- giffer-test.gif (55.42 KiB) Viewed 1770 times
- giffer-opt-test.gif (2.68 KiB) Viewed 1770 times
- hard-test.gif (1.02 KiB) Viewed 1770 times
Here's the code. Hopefully someone finds it useful.
Code: Select all
-- Run the current selection for a given number of steps and
-- create an animated GIF file using the current layer's colors.
-- Based on giffer.pl by Tony Smith.
-- Conversion to Lua by Andrew Trevorrow and Scorbie.
-- Modified to encode only regions of change by blah 2020.
local g = golly()
local gp = require "gplus"
local getcell = g.getcell
local int = gp.int
local chr = string.char
local r = g.getselrect()
if #r == 0 then g.exit("There is no selection.") end
local x, y, width, height = table.unpack(r)
if width >= 65536 or height >= 65536 then
g.exit("The width and height of the selection must be less than 65536.")
end
-- get the parameters given last time
local inifilename = g.getdir("data").."giffer.ini"
local oldparams = "100 1"
local f = io.open(inifilename, "r")
if f then
oldparams = f:read("*l") or ""
f:close()
end
local prompt = [[
Enter the number of frames, and the pause
time between each frame (in centisecs):
]]
local answer = g.getstring(prompt, oldparams, "Create animated GIF")
local frames, pause = gp.split(answer)
-- validate given parameters
frames = frames or 100
pause = pause or 1
if not gp.validint(frames) then g.exit("Bad frames value: "..frames) end
if not gp.validint(pause) then g.exit("Bad pause value: "..pause) end
frames = tonumber(frames)
pause = tonumber(pause)
-- given parameters are valid so save them for next run
f = io.open(inifilename, "w")
if f then
f:write(answer)
f:close()
end
local depth = g.numstates()
local bitdepth = 0
while depth > 2^(bitdepth+1) do bitdepth = bitdepth + 1 end
local codesize = 2
if bitdepth > 0 then codesize = bitdepth + 1 end
--------------------------------------------------------------------------------
local function getrectdata(sx, sy, w, h)
local data = {}
for row = sy, sy+h-1 do
for col = sx, sx+w-1 do
data[#data+1] = chr( getcell(col, row) )
end
end
return data
end
--------------------------------------------------------------------------------
local function compress(data)
local t = {}
for i = 0, depth-1 do t[chr(i)] = i end
local curr = 2^codesize
local cc = 2^codesize
local used = cc + 1
local bits = codesize + 1
local size = codesize + 1
local mask = 2^size - 1
local output = ""
local code = ""
for _, nextch in ipairs(data) do
if t[code .. nextch] then
code = code .. nextch
else
used = used + 1
t[code .. nextch] = used
curr = curr + (t[code] << bits)
bits = bits + size
while bits >= 8 do
output = output .. chr(curr & 255)
curr = curr >> 8
bits = bits - 8
end
if used > mask then
if size < 12 then
size = size + 1
mask = mask*2 + 1
else
curr = curr + (cc << bits)
bits = bits + size
while bits >= 8 do
output = output .. chr(curr & 255)
curr = curr >> 8
bits = bits - 8
end
-- reset t
t = {}
for j = 0, depth-1 do t[chr(j)] = j end
used = cc + 1
size = codesize + 1
mask = 2^size - 1
end
end
code = nextch
end
end
curr = curr + (t[code] << bits)
bits = bits + size
while bits >= 8 do
output = output .. chr(curr & 255)
curr = curr >> 8
bits = bits - 8
end
output = output .. chr(curr)
local subbed = ""
while #output > 255 do
subbed = subbed .. chr(255) .. output:sub(1,255)
output = output:sub(256)
end
return subbed .. chr(#output) .. output .. chr(0)
end
--------------------------------------------------------------------------------
-- This function packs a list of +ve integers into a binary string using
-- little-endian ordering. The format parameter is a string composed of
-- ASCII digits which specify the size in bytes of the corresponding value.
-- Based on code at http://lua-users.org/wiki/ReadWriteFormat.
local function mypack(format, ...)
local result = ""
local values = {...}
for i = 1, #format do
local size = tonumber(format:sub(i,i))
local value = values[i]
local str = ""
for j = 1, size do
str = str .. chr(value % 256)
value = math.floor(value / 256)
end
result = result .. str
end
return result
end
--------------------------------------------------------------------------------
-- For information on GIF format:
-- http://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
local function savegiffile(gifpath)
local header = "GIF89a"
local screendesc = mypack("22111", width, height, 0xF0 + bitdepth, 0, 0)
local colortable = ""
for state = 0, depth-1 do
local s, r, g, b = table.unpack(g.getcolors(state))
colortable = colortable .. mypack("111", r, g, b)
end
local fullength = 6 * 2^bitdepth
while #colortable < fullength do
colortable = colortable .. mypack("111", 0, 0, 0)
end
-- this application extension allows looping
local applicext = "\x21\xFF\x0BNETSCAPE2.0" .. mypack("1121", 3, 1, 0, 0)
local controlext = "\x21\xF9" .. mypack("11211", 4, 4, pause, 0, 0)
local imagedesc = "," .. mypack("222211", 0, 0, width, height, 0, codesize)
local prev_data = getrectdata(x,y,width,height) -- whole selection
local gif = io.open(gifpath,"wb")
if not gif then g.exit("Unable to create GIF file: "..gifpath) end
gif:write(header)
gif:write(screendesc)
gif:write(colortable)
gif:write(applicext)
-- Write first frame
gif:write(controlext)
gif:write(imagedesc)
gif:write(compress(prev_data))
for f = 2, frames do
-- Write the data for this frame
g.step()
g.update()
-- Determine bounding box of area of change
local leftlim, rightlim, toplim, botlim=x+width,x,y+height,y
for row = 1, height do
local absy = y+row-1
for col = 1, width do
local absx = x+col-1
if chr(getcell(absx,absy)) ~= prev_data[(row-1)*width+col] then
if leftlim >absx then leftlim =absx end
if rightlim<absx then rightlim=absx end
if toplim >absy then toplim =absy end
if botlim <absy then botlim =absy end
end
end
end
local framewidth = (rightlim-leftlim)+1
local frameheight = (botlim-toplim)+1
gif:write(controlext)
if framewidth < 1 then -- Nothing changed; null frame.
leftlim, rightlim = 0, 0
framewidth, frameheight = 1, 1
end
-- Image descriptor:
gif:write(","..mypack("222211",leftlim-x,toplim-y,
framewidth,frameheight,0,codesize))
gif:write(compress(getrectdata(leftlim,toplim,framewidth,frameheight)))
g.show("Frame: "..f.."/".. frames)
prev_data = getrectdata(x,y,width,height)
end
gif:write("\x3B")
gif:close()
g.show("GIF animation saved in "..gifpath)
end
--------------------------------------------------------------------------------
-- set initial directory for the save dialog
local initdir = g.getdir("app")
local savedirfile = g.getdir("data").."gifdir.ini"
local f = io.open(savedirfile, "r")
if f then
initdir = f:read("*l") or ""
f:close()
end
-- remove any existing extension from layer name and append .gif
local initfile = gp.split(g.getname(),"%.")..".gif"
-- prompt for file name and location
local gifpath = g.savedialog("Save as GIF file", "GIF (*.gif)|*.gif",
initdir, initfile)
if #gifpath == 0 then g.exit() end
-- save directory for next time
f = io.open(savedirfile, "w")
if f then
local pathsep = g.getdir("app"):sub(-1)
f:write(gifpath:gsub("[^"..pathsep.."]+$",""))
f:close()
end
savegiffile(gifpath)