get introspection in lua

まず、リンクされている Darktable-xmp スクリプトと TODO リストで言及されている base64.lua ファイルを確認します。想定されているイントロスペクションインターフェースと、既存の Lua XML ライブラリが params をどのように読み書きすべきかを明確にします。合意されたスコープが定まり、圧縮値の処理とパラメータの自動読み書きが動作すれば完了です。

hello,

I was willing to write a lua script that changes some values (like exposure) in a bunch of pictures, I didn't found any.

I thougth to start writing a "tool" to do this, it is far from ready but i think it is a good starting point if someone would like to collaborate

I never used lua before so you may find some weird syntax, you can find the code here
https://repl.it/@VincenzoG/Darktable-xmp

example code:

require "tools/xmp_utility"

input = "0000000010c7babce0ce773e00004842000080c0"

exposure_params = {mode = 1, black = 2, exposure = 3, deflicker_percentile = 4, deflicker_target_level = 5}
exposure_table = dt_xmp_decode(input)

print(table.concat(exposure_table, " "))
print("Mode:", exposure_table[exposure_params.mode])
print("black:", exposure_table[exposure_params.black])
print("exposure:", exposure_table[exposure_params.exposure])
print("deflicker_percentile:", exposure_table[exposure_params.deflicker_percentile])
print("deflicker_target_level:", exposure_table[exposure_params.deflicker_target_level])

print(dt_xmp_encode(exposure_table))

exposure_table[exposure_params.exposure] = exposure_table[exposure_params.exposure] - 0.02
print("new exposure:", exposure_table[exposure_params.exposure])
print(dt_xmp_encode(exposure_table))

and it's output:

0 -0.022799998521805 0.24200010299683 50 -4
Mode:   0
black:  -0.022799998521805
exposure:   0.24200010299683
deflicker_percentile:   50
deflicker_target_level: -4
0000000010c7babce0ce773e00004842000080c0
new exposure:   0.22200010299683
0000000010c7babcfe53633e00004842000080c0

todo list:

• use compressed values: i found on google some part of code but i didn't integrated them, yet, you could find them in the base64.lua file
• automatically read/write the params: this can be done knowing the file path and using one of the already existing xml library for lua

If someone would like to collaborate tell me!