Resizing a NSImage in a Cocoa command line tool

Dimitri Bouniol Resizing a NSImage in a Cocoa command line tool Aug 05 2008, 11:44

I have been trying relentlessly to resize a NSImage and save it as a
png file in a command line tool (not a windowed app, but I included
AppKit to get NSImage support). I tried using setScalesWhenResized
along with setSize to no avail (image is not resized when saved), and
I also tried locking focus to another image and drawing at a smaller
size, but that simply crashes with the following:

2008-08-03 20:49:40.127 imagecompressor[16757:10b] _NXCreateWindow:
error setting window property (1002)
2008-08-03 20:49:40.132 imagecompressor[16757:10b] _NXPlaceWindow:
error setting window shape (1002)
2008-08-03 20:49:40.132 imagecompressor[16757:10b]
_NSShapePlainWindow: error setting window shape (1002)
2008-08-03 20:49:40.144 imagecompressor[16757:10b]
PScurrentwindowbounds: CGSGetWindowBounds returned error (1002)
Sun Aug 3 20:49:40 imagecompressor[16757] <Error>:
CGSImageDataLockDevice: Bad device image source
Sun Aug 3 20:49:40 imagecompressor[16757] <Error>:
ripc_DrawWindowContents - Cannot acquire window image
2008-08-03 20:49:40.146 imagecompressor[16757:10b] *** -
[NSCachedImageRep representationUsingType:properties:]: unrecognized
selector sent to instance 0x116c30
2008-08-03 20:49:40.146 imagecompressor[16757:10b] *** Terminating app
due to uncaught exception 'NSInvalidArgumentException', reason: '*** -
[NSCachedImageRep representationUsingType:properties:]: unrecognized
selector sent to instance 0x116c30'
2008-08-03 20:49:40.146 imagecompressor[16757:10b] Stack: (
2527650123,
2500743419,
2527679306,
2527672652,
2527672850,
11646,
10094
)
Trace/BPT trap

I hope someone could come to my aid!
--
å®šé…åˆ€åˆ©
Dimitri Bouniol
<dimitri008...>
http://www.appkainime.com/
Ken Ferry Re: Resizing a NSImage in a Cocoa command line tool Aug 05 2008, 16:20

Hi Dimitri,

The size property describes a more abstract size than pixels. If you
set it, you're changing the DPI of the image you write out, not how
many pixels it has.

It's not safe in general to use AppKit from an app that cannot connect
to the window server ¨C see
<http://developer.apple.com/technotes/tn2005/tn2083.html#SECLIVINGDANGEROUSL
Y>.
If you _can_ connect to the window server (i.e. this app isn't
running headless on some machine where you aren't logged in to
console) then you might just need to call NSApplicationLoad() in your
main method. This function does some AppKit global setup that is
normally done in NSApplicationMain, but NSApplicationLoad returns
control to you.

That said, if you can restrict yourself to NSBitmapImageRep, that
should work without a windowserver connection. You can draw from your
original bitmap into a new, smaller one like this:

NSBitmapImageRep *newBitmap = [[NSBitmapImageRep alloc]
initWithBitmapDataPlanes:NULL pixelsWide:pixelsWide
pixelsHigh:pixelsHigh bitsPerSample:8 samplesPerPixel:4 hasAlpha:YES
isPlanar:NO colorSpaceName:NSCalibratedRGBColorSpace
bitmapFormat:NSAlphaFirstBitmapFormat bytesPerRow:0 bitsPerPixel:32];
[NSGraphicsContext saveGraphicsState];
[NSGraphicsContext setCurrentContext:[NSGraphicsContext
graphicsContextWithBitmapImageRep:newBitmap]];
[oldBitmap drawInRect:NSMakeRect(0,0,pixelsWide,pixelsHigh)];
[NSGraphicsContext restoreGraphicsState];

and write it to png data with -[NSBitmapImageRep
representationUsingType:properties:].

Also, the technote I referenced above doesn't mention that the
CoreGraphics framework is daemon safe, which it is.

-Ken
Cocoa Frameworks

On Tue, Aug 5, 2008 at 2:44 AM, Dimitri Bouniol <dimitri008...> wrote:

> I have been trying relentlessly to resize a NSImage and save it as a png
> file in a command line tool (not a windowed app, but I included AppKit to
> get NSImage support). I tried using setScalesWhenResized along with setSize
> to no avail (image is not resized when saved), and I also tried locking
> focus to another image and drawing at a smaller size, but that simply
> crashes with the following:
>
> 2008-08-03 20:49:40.127 imagecompressor[16757:10b] _NXCreateWindow: error
> setting window property (1002)
> 2008-08-03 20:49:40.132 imagecompressor[16757:10b] _NXPlaceWindow: error
> setting window shape (1002)
> 2008-08-03 20:49:40.132 imagecompressor[16757:10b] _NSShapePlainWindow:
> error setting window shape (1002)
> 2008-08-03 20:49:40.144 imagecompressor[16757:10b] PScurrentwindowbounds:
> CGSGetWindowBounds returned error (1002)
> Sun Aug 3 20:49:40 imagecompressor[16757] <Error>: CGSImageDataLockDevice:
> Bad device image source
> Sun Aug 3 20:49:40 imagecompressor[16757] <Error>: ripc_DrawWindowContents
> - Cannot acquire window image
> 2008-08-03 20:49:40.146 imagecompressor[16757:10b] *** -[NSCachedImageRep
> representationUsingType:properties:]: unrecognized selector sent to instance
> 0x116c30
> 2008-08-03 20:49:40.146 imagecompressor[16757:10b] *** Terminating app due
> to uncaught exception 'NSInvalidArgumentException', reason: '***
> -[NSCachedImageRep representationUsingType:properties:]: unrecognized
> selector sent to instance 0x116c30'
> 2008-08-03 20:49:40.146 imagecompressor[16757:10b] Stack: (
> 2527650123,
> 2500743419,
> 2527679306,
> 2527672652,
> 2527672850,
> 11646,
> 10094
> )
> Trace/BPT trap
>
> I hope someone could come to my aid!
> --
> ¶¨÷Èµ¶Àû
> Dimitri Bouniol
> <dimitri008...>
> http://www.appkainime.com/
>
Dimitri Bouniol Re: [SOLVED] Resizing a NSImage in a Cocoa command line tool Aug 06 2008, 01:48

