[Gambas-user] Help for Image and Picture Colors

[Benoît Minisini]

Le 06/02/2012 21:19, tobias a écrit :
> hi,
>
> Benoît Minisini wrote:
>> Le 04/02/2012 01:19, tobias a écrit :
>>> On 04.02.2012 01:12, tobias wrote:
>>>> Hi,
>>>>
>>>> I really need help. There's a lot of work with colors in Images and
>>>> Pictures in a project and between these classes. This is generally
>>>> speaking as follows: I have a class which has an 8*8px Image which is
>>>> manipulated (due to the easy of accessing pixels directly). Using a
>>>> property of my class, I provide access to a scaled version of the Image
>>>> as a Picture (which is created when requested). So I do some things and
>>>> when manually resizing the Image to get the prototype of the Picture to
>>>> return (it is needed as bigger version of the Image without
>>>> anti-aliasing, I don't get this result with Image.Stretch(), and doing
>>>> it manually is not a problem) there seem to appear problems with
>>>> transparency. I read that Pictures do not have an alpha channel and I
>>>> noticed that colors from the ColorChooser or Color class are given with
>>>> alpha channel set to 0x00 which will be transparent for the Image
>>>> class... so I tried adding&Hff000000&    to whatever color is assigned to
>>>> any pixel in the 8*8px Image or not to do it and some other experiments
>>>> but nothing worked on the entire project. there's always something
>>>> transparent or black or whatever. I really go nuts with this. Anyone to
>>>> my rescue?
>>>>
>>>> Regards,
>>>> Tobi
>>> wait a minute. I forgot to say that I don't even need the transparency
>>> feature of the Image class. I only use Image - as I said - because of
>>> Image[x, y] pixel access. For the meantime - or as a final solution?
>>> there may be a lot of those accesses and I thought using Image[x, y]
>>> will be the most efficient way to go - I switch to using an 8*8px
>>> Picture and Draw.Pixel() instead but I would really appreciate anyone
>>> clarify this topic to me.
>>>
>>
>> I understand nothing. Maybe because I'm a little sick, but if you can be
>> clearer...
>>
>
> it's a messy explanation, i just recalled too...
>
> the situation is as follows: i have a class that takes care of designing
> a picture for me according to user input. because of the ease of
> accessing pixels with the image class i took an image behind the scenes
> but it has to be converted to a picture for display in a PictureBox at
> the front end. moreover it has to be resized which i do manually and is
> no big deal for my format. i used to import pictures and images into the
> class, etc. which overall introduces as big back and forth of image<->
> picture conversion, resizing, etc.
> the problem first came up when i incorporated palettes created by
> another program and stored in binary files. i noticed that these were in
> ARGB format with the A component set to 0x00 all the time (colors came
> from a ColorChooser, later i noticed that the constants in the Color
> class do likewise). while this works (color is displayed) when drawing
> it to a picture, it doesn't when writing it to an image pixel. i tried
> conversion functions and everything that came in my mind.
> at the end i rewrote the class to use pictures. those pictures are
> created with the Transparent = False instanciation parameter. from those
> i can derive Picture.Image on which i operate to speed things up.
> this is sort of solved and the program works fine now.
>
> i seem to repress the memory of what i tried (pathetic programmer's
> brain :) ) but i can tell that nothing worked on the entire project
> (which was certainly a fault due to my quick fixes or project
> infrastructure) but to clarify things:
> it resulted in transparency in all kinds of places in the whole program
> originally introduced by reading colors from standard components that
> had their alpha channel zeroed which according to the docs signaled the
> image class that this color is fully transparent.
>
> i hope it didn't get as complicated but recalling the situation pointed
> me to the fact that actually i do not know why it is working now (seems
> to rely on the Transparent = False picture instanciation?)...
>
> regards,
> tobi
>

Mff... If you need to create a Picture, start from an Image, and convert 
it to a Picture at the last step. Do not use the Transparent property of 
Pictures.

As for transparency: it is inverted between pixels in memory and Gambas 
color values. If you use the Image class and the [] operator, then this 
is taken into account transparently.

This is all I can say: I hope it will help you!

-- 
Benoît Minisini