fosphor/gl_cmap_gen: Add new function to generate GL colormap from a PNG

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

3 files changed, 95 insertions, 2 deletions

diff --git a/lib/fosphor/Makefile b/lib/fosphor/Makefile
index a8fb3bb..051afd4 100644
--- a/lib/fosphor/Makefile
+++ b/lib/fosphor/Makefile
@@ -1,7 +1,7 @@
 UNAME=$(shell uname)
 CC=gcc
-CFLAGS=-Wall -Werror -O2 `pkg-config freetype2 glfw3 --cflags` -g
-LDLIBS=`pkg-config freetype2 glfw3 --libs` -lm
+CFLAGS=-Wall -Werror -O2 `pkg-config freetype2 glfw3 libpng --cflags` -g
+LDLIBS=`pkg-config freetype2 glfw3 libpng --libs` -lm
 ifneq ($(AMDAPPSDKROOT), )
 CFLAGS+=-I$(AMDAPPSDKROOT)/include
 endif
diff --git a/lib/fosphor/gl_cmap_gen.c b/lib/fosphor/gl_cmap_gen.c
index 2d0c35c..4bc21f8 100644
--- a/lib/fosphor/gl_cmap_gen.c
+++ b/lib/fosphor/gl_cmap_gen.c
@@ -27,10 +27,16 @@
  *  \brief OpenGL color map generators
  */
 
+#include <errno.h>
 #include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
 #include <math.h>
 
+#include <png.h>
+
 #include "gl_cmap_gen.h"
+#include "resource.h"
 
 
 static void
@@ -128,6 +134,33 @@ _set_rgba_from_hsv(uint32_t *rgba, float h, float s, float v)
 }
 
 
+static inline uint32_t
+_rgba_interpolate(uint32_t *rgba, int sz, int p, int N)
+{
+	int pos_i = (p * (sz-1)) / (N-1);
+	int pos_f = (p * (sz-1)) - (pos_i * (N-1));
+	uint32_t vl, vh, vf = 0;
+	int i;
+
+	if (pos_f == 0)
+		return rgba[pos_i];
+
+	vl = rgba[pos_i];
+	vh = rgba[pos_i+1];
+
+	for (i=0; i<4; i++)
+	{
+		uint32_t nv =
+			((vl >> (8 * i)) & 0xff) * ((N-1) - pos_f) +
+			((vh >> (8 * i)) & 0xff) * pos_f;
+
+		vf |= ((nv / (N-1)) & 0xff) << (8 * i);
+	}
+
+	return vf;
+}
+
+
 int
 fosphor_gl_cmap_histogram(uint32_t *rgba, int N, void *arg)
 {
@@ -179,4 +212,63 @@ fosphor_gl_cmap_waterfall(uint32_t *rgba, int N, void *arg)
 	return 0;
 }
 
+int
+fosphor_gl_cmap_png(uint32_t *rgba, int N, void *arg)
+{
+	const char *rsrc_name = arg;
+	png_image img;
+	const void *png_data = NULL;
+	void *png_rgba = NULL;
+	int png_len, i, rv;
+
+	/* Grab the file */
+	png_data = resource_get(rsrc_name, &png_len);
+	if (!png_data)
+		return -ENOENT;
+
+	/* Read PNG */
+	memset(&img, 0x00, sizeof(img));
+	img.version = PNG_IMAGE_VERSION;
+
+	rv = png_image_begin_read_from_memory(&img, png_data, png_len);
+	if (!rv) {
+		rv = -EINVAL;
+		goto error;
+	}
+
+	img.format = PNG_FORMAT_RGBA;
+
+	png_rgba = malloc(sizeof(uint32_t) * img.width * img.height);
+	if (!png_rgba) {
+		rv = -ENOMEM;
+		goto error;
+	}
+
+	rv = png_image_finish_read(&img,
+		NULL,				/* background */
+		png_rgba,			/* buffer */
+		sizeof(uint32_t) * img.width,	/* row_stride */
+		NULL				/* colormap */
+	);
+	if (!rv) {
+		rv = -EINVAL;
+		goto error;
+	}
+
+	/* Interpolate the PNG to the requested linear scale */
+	for (i=0; i<N; i++)
+		rgba[i] = _rgba_interpolate(png_rgba, img.width, i, N);
+
+	/* Done */
+	rv = 0;
+
+error:
+	free(png_rgba);
+
+	if (png_data)
+		resource_put(png_data);
+
+	return rv;
+}
+
 /*! @} */
diff --git a/lib/fosphor/gl_cmap_gen.h b/lib/fosphor/gl_cmap_gen.h
index df98878..369ffd0 100644
--- a/lib/fosphor/gl_cmap_gen.h
+++ b/lib/fosphor/gl_cmap_gen.h
@@ -34,6 +34,7 @@
 
 int fosphor_gl_cmap_histogram(uint32_t *rgba, int N, void *arg);
 int fosphor_gl_cmap_waterfall(uint32_t *rgba, int N, void *arg);
+int fosphor_gl_cmap_png(uint32_t *rgba, int N, void *rsrc_name);
 
 /*! @} */