add brightness and contrast (#396)

* Imlib2 supports modifying gamma, brightness and contrast directly
  while sxiv only supports gamma. Makes sense to extend it to brightness
  and contrast as well.

* Since color corrections need to be aware of each other, they have been
  refactored into one centralized function.

* This also makes the code more hackable as it makes it easier to add
  more color correction functions without them interfering with each
  other.

Co-authored-by: 0ion9 <finticemo@gmail.com>
Co-authored-by: NRK <nrk@disroot.org>
Reviewed-on: https://codeberg.org/nsxiv/nsxiv/pulls/396
Reviewed-by: NRK <nrk@disroot.org>
Reviewed-by: TAAPArthur <taaparthur@noreply.codeberg.org>
Co-authored-by: Berke Kocaoğlu <kberke@metu.edu.tr>
Co-committed-by: Berke Kocaoğlu <kberke@metu.edu.tr>

1 files changed, 4 insertions, 0 deletions

diff --git a/commands.h b/commands.h
index c4c3973..76b1330 100644
--- a/commands.h
+++ b/commands.h
@@ -4,6 +4,8 @@
 
 /* global */
 bool cg_change_gamma(arg_t);
+bool cg_change_brightness(arg_t);
+bool cg_change_contrast(arg_t);
 bool cg_first(arg_t);
 bool cg_mark_range(arg_t);
 bool cg_n_or_last(arg_t);
@@ -47,6 +49,8 @@ bool ct_select(arg_t);
 #ifdef INCLUDE_MAPPINGS_CONFIG
 /* global */
 #define g_change_gamma { cg_change_gamma, MODE_ALL }
+#define g_change_brightness { cg_change_brightness, MODE_ALL }
+#define g_change_contrast { cg_change_contrast, MODE_ALL }
 #define g_first { cg_first, MODE_ALL }
 #define g_mark_range { cg_mark_range, MODE_ALL }
 #define g_n_or_last { cg_n_or_last, MODE_ALL }