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