自定义的一个SwitchButton控件

这个控件是在网上看到的，忘记是从哪里看的了，当时抄录下来看了看，前几天电脑宕机了一次，今天传上来记录一下。

public class SwitchView extends View {    private final Paint paint = new Paint();    private final Path sPath = new Path();    private final Path bPath = new Path();    private final RectF bRectF = new RectF();    private float sAnim, bAnim;    private RadialGradient shadowGradient;    private final AccelerateInterpolator aInterpolator = new AccelerateInterpolator(2);    /**     * state switch on     */    public static final int STATE_SWITCH_ON = 4;    /**     * state prepare to off     */    public static final int STATE_SWITCH_ON2 = 3;    /**     * state prepare to on     */    public static final int STATE_SWITCH_OFF2 = 2;    /**     * state prepare to off     */    public static final int STATE_SWITCH_OFF = 1;    /**     * current state     */    private int state = STATE_SWITCH_OFF;    /**     * last state     */    private int lastState = state;    private boolean isOpened = false;    private int mWidth, mHeight;    private float sWidth, sHeight;    private float sLeft, sTop, sRight, sBottom;    private float sCenterX, sCenterY;    private float sScale;    private float bOffset;    private float bRadius, bStrokeWidth;    private float bWidth;    private float bLeft, bTop, bRight, bBottom;    private float bOnLeftX, bOn2LeftX, bOff2LeftX, bOffLeftX;    private float shadowHeight;    public SwitchView(Context context) {        this(context, null);    }    public SwitchView(Context context, AttributeSet attrs) {        super(context, attrs);        setLayerType(LAYER_TYPE_SOFTWARE, null);    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        int widthSize = MeasureSpec.getSize(widthMeasureSpec);        int heightSize = (int) (widthSize * 0.6f);        setMeasuredDimension(widthSize, heightSize);    }    @Override    protected void onSizeChanged(int w, int h, int oldw, int oldh) {        super.onSizeChanged(w, h, oldw, oldh);        mWidth = w;        mHeight = h;        sLeft = sTop = 0;        sRight = mWidth;        sBottom = mHeight * 0.91f;        sWidth = sRight - sLeft;        sHeight = sBottom - sTop;        sCenterX = (sRight + sLeft) / 2;        sCenterY = (sBottom + sTop) / 2;        shadowHeight = mHeight - sBottom;        bLeft = bTop = 0;        bRight = bBottom = sBottom;        bWidth = bRight - bLeft;        final float halfHeightOfS = (sBottom - sTop) / 2;        bRadius = halfHeightOfS * 0.95f;        bOffset = bRadius * 0.2f;        bStrokeWidth = (halfHeightOfS - bRadius) * 2;        bOnLeftX = sWidth - bWidth;        bOn2LeftX = bOnLeftX - bOffset;        bOffLeftX = 0;        bOff2LeftX = 0;        sScale = 1 - bStrokeWidth / sHeight;        RectF sRectF = new RectF(sLeft, sTop, sBottom, sBottom);        sPath.arcTo(sRectF, 90, 180);        sRectF.left = sRight - sBottom;        sRectF.right = sRight;        sPath.arcTo(sRectF, 270, 180);        sPath.close();        bRectF.left = bLeft;        bRectF.right = bRight;        bRectF.top = bTop + bStrokeWidth / 2;        bRectF.bottom = bBottom - bStrokeWidth / 2;        shadowGradient = new RadialGradient(bWidth / 2, bWidth / 2, bWidth / 2, 0xff000000, 0x00000000, Shader.TileMode.CLAMP);    }    private void calcBPath(float percent) {        bPath.reset();        bRectF.left = bLeft + bStrokeWidth / 2;        bRectF.right = bRight - bStrokeWidth / 2;        bPath.arcTo(bRectF, 90, 180);        bRectF.left = bLeft + percent * bOffset + bStrokeWidth / 2;        bRectF.right = bRight + percent * bOffset - bStrokeWidth / 2;        bPath.arcTo(bRectF, 270, 180);        bPath.close();    }    private float calcBTranslate(float percent) {        float result = 0;        int wich = state - lastState;        switch (wich) {            case 1:                // off -> off2                if (state == STATE_SWITCH_OFF2) {                    result = bOff2LeftX - (bOff2LeftX - bOffLeftX) * percent;                }                // on2 -> on                else if (state == STATE_SWITCH_ON) {                    result = bOnLeftX - (bOnLeftX - bOn2LeftX) * percent;                }                break;            case 2:                // off2 -> on                if (state == STATE_SWITCH_ON) {                    result = bOnLeftX - (bOnLeftX - bOff2LeftX) * percent;                }                // off -> on2                else if (state == STATE_SWITCH_ON) {                    result = bOn2LeftX - (bOn2LeftX - bOffLeftX) * percent;                }                break;            case 3: // off -> on                result = bOnLeftX - (bOnLeftX - bOffLeftX) * percent;                break;            case -1:                // on -> on2                if (state == STATE_SWITCH_ON2) {                    result = bOn2LeftX + (bOnLeftX - bOn2LeftX) * percent;                }                // off2 -> off                else if (state == STATE_SWITCH_OFF) {                    result = bOffLeftX + (bOff2LeftX - bOffLeftX) * percent;                }                break;            case -2:                // on2 -> off                if (state == STATE_SWITCH_OFF) {                    result = bOffLeftX + (bOn2LeftX - bOffLeftX) * percent;                }                // on -> off2                else if (state == STATE_SWITCH_OFF2) {                    result = bOff2LeftX + (bOnLeftX - bOff2LeftX) * percent;                }                break;            case -3: // on -> off                result = bOffLeftX + (bOnLeftX - bOffLeftX) * percent;                break;        }        return result - bOffLeftX;    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        paint.setAntiAlias(true);        final boolean isOn = (state == STATE_SWITCH_ON || state == STATE_SWITCH_ON2);        // draw background        paint.setStyle(Style.FILL);        paint.setColor(isOn ? 0xffE2BA79 : 0xffe3e3e3);        canvas.drawPath(sPath, paint);        sAnim = sAnim - 0.1f > 0 ? sAnim - 0.1f : 0;        bAnim = bAnim - 0.1f > 0 ? bAnim - 0.1f : 0;        final float dsAnim = aInterpolator.getInterpolation(sAnim);        final float dbAnim = aInterpolator.getInterpolation(bAnim);        // draw background animation        final float scale = sScale * (isOn ? dsAnim : 1 - dsAnim);        final float scaleOffset = (bOnLeftX + bRadius - sCenterX) * (isOn ? 1 - dsAnim : dsAnim);        canvas.save();        canvas.scale(scale, scale, sCenterX + scaleOffset, sCenterY);        paint.setColor(0xffffffff);        canvas.drawPath(sPath, paint);        canvas.restore();        // draw center bar        canvas.save();        canvas.translate(calcBTranslate(dbAnim), shadowHeight);        final boolean isState2 = (state == STATE_SWITCH_ON2 || state == STATE_SWITCH_OFF2);        calcBPath(isState2 ? 1 - dbAnim : dbAnim);        // draw shadow        paint.setStyle(Style.FILL);        paint.setColor(0xff333333);        paint.setShader(shadowGradient);        canvas.drawPath(bPath, paint);        paint.setShader(null);        canvas.translate(0, -shadowHeight);        canvas.scale(0.98f, 0.98f, bWidth / 2, bWidth / 2);        paint.setStyle(Style.FILL);        paint.setColor(0xffffffff);        canvas.drawPath(bPath, paint);        paint.setStyle(Style.STROKE);        paint.setStrokeWidth(bStrokeWidth * 0.5f);        paint.setColor(isOn ? 