最终效果图
image
- FlowLayout自定义控件
自定义view继承ViewGroup,重写onMeasure（），onLayout（）方法。可根据子元素宽度动态测量宽高
public class FlowLayout extends ViewGroup {
public FlowLayout(Context context) {
super(context);
}
public FlowLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
public FlowLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// super.onMeasure(widthMeasureSpec, heightMeasureSpec);
//遍历去调用所有子元素的measure方法（child.getMeasuredHeight()才能获取到值，否则为0）
measureChildren(widthMeasureSpec, heightMeasureSpec);
int measuredWidth = 0, measuredHeight = 0;
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int widtMode = MeasureSpec.getMode(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
//由于计算子view所占宽度，这里传值需要自身减去PaddingRight宽度，PaddingLeft会在接下来计算子元素位置时加上
Map<String, Integer> compute = compute(widthSize-getPaddingRight());
//EXACTLY模式：对应于给定大小或者match_parent情况
if (widtMode == MeasureSpec.EXACTLY) {
measuredWidth = widthSize;
//AT_MOS模式：对应wrap-content（需要手动计算大小，否则相当于match_parent）
} else if (widtMode == MeasureSpec.AT_MOST) {
measuredWidth = compute.get("allChildWidth");
}
if (heightMode == MeasureSpec.EXACTLY) {
measuredHeight = heightSize;
} else if (heightMode == MeasureSpec.AT_MOST) {
measuredHeight = compute.get("allChildHeight");
}
//设置flow的宽高
setMeasuredDimension(measuredWidth,measuredHeight);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
for (int i = 0; i < getChildCount(); i++) {
View child = getChildAt(i);
Rect rect = (Rect) getChildAt(i).getTag();
child.layout(rect.left,rect.top,rect.right,rect.bottom);
}
}
/**
* 测量过程
* @param flowWidth 该view的宽度
* @return 返回子元素总所占宽度和高度（用于计算Flowlayout的AT_MOST模式设置宽高）
*/
private Map<String, Integer> compute(int flowWidth) {
//是否是单行
boolean aRow = true;
MarginLayoutParams marginParams;//子元素margin
int rowsWidth = getPaddingLeft();//当前行已占宽度(注意需要加上paddingLeft)
int columnHeight =getPaddingTop();//当前行顶部已占高度(注意需要加上paddingTop)
int rowsMaxHeight = 0;//当前行所有子元素的最大高度（用于换行累加高度）
for (int i = 0; i < getChildCount(); i++) {
View child = getChildAt(i);
//获取元素测量宽度和高度
int measuredWidth = child.getMeasuredWidth();
int measuredHeight = child.getMeasuredHeight();
//获取元素的margin
marginParams = (MarginLayoutParams) child.getLayoutParams();
//子元素所占宽度 = MarginLeft+ child.getMeasuredWidth+MarginRight 注意此时不能child.getWidth,因为界面没有绘制完成，此时wdith为0
int childWidth = marginParams.leftMargin + marginParams.rightMargin + measuredWidth;
int childHeight = marginParams.topMargin + marginParams.bottomMargin + measuredHeight;
//判断是否换行： 该行已占大小+该元素大小>父容器宽度 则换行
rowsMaxHeight = Math.max(rowsMaxHeight, childHeight);
//换行
if (rowsWidth + childWidth > flowWidth) {
//重置行宽度
rowsWidth = getPaddingLeft()+getPaddingRight();
//累加上该行子元素最大高度
columnHeight += rowsMaxHeight;
//重置该行最大高度
rowsMaxHeight = childHeight;
aRow = false;
}
//累加上该行子元素宽度
rowsWidth += childWidth;
//判断时占的宽段时加上margin计算，设置顶点位置时不包括margin位置，不然margin会不起作用，这是给View设置tag,在onlayout给子元素设置位置再遍历取出
child.setTag(new Rect(rowsWidth - childWidth + marginParams.leftMargin, columnHeight + marginParams.topMargin, rowsWidth - marginParams.rightMargin, columnHeight + childHeight - marginParams.bottomMargin));
}
//返回子元素总所占宽度和高度（用于计算Flowlayout的AT_MOST模式设置宽高）
Map<String, Integer> flowMap = new HashMap<>();
//单行
if (aRow) {
flowMap.put("allChildWidth", rowsWidth);
} else {
//多行
flowMap.put("allChildWidth", flowWidth);
}
//FlowLayout测量高度 = 当前行顶部已占高度 +当前行内子元素最大高度+FlowLayout的PaddingBottom
flowMap.put("allChildHeight", columnHeight+rowsMaxHeight+getPaddingBottom());
return flowMap;
}
- xml
<com.ys.view.widget.FlowLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#e8e8e8"
android:padding="5dp"
android:id="@+id/flow"/>
- Activity调用
public class MainActivity extends AppCompatActivity {
private FlowLayout flowLayout;
private List<String> list=new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
flowLayout = findViewById(R.id.flow);
for (int i = 0; i <10; i++) {
list.add("Android");
list.add("Java");
list.add("IOS");
list.add("python");
}
//往容器内添加TextView数据
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
layoutParams.setMargins(10, 5, 10, 5);
if (flowLayout != null) {
flowLayout.removeAllViews();
}
for (int i = 0; i < list.size(); i++) {
TextView tv = new TextView(this);
tv.setPadding(28, 10, 28, 10);
tv.setText(loveList.get(i));
tv.setMaxEms(10);
tv.setSingleLine();
tv.setBackgroundResource(R.drawable.selector_playsearch);
tv.setLayoutParams(layoutParams);
flowLayout.addView(tv, layoutParams);
}
}
}
