OpenEuphoria

Re: Masking

• Posted by jiri babor <jbabor at paradise.net.nz> Nov 08, 2003
• 695 views

Stewart,

if you are after a purely Euphorian solution, have a look at the following
routine that I wrote many years ago. It may not be good enough for whatever
you are doing, but give it a try. In comparison with yours, it has three
common, often quite significant optimizations:

    1. reduced indexing level
    2. a whole *run* of pixels is written instead of each one separately
    3. unnecessary addition of 'y' coordinates is eliminated.

jiri

global procedure merge_image(
    sequence xy,            -- top left corner
    sequence image,         -- 2-d image sequence
    integer c)              -- transparent cell color index

    --  display 2-d sequence image at point x,y
    --  image cells of color c are considered transparent

    sequence row
    integer f,k,w,x,y

    x = xy[1]-1
    y = xy[2]
    for i=1 to length(image) do
        row=image[i]
        w = length(row)
        f=0                 -- not in run
        for j=1 to w do
            if row[j]=c then
                if f then
                    pixel(row[k..j-1],{x+k,y})
                    f=0
                end if
            else
                if not f then
                    k=j
                    f=1
                end if
            end if
        end for
        if f then
            pixel(row[k..w],{x+k,y})
        end if
        y+=1
    end for
end procedure -- merge_image


----- Original Message ----- 
From: "Stewart MacKenzie-Leigh" <stewartml89 at msn.com>
To: <EUforum at topica.com>
Sent: 09 November 2003 8:30 AM
Subject: Masking


>
>
> Is there a fster way to display a bitmap on the screen without the pixels
> which are the mask color, other than plotting each color individually in a
> loop?
>
> this is the code im using at the moment:
>
> for y = 1 to length(img) do
>     for x = 1 to length(img[y]) do
>         if img[y][x] != MASK_COLOR then
>             pixel(img[y][x], {imgX + x, imgY + y})
>         end if
>     end if
> end for
>
> this is too slow for what i am doing.
>
>
> thanks in advance
>
> StewartML
>
>
>
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