Android开发仿IOS滑动开关实现代码

width = w;    height = h;    left = top = 0;    right = width;    bottom = height * 0.8f;    cx = (right + left) / 2;    cy = (bottom + top) / 2;    RectF rectF = new RectF(left, top, bottom, bottom);    path.arcTo(rectF, 90, 180);    rectF.left = right - bottom;    rectF.right = right;    path.arcTo(rectF, 270, 180);    path.close();    circle_left = 0;    circle_right = bottom;    circle_width = circle_right - circle_left;    float circle_height = (bottom - top) / 2;    radius = circle_height * 0.9f;    borderwidth = (int) (2 * (circle_height - radius));    circle_cx = width - circle_height;

protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    paint.setStyle(Style.FILL);    paint.setAntiAlias(true);    canvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG));    if (isChoose) {      paint.setColor(onColor);    } else {      paint.setColor(offColor);    }    canvas.drawPath(path, paint);    isAnimation = isAnimation - 0.1f > 0 ? isAnimation - 0.1f : 0;    //缩放大小参数随isAnimation变化而变化    final float scale = 0.98f * (isChoose ? isAnimation : 1 - isAnimation);    //保存canvas状态    canvas.save();    canvas.scale(scale, scale, circle_cx, cy);    paint.setColor(offColor);    canvas.drawPath(path, paint);    canvas.restore();    paint.reset();    float bTranslateX = width - circle_width;    final float translate = bTranslateX * (isChoose ? 1 - isAnimation : isAnimation);    canvas.translate(translate, 0);    if (isAnimation > 0) {      invalidate();    }    canvas.save();    paint.setStyle(Style.FILL);    paint.setColor(offColor);    canvas.drawCircle(circle_width / 2, circle_width / 2, radius, paint); // 按钮白底    paint.setStyle(Style.STROKE);    paint.setColor(borderColor);    paint.setStrokeWidth(borderwidth);    canvas.drawCircle(circle_width / 2, circle_width / 2, radius, paint); // 按钮灰边    canvas.restore();  }

  public boolean onTouchEvent(MotionEvent event) {    switch (event.getAction()) {      case MotionEvent.ACTION_DOWN:        return true;      case MotionEvent.ACTION_CANCEL:        return true;      case MotionEvent.ACTION_UP:          isAnimation = 1;          isChoose = !isChoose;          listener.onStateChanged(isChoose);          invalidate();        break;    }    return super.onTouchEvent(event);  }