Re: CILinearGradient and 10.5 mess

// return TRUE if we're using 10.4 behavor.

- (BOOL)linearGradient_10_4_Behavior

{

static BOOL checked = NO;

static BOOL behavior_10_4 = YES;

if ( !checked )

{

CIFilter *gradient_filter = [CIFilter filterWithName:@"CILinearGradient"];

[gradient_filter setValue:[CIVector vectorWithX:0 Y:0] forKey:@"inputPoint0"];

[gradient_filter setValue:[CIVector vectorWithX:32 Y:0] forKey:@"inputPoint1"];

[gradient_filter setValue:[[[CIColor alloc] initWithColor:[NSColor blueColor]] autorelease] forKey:@"inputColor0"];

[gradient_filter setValue:[[[CIColor alloc] initWithColor:[NSColor redColor]] autorelease] forKey:@"inputColor1"];

CIImage *ci_image = [gradient_filter valueForKey:@"outputImage"];

CIFilter *ci_crop = [CIFilter filterWithName:@"CICrop"];

[ci_crop setValue:ci_image forKey:@"inputImage"];

[ci_crop setValue:[CIVector vectorWithX:0 Y:0 Z:32 W:8] forKey:@"inputRectangle"];

CIImage *final_image = [ci_crop valueForKey:@"outputImage"];

NSImage *image = [[[NSImage alloc] initWithSize:NSMakeSize(32,8)] autorelease];

[image addRepresentation:[NSCIImageRep imageRepWithCIImage:final_image]];

NSBitmapImageRep *bitmap = [[[NSBitmapImageRep alloc] initWithData:[image TIFFRepresentation]] autorelease];

NSColor *color = [bitmap colorAtX:0 y:4];

float red, green, blue, alpha;

[color getRed:&red green:&green blue:&blue alpha:&alpha];

// should be blue. if it is not, then it is NOT the 10.4 (buggy) behavior.

if ( blue > red )

behavior_10_4 = NO;

checked = YES;

}

return behavior_10_4;

}

On Thu, Mar 20, 2008 at 4:57 PM, Adam R. Maxwell <email@hidden> wrote:

On Mar 20, 2008, at 4:07 PM, Chris Meyer wrote:
> > I don't know exactly what they assumed or how this was implemented,
> > but I do think that the behavior you're describing sounds like a bug
> > in CoreImage.
>
> At this point, fixing it is only going break any code that I write
> to work around it. Not a great situation. Maybe I'll just write code
> that makes a gradient, samples it, and chooses based on empirical
> evidence. Ugh!

FWIW, we noticed that the documented behavior was broken when 10.5
came out and worked around it using

if (floor(NSAppKitVersionNumber) > NSAppKitVersionNumber10_4) {
// assume gradients are in sensible order
}
else {
// assume gradients are in 10.4 order
}

If Apple fixes this to work as documented, it will probably break
numerous apps.

> > Most apps don't need to know what SDK they were built against; they
> > need to know what the current OS version is. That's what
> > NSAppKitVersionNumber is meant to provide - what version of AppKit
> are
> > you currently running against. It has _never_ been meant to indicate
> > what version of the SDK you linked against.
>
> OK. No reason to bang my head against a wall even though this
> behavior seems to be of limited usefulness. But it is what it is.

It's useful for cases like this, where functionality changes based on
framework version instead of linkage (as it was apparently supposed to).

--
adam

>
>
> On Thu, Mar 20, 2008 at 3:48 PM, Eric Schlegel <email@hidden>
> wrote:
>
> On Mar 20, 2008, at 3:45 PM, Chris Meyer wrote:
> > How would an application ever tell which SDK it was built against?
>
> Most apps don't need to know what SDK they were built against; they
> need to know what the current OS version is. That's what
> NSAppKitVersionNumber is meant to provide - what version of AppKit are
> you currently running against. It has _never_ been meant to indicate
> what version of the SDK you linked against.
>
> > Before you dismiss this message (Eric), I think the case in point is
> > how CILinearGradient works. It is NOT backwards compatible. The Core
> > Image guys probably (correctly) assumed that NSAppKitVersionNumber
> > would return the version of AppKit _linked_ against rather than
> > _available on the system_.
>
> I don't know exactly what they assumed or how this was implemented,
> but I do think that the behavior you're describing sounds like a bug
> in CoreImage.
>
> -eric
>
>

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References:
	>CILinearGradient and 10.5 mess (From: "Chris Meyer" <email@hidden>)
	>Re: CILinearGradient and 10.5 mess (From: Jack Small <email@hidden>)
	>Re: CILinearGradient and 10.5 mess (From: "Chris Meyer" <email@hidden>)
	>Re: CILinearGradient and 10.5 mess (From: Eric Schlegel <email@hidden>)
	>Re: CILinearGradient and 10.5 mess (From: "Chris Meyer" <email@hidden>)
	>Re: CILinearGradient and 10.5 mess (From: Eric Schlegel <email@hidden>)
	>Re: CILinearGradient and 10.5 mess (From: "Chris Meyer" <email@hidden>)
	>Re: CILinearGradient and 10.5 mess (From: "Adam R. Maxwell" <email@hidden>)