Objective c 子类化NSScrollView drawRect:方法

我正在为我的一个应用程序定制UI，其想法是，文本区域在失焦时最初是灰色边框，当它进入焦点时，边框变成亮白色。我的应用程序使用黑色主题，对于单行的

NSTextField

，效果非常好

但是，我在使用子类

NSTextView

时遇到了问题。为了正确地修改边框，我最终不得不对父级

NSScrollView

进行子类化，但仍然看到奇怪的行为。（请参见下面的屏幕截图。）我希望红色框填充整个滚动视图，因为这将允许我笔划（而不是填充，这只是为了测试）路径，产生一个漂亮的边框。相反，红色框似乎只填充内部子视图

以下代码片段，用于

NSScrollView

子类：

- (void)drawRect:(NSRect)dirtyRect {
    [super drawRect:dirtyRect];

    NSRect borderRect = self.bounds;
    borderRect.origin.y += 1;
    borderRect.size.width -= 1;
    borderRect.size.height -= 4;

    BOOL inFocus = ([[self window] firstResponder] == self);

    if (!inFocus) {
        inFocus = [self anySubviewHasFocus:self];
    }

    if (inFocus) {
        [[NSColor colorWithDeviceRed:.8 green:.2 blue:0 alpha:1] set];
    } else {
        [[NSColor colorWithDeviceRed:.1 green:.8 blue:0 alpha:1] set];
    }

    [NSGraphicsContext saveGraphicsState];
    [[NSGraphicsContext currentContext] setShouldAntialias:NO];
    [NSBezierPath fillRect:borderRect];
    [NSGraphicsContext restoreGraphicsState];

    NSLog(@"My bounds: %@", NSStringFromRect(borderRect));
    NSLog(@"Super (%@) bounds: %@", [self superview], NSStringFromRect(borderRect));
}

生成如下所示的屏幕截图。另外，请参阅日志中的输出，这表明应该填充整个视图。这是唯一显示的输出，无论内部文本大小如何。输入回车会增加红色框的高度，但不会产生不同的输出。（我希望红色的框填充整个边界。）

2011-04-08 21:30:29.789 MyApp[6515:903]我的界限：{{0,1}，{196,87}
2011-04-08 21:30:29.789 MyApp[6515:903]Super（）界限：{{0,1}，{196,87}

编辑：感谢Josh Caswell的回答。请参阅下文，了解未聚焦和聚焦时的正确行为

---

正如ughoavgfhw所指出的，

NSScrollView

通常不进行任何绘图，并且可能以这种方式与其子视图进行奇怪的交互。我建议在文本视图的绘图代码中添加如下内容，以绘制所需的自定义聚焦环*：

// We're going to be modifying the state for this, 
// so allow it to be restored later
[NSGraphicsContext saveGraphicsState];

// Choose the correct color; isFirstResponder is a custom     
// ivar set in becomeFirstResponder and resignFirstResponder
if( isFirstResponder && [[self window] isKeyWindow]){
    [myFocusedColor set];
} 
else {
    [myNotFocusedColor set];
}

// Create two rects, one slightly outset from the bounds,
// one slightly inset
NSRect bounds = [self bounds];
NSRect innerRect = NSInsetRect(bounds, 2, 2);
NSRect outerRect = NSMakeRect(bounds.origin.x - 2, 
                              bounds.origin.y - 2,
                              bounds.size.width + 4,
                              bounds.size.height + 4);

// Create a bezier path using those two rects; this will
// become the clipping path of the context
NSBezierPath * clipPath = [NSBezierPath bezierPathWithRect:outerRect];
[clipPath appendBezierPath:[NSBezierPath bezierPathWithRect:innerRect]];

// Change the current clipping path of the context to 
// the enclosed area of clipPath; "enclosed" defined by 
// winding rule. Drawing will be restricted to this area.
// N.B. that the winding rule makes the order that the
// rects were added to the path important.
[clipPath setWindingRule:NSEvenOddWindingRule];
[clipPath setClip];
// Fill the rect; drawing is clipped and the inner rect
// is not drawn in
[[NSBezierPath bezierPathWithRect:outerRect] fill];
[NSGraphicsContext restoreGraphicsState];

这应该是AppKit绘制聚焦环时的合理近似值。当然，AppKit有点允许在视图的边界之外绘制——我不能保证这是完全安全的，但您似乎可以使用3px的余量。如果你愿意，你可以把戒指完全画在边界内。一个真正的聚焦环在视图内部略微延伸（2像素）（正如我在这里所做的）

苹果公司的文件

编辑：在重新阅读了你对这个问题的评论之后，我意识到我可能已经长篇大论地掩盖了真正的答案。尝试子类化

NSClipView

并切换滚动视图的剪辑视图，或者使用自定义视图作为文档视图

---

---

*：您还可以将其放入自定义视图子类的图形代码中，该子类被设置为

NSScrollView

的文档视图；然后，您的文本视图可以是该视图的子视图。或者替换自定义的

NSClipView

子类。

您希望边框始终完全可见，还是只在文本视图边缘可见的区域可见？好问题。我希望边框在滚动视图的边界周围始终可见。（不是文本视图的边界。）边界将始终可见，但如果不是第一个响应者，则为浅灰色，如果有焦点，则为亮白色。（背景是深色的。）这可能是剪辑的问题。使用

cgcontextgetclipboondingbox（（CGContextRef）[[NSGraphicsContext currentContext]graphicsPort]查找当前剪辑矩形并发布它是什么。您可以通过不调用
[super drawRect://code>来解决此问题，这是可以的，因为NSScrollView通常不会进行任何绘图。完美-我实际上需要做的就是使用滚动视图的边界创建NSBezier*clipPath，然后调用setClip！谢谢@克雷格：我很高兴你能从中挑出一些有用的信息！通过使用NSRect outerRect=NSInsetRect（界限，-2，-2），可以再次将NSInsetRect用于outerRect
// We're going to be modifying the state for this, 
// so allow it to be restored later
[NSGraphicsContext saveGraphicsState];

// Choose the correct color; isFirstResponder is a custom     
// ivar set in becomeFirstResponder and resignFirstResponder
if( isFirstResponder && [[self window] isKeyWindow]){
    [myFocusedColor set];
} 
else {
    [myNotFocusedColor set];
}

// Create two rects, one slightly outset from the bounds,
// one slightly inset
NSRect bounds = [self bounds];
NSRect innerRect = NSInsetRect(bounds, 2, 2);
NSRect outerRect = NSMakeRect(bounds.origin.x - 2, 
                              bounds.origin.y - 2,
                              bounds.size.width + 4,
                              bounds.size.height + 4);

// Create a bezier path using those two rects; this will
// become the clipping path of the context
NSBezierPath * clipPath = [NSBezierPath bezierPathWithRect:outerRect];
[clipPath appendBezierPath:[NSBezierPath bezierPathWithRect:innerRect]];

// Change the current clipping path of the context to 
// the enclosed area of clipPath; "enclosed" defined by 
// winding rule. Drawing will be restricted to this area.
// N.B. that the winding rule makes the order that the
// rects were added to the path important.
[clipPath setWindingRule:NSEvenOddWindingRule];
[clipPath setClip];
// Fill the rect; drawing is clipped and the inner rect
// is not drawn in
[[NSBezierPath bezierPathWithRect:outerRect] fill];
[NSGraphicsContext restoreGraphicsState];