NSCell 的 NSColorPanel
我有一个自定义 NSCell，其中包含以下代码，用于在单击时显示 NSColorPanel：
-(void)setColorFromPanel:(NSColorPanel*)panel{
NSLog(@"COLOR is HERE!");
[self setObjectValue:[panel color]];
}
- (NSUInteger)hitTestForEvent:(NSEvent *)event inRect:(NSRect)cellFrame ofView:(NSView *)controlView{
if(self.isColor){
if([event type]==NSLeftMouseDown){
NSColorPanel *panel=[NSColorPanel sharedColorPanel];
[panel setColor:[self objectValue]];
[panel setShowsAlpha:YES];
[panel setAction:@selector(setColorFromPanel:)];
[panel setTarget:self];
[panel makeKeyAndOrderFront:nil];
}
return NSCellHitContentArea;
}
return NSCellHitNone;
}
此代码显示颜色选择器，但是，当我单击颜色时，它会崩溃。如果删除 [panel setTarget:self] 行，那么它工作正常，尽管没有效果（因为我从未收到颜色值，因为没有目标）。
这是堆栈跟踪。错误是 EXC_BAD_ACCESS。
#0 0x00007fff8667811c in objc_msgSend ()
#1 0x00007fff87081e9a in -[NSApplication sendAction:to:from:] ()
#2 0x00007fff871fa1cd in -[NSColorPanel _forceSendAction:notification:firstResponder:] ()
#3 0x00007fff871fe384 in -[NSColorPanel setColor:] ()
#4 0x00007fff8721d112 in -[NSColorPickerWheel setColor:] ()
#5 0x00007fff8721d5ae in -[NSColorPickerWheel brightnessSlider:] ()
#6 0x00007fff87081e9a in -[NSApplication sendAction:to:from:] ()
#7 0x00007fff87081df9 in -[NSControl sendAction:to:] ()
#8 0x00007fff8710d400 in -[NSCell trackMouse:inRect:ofView:untilMouseUp:] ()
#9 0x00007fff873eaf01 in -[NSSliderCell trackMouse:inRect:ofView:untilMouseUp:] ()
#10 0x00007fff8710c215 in -[NSControl mouseDown:] ()
#11 0x00007fff8702634f in -[NSWindow sendEvent:] ()
#12 0x00007fff86f5ba86 in -[NSApplication sendEvent:] ()
#13 0x00007fff86ef24da in -[NSApplication run] ()
#14 0x00007fff86eeb1a8 in NSApplicationMain ()
#15 0x00000001000029bb in main (argc=1, argv=0x7fff5fbff6a0)
I have a custom NSCell with the following code to display an NSColorPanel when it is clicked:
-(void)setColorFromPanel:(NSColorPanel*)panel{
NSLog(@"COLOR is HERE!");
[self setObjectValue:[panel color]];
}
- (NSUInteger)hitTestForEvent:(NSEvent *)event inRect:(NSRect)cellFrame ofView:(NSView *)controlView{
if(self.isColor){
if([event type]==NSLeftMouseDown){
NSColorPanel *panel=[NSColorPanel sharedColorPanel];
[panel setColor:[self objectValue]];
[panel setShowsAlpha:YES];
[panel setAction:@selector(setColorFromPanel:)];
[panel setTarget:self];
[panel makeKeyAndOrderFront:nil];
}
return NSCellHitContentArea;
}
return NSCellHitNone;
}
This code displays a color picker, however, when I click on a color, it crashes. If if remove the [panel setTarget:self] line, then it works fine, albeit with no effect (because I never receive the color value as there is no target).
Here is the stack trace. The error is EXC_BAD_ACCESS.
#0 0x00007fff8667811c in objc_msgSend ()
#1 0x00007fff87081e9a in -[NSApplication sendAction:to:from:] ()
#2 0x00007fff871fa1cd in -[NSColorPanel _forceSendAction:notification:firstResponder:] ()
#3 0x00007fff871fe384 in -[NSColorPanel setColor:] ()
#4 0x00007fff8721d112 in -[NSColorPickerWheel setColor:] ()
#5 0x00007fff8721d5ae in -[NSColorPickerWheel brightnessSlider:] ()
#6 0x00007fff87081e9a in -[NSApplication sendAction:to:from:] ()
#7 0x00007fff87081df9 in -[NSControl sendAction:to:] ()
#8 0x00007fff8710d400 in -[NSCell trackMouse:inRect:ofView:untilMouseUp:] ()
#9 0x00007fff873eaf01 in -[NSSliderCell trackMouse:inRect:ofView:untilMouseUp:] ()
#10 0x00007fff8710c215 in -[NSControl mouseDown:] ()
#11 0x00007fff8702634f in -[NSWindow sendEvent:] ()
#12 0x00007fff86f5ba86 in -[NSApplication sendEvent:] ()
#13 0x00007fff86ef24da in -[NSApplication run] ()
#14 0x00007fff86eeb1a8 in NSApplicationMain ()
#15 0x00000001000029bb in main (argc=1, argv=0x7fff5fbff6a0)
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您需要发布崩溃报告/调试器输出的相关部分；否则，很难猜出究竟出了什么问题！你知道，我们不是通灵者。崩溃报告包含崩溃原因的宝贵信息。
也就是说，此处提供了一个开源色孔单元。它仅适用于支持 GC 的应用程序，但如果该代码的许可证适合您的使用，那么应该是一个良好的开始。不要重新发明轮子。
让我补充几句话。NSCell 都会生成。从当前系统内存充足的角度来看，这没有多大意义，但在 15 年前 NeXTStep 首次设计时就有意义了。
NSTableView中的NSCell用作标记来为每行绘制条目，并且通常会重复使用，并且它不是一个无论如何，由于这个原因，细胞将自己设置为另一个对象的目标通常不是一个好主意，因为该细胞往往不会持久存在。我想这就是导致这次崩溃的原因，即 NSTableColumn 已经释放了该单元格，因为它已完成使用该特定单元格。通常，将控制器类作为面板的目标而不是单元本身更安全。
You need to post the relevant part of the crash reports/debugger outputs; otherwise, it's hard to guess exactly what went wrong! We're not psychics, you know. The crash report contains valuable info why it crashed.
That said, there's an open-source color-well cell available here. It's only for GC-enabled app, but should be a good start to build upon, if the license of that code fits your usage. Don't re-invent the wheel.
let me add a few words.
NSCellin anNSTableViewis used as a stamp to draw entries for each row and typically is re-used, and it's not that anNSCellfor each row is generated. This doesn't make much sense from the current point of view with abundant memory in a system, but it made sense 15 years ago when NeXTStep was first designed.Anyway, because of this reason, it's not typically a good idea for a cell to set itself as a target of another object, because that cell tends not to persist. I guess that's what's causing this crash, i.e.
NSTableColumnhad already released the cell because it finished using that particular cell. It's generally safer to have a controller class as the target of the panel, not the cell itself.