-- demo\rosetta\Image_convolution.exw
include pGUI.e

constant filters = {-- Emboss
                    {{-2.0, -1.0, 0.0},
                     {-1.0,  1.0, 1.0},
                     { 0.0,  1.0, 2.0}},
                    -- Sharpen
                    {{-1.0, -1.0, -1.0},
                     {-1.0,  9.0, -1.0},
                     {-1.0, -1.0, -1.0}},
                    -- Sobel_emboss
                    {{-1.0, -2.0, -1.0},
                     { 0.0,  0.0,  0.0},
                     { 1.0,  2.0,  1.0}},
                    -- Box_blur
                    {{ 1.0, 1.0, 1.0},
                     { 1.0, 1.0, 1.0},
                     { 1.0, 1.0, 1.0}},
                    -- Gaussian_blur
                    {{1,  4,  7,  4, 1},
                     {4, 16, 26, 16, 4},
                     {7, 26, 41, 26, 7},
                     {4, 16, 26, 16, 4},
                     {1,  4,  7,  4, 1}}}

function convolute(imImage img, integer fdx)
integer width = im_width(img),
        height = im_height(img)
sequence original = repeat(repeat(0,width),height),
         new_image,
         filter = filters[fdx]
integer fh = length(filter), hh=(fh-1)/2,
        fw = length(filter[1]), hw=(fw-1)/2,
        divisor = max(sum(filter),1)

    for y=height-1 to 0 by -1 do
        for x=0 to width-1 do
            original[height-y,x+1] = im_pixel(img, x, y)
        end for
    end for
    new_image = original

    for y=hh+1 to height-hh-1 do
        for x=hw+1 to width-hw-1 do
            sequence newrgb = {0,0,0}
            for i=-hh to +hh do
                for j=-hw to +hw do
                    newrgb = sq_add(newrgb,sq_mul(filter[i+hh+1,j+hw+1],original[y+i,x+j]))
                end for
            end for
            new_image[y,x] = sq_max(sq_min(sq_floor_div(newrgb,divisor),255),0)
        end for
    end for

    new_image = flatten(new_image) -- (as needed by IupImageRGB)
    Ihandle new_img = IupImageRGB(width, height, new_image)
    return new_img
end function

IupOpen()

constant w = machine_word(),
         TITLE = "Image convolution"
atom pError = allocate(w)
imImage im1 = imFileImageLoadBitmap("Quantum_frog.512.png",0,pError)

if im1=NULL then
    ?{"error opening image",peekNS(pError,w,1)}
    {} = wait_key()
    abort(0)
end if

Ihandle dlg,
        filter = IupList("DROPDOWN=YES, VALUE=1")

Ihandln image1 = IupImageFromImImage(im1),
        image2 = convolute(im1,1),
        label1 = IupLabel(),
        label2 = IupLabel()
IupSetAttributeHandle(label1, "IMAGE", image1)
IupSetAttributeHandle(label2, "IMAGE", image2)

function valuechanged_cb(Ihandle /*filter*/)
    IupSetAttribute(dlg,"TITLE","Working...")
    IupSetAttributeHandle(label2, "IMAGE", NULL)
    IupDestroy(image2)
    image2 = convolute(im1,IupGetInt(filter,"VALUE"))
    IupSetAttributeHandle(label2, "IMAGE", image2)
    IupSetAttribute(dlg,"TITLE",TITLE)
    IupRefresh(dlg)
    return IUP_DEFAULT
end function
IupSetCallback(filter,"VALUECHANGED_CB",Icallback("valuechanged_cb"))

IupSetAttributes(filter,"1=Emboss, 2=Sharpen, 3=\"Sobel emboss\", 4=\"Box_blur\", 5=Gaussian_blur")
IupSetAttributes(filter,"VISIBLEITEMS=6") -- (still dunno why this trick works)
dlg = IupDialog(IupVbox({filter,
                         IupFill(),
                         IupHbox({IupFill(),label1, label2,IupFill()}),
                         IupFill()}))
IupSetAttribute(dlg, "TITLE", TITLE)
IupCloseOnEscape(dlg)
IupShow(dlg)

IupMainLoop()
IupClose()