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好久没有机会画画控件，最近画了一个换汤不换药的控价，之前的开关是点击事件，这个响应拖拽。

说下我这个控件拖拽的原理，手指按下，判断当前手指位置是否为拖拽元素所处位置，如果是，将控制变量值改为true

在onMove 事件中重新计算拖拽元素位置并重绘

在其他事件中重新将控制变量值改为false,并且用回调返回当前控件选中值，先上一个效果图，然后源代码走起

public class MySeekBar extends View {    private int textColor;    private float textSize;    private int bgColor;    private int fgColor;    private float corner;    private int scope;    private float blockWidth;    private int blockColor;    private DragerListener dragerListener;    private boolean changeComplete = true;    private int nowPoint;    private float blockHeight;    private float scaleWidth;    private float space;    private float blockCorner;    float step=0;    private int getNowSelect(){        return scope-nowPoint;    }    public int getNowPoint() {        return nowPoint;    }    public void setNowPoint(int nowPoint) {        this.nowPoint = nowPoint;    }    public boolean isChangeComplete() {        return changeComplete;    }    public void setChangeComplete(boolean changeComplete) {        this.changeComplete = changeComplete;    }    public DragerListener getDragerListener() {        return dragerListener;    }    public void setDragerListener(DragerListener dragerListener) {        this.dragerListener = dragerListener;    }    //    private int Width;//    private int Height;    public MySeekBar(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        // TODO Auto-generated constructor stub    }    public MySeekBar(Context context, AttributeSet attrs) {        super(context, attrs);        // TODO Auto-generated constructor stub        TypedArray a = context.obtainStyledAttributes(attrs,                R.styleable.MySeekBar);        textColor = a.getColor(R.styleable.MySeekBar_seek_textColor,                0XFFFFFFFF);        blockColor = a.getColor(R.styleable.MySeekBar_seek_blockColor, 0XFFFFFFFF);        textSize = a.getDimension(R.styleable.MySeekBar_seek_textSize, 36);        corner = a.getDimension(R.styleable.MySeekBar_seek_corner, 0);        bgColor = a.getColor(R.styleable.MySeekBar_seek_bgColor,                0XFFEAEAEA);        blockWidth=a.getDimension(R.styleable.MySeekBar_seek_blockWidth,30);        scope=a.getInteger(R.styleable.MySeekBar_seek_scope,30);        fgColor = a.getColor(R.styleable.MySeekBar_seek_fgColor, 0XFFFF0000);        blockHeight=a.getDimension(R.styleable.MySeekBar_seek_blockHeight,30);        space=a.getDimension(R.styleable.MySeekBar_seek_space,5);        scaleWidth=a.getDimension(R.styleable.MySeekBar_seek_scale_width,30);        blockCorner=a.getDimension(R.styleable.MySeekBar_seek_block_corner,10);        nowPoint=1;        a.recycle();    }    public MySeekBar(Context context) {        super(context);    }    @Override    protected void onDraw(Canvas canvas) {       step=(getHeight() - corner * 2) / scope;        float lineStart = corner + step / 2;        Paint tPaint = new Paint();        tPaint.setAntiAlias(true);        tPaint.setTextSize(textSize);        tPaint.setColor(textColor);        Paint.FontMetricsInt fontMetrics = tPaint.getFontMetricsInt();        Paint bgPaint = new Paint();        bgPaint.setColor(bgColor);        Paint fgPaint = new Paint();        fgPaint.setColor(fgColor);        Paint blockPaint = new Paint();        blockPaint.setColor(blockColor);        blockPaint.setStyle(Paint.Style.FILL_AND_STROKE);        RectF bgRect = new RectF();        bgRect.top = 0;        bgRect.right = getWidth();        bgRect.left = 0;        bgRect.bottom = getHeight();        canvas.drawRoundRect(bgRect, corner, corner, bgPaint);        RectF fgRect = new RectF();        fgRect.top = corner;        fgRect.right = scaleWidth+space+blockWidth/2+3;        fgRect.left = scaleWidth+space+blockWidth/2-3;        fgRect.bottom = getHeight()-corner;        canvas.drawRoundRect(fgRect, 0, 0, fgPaint);        for (int i = 0; i < scope; i++) {            canvas.drawLine(0, lineStart + step * i, scaleWidth, lineStart + step * i,                    fgPaint);            canvas.drawLine(0+scaleWidth+blockWidth+space*2, lineStart + step * i, scaleWidth*2+blockWidth+space*2, lineStart + step * i,                    fgPaint);            float baseline = corner+step*i - fontMetrics.bottom - fontMetrics.top;//垂直居中            canvas.drawText((scope - i) + "", scaleWidth*2+space*2+blockWidth, baseline, tPaint);        }        RectF blockRect = new RectF();        blockRect.top = step*nowPoint+corner;        blockRect.right = scaleWidth+space+blockWidth;        blockRect.left = scaleWidth+space;        blockRect.bottom = step*nowPoint+corner+blockHeight;        canvas.drawRoundRect(blockRect, blockCorner, blockCorner, blockPaint);    }    boolean isDrag=false;    @Override    public boolean onTouchEvent(MotionEvent event) {       if(event.getAction()==MotionEvent.ACTION_DOWN){          if(event.getY()> corner+step*nowPoint&&event.getY()
   
    = scope) {                   nowPoint = scope-1;               }               invalidate();           }       } else{         isDrag=false;         dragerListener.change(getNowSelect());       }        return true;    }    public interface DragerListener {        void change(int select);    }}
   

   <包名（路径名）.myseekbar android:visibility="gone" xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent" app:seek_bgColor="#adadad" app:seek_fgColor="#f3000000" app:seek_textSize="8dp" app:seek_padding="2dp" app:seek_blockColor="#ff0f0f0f" app:seek_textColor="@color/black" app:seek_block_corner="3dp" app:seek_scope="30" app:seek_blockWidth="30dp" app:seek_corner="5dp" app:seek_scale_width="10dp" app:seek_blockHeight="10dp" app:seek_space="3dp" android:id="@+id/seekBar" />

binding.seekBar.setDragerListener {            selected->            Toast.makeText(context, "selected$selected", Toast.LENGTH_SHORT).show();        }