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
// 父控件传进来的宽度和高度以及对应的测量模式
int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
int modeHeight = MeasureSpec.getMode(heightMeasureSpec);
// 如果当前ViewGroup的宽高为wrap_content的情况
int width = getPaddingLeft() + getPaddingRight();// 自己测量的 宽度
int height = getPaddingTop() + getPaddingBottom();// 自己测量的高度
// 记录每一行的宽度和高度
int lineWidth = 0;
int lineHeight = 0;
// 每行中的View的个数
int lineViewCount = 0;
// 每行中View的宽度的最大值
int lineViewMaxWidth = 0;
// 获取子view的个数
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
boolean lastChild = i == childCount - 1;
// 不占控件的View跳过
if (child.getVisibility() == View.GONE) {
if (lastChild) {
width = Math.max(width, lineWidth);
height += lineHeight;
}
continue;
}
// 测量子View的宽和高
measureChild(child, widthMeasureSpec, heightMeasureSpec);
MarginLayoutParams lp = (MarginLayoutParams) child
.getLayoutParams();
int childWidthMode = MeasureSpec.AT_MOST;
// 子View占据的宽度
int childWidthSize = child.getMeasuredWidth();
int childHeightMode = MeasureSpec.AT_MOST;
// 子View占据的高度
int childHeightSize = child.getMeasuredHeight();
if (lp.height >= 0) {
childHeightMode = MeasureSpec.EXACTLY;
// childHeightSize = lp.height;
} else if (modeHeight == MeasureSpec.UNSPECIFIED) {
childHeightMode = MeasureSpec.UNSPECIFIED;
childHeightSize = 0;
}
// 测量子View的宽和高
child.measure(MeasureSpec.makeMeasureSpec(childWidthSize,
childWidthMode), MeasureSpec.makeMeasureSpec(
childHeightSize, childHeightMode));
int childWidth = child.getMeasuredWidth() + lp.leftMargin
+ lp.rightMargin;
lineViewMaxWidth = lineViewMaxWidth == 0 ? childWidth : Math.max(
lineViewMaxWidth, childWidth);
// 换行时候
if (lineWidth + childWidth > sizeWidth
|| (lineMaxColumn > 0 && lineViewCount >= lineMaxColumn)
|| (!checkAddCurLineViews(sizeWidth, lineViewMaxWidth,
lineViewCount))) {
// 对比得到最大的宽度
width = Math.max(width, lineWidth);
// 重置lineWidth
lineWidth = childWidth;
// 记录行高
height += lineHeight;
lineHeight = child.getMeasuredHeight() + lp.topMargin
+ lp.bottomMargin;
lineViewCount = 1;
lineViewMaxWidth = childWidth;
} else {// 不换行情况
// 叠加行宽
lineWidth += childWidth;
// 得到最大行高
lineHeight = Math.max(lineHeight, child.getMeasuredHeight()
+ lp.topMargin + lp.bottomMargin);
lineViewCount++;
}
// 处理最后一个子View的情况
if (lastChild) {
width = Math.max(width, lineWidth);
height += lineHeight;
}
}
// wrap_content
width += getPaddingLeft() + getPaddingRight();
setMeasuredDimension((modeWidth == MeasureSpec.EXACTLY) ? sizeWidth
: width, (modeHeight == MeasureSpec.EXACTLY) ? sizeHeight
: height);
// 显示的大小
}重新计算当前行中所有的View的宽度，宽度为所有View平分当前的FlowView的宽度
private void reMeasureLineViews(List<View> lineViews) {
// 当前行的View的个数
int count = lineViews.size();
if (count == 0) {
return;
}
// 当前行中每个View占用的宽度
int itemWidth = (this.getMeasuredWidth() - this.getLeftPaddingOffset() - this
.getRightPaddingOffset()) / count;
for (int i = 0; i < count; i++) {
View child = lineViews.get(i);
MarginLayoutParams lp = (MarginLayoutParams) child
.getLayoutParams();
int childWidthSize = itemWidth - lp.leftMargin - lp.rightMargin;
int childHeightSize = child.getMeasuredHeight();
child.measure(MeasureSpec.makeMeasureSpec(childWidthSize,
MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(
childHeightSize, MeasureSpec.EXACTLY));
}
}重新测量最后一行
onLayout中完成对所有childView的位置以及大小的指定
private void reMeasureLineViews(List<View> lineViews, int prveLineViewCount) {
// 当前行的View的个数
int count = lineViews.size();
if (count == 0) {
return;
}
// 只有一行时，设置上一行的个数为最大个数
prveLineViewCount = prveLineViewCount == 0 ? lineMaxColumn
: prveLineViewCount;
// 如果当前行中View的个数大于等于上一行中View的个数时，所有View的宽度为总宽度的平均值
if (prveLineViewCount <= count) {
reMeasureLineViews(lineViews);
return;
}
// 上一行中View的个数为基数并且当前行中View的个数大于上一行中View的个数的一半时，所有View的宽度为总宽度的平均值
else if (prveLineViewCount % 2 == 1
&& count > (int) (prveLineViewCount * 1.0 / 2)) {
reMeasureLineViews(lineViews);
return;
}
// 上一行中每个View占用的宽度
int prveItemWidth = (this.getMeasuredWidth()
- this.getLeftPaddingOffset() - this.getRightPaddingOffset())
/ prveLineViewCount;
// 当前行中的最大宽度
