Re: scribbling
Re: scribbling
- Subject: Re: scribbling
- From: John Randolph <email@hidden>
- Date: Wed, 13 Aug 2003 11:56:56 -0700
On Wednesday, August 13, 2003, at 7:35 AM, Richard Chamberlain wrote:
Thanks Alastair,
On Wednesday, August 13, 2003, at 02:48 pm, Alastair J.Houghton wrote:
On Wednesday, August 13, 2003, at 12:45 pm, Richard Chamberlain
wrote:
I tried drawing in the mouseDragged method but that doesn't seem to
work.
This should work, but only if you remembered to do [self lockFocus]
and [self unlockFocus] around your drawing. (Assuming, that is, that
you're drawing in the view that received the -mouseDragged: message.)
Sorry I hadn't noticed those methods. So I've got this:
- (void)mouseDragged:(NSEvent *)event
{
NSPoint currentPoint = [self convertPoint:[event locationInWindow]
fromView:nil];
NSBezierPath* path = [[NSBezierPath alloc] init];
[self lockFocus];
[[NSColor redColor] set];
[path setLineWidth: 2.0];
[path moveToPoint:lastPoint];
[path lineToPoint: currentPoint];
[path closePath];
[path stroke];
[self unlockFocus];
[lines addObject:path];
[path release];
lastPoint = currentPoint;
}
and it doesn't work :-(
Eventually the scribbles appear but not straight away for some reason.
I set the drawRect code to use a different colour so I can see what is
being drawn where and red lines do appear.
Any suggestions?
First suggestion: don't do any drawing in an event-handling method,
and don't call -lockFocus yourself. Just update the info you need to
do the drawing, and call -setNeedsDisplayInRect:.
Second suggestion: don't throw away the path every time. You can
empty a path by sending it a -removeAllPoints message.
Third suggestion: check out the "cropped image" sample at:
http://developer.apple.com/samplecode/Sample_Code/Cocoa/
Cropped_Image.htm
Look at how the "LassoStyleCropMarker" was implemented.
-jcr
John C. Randolph <email@hidden> (408) 974-8819
Sr. Cocoa Software Engineer,
Apple Worldwide Developer Relations
http://developer.apple.com/cocoa/index.html
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| | >Re: scribbling (From: Richard Chamberlain <email@hidden>) |