Objective-C

Question

我有一个带有跟踪区域的自定义视图 class。我想要的是，当鼠标进入跟踪区域时，用一种颜色绘制贝塞尔曲线，当鼠标离开该区域时，贝塞尔曲线消失。为了让它消失，我读到唯一的方法是用 window 背景颜色改变它的颜色。

我成功添加了跟踪区域，但我不知道如何绘制贝塞尔曲线。如果我把代码放在

-(void)drawRect:(NSRect)dirtyRect

它是在应用程序启动时绘制的，但我不想这样。我试过这个：

@implementation MSBezier

- (void) viewWillMoveToWindow:(NSWindow *)newWindow {
    // Setup a new tracking area when the view is added to the window.
    NSTrackingArea* trackingArea = [[NSTrackingArea alloc] initWithRect:NSMakeRect(164.5, 17.5, 270, 65) options: (NSTrackingMouseEnteredAndExited | NSTrackingActiveAlways) owner:self userInfo:nil];
    [self addTrackingArea:trackingArea];
}

- (void) mouseEntered:(NSEvent*)theEvent {
    NSLog(@"Entered");
    color = [NSColor colorWithCalibratedRed: 0.044 green: 0.813 blue: 0.044 alpha: 0.441];
    CGFloat rectangleCornerRadius = 31;
    NSRect rectangleRect = NSMakeRect(164.5, 17.5, 270, 65);
    NSRect rectangleInnerRect = NSInsetRect(rectangleRect, rectangleCornerRadius, rectangleCornerRadius);
    rectanglePath = NSBezierPath.bezierPath;
    [rectanglePath appendBezierPathWithArcWithCenter: NSMakePoint(NSMinX(rectangleInnerRect), NSMinY(rectangleInnerRect)) radius: rectangleCornerRadius startAngle: 180 endAngle: 270];
    [rectanglePath appendBezierPathWithArcWithCenter: NSMakePoint(NSMaxX(rectangleInnerRect), NSMinY(rectangleInnerRect)) radius: rectangleCornerRadius startAngle: 270 endAngle: 360];
    [rectanglePath appendBezierPathWithArcWithCenter: NSMakePoint(NSMaxX(rectangleInnerRect), NSMaxY(rectangleInnerRect)) radius: rectangleCornerRadius startAngle: 0 endAngle: 90];
    [rectanglePath lineToPoint: NSMakePoint(NSMinX(rectangleRect), NSMaxY(rectangleRect))];
    [rectanglePath closePath];
    [color setStroke];
    [rectanglePath setLineWidth: 3];
    [rectanglePath stroke];

}

- (void) mouseExited:(NSEvent*)theEvent {
    NSLog(@"Exited");
    color = [NSColor colorWithCalibratedRed: 0.949 green: 0.949 blue: 0.949 alpha: 1];
    CGFloat rectangleCornerRadius = 31;
    NSRect rectangleRect = NSMakeRect(164.5, 17.5, 270, 65);
    NSRect rectangleInnerRect = NSInsetRect(rectangleRect, rectangleCornerRadius, rectangleCornerRadius);
    rectanglePath = NSBezierPath.bezierPath;
    [rectanglePath appendBezierPathWithArcWithCenter: NSMakePoint(NSMinX(rectangleInnerRect), NSMinY(rectangleInnerRect)) radius: rectangleCornerRadius startAngle: 180 endAngle: 270];
    [rectanglePath appendBezierPathWithArcWithCenter: NSMakePoint(NSMaxX(rectangleInnerRect), NSMinY(rectangleInnerRect)) radius: rectangleCornerRadius startAngle: 270 endAngle: 360];
    [rectanglePath appendBezierPathWithArcWithCenter: NSMakePoint(NSMaxX(rectangleInnerRect), NSMaxY(rectangleInnerRect)) radius: rectangleCornerRadius startAngle: 0 endAngle: 90];
    [rectanglePath lineToPoint: NSMakePoint(NSMinX(rectangleRect), NSMaxY(rectangleRect))];
    [rectanglePath closePath];
    [color setStroke];
    [rectanglePath setLineWidth: 3];
    [rectanglePath stroke];
}

@end

但是没有绘制贝塞尔曲线。

感谢您的帮助！

编辑 @uchugaka

这是目前为止的代码，似乎什么都没做：

@implementation MSBezier

bool shouldDrawMyPath = YES;
NSBezierPath *rectanglePath;

