自动换行的ViewGroup：FlowLayout

　　viewgroup简单说就是可以装view的view.今天遇到一个问题，就是需要一个可以自动根据一行中view的宽度自动换行的布局，网上找了下，没有相关的例子，但是找到了思路：自定义一个viewgroup,然后在onlayout文件里面自动检测view的右边缘的横坐标值，和你的view的parent view的况度判断是否换行显示view就可以了。因为代码比较简单，就不多说了：

public class MyViewGroup extends ViewGroup {
     private final static String TAG = "MyViewGroup";
     
     private final static int VIEW_MARGIN=2;
 
     public MyViewGroup(Context context) {
         super(context);
     }
     @Override
     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
         Log.d(TAG, "widthMeasureSpec = "+widthMeasureSpec+" heightMeasureSpec"+heightMeasureSpec);
         
         for (int index = 0; index < getChildCount(); index++) {
             final View child = getChildAt(index);
             // measure
             child.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
         }
 
         super.onMeasure(widthMeasureSpec, heightMeasureSpec);
     }
 
     @Override
     protected void onLayout(boolean arg0, int arg1, int arg2, int arg3, int arg4) {
         Log.d(TAG, "changed = "+arg0+" left = "+arg1+" top = "+arg2+" right = "+arg3+" botom = "+arg4);
         final int count = getChildCount();
         int row=0;// which row lay you view relative to parent
         int lengthX=arg1;    // right position of child relative to parent
         int lengthY=arg2;    // bottom position of child relative to parent
         for(int i=0;i<count;i++){
             
             final View child = this.getChildAt(i);
             int width = child.getMeasuredWidth();
             int height = child.getMeasuredHeight();
             lengthX+=width+VIEW_MARGIN;
             lengthY=row*(height+VIEW_MARGIN)+VIEW_MARGIN+height+arg2;
             //if it can't drawing on a same line , skip to next line
             if(lengthX>arg3){
                 lengthX=width+VIEW_MARGIN+arg1;
                 row++;
                 lengthY=row*(height+VIEW_MARGIN)+VIEW_MARGIN+height+arg2;
                 
             }
             
             child.layout(lengthX-width, lengthY-height, lengthX, lengthY);
         }
 
     }
 
 }

　　这里有个地方要注意，那就要明白ViewGroup的绘图流程：ViewGroup绘制包括两个步骤：1.measure 2.layout
　　在两个步骤中分别调用回调函数：1.onMeasure()   2.onLayout()
　　1.onMeasure() 在这个函数中，ViewGroup会接受childView的请求的大小，然后通过childView的 measure(newWidthMeasureSpec, heightMeasureSpec)函数存储到childView中，以便childView的getMeasuredWidth() andgetMeasuredHeight() 的值可以被后续工作得到。
　　2.onLayout() 在这个函数中，ViewGroup会拿到childView的getMeasuredWidth() andgetMeasuredHeight()，用来布局所有的childView。
　　3.View.MeasureSpec 与 LayoutParams 这两个类，是ViewGroup与childView协商大小用的。其中，View.MeasureSpec是ViewGroup用来部署 childView用的， LayoutParams是childView告诉ViewGroup 我需要多大的地方。
　　4.在View 的onMeasure的最后要调用setMeasuredDimension()这个方法存储View的大小，这个方法决定了当前View的大小。
　　


http://www.cnblogs.com/slider/archive/2011/11/24/2262161.html

还可以试试这个：

import android.content.Context;

import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;

/**
 *
 * @author RAW
 */
public class FlowLayout extends ViewGroup {
    private final static int PAD_H = 2, PAD_V = 2; // Space between child views.
    private int mHeight;

    public FlowLayout(Context context) {
        super(context);
    }

    public FlowLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        assert (MeasureSpec.getMode(widthMeasureSpec) != MeasureSpec.UNSPECIFIED);
        final int width = MeasureSpec.getSize(widthMeasureSpec) - getPaddingLeft() - getPaddingRight();
        int height = MeasureSpec.getSize(heightMeasureSpec) - getPaddingTop() - getPaddingBottom();
        final int count = getChildCount();
        int xpos = getPaddingLeft();
        int ypos = getPaddingTop();
        int childHeightMeasureSpec;
        if(MeasureSpec.getMode(heightMeasureSpec) == MeasureSpec.AT_MOST)
            childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.AT_MOST);
        else
            childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
        mHeight = 0;
        for(int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            if(child.getVisibility() != GONE) {
                child.measure(MeasureSpec.makeMeasureSpec(width, MeasureSpec.AT_MOST), childHeightMeasureSpec);
                final int childw = child.getMeasuredWidth();
                mHeight = Math.max(mHeight, child.getMeasuredHeight() + PAD_V);
                if(xpos + childw > width) {
                    xpos = getPaddingLeft();
                    ypos += mHeight;
                }
                xpos += childw + PAD_H;
            }
        }
        if(MeasureSpec.getMode(heightMeasureSpec) == MeasureSpec.UNSPECIFIED) {
            height = ypos + mHeight;
        } else if(MeasureSpec.getMode(heightMeasureSpec) == MeasureSpec.AT_MOST) {
            if(ypos + mHeight < height) {
                height = ypos + mHeight;
            }
        }
        height += 5; // Fudge to avoid clipping bottom of last row.
        setMeasuredDimension(width, height);
    } // end onMeasure()

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        final int width = r - l;
        int xpos = getPaddingLeft();
        int ypos = getPaddingTop();
        for(int i = 0; i < getChildCount(); i++) {
            final View child = getChildAt(i);
            if(child.getVisibility() != GONE) {
                final int childw = child.getMeasuredWidth();
                final int childh = child.getMeasuredHeight();
                if(xpos + childw > width) {
                    xpos = getPaddingLeft();
                    ypos += mHeight;
                }
                child.layout(xpos, ypos, xpos + childw, ypos + childh);
                xpos += childw + PAD_H;
            }
        }
    } // end onLayout()
}

How to Implement Flipboard Animation on Android


还可以看看这个：
Android标签流控件的实现
http://www.open-open.com/lib/view/open1425526186540.html

自动换行的线性布局，当排满一排或者一列，自动排列在下一行或者下一列。和另外一个FlowLayout（见下面的相关项目）不同的是，该项目可以设置对齐方式与排列方向，非常灵活。
https://github.com/ApmeM/android-flowlayout


Android TagFlowLayout完全解析 一款针对Tag的布局
http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2015/0914/3448.html

https://github.com/2dxgujun/AndroidTagGroup

流式布局，支持多种布局优化
https://github.com/lankton/android-flowlayout

评论

1 楼 yq135314 2012-07-26  

谢谢，第二种不错，可以和ScrollView一起用，进行滚屏，太感谢了。