0xffE2BA79 : 0xffbfbfbf);        canvas.drawPath(bPath, paint);        canvas.restore();        paint.reset();        if (sAnim > 0 || bAnim > 0) invalidate();    }    @Override    public boolean onTouchEvent(MotionEvent event) {        if ((state == STATE_SWITCH_ON || state == STATE_SWITCH_OFF) && (sAnim * bAnim == 0)) {            switch (event.getAction()) {                case MotionEvent.ACTION_DOWN:                    return true;                case MotionEvent.ACTION_UP:                    lastState = state;                    if (state == STATE_SWITCH_OFF) {                        refreshState(STATE_SWITCH_OFF2);                    } else if (state == STATE_SWITCH_ON) {                        refreshState(STATE_SWITCH_ON2);                    }                    bAnim = 1;                    invalidate();                    if (state == STATE_SWITCH_OFF2) {                        listener.toggleToOn(this);                    } else if (state == STATE_SWITCH_ON2) {                        listener.toggleToOff(this);                    }                    break;            }        }        return super.onTouchEvent(event);    }    private void refreshState(int newState) {        if (!isOpened && newState == STATE_SWITCH_ON) {            isOpened = true;        } else if (isOpened && newState == STATE_SWITCH_OFF) {            isOpened = false;        }        lastState = state;        state = newState;        postInvalidate();    }    /**     * @return the state of switch view     */    public boolean isOpened() {        return isOpened;    }    /**     * if set true , the state change to on;     * if set false, the state change to off     *     * @param isOpened     */    public void setOpened(boolean isOpened) {        refreshState(isOpened ? STATE_SWITCH_ON : STATE_SWITCH_OFF);    }    /**     * if set true , the state change to on;     * if set false, the state change to off     * <br><b>change state with animation</b>     *     * @param isOpened     */    public void toggleSwitch(final boolean isOpened) {        this.isOpened = isOpened;        postDelayed(new Runnable() {            @Override            public void run() {                toggleSwitch(isOpened ? STATE_SWITCH_ON : STATE_SWITCH_OFF);            }        }, 300);    }    private synchronized void toggleSwitch(int wich) {        if (wich == STATE_SWITCH_ON || wich == STATE_SWITCH_OFF) {            if ((wich == STATE_SWITCH_ON && (lastState == STATE_SWITCH_OFF || lastState == STATE_SWITCH_OFF2))                    || (wich == STATE_SWITCH_OFF && (lastState == STATE_SWITCH_ON || lastState == STATE_SWITCH_ON2))) {                sAnim = 1;            }            bAnim = 1;            refreshState(wich);        }    }    public interface OnStateChangedListener {        void toggleToOn(View view);        void toggleToOff(View view);    }    private OnStateChangedListener listener = new OnStateChangedListener() {        @Override        public void toggleToOn(View view) {            toggleSwitch(STATE_SWITCH_ON);        }        @Override        public void toggleToOff(View view) {            toggleSwitch(STATE_SWITCH_OFF);        }    };    public void setOnStateChangedListener(OnStateChangedListener listener) {        if (listener == null) throw new IllegalArgumentException("empty listener");        this.listener = listener;    }    @Override    public Parcelable onSaveInstanceState() {        Parcelable superState = super.onSaveInstanceState();        SavedState ss = new SavedState(superState);        ss.isOpened = isOpened;        return ss;    }    @Override    public void onRestoreInstanceState(Parcelable state) {        SavedState ss = (SavedState) state;        super.onRestoreInstanceState(ss.getSuperState());        this.isOpened = ss.isOpened;        this.state = this.isOpened ? STATE_SWITCH_ON : STATE_SWITCH_OFF;    }    static final class SavedState extends BaseSavedState {        private boolean isOpened;        SavedState(Parcelable superState) {            super(superState);        }        private SavedState(Parcel in) {            super(in);            isOpened = 1 == in.readInt();        }        @Override        public void writeToParcel(Parcel out, int flags) {            super.writeToParcel(out, flags);            out.writeInt(isOpened ? 1 : 0);        }    }}