Add Random Pixels example

Author: dacap

Random Pixels.lua

@@ -0,0 +1,69 @@
+----------------------------------------------------------------------
+-- Randomize pixels of the active cel/image.
+--
+-- It works for all color modes (RGB/GRAY/INDEXED).
+----------------------------------------------------------------------
+
+if app.apiVersion < 1 then
+  return app.alert("This script requires Aseprite v1.2.10-beta3")
+end
+
+local cel = app.activeCel
+if not cel then
+  return app.alert("There is no active image")
+end
+
+math.randomseed(os.time())
+
+-- The best way to modify a cel image is to clone it (the new cloned
+-- image will be an independent image, without undo information).
+-- Then we can change the cel image generating only one undoable
+-- action.
+local img = cel.image:clone()
+
+-- For RGB mode we change the RGB values keeping the Alpha value intact
+if img.colorMode == ColorMode.RGB then
+  local rgba = app.pixelColor.rgba
+  local rgbaA = app.pixelColor.rgbaA
+  for it in img:pixels() do
+    it(rgba(math.random(256)-1,
+            math.random(256)-1,
+            math.random(256)-1, rgbaA(it())))
+  end
+-- For GRAY mode we change the grayscale value keeping the Alpha value intact
+elseif img.colorMode == ColorMode.GRAY then
+  local graya = app.pixelColor.graya
+  local grayaA = app.pixelColor.grayaA
+  for it in img:pixels() do
+    it(graya(math.random(256)-1, grayaA(it())))
+  end
+-- For INDEXED mode we change the color index of non-transparent
+-- pixels with a ranom index that is not transparent too
+elseif img.colorMode == ColorMode.INDEXED then
+  local n = #app.activeSprite.palettes[1]
+  if n > 2 then
+    local mask = img.spec.transparentColor
+    for it in img:pixels() do
+      -- For pixels that are not the mask
+      if it() ~= mask then
+        -- We try to put a new index value that is not the mask color
+        -- (for transparent layers, because the background layer can
+        -- have the mask color as a solid color)
+        local c = math.random(n)-1
+        if cel.layer.isTransparent then
+          while c == mask do
+            c = math.random(n)-1
+          end
+        end
+        it(c) -- Here we set the pixel value
+      end
+    end
+  end
+end
+
+-- Here we change the cel image, this generates one undoable action
+cel.image = img
+
+-- Here we redraw the screen to show the modified pixels, in a future
+-- this shouldn't be necessary, but just in case...
+app.refresh()