Re: Drawing in a NSView out side of drawRect
Thanks to everyone that has responded to me. It has been a big help. I want to draw in a NSView but not when drawRect is called. Others have pointed this out, but I want to reiterate: no you don't. Trying to draw outside of drawRect: will only lead to pain. (It is useful, on rare occasions. You are not experiencing one of them.) Work with the view machinery. Call -setNeedsDisplay:. I understand that the preferred method of doing thing is do your drawing in drawRect:. I would like to understand better what are the issues and draw backs to using lockFocus and then drawing. thanks -dave ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Drawing in a NSView out side of drawRect
On Tue, Dec 23, 2008 at 12:44 PM, David Alter alterconsult...@gmail.com wrote: Thanks to everyone that has responded to me. It has been a big help. I want to draw in a NSView but not when drawRect is called. Others have pointed this out, but I want to reiterate: no you don't. Trying to draw outside of drawRect: will only lead to pain. (It is useful, on rare occasions. You are not experiencing one of them.) Work with the view machinery. Call -setNeedsDisplay:. I understand that the preferred method of doing thing is do your drawing in drawRect:. I would like to understand better what are the issues and draw backs to using lockFocus and then drawing. The major problem is that the system can ask your view to redisplay at any time. For example, your view might get redisplayed because the user resized your window, or deminimized it, or even just moved a window that's sitting on top of it (although in OS X, that last one doesn't actually apply). So your view needs to be prepared to completely recreate its content at any time using the drawRect: method. Given that requirement, using -lockFocus *usually* means something is wrong. If the code that you have inside the lock/unlockFocus pair is not duplicated in -drawRect:, then you won't be able to redraw your contents on demand, and your view could end up looking very strange to the user. If it *is* duplicated in -drawRect:, well, code duplication is a bad thing, and anyway if the necessary stuff is in -drawRect: then you can simply mark the view as needing to be redisplayed instead of drawing directly. There's also an efficiency advantage to not using lockFocus. Multiple invalidations to the same view within the same event processing cycle will result in a single call to -drawRect: and a single flush of the window to the screen. This coalescing can't be done when calling lockFocus. Mike ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Drawing in a NSView out side of drawRect
CGContextRef myContext = (CGContextRef)[[NSGraphicsContext currentContext]graphicsPort]; Right now you're getting the current graphics context, which is purely arbitrary. Nothing has set it yet, so you're getting whatever happened to be hanging around. Is there a way to create a NSGraphicsContext for the view? ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Drawing in a NSView out side of drawRect
On Mon, Dec 22, 2008 at 4:22 PM, David Alter alterconsult...@gmail.com wrote: CGContextRef myContext = (CGContextRef)[[NSGraphicsContext currentContext]graphicsPort]; Right now you're getting the current graphics context, which is purely arbitrary. Nothing has set it yet, so you're getting whatever happened to be hanging around. Is there a way to create a NSGraphicsContext for the view? The paragraph immediately following the one you quoted describes how. Mike ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Drawing in a NSView out side of drawRect
I want to draw in a NSView but not when drawRect is called. To do this I
understand that I need to call lockFocus before drawing and unlockFocus
after. The drawing appears to happen but it is not until I deactivate the
window do I see my results. How can I get it to refresh once I have done my
drawing?
To test this out I have sub classed NSView and overloaded mouseDown. I added
the following code.
- (void)mouseDown:(NSEvent *)theEvent ;
{
NSPoint loc = [[self window] mouseLocationOutsideOfEventStream];
loc = [self convertPoint:loc fromView:[[self window] contentView]];
CGContextRef myContext =
(CGContextRef)[[NSGraphicsContext currentContext]graphicsPort];
[self lockFocus];
CGContextSetRGBFillColor (myContext, 1, 0, 0, 1);
CGContextFillRect (myContext, CGRectMake (loc.x, loc.y, 10, 10 ));
[self unlockFocus];
}
This will draw a box for each mouse click, but not until I deactivate my
window.
thanks for the help
-dave
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Re: Drawing in a NSView out side of drawRect
On Dec 19, 2008, at 6:20 PM, David Alter wrote:
I want to draw in a NSView but not when drawRect is called. To do
this I
understand that I need to call lockFocus before drawing and
unlockFocus
after. The drawing appears to happen but it is not until I
deactivate the
window do I see my results. How can I get it to refresh once I have
done my
drawing?
To test this out I have sub classed NSView and overloaded mouseDown.
I added
the following code.
- (void)mouseDown:(NSEvent *)theEvent ;
{
NSPoint loc = [[self window] mouseLocationOutsideOfEventStream];
loc = [self convertPoint:loc fromView:[[self window] contentView]];
CGContextRef myContext =
(CGContextRef)[[NSGraphicsContext currentContext]graphicsPort];
[self lockFocus];
CGContextSetRGBFillColor (myContext, 1, 0, 0, 1);
CGContextFillRect (myContext, CGRectMake (loc.x, loc.y, 10, 10 ));
[self unlockFocus];
}
This will draw a box for each mouse click, but not until I
deactivate my
window.
What you should do is do all drawing in drawRect:. What happens when
your drawRect: is called? I bet you won't see any of the rects you
had when clicking around.
Instead, maintain a list of rects that need to be drawn. mouseDown:
then simply adds a new rect to the list and calls setNeedsDisplay:.
Or, if you profile things and need more speed, setNeedsDisplayInRect:
If you want things such that only one rect ever is drawn, just have
mouseDown: set the values of that single rect and still call
setNeedsDisplay:
___
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Instant Interactive(tm) http://www.instantinteractive.com
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Re: Drawing in a NSView out side of drawRect
On 20 Dec 2008, at 11:20 am, David Alter wrote: I want to draw in a NSView but not when drawRect is called. Why? There are very few situations when this is required or appropriate. To do this I understand that I need to call lockFocus before drawing and unlockFocus after. The drawing appears to happen but it is not until I deactivate the window do I see my results. How can I get it to refresh once I have done my drawing? You need to flush it to the screen. But don't - it's just not the right way to do drawing. To test this out I have sub classed NSView and overloaded mouseDown. I added the following code. Store the rects to be drawn in a list - your view could own this list for simplicity while you are experimenting. Then invalidate the rect you need to repaint in mouse down. -drawRect: then just iterates over the list and draws those rects that intersect the update area. This is way, way easier than trying to fudge around drawing in a non- standard manner. Learn it and love it. hth, Graham ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Drawing in a NSView out side of drawRect
On Fri, Dec 19, 2008 at 7:20 PM, David Alter alterconsult...@gmail.com wrote: I want to draw in a NSView but not when drawRect is called. Others have pointed this out, but I want to reiterate: no you don't. Trying to draw outside of drawRect: will only lead to pain. (It is useful, on rare occasions. You are not experiencing one of them.) Work with the view machinery. Call -setNeedsDisplay:. However, I'll also point out why your code currently doesn't work, just for posterity: CGContextRef myContext = (CGContextRef)[[NSGraphicsContext currentContext]graphicsPort]; Right now you're getting the current graphics context, which is purely arbitrary. Nothing has set it yet, so you're getting whatever happened to be hanging around. [self lockFocus]; Now you lock focus, which sets the current context to the one for your view. Since you grab the context before you set it, things don't work very well. Mike ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
