@interface YQBAddHomeWorkBtn()<UIGestureRecognizerDelegate>

@end
@implementation YQBAddHomeWorkBtn
{
    CGPoint originalLocation;   //全局變量 用于存儲起始位置
    
    BOOL shouldPassEvent; // 是否需要傳遞事件
}

- (instancetype)initWithFrame:(CGRect)frame
{
    if (self = [super initWithFrame:frame]) {
        
        self.userInteractionEnabled = YES;
        // 取消高亮
        [self setAdjustsImageWhenHighlighted:NO];
        [self setNeedsUpdateConstraints];
    }
    return self;
}

- (instancetype)init
{
    if (self = [super init]) {
        
        self.userInteractionEnabled = YES;
        // 取消高亮
        [self setAdjustsImageWhenHighlighted:NO];
        [self setNeedsUpdateConstraints];
    }
    return self;
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    [super touchesBegan:touches withEvent:event];
    
    UITouch *touch = [touches  anyObject];
    originalLocation = [touch locationInView:self];
    
    shouldPassEvent = YES;

    [[self superview] bringSubviewToFront:self];
}


-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    [super touchesMoved:touches withEvent:event];
    //計算位移=當前位置-起始位置
    CGPoint point = [[touches anyObject] locationInView:self];
    float dx = point.x - originalLocation.x;
    float dy = point.y - originalLocation.y;
    
    //計算移動后的view中心點
    CGPoint newcenter = CGPointMake(self.center.x + dx, self.center.y + dy);
    
    /* 限制用戶不可將視圖拖出屏幕 */
    float halfx = CGRectGetMidX(self.bounds);
    //x坐標左邊界
    newcenter.x = MAX(halfx + offset, newcenter.x);
    //x坐標右邊界
    newcenter.x = MIN(self.superview.bounds.size.width - halfx - offset, newcenter.x);
    
    //y坐標同理
    float halfy = CGRectGetMidY(self.bounds);
    // y坐標上邊界
    newcenter.y = MAX(halfy + 80, newcenter.y);
    newcenter.y = MIN(self.superview.bounds.size.height - halfy - offset, newcenter.y);
    
    // 判斷是否需要傳遞事件
    shouldPassEvent = CGPointEqualToPoint(newcenter, originalLocation);
    //移動view
    self.center = newcenter;
}

- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{

    if (shouldPassEvent) {//點擊事件 需要傳遞點擊
        [super touchesEnded:touches withEvent:event];
    }
}

- (void)updateConstraints
{
    [self.imageView mas_makeConstraints:^(MASConstraintMaker *make) {
        
        make.edges.mas_equalTo(self);
    }];
    [super updateConstraints];
    
}