- (void)viewWillDraw {

    if (shouldDrawMyPath == YES) {
        NSColor *color = [NSColor colorWithCalibratedRed: 0.044 green: 0.813 blue: 0.044 alpha: 0.441];
        CGFloat rectangleCornerRadius = 31;
        NSRect rectangleRect = NSMakeRect(164.5, 17.5, 270, 65);
        NSRect rectangleInnerRect = NSInsetRect(rectangleRect, rectangleCornerRadius, rectangleCornerRadius);
        rectanglePath = NSBezierPath.bezierPath;
        [rectanglePath appendBezierPathWithArcWithCenter: NSMakePoint(NSMinX(rectangleInnerRect), NSMinY(rectangleInnerRect)) radius: rectangleCornerRadius startAngle: 180 endAngle: 270];
        [rectanglePath appendBezierPathWithArcWithCenter: NSMakePoint(NSMaxX(rectangleInnerRect), NSMinY(rectangleInnerRect)) radius: rectangleCornerRadius startAngle: 270 endAngle: 360];
        [rectanglePath appendBezierPathWithArcWithCenter: NSMakePoint(NSMaxX(rectangleInnerRect), NSMaxY(rectangleInnerRect)) radius: rectangleCornerRadius startAngle: 0 endAngle: 90];
        [rectanglePath lineToPoint: NSMakePoint(NSMinX(rectangleRect), NSMaxY(rectangleRect))];
        [rectanglePath closePath];
        [color setStroke];
        [rectanglePath setLineWidth: 3];
    } else {
        rectanglePath = nil;
    }

}

- (void)drawRect:(NSRect)dirtyRect {
    [[NSColor clearColor] set];
    NSRectFill(self.bounds);

    if (shouldDrawMyPath == YES) {
        [rectanglePath stroke];
    }
}

- (void) viewWillMoveToWindow:(NSWindow *)newWindow {
    NSTrackingArea* trackingArea = [[NSTrackingArea alloc] initWithRect:NSMakeRect(164.5, 17.5, 270, 65) options: (NSTrackingMouseEnteredAndExited | NSTrackingActiveAlways) owner:self userInfo:nil];
    [self addTrackingArea:trackingArea];
}

- (void) mouseEntered:(NSEvent*)theEvent {
    NSLog(@"Entered");
    shouldDrawMyPath = YES;
    [self setNeedsDisplay:YES];
}

- (void) mouseExited:(NSEvent*)theEvent {
    NSLog(@"Exited");
    shouldDrawMyPath = NO;
    [self setNeedsDisplay:YES];
}

@end

我确定我做错了什么。

编辑 2

我只需要在 drawRect: 中设置颜色。所以：

-(void)drawRect:(NSRect)dirtyRect {
    if (shouldDrawMyPath == YES) {
        NSColor *color = [NSColor colorWithCalibratedRed: 0.044 green: 0.813 blue: 0.044 alpha: 0.441];
        [color setStroke];
        [rectanglePath stroke];
    }
}

Answer 1

所以这很简单。你需要重新安排事情。首先创建一个 BOOL 属性像 shouldDrawMyPath 这应该默认为 NO。

接下来，在mouseEntered中：将其设置为是调用自己setNeedsDisplay:YES

接下来，mouseExited：将其设置为否调用自己setNeedsDisplay:YES

添加一个 NSBezierPath 属性。在viewWillDraw中如果 shouldDrawMyPath == YES 设置您的贝塞尔曲线路径。否则将其设置为零（我假设您的视图可能会随时调整大小）如果您的视图永远不会调整大小，您可以创建一次路径。

在drawRect中首先清除面板，特别是如果您的视图可以调整大小。 [[NSColor clearColor] 设置]; NSRectFill(self.bounds);

如果有的话，总是在那里画任何东西。

如果 shouldDrawMyPath == YES 填充 and/or 描边你的路径。别的在没有路径的情况下做任何其他绘图。

只要您正确设置了跟踪区域，就可以顺利进行。

根据具体情况，总会有优化。

除非您知道自己在做什么，否则切勿在 drawRect 之外绘制。

保持 drawRect 代码简单。

只在需要的时候画你需要的东西。（你还没有做到这一点，但是可以做很多优化来使特定的矩形无效并只绘制特定的矩形）

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drawrect

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