Which method should I call my NSCell
I am writing a custom NSControl with custom NSCells. It is a control, so it must be mouse responsive. I created an NSTrackingArea above my controls, implemented -mouseEntered:
, -mouseExited:
and -mouseMoved:
. (And I'll have to implement -mouseUp/Down:
, but I don't know what to do there, so I haven't overridden these methods yet.) In these methods, I successfully determine which cell the mouse is in. Now I have two questions:
- Is this a good approach for mouse tracking? If not, what should I do instead?
- What method should I call on my NSCell with a mouse click, when the mouse enters the cell, when the mouse leaves the cell, etc.? Apple docs are not entirely clear.
So, basically: When should I call which method on my NSCell to allow it to respond to mouse events?
EDIT:
Rereading the docs, I think I should call NSCell -trackMouse:inRect:ofView:untilMouseUp:
and override -startTrackingAt:inView:
, -continueTracking:at:inView:
and -stopTracking:at:inView:mouseIsUp:
. Again two questions: 1) the documents give the impression that they are called only when the mouse is turned off. It's right? Then what should I do instead? 2) Where / when should I call NSCell -trackMouse:inRect:ofView:untilMouseUp:
?
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As a result, I created my own mouse tracking mechanism:
// MyControl.m:
- (void)mouseDown:(NSEvent *)theEvent {
int currentCellIndex = [self indexOfCellAtPoint:[self convertPoint:[theEvent locationInWindow] fromView:nil]];
if (currentCellIndex < [cells count]) {
MKListCell *cell = [cells objectAtIndex:currentCellIndex];
currentCell = cell;
[currentCell mouseDown:theEvent];
}
}
- (void)mouseUp:(NSEvent *)theEvent {
int currentCellIndex = [self indexOfCellAtPoint:[self convertPoint:[theEvent locationInWindow] fromView:nil]];
if (currentCellIndex < [cells count]) {
MKListCell *cell = [cells objectAtIndex:currentCellIndex];
[cell mouseUp:theEvent];
}
}
- (void)mouseEntered:(NSEvent *)theEvent {
int currentCellIndex = [self indexOfCellAtPoint:[self convertPoint:[theEvent locationInWindow] fromView:nil]];
if (currentCellIndex < [cells count]) {
MKListCell *cell = [cells objectAtIndex:currentCellIndex];
currentCell = cell;
[currentCell mouseEntered:theEvent];
}
}
- (void)mouseExited:(NSEvent *)theEvent {
int currentCellIndex = [self indexOfCellAtPoint:[self convertPoint:[theEvent locationInWindow] fromView:nil]];
if (currentCellIndex < [cells count]) {
MKListCell *cell = [cells objectAtIndex:currentCellIndex];
[cell mouseExited:theEvent];
currentCell = nil;
}
}
- (void)mouseMoved:(NSEvent *)theEvent {
int currentCellIndex = [self indexOfCellAtPoint:[self convertPoint:[theEvent locationInWindow] fromView:nil]];
MKListCell *cell;
if (currentCellIndex < [cells count]) {
cell = [cells objectAtIndex:currentCellIndex];
}
if (currentCell != cell) {
[currentCell mouseExited:theEvent];
[cell mouseEntered:theEvent];
currentCell = cell;
}
else {
[currentCell mouseMoved:theEvent];
}
}
- (void)mouseDragged:(NSEvent *)theEvent {
int currentCellIndex = [self indexOfCellAtPoint:[self convertPoint:[theEvent locationInWindow] fromView:nil]];
MKListCell *cell = nil;
if (currentCellIndex < [cells count]) {
cell = [cells objectAtIndex:currentCellIndex];
}
if (currentCell != cell) {
[currentCell mouseExited:theEvent];
[cell mouseEntered:theEvent];
currentCell = cell;
}
else {
[currentCell mouseMoved:theEvent];
}
}
- (int)indexOfCellAtPoint:(NSPoint)p {
int cellIndex = (self.bounds.size.height - p.y) / cellHeight;
return cellIndex;
}
And, of course, in MyCell.h
:
- (void)mouseDown:(NSEvent *)event;
- (void)mouseUp:(NSEvent *)event;
- (void)mouseMoved:(NSEvent *)event;
- (void)mouseEntered:(NSEvent *)event;
- (void)mouseExited:(NSEvent *)event;
With an empty implementation for these methods (so the compiler doesn't complain and I can leave the implementation of the mouse handling methods to subclasses).
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