From 9d09c6b4c581f0ffeb988c4cf5ce2ebf6781a639 Mon Sep 17 00:00:00 2001
From: Sylvain Munaut <tnt@246tNt.com>
Date: Wed, 11 Mar 2015 13:23:12 +0100
Subject: [PATCH] fosphor/gl_cmap_gen: Add new function to generate GL colormap
 from a PNG

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
---
 CMakeLists.txt            |   6 +++
 lib/CMakeLists.txt        |   6 +++
 lib/fosphor/Makefile      |   4 +-
 lib/fosphor/gl_cmap_gen.c | 101 ++++++++++++++++++++++++++++++++++++++
 lib/fosphor/gl_cmap_gen.h |   1 +
 5 files changed, 116 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index da049f8..f2ebef3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -130,6 +130,8 @@ if (Qt5_FOUND)
        endforeach(module)
 endif (Qt5_FOUND)
 
+find_package(PNG 1.6.19)
+
 ########################################################################
 # Find gnuradio build dependencies
 ########################################################################
@@ -165,6 +167,10 @@ endif(DOXYGEN_FOUND)
 
 include(GrComponent)
 
+GR_REGISTER_COMPONENT("PNG" ENABLE_PNG
+    PNG_FOUND
+)
+
 GR_REGISTER_COMPONENT("Python" ENABLE_PYTHON
     PYTHONLIBS_FOUND pybind11_FOUND
 )
diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index 4c1117a..51c3694 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -85,6 +85,12 @@ if(ENABLE_QT)
     target_link_libraries(gnuradio-fosphor ${Qt5_LIBRARIES})
 endif(ENABLE_QT)
 
+if(ENABLE_PNG)
+    add_definitions(-DENABLE_PNG)
+    target_include_directories(gnuradio-fosphor PRIVATE ${PNG_INCLUDE_DIRS})
+    target_link_libraries(gnuradio-fosphor ${PNG_LIBRARIES})
+endif(ENABLE_PNG)
+
 set_target_properties(gnuradio-fosphor PROPERTIES DEFINE_SYMBOL "gnuradio_fosphor_EXPORTS")
 
 if(APPLE)
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 59df6c3..c0be4ff 100644
--- a/lib/fosphor/gl_cmap_gen.c
+++ b/lib/fosphor/gl_cmap_gen.c
@@ -15,10 +15,14 @@
  *  \brief OpenGL color map generators
  */
 
+#include <errno.h>
 #include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
 #include <math.h>
 
 #include "gl_cmap_gen.h"
+#include "resource.h"
 
 
 static void
@@ -116,6 +120,33 @@ _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)
 {
@@ -167,4 +198,74 @@ fosphor_gl_cmap_waterfall(uint32_t *rgba, int N, void *arg)
 	return 0;
 }
 
+
+#ifdef ENABLE_PNG
+#include <png.h>
+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;
+}
+#else
+int
+fosphor_gl_cmap_png(uint32_t *rgba, int N, void *arg)
+{
+	return -ENOTSUP;
+}
+#endif
+
+
 /*! @} */
diff --git a/lib/fosphor/gl_cmap_gen.h b/lib/fosphor/gl_cmap_gen.h
index a695b8a..cd7efa5 100644
--- a/lib/fosphor/gl_cmap_gen.h
+++ b/lib/fosphor/gl_cmap_gen.h
@@ -21,5 +21,6 @@
 
 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);
 
 /*! @} */