Re: Scaling an NSImage makes the edges disappear.
Re: Scaling an NSImage makes the edges disappear.
- Subject: Re: Scaling an NSImage makes the edges disappear.
- From: "David Springer" <email@hidden>
- Date: Thu, 21 Aug 2008 14:34:44 -0600
Hi Ken,
I can build a test app - give me a couple hours to put it together.
As for antialiasing, I thought that might be the problem, but I set
the image interpolation on the graphics context to
NSImageInterpolationNone and get the same results.
I am on Leopard 10.5.4 (this all has to work on Tiger, as well though).
Thanks
- Dave.S
On Thu, Aug 21, 2008 at 2:26 PM, Ken Ferry <email@hidden> wrote:
> Hi David,
>
> Could you post a complete test app? There's nothing in what you've
> posted that looks problematic[1]. Also, what OS are you working on?
>
> -Ken
>
> [1]: well, except maybe that you're likely to see antialiasing on the edges.
> Your problem looks more severe than antialiasing, though.
>
> On Thu, Aug 21, 2008 at 12:47 PM, David Springer <email@hidden> wrote:
>> Folks,
>>
>> For some reason, I am not able to figure this out. I want to draw a
>> scaled NSImage, but the edges of the image are not drawn, it seems
>> like the resizing actually clips the image.
>>
>> I have an NSBitmapImageRep created from some data. I then create the
>> NSImage like this:
>>
>> NSImage *image = [[NSImage alloc] initWithSize:NSMakeSize([myBitmap
>> pixelsWide], [myBitmap pixelsHigh]);
>> [image addRepresentation:myBitmap];
>> [image setScalesWhenResized:YES];
>>
>> // Figure out the new image size so that it is proportionally scaled
>> by |scaleFactor|.
>> NSSize scaledSize = ProportionallyScale([image size], scaleFactor);
>> [image drawInRect:NSMakeRect((kTileImageSize - scaledSize.width) * 0.5,
>> (kTileImageSize - scaledSize.height) * 0.5,
>> scaledSize.width,
>> scaledSize.height)
>> fromRect:NSZeroRect
>> operation:NSCompositeSourceOver
>> fraction:1.0];
>>
>> This sometimes works (that is, the entire original image is visible).
>> But more often than not, the edges of the original image are not
>> drawn. See the screen shots for a picture of what I get.
>>
>> What am I doing wrong here? I have scoured the archives, I have tried
>> things like making sure scaledSize has integer values, I have even
>> done crazy things like add one to the height just to see what would
>> happen. Note that if I write out the TIFFRepresentation of |image|
>> (both before and after) the entire image gets into the file (that is,
>> the edges are not clipped).
>>
>> In the attached picture, the top tile is correct (you see all the
>> black edges), the bottom two tiles are incorrect (not all the black
>> edges are visible).
>>
>> Help?
>> Thanks!
>> - Dave.S
>>
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