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

  1 import android.content.Context;
  2 import android.graphics.Canvas;
  3 import android.util.AttributeSet;
  4 import android.view.MotionEvent;
  5 import android.view.ViewConfiguration;
  6 import android.view.ViewParent;
  7 import android.widget.SeekBar;
  8
  9
 10
 11 public class VerticalSeekBar extends SeekBar {
 12     private boolean mIsDragging;
 13     private float mTouchDownY;
 14     private int mScaledTouchSlop;
 15     private boolean isInScrollingContainer = false;
 16
 17     public boolean isInScrollingContainer() {
 18         return isInScrollingContainer;
 19     }
 20
 21     public void setInScrollingContainer(boolean isInScrollingContainer) {
 22         this.isInScrollingContainer = isInScrollingContainer;
 23     }
 24
 25     /**
 26      * On touch, this offset plus the scaled value from the position of the
 27      * touch will form the progress value. Usually 0.
 28      */
 29     float mTouchProgressOffset;
 30
 31     public VerticalSeekBar(Context context, AttributeSet attrs, int defStyle) {
 32         super(context, attrs, defStyle);
 33         mScaledTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
 34
 35     }
 36
 37     public VerticalSeekBar(Context context, AttributeSet attrs) {
 38         super(context, attrs);
 39     }
 40
 41     public VerticalSeekBar(Context context) {
 42         super(context);
 43     }
 44
 45     @Override
 46     protected void onSizeChanged(int w, int h, int oldw, int oldh) {
 47         super.onSizeChanged(h, w, oldh, oldw);
 48     }
 49
 50     @Override
 51     protected synchronized void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 52         super.onMeasure(heightMeasureSpec, widthMeasureSpec);
 53         setMeasuredDimension(getMeasuredHeight(), getMeasuredWidth());
 54     }
 55
 56     @Override
 57     protected synchronized void onDraw(Canvas canvas) {
 58         canvas.rotate(-90);
 59         canvas.translate(-getHeight(), 0);
 60         super.onDraw(canvas);
 61     }
 62
 63     @Override
 64     public boolean onTouchEvent(MotionEvent event) {
 65         if (!isEnabled()) {
 66             return false;
 67         }
 68
 69         switch (event.getAction()) {
 70             case MotionEvent.ACTION_DOWN:
 71                 if (isInScrollingContainer()) {
 72                     mTouchDownY = event.getY();
 73                 }
 74                 else {
 75                     setPressed(true);
 76
 77                     invalidate();
 78                     onStartTrackingTouch();
 79                     trackTouchEvent(event);
 80                     attemptClaimDrag();
 81
 82                     onSizeChanged(getWidth(), getHeight(), 0, 0);
 83                 }
 84                 break;
 85
 86             case MotionEvent.ACTION_MOVE:
 87                 if (mIsDragging)
 88                 {
 89                     trackTouchEvent(event);
 90
 91                 }
 92                 else
 93                 {
 94                     final float y = event.getY();
 95                     if (Math.abs(y - mTouchDownY) > mScaledTouchSlop)
 96                     {
 97                         setPressed(true);
 98
 99                         invalidate();
100                         onStartTrackingTouch();
101                         trackTouchEvent(event);
102                         attemptClaimDrag();
103
104                     }
105                 }
106                 onSizeChanged(getWidth(), getHeight(), 0, 0);
107                 break;
108
109             case MotionEvent.ACTION_UP:
110                 if (mIsDragging)
111                 {
112                     trackTouchEvent(event);
113                     onStopTrackingTouch();
114                     setPressed(false);
115
116                 }
117                 else
118                 {
119                     // Touch up when we never crossed the touch slop threshold
120                     // should
121                     // be interpreted as a tap-seek to that location.
122                     onStartTrackingTouch();
123                     trackTouchEvent(event);
124                     onStopTrackingTouch();
125
126                 }
127                 onSizeChanged(getWidth(), getHeight(), 0, 0);
128                 // ProgressBar doesn‘t know to repaint the thumb drawable
129                 // in its inactive state when the touch stops (because the
130                 // value has not apparently changed)
131                 invalidate();
132                 break;
133         }
134         return true;
135
136     }
137
138     private void trackTouchEvent(MotionEvent event)
139     {
140         final int height = getHeight();
141         final int top = getPaddingTop();
142         final int bottom = getPaddingBottom();
143         final int available = height - top - bottom;
144
145         int y = (int) event.getY();
146
147         float scale;
148         float progress = 0;
149
150         // 下面是最小值
151         if (y > height - bottom)
152         {
153             scale = 0.0f;
154         }
155         else if (y < top)
156         {
157             scale = 1.0f;
158         }
159         else
160         {
161             scale = (float) (available - y + top) / (float) available;
162             progress = mTouchProgressOffset;
163         }
164
165         final int max = getMax();
166         progress += scale * max;
167
168         setProgress((int) progress);
169
170     }
171
172     /**
173      * This is called when the user has started touching this widget.
174      */
175     void onStartTrackingTouch()
176     {
177         mIsDragging = true;
178     }
179
180     /**
181      * This is called when the user either releases his touch or the touch is
182      * canceled.
183      */
184     void onStopTrackingTouch()
185     {
186         mIsDragging = false;
187     }
188
189     private void attemptClaimDrag()
190     {
191         ViewParent p = getParent();
192         if (p != null)
193         {
194             p.requestDisallowInterceptTouchEvent(true);
195         }
196     }
197
198     @Override
199     public synchronized void setProgress(int progress)
200     {
201
202         super.setProgress(progress);
203         onSizeChanged(getWidth(), getHeight(), 0, 0);
204
205     }
206 }

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