int lineViewMaxWidth = 0;
for (int i = 0; i < count; i++) {
View child = lineViews.get(i);
MarginLayoutParams lp = (MarginLayoutParams) child
.getLayoutParams();
lineViewMaxWidth = Math.max(lineViewMaxWidth,
child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin);
}
// 如果当前行中View的最大宽度大于上一行的平均值时，当前行中每个View的宽度为上一行平均值的2倍，否则为上一行的平均值。
int itemWidth = prveItemWidth;
if (prveItemWidth < lineViewMaxWidth) {
if (prveLineViewCount % 2 == 0
|| count > (int) (prveLineViewCount * 1.0 / 2)) {
reMeasureLineViews(lineViews);
return;
}
itemWidth = 2 * prveItemWidth;
}
for (int i = 0; i < count; i++) {
View child = lineViews.get(i);
MarginLayoutParams lp = (MarginLayoutParams) child
.getLayoutParams();
int childWidthSize = itemWidth - lp.leftMargin - lp.rightMargin;
int childHeightSize = child.getMeasuredHeight();
child.measure(MeasureSpec.makeMeasureSpec(childWidthSize,
MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(
childHeightSize, MeasureSpec.EXACTLY));
}
}检查是否能够添加到当前行中
private boolean checkAddCurLineViews(int totalWidth, int maxWidth,
int curCount) {
if (totalWidth / (curCount + 1) > maxWidth) {
return true;
}
return false;
}
@SuppressLint("DrawAllocation")
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
mAllChildViews.clear();
mLineHeight.clear();
// 获取当前ViewGroup的宽度
int width = getWidth();
int lineWidth = 0;
int lineHeight = 0;
//
int lineItemMaxWidth = 0;
//
int prevLineViewCount = 0;
// 记录当前行的view
List<View> lineViews = new ArrayList<View>();
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
boolean lastChild = i == childCount - 1;
MarginLayoutParams lp = (MarginLayoutParams) child
.getLayoutParams();
int childWidth = child.getMeasuredWidth();
int childHeight = child.getMeasuredHeight();
// 如果需要换行
if ((lineViews.size() != 0 && childWidth + lineWidth
+ lp.leftMargin + lp.rightMargin > width)
|| (lineMaxColumn > 0 && lineViews.size() >= lineMaxColumn)) {
mAllChildViews.add(lineViews);
// 记录LineHeight
mLineHeight.add(lineHeight);
// 记录当前行的Views
reMeasureLineViews(lineViews);
prevLineViewCount = lineViews.size();
// 重置行的宽高
lineWidth = 0;
lineHeight = childHeight + lp.topMargin + lp.bottomMargin;
// 重置view的集合
lineViews = new ArrayList<View>();
lineItemMaxWidth = 0;
}
lineItemMaxWidth = lineItemMaxWidth == 0 ? childWidth
+ lp.leftMargin + lp.rightMargin : Math.max(
lineItemMaxWidth, childWidth + lp.leftMargin
+ lp.rightMargin);
if (!checkAddCurLineViews(width, lineItemMaxWidth, lineViews.size())) {
if (lineViews.size() != 0) {
mAllChildViews.add(lineViews);
}
// 记录LineHeight
mLineHeight.add(lineHeight);
// 记录当前行的Views
reMeasureLineViews(lineViews);
prevLineViewCount = lineViews.size();
// 重置行的宽高
lineWidth = 0;
lineHeight = childHeight + lp.topMargin + lp.bottomMargin;
// 重置view的集合
lineViews = new ArrayList<View>();
lineItemMaxWidth = childWidth + lp.leftMargin + lp.rightMargin;
}
lineWidth += childWidth + lp.leftMargin + lp.rightMargin;
lineHeight = Math.max(lineHeight, childHeight + lp.topMargin
+ lp.bottomMargin);
lineViews.add(child);
if (lastChild) {
// 处理最后一行
mLineHeight.add(lineHeight);
mAllChildViews.add(lineViews);
// 记录当前行的Views
reMeasureLineViews(lineViews, prevLineViewCount);
}
}
// 设置子View的位置
int left = 0;
int top = 0;
// 获取行数
int lineCount = mAllChildViews.size();
for (int i = 0; i < lineCount; i++) {
// 当前行的views和高度
lineViews = mAllChildViews.get(i);
lineHeight = mLineHeight.get(i);
for (int j = 0; j < lineViews.size(); j++) {
View child = lineViews.get(j);
// 判断是否显示
if (child.getVisibility() == View.GONE) {
continue;
}
MarginLayoutParams lp = (MarginLayoutParams) child
.getLayoutParams();
int cLeft = left + lp.leftMargin;
int cTop = top + lp.topMargin;
int cRight = cLeft + child.getMeasuredWidth();
int cBottom = cTop + child.getMeasuredHeight();
// 进行子View进行布局
child.layout(cLeft, cTop, cRight, cBottom);
left += child.getMeasuredWidth() + lp.leftMargin
+ lp.rightMargin;
}
left = 0;
top += lineHeight;
}
}与当前ViewGroup对应的LayoutParams
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs) {
return new MarginLayoutParams(getContext(), attrs);
}完整代码下载地址