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<  Advanced Erlang/OTP  ~  SetPixel or BitBlt equivalent
viovanov
Posted: Fri Apr 25, 2008 6:14 pm Reply with quote
Joined: 25 Apr 2008 Posts: 3 Location: Arad, Romania
I am developing some code that will plot a function that has complex arguments and results. So i reprezent the result by using colors:
http://www.kfunigraz.ac.at/imawww/vqm/pages/colormap.html
Somthing like that.
The code works perfectly, but I'm drawing the dots on the plot using 2x2 rectangles (the gs module).
This is obviously EXTREMELY slow Mad (i only wrote that code for testing purposes).
Now I'd like to finish the project and plot the fucntion as it should be plotted (fast Cool ).

So I was wondering if any of you guys know of a way to mimic what SetPixel or BitBlt do.

I tried using esdl, but the thing won't work (I'm using the eclipse IDE and the code is filled with errors).

Any thoughts are appreciated.
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viovanov
Posted: Fri Apr 25, 2008 6:30 pm Reply with quote
Joined: 25 Apr 2008 Posts: 3 Location: Arad, Romania
PS

I'm on Windows
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viovanov
Posted: Tue Apr 29, 2008 7:58 pm Reply with quote
Joined: 25 Apr 2008 Posts: 3 Location: Arad, Romania
So...
After no replies I tried searching for altenate solutions and I came up with this: i'm generating PNG files using the EGD library:
Code:
   

    Values = zeta:getZetaValues(X_Min, X_Max, Y_Min, Y_Max, Increment, false),
   
    Im = egd:create(round((X_Max - X_Min) / Increment),
        round((Y_Max - Y_Min) / Increment)),
   
    lists:map(
        fun({{X, Y},{A, B}}) ->
            egd:rectangle(Im,
                {round((X - X_Min)/Increment), round((Y - Y_Min)/Increment)},
                {round((X - X_Min)/Increment), round((Y - Y_Min)/Increment)},
                egd:color(fn:color_c({A, B})))
        end, Values),

    egd:save(egd:render(Im, png), string:concat(string:concat("test", integer_to_list(Index)), ".png"))


This is really fast, plus I'll be able to export the plots with no extra code. There is a problem though: I need to load the PNG(s) in the window generated using GS.

Any ideeas on how to do that?  Question

Thanks,Vlad
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