[vwnc] Epigent AlphaChannelImage

> Hi
>
> The Epigent package is easy to implement and  makes the toolbar look  
> a good deal better.
>
> However on OSX it does not produce the same effect.
>
>
> <Capturer1.PNG>              <capture2.png>
>
>
> Does anyone has dealt with this ?

> I looked at this problem using an example Thomas sent me. Using the
> image (provided as Smalltalk code) I reproduced the problem at 16 bit
> color depth at my PC. But using my own test image, the problem does
> not occur.
>
> To get my test image inspect: AlphaChannelImage iconExample16by16image
>
> Anyone having problems should probably look at this image and see if
> it displays ok. Note how the first top-left three pixels are Red,
> Green, and Blue. The PNG is attached.
>
> What I found is that Thomas' supplied a Depth32Image that uses a
> different palette than I use in my tests. Thomas' Depth32Image has
> this palette:
> (Graphics.FixedPalette
> redShift: 16 redMask: 255
> greenShift: 8 greenMask: 255
> blueShift: 0 blueMask: 255)
>
>
>
> While, my Depth32Image has this palette:
> (Graphics.FixedPalette
> redShift: 0 redMask: 255
> greenShift: 8 greenMask: 255
> blueShift: 16 blueMask: 255)
>
> Note how my palette shifts the RGB bits in increasing order; R is at
> bit position 0, G at 8, and B at 16. I am pretty sure this is causing
> the problems, but I have not looked into the details of the rendering
> code to confirm this. So there is a bug in the code, which I will look
> at later.
>
> The workaround is to always use a Depth32Image with the palette format
> I use in my examples. To create an image I do the following:
>
> - Edit the image in Paint.NET.
> - Save the image as PNG in 32 bit format.
> - Create the Depth32Image using class PNGImageReader. I use instance
> method #from: where the argument is the raw PNG image file as a
> Stream.
>
> See references to method  #iconExample16by16 for the details. Note how
> #iconExample16by16 answers only a ByteArray which is an exact copy of
> the bytes found in the PNG file I saved from the image editing
> program. This uses "Epigent File In Method". (
> http://www.cincomsmalltalk.com/publicRepository/Epigent%20File%20In%20Method(Bundle).html
> )
>
> Runar
>  
>
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>  

>
> Hi,
> Here is a small patch to be able to display incomplete images.
> AlphaChannelImage>>displayOn: aGraphicsContext at: aPoint
>
>             | toScreenImage rectangle  |
>
>             rectangle := aGraphicsContext clippingBounds moveBy:
> aGraphicsContext translation.
>             rectangle extent: self extent.
>
>             rectangle area positive ifFalse: [^self].
>
>             [toScreenImage := aGraphicsContext medium
> completeContentsOfArea:  (rectangle intersect: (0@0 extent:
> (aGraphicsContext medium extent)))]
>                         on: Error
>                         do: [:exception | ^self].
>             self displayOnImage: toScreenImage.
>             aGraphicsContext copyImage: toScreenImage to: aPoint
> ============
> Besides, I was not able to translate the palettes. I managed the mask by
> using png : I draw on cairo, then save as png bits, and reimport the result
> into an alphaChannelImage.
> Best regards
> Annick Fron

> AR 55950...
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf Of Henrik Johansen
> Sent: Wednesday, November 12, 2008 3:40 AM
> To: [hidden email]
> Subject: [vwnc] List vs OrderedCollection addLast:
>
> addLast: in List is implemented with a check if there's a need to grow,
> and a call to a privateAddLast:.
> In OrderedCollection, addLast: has the same structure, but no separate
> privateAddLast:.
> Instead it has a addLastNoCheck: which basically does the same thing as
> privateAddLast, but gets used by other methods than addLast:...
> Would it perhaps be a good idea to make these two methods work the same
> way?
> (ie: the List way, so in OrderedCollection rename addLastNoCheck: (or
> have it call privateAddLast: for compatability reasons), and have
> addLast: call it)
>
> Cheers,
> Henry
>
>  
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