macOS NSView Subclass

[MacRumors Guy]

I have question about NSView:

Imagine a Custom View where the mouseDown, mouseDrag and mouseUp methods are overriden so the user can drag a point (NSRect) on the screen. To drag it I need the mouse coordinates relative to the current view. This is not a problem when the parent of the view is the window, but how do I get them when the view is inside another view?

@implementation MyView

- (id)initWithFrame:(NSRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        pointXPosition = 200.0f;
        pointYPosition = 200.0f;
        
        locked = NO;
    }
    return self;
}

- (void) drawRect:(NSRect)rect {

    NSRect point = NSMakeRect(pointXPosition, pointYPosition, 6.0f, 6.0f);
    [[NSColor redColor] set];
    NSRectFill(point);
    
}

- (void)mouseDown:(NSEvent *)theEvent {
    NSPoint mousePos = [theEvent locationInWindow];
    NSRect frame = [super frame];
    CGFloat deltaX = mousePos.x - frame.origin.x - pointXPosition;
    CGFloat deltaY = mousePos.y - frame.origin.y - pointYPosition;
    if(sqrtf(deltaX * deltaX + deltaY * deltaY) < 100.0f)
        locked = YES;
}

- (void)mouseUp:(NSEvent *)theEvent {
    locked = NO;
}

- (void)mouseDragged:(NSEvent *)theEvent {
    
    if(locked) {
        NSPoint mousePos = [theEvent locationInWindow];
        
        NSRect frame = [super frame];
        
        CGFloat oldXPos = pointXPosition;
        CGFloat oldYPos = pointYPosition;
        
        pointXPosition = mousePos.x - frame.origin.x;
        pointYPosition = mousePos.y - frame.origin.y;
        
        CGFloat rectToDisplayXMin = MIN(oldXPos, pointXPosition);
        CGFloat rectToDisplayYMin = MIN(oldYPos, pointYPosition);
        
        CGFloat rectWidthToDisplay = MAX(oldXPos, pointXPosition) - rectToDisplayXMin;
        CGFloat rectHeigthToDisplay = MAX(oldYPos, pointYPosition) - rectToDisplayYMin;
        
        NSRect dirtyRect = NSMakeRect(rectToDisplayXMin,
                                      rectToDisplayYMin,
                                      rectWidthToDisplay + 6.0f,
                                      rectHeigthToDisplay + 6.0f);
        
        [self setNeedsDisplayInRect:dirtyRect];
    }
}

 

[kainjow]

Do this:

NSPoint mousePos = [self convertPoint:[theEvent locationInWindow] fromView:nil];

By passing nil, you're converting the coordinates from the window to the view (self).

 

[MacRumors Guy]

Thanks!!!