android拖拽控件

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 stubTypedArray 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);}@Overrideprotected 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;@Overridepublic 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）.MySeekBarandroid: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();}