[SOLVED]: Scaling an NSImage makes the edges disappear.
[SOLVED]: Scaling an NSImage makes the edges disappear.
- Subject: [SOLVED]: Scaling an NSImage makes the edges disappear.
- From: "David Springer" <email@hidden>
- Date: Thu, 21 Aug 2008 16:07:18 -0600
Ken,
I played around with this some more and I can get satisfactory results
by setting the image interpolation to NSImageInterpolationHigh, along
with making sure the dest size lies on integers. So it looks like I
was being bit by the default resampling method.
Thanks!
- Dave.S
On Thu, Aug 21, 2008 at 2:34 PM, David Springer <email@hidden> wrote:
> 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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