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这里所说的FlowLayout组件是来自鸿洋提供的一个流式布局的框架
框架源码看这里
框架作者博客介绍看这里
废话不多说,直接上代码,主要就是修改FlowLayout的onMeasure和onLayout方法,同时我这里还对onLayout方法优化了一下,减少了一次for循环处理行view,行高,行宽等信息
public class FlowLayout extends ViewGroup {
private static final String TAG = "FlowLayout";
protected static final int LEFT = -1;
protected static final int CENTER = 0;
protected static final int RIGHT = 1;
protected List<List<View>> mAllViews = new ArrayList<List<View>>();//记录所有行
protected List<Integer> mLineHeight = new ArrayList<Integer>();//记录所有行高
protected List<Integer> mLineWidth = new ArrayList<Integer>();//记录所有行宽
protected List<View> lineViews = new ArrayList<>();//临时记录每行的view
protected int mGravity;
private int maxLine = -1;//最大行数
public void setMaxLine(int maxLine) {
this.maxLine = maxLine;
}
public FlowLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.TagFlowLayout);
mGravity = ta.getInt(R.styleable.TagFlowLayout_tag_gravity, LEFT);
int layoutDirection = TextUtilsCompat.getLayoutDirectionFromLocale(Locale.getDefault());
if (layoutDirection == LayoutDirection.RTL) {
if (mGravity == LEFT) {
mGravity = RIGHT;
} else {
mGravity = LEFT;
}
}
ta.recycle();
}
public FlowLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public FlowLayout(Context context) {
this(context, null);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
mAllViews.clear();//记录所有行的view
mLineHeight.clear();//记录每一行的高度
mLineWidth.clear();//记录每一行的宽度
lineViews.clear();//记录每一行的view
int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
int modeHeight = MeasureSpec.getMode(heightMeasureSpec);
// wrap_content 最终宽高
int width = 0;
int height = 0;
//当前已用行宽高
int lineWidth = 0;
int lineHeight = 0;
int cCount = getChildCount();
for (int i = 0; i < cCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() == View.GONE) {
continue;
}
//测量子view
measureChild(child, widthMeasureSpec, heightMeasureSpec);
MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
//子View宽高
int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;
if (lineWidth + childWidth > sizeWidth - getPaddingLeft() - getPaddingRight()) {
if (maxLine > 0 && mAllViews.size() + 1 >= maxLine) { //+1是因为后面还有最后一行
break;//超过最大行数跳出循环
}
//需要换行
width = Math.max(width, lineWidth);//记录最大行宽
height += lineHeight;//累加包裹内容所需的高度
//换行,保存上一行数据
mLineHeight.add(lineHeight);
mLineWidth.add(lineWidth);
mAllViews.add(lineViews);
//重置新行变量
lineWidth = 0;//重新赋值行宽
lineHeight = 0;//重新赋值行高
lineViews = new ArrayList<View>();
}
//记录当前行数据
lineWidth += childWidth;//累加行宽
lineHeight = Math.max(lineHeight, childHeight);//取当前行最大高度作为行高
lineViews.add(child);
}
//添加最后一行数据
//包裹内容所需的最大宽度
width = Math.max(lineWidth, width);
height += lineHeight;
mLineHeight.add(lineHeight);
mLineWidth.add(lineWidth);
mAllViews.add(lineViews);
setMeasuredDimension(
//父控件宽高确定则用确定的,否则用测量后的
modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width + getPaddingLeft() + getPaddingRight(),
modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height + getPaddingTop() + getPaddingBottom()//
);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
//总宽
int width = getWidth();
//当前已用行宽高
int lineHeight = 0;
//下面是对每一行的View进行布局
int left = getPaddingLeft();
int top = getPaddingTop();
int lineNum = mAllViews.size();
for (int i = 0; i < lineNum; i++) {
//获取当前行和行高
lineViews = mAllViews.get(i);
lineHeight = mLineHeight.get(i);
// set gravity
int currentLineWidth = this.mLineWidth.get(i);
switch (this.mGravity) {
case LEFT:
left = getPaddingLeft();
break;
case CENTER:
left = (width - currentLineWidth) / 2 + getPaddingLeft();
break;
case RIGHT:
// 适配了rtl，需要补偿一个padding值 ,从右边向左开始布局
left = width - (currentLineWidth + getPaddingLeft()) - getPaddingRight();
// 适配了rtl，需要把lineViews里面的数组倒序排,从右边开始存放view
Collections.reverse(lineViews);
break;
}
//开始一行行地布局子view
for (int j = 0; j < lineViews.size(); j++) {
View child = lineViews.get(j);
if (child.getVisibility() == View.GONE) {
continue;
}
MarginLayoutParams lp = (MarginLayoutParams) child
.getLayoutParams();
int lc = left + lp.leftMargin;
int tc = top + lp.topMargin;
int rc = lc + child.getMeasuredWidth();
int bc = tc + child.getMeasuredHeight();
child.layout(lc, tc, rc, bc);
//更新下一个view添加到当前行的left
left += child.getMeasuredWidth() + lp.leftMargin
+ lp.rightMargin;
}
//更新下一个view添加到下一行的top
top += lineHeight;
}
}
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs) {
return new MarginLayoutParams(getContext(), attrs);
}
@Override
protected LayoutParams generateDefaultLayoutParams() {
return new MarginLayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
}
@Override
protected LayoutParams generateLayoutParams(LayoutParams p) {
return new MarginLayoutParams(p);
}
/**
* 获取指定行数内的item个数
*
* @return 每行的个数之和
* @lineNum 总行数
*/
public int getTotalByLine(int lineNum) {
int count = 0;
if (lineNum <= mAllViews.size()) {
for (int i = 0; i < lineNum; i++) {
List<View> line = mAllViews.get(i);
count += line.size();
}
}
return count;
}
}