Thank you very much - that worked perfectly.

On Aug 5, 2008, at 7:20 AM, Ken Ferry wrote:

> Hi Dimitri,
>
> The size property describes a more abstract size than pixels. If you
> set it, you're changing the DPI of the image you write out, not how
> many pixels it has.
>
> It's not safe in general to use AppKit from an app that cannot connect
> to the window server ¨C see
> <http://developer.apple.com/technotes/tn2005/tn2083.html#SECLIVINGDANGEROUSL
Y

> >.

> If you _can_ connect to the window server (i.e. this app isn't
> running headless on some machine where you aren't logged in to
> console) then you might just need to call NSApplicationLoad() in your
> main method. This function does some AppKit global setup that is
> normally done in NSApplicationMain, but NSApplicationLoad returns
> control to you.
>
> That said, if you can restrict yourself to NSBitmapImageRep, that
> should work without a windowserver connection. You can draw from your
> original bitmap into a new, smaller one like this:
>
> NSBitmapImageRep *newBitmap = [[NSBitmapImageRep alloc]
> initWithBitmapDataPlanes:NULL pixelsWide:pixelsWide
> pixelsHigh:pixelsHigh bitsPerSample:8 samplesPerPixel:4 hasAlpha:YES
> isPlanar:NO colorSpaceName:NSCalibratedRGBColorSpace
> bitmapFormat:NSAlphaFirstBitmapFormat bytesPerRow:0 bitsPerPixel:32];
> [NSGraphicsContext saveGraphicsState];
> [NSGraphicsContext setCurrentContext:[NSGraphicsContext
> graphicsContextWithBitmapImageRep:newBitmap]];
> [oldBitmap drawInRect:NSMakeRect(0,0,pixelsWide,pixelsHigh)];
> [NSGraphicsContext restoreGraphicsState];
>
> and write it to png data with -[NSBitmapImageRep
> representationUsingType:properties:].
>
> Also, the technote I referenced above doesn't mention that the
> CoreGraphics framework is daemon safe, which it is.
>
> -Ken
> Cocoa Frameworks
>
> On Tue, Aug 5, 2008 at 2:44 AM, Dimitri Bouniol <dimitri008...>
> wrote:
>> I have been trying relentlessly to resize a NSImage and save it as
>> a png
>> file in a command line tool (not a windowed app, but I included
>> AppKit to
>> get NSImage support). I tried using setScalesWhenResized along with
>> setSize
>> to no avail (image is not resized when saved), and I also tried
>> locking
>> focus to another image and drawing at a smaller size, but that simply
>> crashes with the following:
>>
>> 2008-08-03 20:49:40.127 imagecompressor[16757:10b] _NXCreateWindow:
>> error
>> setting window property (1002)
>> 2008-08-03 20:49:40.132 imagecompressor[16757:10b] _NXPlaceWindow:
>> error
>> setting window shape (1002)
>> 2008-08-03 20:49:40.132 imagecompressor[16757:10b]
>> _NSShapePlainWindow:
>> error setting window shape (1002)
>> 2008-08-03 20:49:40.144 imagecompressor[16757:10b]
>> PScurrentwindowbounds:
>> CGSGetWindowBounds returned error (1002)
>> Sun Aug 3 20:49:40 imagecompressor[16757] <Error>:
>> CGSImageDataLockDevice:
>> Bad device image source
>> Sun Aug 3 20:49:40 imagecompressor[16757] <Error>:
>> ripc_DrawWindowContents
>> - Cannot acquire window image
>> 2008-08-03 20:49:40.146 imagecompressor[16757:10b] *** -
>> [NSCachedImageRep
>> representationUsingType:properties:]: unrecognized selector sent to
>> instance
>> 0x116c30
>> 2008-08-03 20:49:40.146 imagecompressor[16757:10b] *** Terminating
>> app due
>> to uncaught exception 'NSInvalidArgumentException', reason: '***
>> -[NSCachedImageRep representationUsingType:properties:]: unrecognized
>> selector sent to instance 0x116c30'
>> 2008-08-03 20:49:40.146 imagecompressor[16757:10b] Stack: (
>> 2527650123,
>> 2500743419,
>> 2527679306,
>> 2527672652,
>> 2527672850,
>> 11646,
>> 10094
>> )
>> Trace/BPT trap
>>
>> I hope someone could come to my aid!

--
¶¨÷Èµ¶Àû
Dimitri Bouniol
<dimitri008...>
http://www.appkainime.com/

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Resizing a NSImage in a Cocoa command line tool

Cocoa - August 05, 2008