[Gambas-user] Help for Image and Picture Colors

[tobias]

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