Blit (ComputerCraft)

-- pastebin get bvx6Tipk blit

-- Plays animations.
-- After loading a GIF and processing it, saves the result so as to take
-- less disk space and reduce load times for subsequent playbacks.

local timePerImage = 30

local function loadAPI(API, paste)
    if not _G[API] then
        if not (fs.exists(API) or fs.exists(shell.resolve(API))) then
            shell.run("pastebin get " .. paste .. " " .. API)
            os.loadAPI(shell.resolve(API))
        else os.loadAPI(fs.exists(API) and API or shell.resolve(API)) end
    end
end

loadAPI("bbpack",  "cUYTGbpb")
loadAPI("GIF",     "5uk9uRjC")
loadAPI("blittle", "ujchRSnU")

local GIFlist, BLTlist = fs.list(shell.resolve("")), {}

for i = #GIFlist, 1, -1 do
    local ext = GIFlist[i]:sub(-4):lower()
    if ext == ".blt" then
        BLTlist[#BLTlist + 1] = table.remove(GIFlist, i)
    elseif ext ~= ".gif" then
        table.remove(GIFlist, i)
    end
end

local mon = peripheral.find("monitor") or term
if mon.setTextScale then mon.setTextScale(0.5) end
local MonSizeX, MonSizeY = mon.getSize()
MonSizeX, MonSizeY = MonSizeX * 2, MonSizeY * 3

parallel.waitForAll(
    function()
        if #BLTlist == 0 then os.pullEvent("madeBLT") end

        while true do
            local img = blittle.load(shell.resolve(BLTlist[math.random(#BLTlist)]))

            if img.pal and GIF.applyPalette then GIF.applyPalette(img, mon) end
            mon.clear()

            local x, y = math.floor((MonSizeX / 2 - img[1].width) / 2) + 1, math.floor((MonSizeY / 3 - img[1].height) / 2) + 1
            if #img == 1 then img[1].delay = timePerImage end

            repeat
                local frameTimer, nextTimer, curFrame = os.startTimer(0), os.startTimer(timePerImage), 1

                while true do
                    local event, par1 = os.pullEvent()

                    if event == "timer" then
                        if par1 == frameTimer then
                            local frame = img[curFrame]
                            blittle.draw(type(frame[1]) == "number" and img[frame[1]] or frame, x, y, mon)
                            frameTimer = os.startTimer(img[curFrame].delay)

                            if curFrame == #img then
                                if not nextTimer then break end
                                curFrame = 1
                            else curFrame = curFrame + 1 end
                        elseif par1 == nextTimer then
                            nextTimer = false
                        end
                    elseif event == "char" or event == "mouse_click" or event == "monitor_touch" then
                        break
                    end
                end
            until #BLTlist > 1
        end
    end,

    function()
        for i = 1, #GIFlist do
            local file = GIFlist[i]

            write(file)

            local ok, img = pcall(GIF.loadGIF, shell.resolve(file), term.setPaletteColour and true)

            if ok then
                if MonSizeX < img.width or MonSizeY < img.height then
                    if MonSizeX < math.floor(MonSizeY / img.height * img.width) then
                        img = GIF.resizeGIF(img, MonSizeX)
                    else
                        img = GIF.resizeGIF(img, nil, MonSizeY)
                    end
                end

                img = blittle.shrinkGIF(img)

                print(" - writing...")
                fs.delete(shell.resolve(file))
                file = file:sub(1, -5) .. ".blt"
                blittle.save(img, shell.resolve(file))
                os.queueEvent("madeBLT")
                BLTlist[#BLTlist + 1] = file
            else
                printError(img)
            end
        end

        print("All GIFs processed.")
        GIFlist = nil
    end
)