On Mon, Jul 1, 2019 at 3:42 PM Yordan Karadzhov (VMware)
<y.karadz@xxxxxxxxx> wrote:
>
> OpenGL doesn't provide support for text rendering. Here we add capability
> of printing text to the OpenGL scene by using the single-file public
> domain library "stb_truetype":
> https://github.com/nothings/stb/blob/master/stb_truetype.h
>
> Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@xxxxxxxxx>
> ---
> kernel-shark/src/libkshark-plot.c | 153 +-
> kernel-shark/src/libkshark-plot.h | 35 +
> kernel-shark/src/stb_truetype.h | 4882 +++++++++++++++++++++++++++++
> 3 files changed, 5067 insertions(+), 3 deletions(-)
> create mode 100644 kernel-shark/src/stb_truetype.h
>
> diff --git a/kernel-shark/src/libkshark-plot.c b/kernel-shark/src/libkshark-plot.c
> index cdd0ef8..36982e3 100644
> --- a/kernel-shark/src/libkshark-plot.c
> +++ b/kernel-shark/src/libkshark-plot.c
> @@ -9,13 +9,21 @@
> * @brief Basic tools for OpenGL plotting.
> */
[...]
>
>
> +bool ksplot_init_font(struct ksplot_font *font, float size, const char *file)
> +{
> + unsigned char bitmap[KS_FONT_BITMAP_SIZE * KS_FONT_BITMAP_SIZE];
> + ssize_t buff_size, ret;
> + unsigned char *buffer;
> + stbtt_fontinfo info;
> + FILE *font_file;
> +
> + font_file = fopen(file, "rb");
> + if (!font_file) {
> + fprintf(stderr, "Failed to open font file!\n");
> + return false;
> + }
> +
> + /* Get the size of the file. */
> + fseek(font_file, 0, SEEK_END);
> + buff_size = ftell(font_file);
> + fseek(font_file, 0, SEEK_SET);
> +
> + buffer = malloc(buff_size);
> + if (!buffer) {
font_file doesn't get fclose()d in this case.
>
> + fprintf(stderr, "Failed to allocat memory for font!\n");
> + goto fail;
> + }
> +
> + ret = fread(buffer, buff_size, 1, font_file);
> + fclose(font_file);
> +
> + if (ret == 0) {
> + fprintf(stderr, "Failed to read from font file!\n");
> + goto fail;
> + }
> +
> + if (!stbtt_InitFont(&info, buffer, 0)) {
> + fprintf(stderr, "Failed to init font!\n");
> + goto fail;
> + }
> +
> + ret = stbtt_BakeFontBitmap(buffer,
> + 0,
> + size,
> + bitmap,
> + KS_FONT_BITMAP_SIZE,
> + KS_FONT_BITMAP_SIZE,
> + KS_SPACE_CHAR,
> + KS_N_CHAR,
> + font->cdata);
> +
> + if (ret <= 0) {
> + fprintf(stderr, "Failed to bake font bitmap!\n");
> + goto fail;
> + }
> +
> + free(buffer);
> +
> + glGenTextures(1, &font->texture_id);
> + glBindTexture(GL_TEXTURE_2D, font->texture_id);
> +
> + glTexImage2D(GL_TEXTURE_2D,
> + 0,
> + GL_ALPHA,
> + KS_FONT_BITMAP_SIZE,
> + KS_FONT_BITMAP_SIZE,
> + 0,
> + GL_ALPHA,
> + GL_UNSIGNED_BYTE,
> + bitmap);
> +
> + glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
> + glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
> + glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
> + glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
> +
> + return true;
> +
> + fail:
> + free(buffer);
> + return false;
> +}
[...]
> diff --git a/kernel-shark/src/libkshark-plot.h b/kernel-shark/src/libkshark-plot.h
> index 9a4dbc0..617dca0 100644
> --- a/kernel-shark/src/libkshark-plot.h
> +++ b/kernel-shark/src/libkshark-plot.h
> @@ -12,6 +12,16 @@
> #ifndef _LIB_KSHARK_PLOT_H
> #define _LIB_KSHARK_PLOT_H
>
> +// OpenGL
> +#include <GL/freeglut.h>
Freeglut is used only in ksplot_make_scene() and is not a necessary
dependency for programs that use Qt for window and OpenGL context
management. Can we drop freeglut as a dependency for libkshark-plot
and move ksplot_make_scene() to where its only use is (in
examples/dataplot.cpp)?
The rest of the patch looks great.
Thank you,
-- Slavi
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