From 3a5dd80d20f43626dab37a95d356541af2ac09a9 Mon Sep 17 00:00:00 2001
From: Alexander Orzechowski <alex@ozal.ski>
Date: Sat, 24 Aug 2024 12:57:21 -0400
Subject: [PATCH] render/color: Add COLOR_TRANSFORM_LUT_3x1D type

---
 include/render/color.h | 38 ++++++++++++++++++++++++++++++++++++++
 render/color.c         | 12 ++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/include/render/color.h b/include/render/color.h
index 4ab587be1..e18177c38 100644
--- a/include/render/color.h
+++ b/include/render/color.h
@@ -7,6 +7,7 @@
 enum wlr_color_transform_type {
 	COLOR_TRANSFORM_SRGB,
 	COLOR_TRANSFORM_LUT_3D,
+	COLOR_TRANSFORM_LUT_3x1D,
 };
 
 struct wlr_color_transform {
@@ -37,6 +38,36 @@ struct wlr_color_transform_lut3d {
 	size_t dim_len;
 };
 
+/**
+ * This is a color transform that is specified by three seperate ramps that
+ * modify the RGB values individually. This means that this color transform type
+ * cannot be used to create a transform that can infruence color channels
+ * depending on the values of other color channels.
+ *
+ * This color transform is modeled off of the wlr-gamma-control-unstable-v1
+ * wayland protocol.
+ *
+ * The memory layout of this type requires that the r, g, b color channel ramps
+ * are inline in memory. A ramp value can be retrieved from memory:
+ *
+ *     offset = dim_len * rgb_channel_index + ramp_index
+ *
+ * This is an offset into the `r` pointer and can be used to retrieve the ramps
+ * from the other channels as the ramps are linear in memory. The three pointers
+ * are given for convenience.
+ *
+ * Note that when freeing the color transform, only the `r` channel is freed as
+ * a it's expected that a single malloc will allocate all three channels at once.
+ */
+struct wlr_color_transform_lut3x1d {
+	struct wlr_color_transform base;
+
+	uint16_t *r;
+	uint16_t *g;
+	uint16_t *b;
+	size_t ramp_size;
+};
+
 /**
  * Gets a wlr_color_transform_lut3d from a generic wlr_color_transform.
  * Asserts that the base type is COLOR_TRANSFORM_LUT_3D
@@ -44,4 +75,11 @@ struct wlr_color_transform_lut3d {
 struct wlr_color_transform_lut3d *wlr_color_transform_lut3d_from_base(
 	struct wlr_color_transform *tr);
 
+/**
+ * Gets a wlr_color_transform_lut3x1d from a generic wlr_color_transform.
+ * Asserts that the base type is COLOR_TRANSFORM_LUT_3x1D
+ */
+struct wlr_color_transform_lut3x1d *wlr_color_transform_lut3x1d_from_base(
+	struct wlr_color_transform *tr);
+
 #endif
diff --git a/render/color.c b/render/color.c
index 9f8d76b06..403a6532b 100644
--- a/render/color.c
+++ b/render/color.c
@@ -23,6 +23,11 @@ static void color_transform_destroy(struct wlr_color_transform *tr) {
 			wlr_color_transform_lut3d_from_base(tr);
 		free(lut3d->lut_3d);
 		break;
+	case COLOR_TRANSFORM_LUT_3x1D:;
+		struct wlr_color_transform_lut3x1d *lut3x1d =
+			wlr_color_transform_lut3x1d_from_base(tr);
+		free(lut3x1d->r);
+		break;
 	}
 	wlr_addon_set_finish(&tr->addons);
 	free(tr);
@@ -50,3 +55,10 @@ struct wlr_color_transform_lut3d *wlr_color_transform_lut3d_from_base(
 	struct wlr_color_transform_lut3d *lut3d = wl_container_of(tr, lut3d, base);
 	return lut3d;
 }
+
+struct wlr_color_transform_lut3x1d *wlr_color_transform_lut3x1d_from_base(
+		struct wlr_color_transform *tr) {
+	assert(tr->type == COLOR_TRANSFORM_LUT_3x1D);
+	struct wlr_color_transform_lut3x1d *lut = wl_container_of(tr, lut, base);
+	return lut;
+}