Read the image in a separate thread and ensure each strip is read in its own thread (#1)

Reviewed-on: #1
Co-authored-by: Abdelrahman <said.abdelrahman89@gmail.com>
Co-committed-by: Abdelrahman <said.abdelrahman89@gmail.com>

compile

@@ -9,6 +9,7 @@ INCLUDES="\
 "
 LIBS="\
 	-lm \
+	-pthread \
 	$(pkg-config --libs sdl2) \
 "
 SRC="\

src/main.c

@@ -4,10 +4,12 @@
 #include "tiffread.h"
 #include <SDL2/SDL.h>
 #include <SDL2/SDL_events.h>
+#include <SDL2/SDL_rect.h>
 #include <SDL2/SDL_render.h>
 #include <SDL2/SDL_surface.h>
 #include <SDL2/SDL_video.h>
 #include <netinet/in.h>
+#include <pthread.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -17,6 +19,8 @@
 
 #define WINDOW_WIDTH 800
 #define WINDOW_HEIGHT 600
+#define VIEW_AREA_WIDTH 700
+#define VIEW_AREA_HEIGHT 500
 
 #define AMASK 0xff000000
 #define BMASK 0x00ff0000
@@ -32,8 +36,14 @@ struct point {
 };
 
 internal void write_debug_ppm6(const Image *img);
-internal SDL_Texture *image_to_texture(SDL_Renderer *renderer,
+internal void *load_tiff_image(void *args);
-                                       const Image *img);
+internal SDL_Rect get_dest_rect(SDL_Surface *surface);
+
+typedef struct img_thread_args ImgThreadArgs;
+struct img_thread_args {
+  const char *filename;
+  Arena *arena;
+};
 
 int main(int argc, char *argv[]) {
   int exit_code = EXIT_SUCCESS;
@@ -45,14 +55,13 @@ int main(int argc, char *argv[]) {
 
   const char *file_to_open = argc > 1 ? argv[1] : "./resources/test.tif";
 
-  Image *img = read_baseline_tiff(file_to_open, arena);
+  pthread_t img_thread;
-  if (!img) {
+  ImgThreadArgs args = {.filename = file_to_open, .arena = arena};
+  if (pthread_create(&img_thread, NULL, load_tiff_image, &args) != 0) {
     exit_code = EXIT_FAILURE;
     goto MAIN_DESTROY_ARENA;
   }
 
-  write_debug_ppm6(img);
-
   if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
     exit_code = EXIT_FAILURE;
     goto MAIN_DESTROY_ARENA;
@@ -73,18 +82,19 @@ int main(int argc, char *argv[]) {
     goto MAIN_DESTROY_WINDOW;
   }
 
-  SDL_Texture *texture = image_to_texture(renderer, img);
+  SDL_Surface *surface = NULL;
-  if (!texture) {
+  if (pthread_join(img_thread, (void **)&surface) != 0 || !surface) {
     exit_code = EXIT_FAILURE;
     goto MAIN_DESTROY_RENDERER;
   }
 
-  SDL_Rect dest = {
+  SDL_Texture *texture = SDL_CreateTextureFromSurface(renderer, surface);
-      .h = img->height,
+  if (!texture) {
-      .w = img->width,
+    exit_code = EXIT_FAILURE;
-      .x = (WINDOW_WIDTH - img->width) / 2,
+    goto MAIN_DESTROY_SURFACE;
-      .y = (WINDOW_HEIGHT - img->height) / 2,
+  }
-  };
+
+  SDL_Rect dest = get_dest_rect(surface);
 
   bool running = true;
 
@@ -110,6 +120,9 @@ int main(int argc, char *argv[]) {
 
   SDL_DestroyTexture(texture);
 
+MAIN_DESTROY_SURFACE:
+  SDL_FreeSurface(surface);
+
 MAIN_DESTROY_RENDERER:
   SDL_DestroyRenderer(renderer);
 
@@ -146,17 +159,19 @@ internal void write_debug_ppm6(const Image *img) {
   fclose(out);
 }
 
