1 files changed, 85 insertions, 0 deletions
diff --git a/src/image_writer.c b/src/image_writer.c
new file mode 100644
index 0000000..d01a66c
--- /dev/null
+++ b/src/image_writer.c
@@ -0,0 +1,85 @@
+#include "../include/image_writer.h"
+#include "../include/egl.h"
+
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#include "../external/stb_image_write.h"
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <assert.h>
+
+static unsigned int gl_create_texture(gsr_egl *egl, int width, int height, int internal_format, unsigned int format) {
+    unsigned int texture_id = 0;
+    egl->glGenTextures(1, &texture_id);
+    egl->glBindTexture(GL_TEXTURE_2D, texture_id);
+    egl->glTexImage2D(GL_TEXTURE_2D, 0, internal_format, width, height, 0, format, GL_UNSIGNED_BYTE, NULL);
+
+    egl->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    egl->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    egl->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    egl->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+
+    egl->glBindTexture(GL_TEXTURE_2D, 0);
+    return texture_id;
+}
+
+/* TODO: Support hdr/10-bit */
+bool gsr_image_writer_init(gsr_image_writer *self, gsr_image_writer_source source, gsr_egl *egl, int width, int height) {
+    assert(source == GSR_IMAGE_WRITER_SOURCE_OPENGL);
+    self->source = source;
+    self->egl = egl;
+    self->width = width;
+    self->height = height;
+    self->texture = gl_create_texture(self->egl, self->width, self->height, GL_RGB8, GL_RGB); /* TODO: use GL_RGB16 instead of GL_RGB8 for hdr/10-bit */
+    if(self->texture == 0) {
+        fprintf(stderr, "gsr error: gsr_image_writer_init: failed to create texture\n");
+        return false;
+    }
+    return true;
+}
+
+void gsr_image_writer_deinit(gsr_image_writer *self) {
+    if(self->texture) {
+        self->egl->glDeleteTextures(1, &self->texture);
+        self->texture = 0;
+    }
+}
+
+bool gsr_image_writer_write_to_file(gsr_image_writer *self, const char *filepath, gsr_image_format image_format, int quality) {
+    if(quality < 1)
+        quality = 1;
+    else if(quality > 100)
+        quality = 100;
+
+    uint8_t *frame_data = malloc(self->width * self->height * 3);
+    if(!frame_data) {
+        fprintf(stderr, "gsr error: gsr_image_writer_write_to_file: failed to allocate memory for image frame\n");
+        return false;
+    }
+
+    // TODO: hdr support
+    self->egl->glBindTexture(GL_TEXTURE_2D, self->texture);
+    // We could use glGetTexSubImage, but it's only available starting from opengl 4.5
+    self->egl->glGetTexImage(GL_TEXTURE_2D, 0, GL_RGB, GL_UNSIGNED_BYTE, frame_data);
+    self->egl->glBindTexture(GL_TEXTURE_2D, 0);
+
+    self->egl->glFlush();
+    self->egl->glFinish();
+    
+    bool success = false;
+    switch(image_format) {
+        case GSR_IMAGE_FORMAT_JPEG:
+            success = stbi_write_jpg(filepath, self->width, self->height, 3, frame_data, quality);
+            break;
+        case GSR_IMAGE_FORMAT_PNG:
+            success = stbi_write_png(filepath, self->width, self->height, 3, frame_data, 0);
+            break;
+    }
+
+    if(!success)
+        fprintf(stderr, "gsr error: gsr_image_writer_write_to_file: failed to write image data to output file %s\n", filepath);
+
+    free(frame_data);
+    return success;
+}