Re: Rendering big PDF into thumbnail bitmap - too blurry
Re: Rendering big PDF into thumbnail bitmap - too blurry
- Subject: Re: Rendering big PDF into thumbnail bitmap - too blurry
- From: "Oleg Krupnov" <email@hidden>
- Date: Wed, 24 Sep 2008 09:24:46 +0300
Eurica!
Two things were wrong:
1) There was a 0.5 pixel shift transform in my graphics context
imposed earlier in the stack. I use this to render bezier curves to
integer pixels, but for rendering bitmaps this offset needs to be
reset. After fixing this, however, there was still a little blur, but
way less than before.
2) I switched to using NSBitmapImageRep and +[NSGraphicsContext
graphicsContextWithBitmapImageRep] instead of the offscreen NSImage
and lockFocus. The latter is obsolete BTW. See the example:
http://developer.apple.com/documentation/Cocoa/Conceptual/CocoaDrawingGuide/Images/chapter_7_section_5.html#//apple_ref/doc/uid/TP40003290-CH208-BCICHFGA
(the "Drawing Directly to a Bitmap" section)
On Wed, Sep 24, 2008 at 8:48 AM, Oleg Krupnov <email@hidden> wrote:
> Yes, I tried it and it doesn't seem to have any effect.
>
> I have just double-checked regarding - [NSBitmapImageRep
> initWithFocusedViewRect]. For an experiment I saved the bitmap to a
> tiff file right after capturing the bitmap from screen, and it appears
> that the tiff is sharp, not blurry.
>
> It looks like the temporary thumbnail NSImage spoils the whole thing,
> but I can't figure out how to bypass it.
>
>
>
> On Wed, Sep 24, 2008 at 8:41 AM, Ken Thomases <email@hidden> wrote:
>> On Sep 24, 2008, at 12:33 AM, Oleg Krupnov wrote:
>>
>>> What could be the problem?
>>
>> Have you tried using -[NSGraphicsContext setImageInterpolation:] after
>> locking focus?
>>
>> Cheers,
>> Ken
>>
>>
>
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