android报表控件，任意方向联动

任意方向滑动中间的那块View，上面和左边的滚动条将联动。还支持回弹效果。

先说说这个布局文件

总的思路是获取中间那个自定义View在x，y轴上滚动的偏移量，然后让上面和左边的滚动条滚动相同的偏移量就行。主要是如何实现中间这个自定义的View。

public class ReportScrollview extends LinearLayout {

private Scroller mscroller;
int slop;
    VelocityTracker mVelocityTracker;
int screenW,screenH;
public int visibleW=0,visibleH=0;
public ReportScrollview(Context context) {
super(context);
        init(context);
    }

public ReportScrollview(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
        init(context);
    }

public ReportScrollview(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
        init(context);
    }

private void init(Context context){
        mscroller=new Scroller(context);
        slop= ViewConfiguration.getTouchSlop();
        screenW=context.getResources().getDisplayMetrics().widthPixels;
        screenH=context.getResources().getDisplayMetrics().heightPixels;
    }

@Override
protected void onFinishInflate() {
super.onFinishInflate();

    }

@Override
protected void onMeasure(int widthSpec, int heightSpec) {
super.onMeasure(widthSpec, heightSpec);

    }


float lastx,lasty;
@Override
public boolean onTouchEvent(MotionEvent event) {

if ( mVelocityTracker == null ) {
            mVelocityTracker = VelocityTracker.obtain();
        }
        mVelocityTracker.addMovement(event);
switch (event.getAction()){

case MotionEvent.ACTION_DOWN:
                   lastx=event.getX();
                   lasty=event.getY();
break;
case  MotionEvent.ACTION_MOVE:
float curx=event.getX();
float cury=event.getY();
float disx=curx-lastx;
float disy=cury-lasty;
if(Math.abs(disx)>slop|| Math.abs(disy)>slop){
                       lastx=curx;
                       lasty=cury;
                       scrollBy(-(int)disx,-(int)disy);//让视图顺着手指滑动的方向移动
                   }
break;
case MotionEvent.ACTION_UP:
                   mVelocityTracker.computeCurrentVelocity(1000,2000.0f);
int xVelocity = (int) mVelocityTracker.getXVelocity();
int yVelocity = (int) mVelocityTracker.getYVelocity();
if ( Math.abs(xVelocity) > 10
                           || Math.abs(xVelocity) > 10 ) {
                       mscroller.fling(getScrollX(),getScrollY(),
                               -xVelocity,-yVelocity,0,getMeasuredWidth()-visibleW,0,getMeasuredHeight()-visibleH);//手指拿起后，让视图随着惯性移动，并设置好移动的最大最小范围
                       invalidate();
                   }
break;
           }
return true;
    }

public void startScrollBy(int dx,int dy) {

        mscroller.forceFinished(true);
int startX = getScrollX();
int startY = getScrollY();
        mscroller.startScroll(startX,startY,startX+dx,startY+dy);
        invalidate();
    }

@Override
public void computeScroll() {
super.computeScroll();
if (mscroller.computeScrollOffset()) {

            scrollTo(mscroller.getCurrX(),mscroller.getCurrY());
if (mscroller.getCurrX() == getScrollX()
                    && mscroller.getCurrY() == getScrollY() ) {
                postInvalidate();
            }
        }
    }
@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
if(scrollChangedListener!=null){
//通过接口把这个View横纵坐标上的偏移量暴露出去
           scrollChangedListener.onScrollChanged(l,t,oldl,oldt);
          }
    }

private OnScrollChangedListener scrollChangedListener;

public void setScrollChangedListener(OnScrollChangedListener scrollChangedListener) {
this.scrollChangedListener = scrollChangedListener;
    }

public interface OnScrollChangedListener{
public void onScrollChanged(int l, int t, int oldl, int oldt);
    }

}

中间这个View我是通过继承LinearLayout实现的，主要是重写onTouchEvent，computeScroll()，onScrollChanged(int l, int t, int oldl, int oldt)这几个方法，关键步骤已经注释了。