Re: Creating an Offscreen NSView
Re: Creating an Offscreen NSView
- Subject: Re: Creating an Offscreen NSView
- From: Mark Morrill <email@hidden>
- Date: Mon, 23 May 2005 10:03:23 -0600
Thank you, Thank you! :)
Mark
On 22-May-05, at 11:29, Ali Lalani wrote:
Oops, i forgot one step, don't forget to [myView unlockFocus] after
you create your image rep!
On 22-May-05, at 1:20 PM, Ali Lalani wrote:
Is creating an offscreen NSView as easy as:
NSView* myOffscreenView = [[NSView alloc] initWithFrame:theFrame];
And is drawing into it as easy as:
[myOffscreenView drawRect:myDrawRect];
Unfortunately not :(
There are a few more steps that are required.
In order to get a view to draw like that it needs to be in a window,
so you create a window and put the window offscreen:
NSWindow *hiddenWindow = [[NSWindow alloc] initWithContentRect:
NSMakeRect( -1000,-1000,width,height ) // some arbitrary offscreen
coordinate
styleMask: NSTitledWindowMask | NSClosableWindowMask // doesn't
matter what these are really
backing:NSBackingStoreNonretained
defer:NO]; // if you pass YES for this it won't do any drawing
until the window is onscreen, not good for this situation!
Now that you have the window offscreen, with a width and height of
the view you want to draw, get the content view of the window and add
your view to its subviews:
[[hiddenWindow contentView] addSubview:myView];
now lock focus on your view
[myView lockFocus];
call a method on NSBitmapImageRep to get an image from the focused
view:
NSBitmapImageRep *rep = [[[NSBitmapImageRep alloc]
initWithFocusedViewRect:[self bounds]] autorelease];
make an NSImage from the rep
NSImage *image = [[[NSImage alloc] init] autorelease];
[image addRepresentation:rep];
And then clean up your mess by closing the window, etc...
That *should* work, though i've not tested it extensively(i have a
category method on NSView that does this), but at least it's a start.
Or getting PDF data from it as easy as:
NSData* myPDF = [myOffscreenView drawRect:myDrawRect];
This seems to be too easy. Is there a catch? How does the view know
not to draw on the screen? How does it allocate a graphics context?
Mark
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Cocoa-dev mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Cocoa-dev mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Cocoa-dev mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden