自定义垂直拖动的seekbar进度条

系统自定义的seekbar为横向拖动的样式，需要纵向的时则需要自己定义，网上很多说了重写系统SeekBar中onDraw()的方法，但是我使用的时候不知道为什么拖动条和点偏离了，不在一条直线上，好气。。。

然后用了另一篇中改进之后的自定义bar，效果才正常，下面贴出代码

 import android.content.Context;
 import android.graphics.Canvas;
 import android.util.AttributeSet;
 import android.view.MotionEvent;
 import android.view.ViewConfiguration;
 import android.view.ViewParent;
 import android.widget.SeekBar;

 public class VerticalSeekBar extends SeekBar {
     private boolean mIsDragging;
     private float mTouchDownY;
     private int mScaledTouchSlop;
     private boolean isInScrollingContainer = false;

     public boolean isInScrollingContainer() {
         return isInScrollingContainer;
     }

     public void setInScrollingContainer(boolean isInScrollingContainer) {
         this.isInScrollingContainer = isInScrollingContainer;
     }

     /**
      * On touch, this offset plus the scaled value from the position of the
      * touch will form the progress value. Usually 0.
      */
     float mTouchProgressOffset;

     public VerticalSeekBar(Context context, AttributeSet attrs, int defStyle) {
         super(context, attrs, defStyle);
         mScaledTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();

     }

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

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

     @Override
     protected void onSizeChanged(int w, int h, int oldw, int oldh) {
         super.onSizeChanged(h, w, oldh, oldw);
     }

     @Override
     protected synchronized void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
         super.onMeasure(heightMeasureSpec, widthMeasureSpec);
         setMeasuredDimension(getMeasuredHeight(), getMeasuredWidth());
     }

     @Override
     protected synchronized void onDraw(Canvas canvas) {
         canvas.rotate(-90);
         canvas.translate(-getHeight(), 0);
         super.onDraw(canvas);
     }

     @Override
     public boolean onTouchEvent(MotionEvent event) {
         if (!isEnabled()) {
             return false;
         }

         switch (event.getAction()) {
             case MotionEvent.ACTION_DOWN:
                 if (isInScrollingContainer()) {
                     mTouchDownY = event.getY();
                 }
                 else {
                     setPressed(true);

                     invalidate();
                     onStartTrackingTouch();
                     trackTouchEvent(event);
                     attemptClaimDrag();

                     onSizeChanged(getWidth(), getHeight(), 0, 0);
                 }
                 break;

             case MotionEvent.ACTION_MOVE:
                 if (mIsDragging)
                 {
                     trackTouchEvent(event);

                 }
                 else
                 {
                     final float y = event.getY();
                     if (Math.abs(y - mTouchDownY) > mScaledTouchSlop)
                     {
                         setPressed(true);

                         invalidate();
                         onStartTrackingTouch();
                         trackTouchEvent(event);
                         attemptClaimDrag();

                     }
                 }
                 onSizeChanged(getWidth(), getHeight(), 0, 0);
                 break;

             case MotionEvent.ACTION_UP:
                 if (mIsDragging)
                 {
                     trackTouchEvent(event);
                     onStopTrackingTouch();
                     setPressed(false);

                 }
                 else
                 {
                     // Touch up when we never crossed the touch slop threshold
                     // should
                     // be interpreted as a tap-seek to that location.
                     onStartTrackingTouch();
                     trackTouchEvent(event);
                     onStopTrackingTouch();

                 }
                 onSizeChanged(getWidth(), getHeight(), 0, 0);
                 // ProgressBar doesn't know to repaint the thumb drawable
                 // in its inactive state when the touch stops (because the
                 // value has not apparently changed)
                 invalidate();
                 break;
         }
         return true;

     }

     private void trackTouchEvent(MotionEvent event)
     {
         final int height = getHeight();
         final int top = getPaddingTop();
         final int bottom = getPaddingBottom();
         final int available = height - top - bottom;

         int y = (int) event.getY();

         float scale;
         float progress = 0;

         // 下面是最小值
         if (y > height - bottom)
         {
             scale = 0.0f;
         }
         else if (y < top)
         {
             scale = 1.0f;
         }
         else
         {
             scale = (float) (available - y + top) / (float) available;
             progress = mTouchProgressOffset;
         }

         final int max = getMax();
         progress += scale * max;

         setProgress((int) progress);

     }

     /**
      * This is called when the user has started touching this widget.
      */
     void onStartTrackingTouch()
     {
         mIsDragging = true;
     }

     /**
      * This is called when the user either releases his touch or the touch is
      * canceled.
      */
     void onStopTrackingTouch()
     {
         mIsDragging = false;
     }

     private void attemptClaimDrag()
     {
         ViewParent p = getParent();
         if (p != null)
         {
             p.requestDisallowInterceptTouchEvent(true);
         }
     }

     @Override
     public synchronized void setProgress(int progress)
     {

         super.setProgress(progress);
         onSizeChanged(getWidth(), getHeight(), 0, 0);

     }
 }

代码取自：http://www.cnblogs.com/mengdd/archive/2013/04/08/3008482.html