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Why does a blinking cursor in a text field cause a drawRect call?

I have the following view hierarchy setup in my program.

Window
+ContentView (Subview of Window)
++MyCustomView (Subview of ContentView)
++MyCustomOpaqueView (Subview of ContentView)
+++TextField (Subview of MyCustomOpaqueView)

When the user clicks on the TextField, the cursor inside it starts blinking. Each blink drawRect is called in MyCustomView. Not a big deal, but I wonder why?

In MyCustomOpaqueView, I implement isOpque as,

- (BOOL)isOpaque {return YES;}

I thought this blocks messages for drawRect in MyCustomView, if NSRect is passed drawRect is completely obscured by the opaque view, but when the cursor blinks, MyCustomView still sends a drawRect message with NSRect completely behind the opaque view.

Am I missing a key concept or is this a fad of a blinking cursor?

+5
1

, .

CocoaHeads. NSView hitTest. , NSView hittest :

- (NSView*) hitTest:(NSPoint)aPoint {
    static int depth = 1;
    NSLog([NSString stringWithFormat:@"%%%dd ENTER %%@ - hitTest", depth], 
          depth, [[self class] description]);
    depth++;
    NSView *hitView = [super hitTest:aPoint];
    depth--;
    NSLog([NSString stringWithFormat:@"%%%dd EXIT %%@ - hitTest: %%@", depth], 
          depth, [[self class] description], [[hitView class] description]);
    return hitView;
}

:

MyCustomView contentView.
MyOpaqueCustomView (OCV) contentView.

1 ENTER OCV - hitTest
1 EXIT OCV - hitTest: NSTextField
1 ENTER OCV - hitTest
1 EXIT OCV - hitTest: NSTextField
1 ENTER OCV - hitTest
1 EXIT OCV - hitTest: NSTextView
MyCustomView - Dirty Rect: {{49, 189}, {127, 28} //!!Focus Ring Around Text Field
OCV - Dirty Rect: : {{49, 189}, {127, 28}}
testTextField isOpaque? Yes
1 ENTER OCV - hitTest
1 EXIT OCV - hitTest: NSTextView
MyCustomView - Dirty Rect: {{64, 194}, {1, 17}}
1 ENTER OCV - hitTest
1 EXIT OCV - hitTest: NSTextView
1 ENTER OCV - hitTest
1 EXIT OCV - hitTest: NSTextField
1 ENTER MyCustomView - hitTest
1 EXIT MyCustomView - hitTest: MyCustomView
MyCustomView - Dirty Rect: {{64, 194}, {1, 17}} //!!EVERY BLINK
MyCustomView - Dirty Rect: {{64, 194}, {1, 17}}
MyCustomView - Dirty Rect: {{64, 194}, {1, 17}}
MyCustomView - Dirty Rect: {{64, 194}, {1, 17}}

MyCustomView contentView.
MyOpaqueCustomView (OCV) MyCustomView.

1 ENTER MyCustomView - hitTest
1 ENTER OCV - hitTest
1 EXIT OCV - hitTest: NSTextField
1 EXIT MyCustomView - hitTest: NSTextField
1 ENTER MyCustomView - hitTest
1 ENTER OCV - hitTest
1 EXIT OCV - hitTest: NSTextField
1 EXIT MyCustomView - hitTest: NSTextField
1 ENTER MyCustomView - hitTest
1 ENTER OCV - hitTest
1 EXIT OCV - hitTest: NSTextView
1 EXIT MyCustomView - hitTest: NSTextView
OCV - Dirty Rect: : {{49, 189}, {127, 28}} //!!FOCUS RING
testTextField isOpaque? Yes
1 ENTER MyCustomView - hitTest
1 ENTER OCV - hitTest
1 EXIT OCV - hitTest: NSTextView
1 EXIT MyCustomView - hitTest: NSTextView
1 ENTER MyCustomView - hitTest
1 ENTER OCV - hitTest
1 EXIT OCV - hitTest: NSTextView
1 EXIT MyCustomView - hitTest: NSTextView
1 ENTER MyCustomView - hitTest
1 ENTER OCV - hitTest
1 EXIT OCV - hitTest: NSTextField
1 EXIT MyCustomView - hitTest: NSTextField
//!!BLINKING HERE - But no dirtyRects.

, , hitTest , .

+2

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