From 0e8a501049e9b77f612abfb3c2327a0a6ae83157 Mon Sep 17 00:00:00 2001
From: Jon Michael Aanes <jonjmaa@gmail.com>
Date: Sun, 30 Jun 2019 01:26:42 +0200
Subject: [PATCH] More flexibility for `apply_color_map_to_image_data`.

---
 init.lua | 67 +++++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 54 insertions(+), 13 deletions(-)

diff --git a/init.lua b/init.lua
index 7fe60d8..6639407 100644
--- a/init.lua
+++ b/init.lua
@@ -77,9 +77,33 @@ end
 
 palette_swap.get_palette_from_image_data  = get_palette_of_image_data
 
-function palette_swap.apply_color_map_to_image_data (img_data, map_fn)
+local function concat_functions (first_fn, ...)
+    --
+    local funcs = {first_fn, ...}
+
+    -- Identity function.
+    if #funcs == 0 then
+        return function (...) return ... end
+
+    -- Only one function
+    elseif #funcs <= 1 then
+        return first_fn
+    end
+
+    -- Generic
+    return function (...)
+        local val = {...}
+        for i = 1, #funcs do
+            val = {funcs[i](unpack(val))}
+        end
+        return unpack(val)
+    end
+end
+
+function palette_swap.apply_color_map_to_image_data (img_data, ...)
     assert(img_data)
-    assert(type(map_fn) == 'function')
+    --
+    local map_fn  =  concat_functions(...)
     --
     return apply_change_palette(img_data, change_palette_from_map(map_fn, get_palette_of_image_data(img_data)))
 end
@@ -106,26 +130,43 @@ function palette_swap.color_map.switch_channel (mode)
     return loadstring (func_s)()
 end
 
-function palette_swap.color_map.rotate_hue (rad)
+local function load_colors ()
 
     -- Only need to import colors when needed
     local colors = require 'colors'
     assert(type(colors) == 'table')
     assert(type(colors.rgb1_to_rgb255) == 'function')
-    assert(type(colors.rgb_to_hsl) == 'function')
-    assert(type(colors.hsl_to_rgb1) == 'function')
+    assert(type(colors.rgb_to_hsl)     == 'function')
+    assert(type(colors.hsl_to_rgb1)    == 'function')
 
-    -- Create function
-    return function (r, g, b)
-        local hsl = colors.rgb_to_hsl(colors.rgb1_to_rgb255(r, g, b))
-        --
-        hsl[1] = (hsl[1] + rad) % 1
-        --
-        local rgb1   = colors.hsl_to_rgb1(hsl)
-        return unpack(rgb1)
+    function palette_swap.color_map.increase_saturation (amount)
+        -- Create function
+        return function (r, g, b)
+            local hsl = colors.rgb_to_hsl(colors.rgb1_to_rgb255(r, g, b))
+            --
+            hsl[2] = math.min(1, math.max(0, hsl[2] + amount))
+            --
+            return unpack(colors.hsl_to_rgb1(hsl))
+        end
+    end
+
+    function palette_swap.color_map.rotate_hue (rad)
+        return function (r, g, b)
+            local hsl = colors.rgb_to_hsl(colors.rgb1_to_rgb255(r, g, b))
+            --
+            hsl[1] = (hsl[1] + rad) % 1
+            --
+            return unpack(colors.hsl_to_rgb1(hsl))
+        end
     end
 end
 
+for _, key in ipairs {'rotate_hue', 'increase_saturation'} do
+    palette_swap.color_map[key]  =  function (...)
+        load_colors()
+        return palette_swap.color_map[key](...)
+    end
+end
 
 --------------------------------------------------------------------------------
 -- Return