-internal SDL_Texture *image_to_texture(SDL_Renderer *renderer,
+internal void *load_tiff_image(void *args) {
-                                       const Image *img) {
+  ImgThreadArgs *img_args = (ImgThreadArgs *)args;
-  SDL_Texture *output = NULL;
+  Image *img = read_baseline_tiff(img_args->filename, img_args->arena);
-  if (!renderer || !img) {
+  if (!img) {
-    goto IMAGE_TO_TEXTURE_RETURN;
+    return NULL;
   }
 
+  write_debug_ppm6(img);
+
   SDL_Surface *surface = SDL_CreateRGBSurface(0, img->width, img->height, 32,
                                               RMASK, GMASK, BMASK, AMASK);
   if (!surface) {
-    goto IMAGE_TO_TEXTURE_RETURN;
+    return NULL;
   }
 
   SDL_LockSurface(surface);
@@ -170,10 +185,18 @@ internal SDL_Texture *image_to_texture(SDL_Renderer *renderer,
   }
   SDL_UnlockSurface(surface);
 
-  output = SDL_CreateTextureFromSurface(renderer, surface);
+  return surface;
-
+}
-  SDL_FreeSurface(surface);
+
-
+internal SDL_Rect get_dest_rect(SDL_Surface *surface) {
-IMAGE_TO_TEXTURE_RETURN:
+  f64 ratio = (f64)(surface->h) / (f64)(surface->w);
-  return output;
+  u64 width = surface->w <= VIEW_AREA_WIDTH ? surface->w : VIEW_AREA_WIDTH;
+  u64 height = width * ratio;
+
+  return (SDL_Rect){
+      .w = width,
+      .h = height,
+      .x = (WINDOW_WIDTH - width) / 2,
+      .y = (WINDOW_HEIGHT - height) / 2,
+  };
 }

src/tiff/tiffread.c

@@ -4,8 +4,10 @@
 #include "image.h"
 #include "mem_arena.h"
 #include <assert.h>
+#include <bits/pthreadtypes.h>
 #include <math.h>
 #include <netinet/in.h>
+#include <pthread.h>
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -200,6 +202,7 @@ struct tiff_image {
 
 typedef struct tiff_reader TiffReader;
 struct tiff_reader {
+  const char *filename;
   FILE *fp;
   TiffHdr header;
   TiffIFD ifd;
@@ -207,6 +210,17 @@ struct tiff_reader {
   Pixel *pixels;
 };
 
+typedef struct strip_thread_args StripThreadArgs;
+struct strip_thread_args {
+  FILE *fp;
+  const TiffStrip *strip;
+  u64 pixel_count;
+  u64 samples_per_pixel;
+  u64 main_samples;
+  TiffAlpha alpha;
+  Pixel *pixel_write_start;
+};
+
 internal bool read_tiff_header(TiffReader *reader);
 internal bool read_ifd(TiffReader *reader, Arena *arena);
 internal bool read_ifd_fields(TiffReader *reader);
@@ -214,7 +228,8 @@ internal void read_alpha(TiffReader *reader);
 internal void read_bits_per_sample(TiffReader *reader);
 internal bool read_image_pixels(TiffReader *reader, Arena *arena);
 internal bool read_strip_data(TiffReader *reader, Arena *arena);
-internal void read_strips(TiffReader *reader);
+internal bool read_strips(TiffReader *reader);
+internal void *read_strip(void *arg);
 internal void read_strip_data_field(const TiffReader *reader,
                                     StripDataField *field);
 internal bool read_field(const TiffField *field, TiffImage *img);
@@ -231,7 +246,7 @@ Image *read_baseline_tiff(const char *file, Arena *arena) {
     goto READ_BASELINE_RETURN_IMG;
   }
 
-  TiffReader reader = {.fp = fopen(file, "rb")};
+  TiffReader reader = {.filename = file, .fp = fopen(file, "rb")};
   if (!reader.fp) {
     goto READ_BASELINE_RETURN_IMG;
   }
@@ -534,9 +549,7 @@ internal bool read_image_pixels(TiffReader *reader, Arena *arena) {
     return false;
   }
 
-  read_strips(reader);
+  return read_strips(reader);
-
-  return true;
 }
 
 internal bool read_strip_data(TiffReader *reader, Arena *arena) {
@@ -585,31 +598,81 @@ internal bool read_strip_data(TiffReader *reader, Arena *arena) {
   return true;
 }
 
-internal void read_strips(TiffReader *reader) {
+internal bool read_strips(TiffReader *reader) {
   u64 position = 0;
-  u64 main_samples = reader->img.sample_count - reader->img.extra_samples_count;
+  StripThreadArgs args[reader->img.strip_count];
-  TiffAlpha alpha = reader->img.alpha;
+  pthread_t threads[reader->img.strip_count];
-
-  Pixel *p;
-  u64 start_offset;
-  u64 alpha_offset;
 
   for (u64 i = 0; i < reader->img.strip_count; ++i) {
     const TiffStrip *strip = &(reader->img.strips[i]);
+    u64 pixel_count = strip->byte_count / reader->img.sample_count;
+    args[i] = (StripThreadArgs){
+        .fp = fopen(reader->filename, "rb"),
+        .strip = strip,
+        .pixel_count = pixel_count,
+        .samples_per_pixel = reader->img.sample_count,
+        .main_samples =
+            reader->img.sample_count - reader->img.extra_samples_count,
+        .alpha = reader->img.alpha,
+        .pixel_write_start = &(reader->pixels[position]),
+    };
 
-    for (u64 j = 0; j < strip->byte_count / reader->img.sample_count; ++j) {
+    if (!args[i].fp) {
-      p = &(reader->pixels[position]);
+      for (u64 j = 0; j < i; ++j) {
-      start_offset = strip->offset + j * reader->img.sample_count;
+        fclose(args[j].fp);
-      alpha_offset = start_offset + main_samples + alpha.sample_offset;
+      }
 
-      fread_with_offset(reader->fp, p, main_samples, start_offset);
+      return false;
+    }
 
-      if (alpha.type == ALPHA_TYPE_UNDEFINED) {
+    position += pixel_count;
+  }
+
+  for (u64 i = 0; i < reader->img.strip_count; ++i) {
+    if (pthread_create(&(threads[i]), NULL, read_strip, &(args[i])) != 0) {
+      for (u64 j = 0; j < i; ++j) {
+        pthread_cancel(threads[i]);
+        fclose(args[j].fp);
+      }
+
+      // Close the remaining files
+      for (u64 j = i; j < reader->img.strip_count; ++j) {
+        fclose(args[j].fp);
+      }
+
+      return false;
+    }
+  }
+
+  for (u64 i = 0; i < reader->img.strip_count; ++i) {
+    pthread_join(threads[i], NULL);
+    fclose(args[i].fp);
+  }
+
+  return true;
+}
+
+internal void *read_strip(void *arg) {
+  StripThreadArgs *args = (StripThreadArgs *)arg;
+
+  Pixel *p;
+  u64 write_offset = 0;
+  u64 read_offset;
+  u64 alpha_offset;
+
+  for (u64 j = 0; j < args->pixel_count; ++j) {
+    p = args->pixel_write_start + write_offset;
+    read_offset = args->strip->offset + j * args->samples_per_pixel;
+    alpha_offset = read_offset + args->main_samples + args->alpha.sample_offset;
+
+    fread_with_offset(args->fp, p, args->main_samples, read_offset);
+
+    if (args->alpha.type == ALPHA_TYPE_UNDEFINED) {
       p->a = 255;
     } else {
-        fread_with_offset(reader->fp, &(p->a), 1, alpha_offset);
+      fread_with_offset(args->fp, &(p->a), 1, alpha_offset);
 
-        if (alpha.type == ALPHA_TYPE_UNASSOCIATED) {
+      if (args->alpha.type == ALPHA_TYPE_UNASSOCIATED) {
         f32 a_norm = u8_normalise(p->a);
 
         p->r = u8_denormalise(u8_normalise(p->r) * a_norm);
@@ -618,9 +681,10 @@ internal void read_strips(TiffReader *reader) {
       }
     }
 
-      ++position;
+    ++write_offset;
-    }
   }
+
+  return NULL;
 }
 
 internal void read_strip_data_field(const TiffReader *reader,