Add web app frontend, restructure almost everything

- Add web app frontend code
- Add .html, .js, .wasm to .gitignore
- Restructure Makefile to work with emmake, add build targets for web app,
  add .html, .js, .wasm to make clean
- Explain the pattern in the README
- Add explanation of web frontend to README
- Restructure README generally for better clarity
- Remove "make web app version" from todos in README
- Set Doxygen to EXTRACT_ALL so trivial and useless doc comments are not
  needed when the naming suffices to be explanatory.
- Move ascii_binary_str_to_ints to library code in new file
  hitomezashi_utils.c (and corresponding header) as web app also needs it.
- Fix SDL2 include path so it also works with Emscripten
- Remove some cluttering and unnecessary doc comments
- Improve some doc comments

1 files changed, 102 insertions, 0 deletions

diff --git a/web/hitomezashi_web.c b/web/hitomezashi_web.c
new file mode 100644
index 0000000..4859c20
--- /dev/null
+++ b/web/hitomezashi_web.c
@@ -0,0 +1,102 @@
+#include "hitomezashi_web.h"
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "SDL2/SDL.h"
+#include "emscripten.h"
+#include "hitomezashi.h"
+#include "hitomezashi_utils.h"
+
+int EMSCRIPTEN_KEEPALIVE main(void) {
+  char *param_str = hitomezashi_web_get_args();
+
+  if (param_str[0] == 'i') {
+    return Hitomezashi_Web_Result_Err_Get_Params;
+  }
+
+  char *x_pattern_str = strtok(param_str, "\n");
+  int x_pattern_len = strlen(x_pattern_str);
+  // We needn't bother checking whether
+  // hitomezashi_ascii_binary_str_to_ints() was successful as the strings
+  // passed to it are validated by hitomezashi_web_get_args() in JS.
+  char *x_pattern =
+      hitomezashi_ascii_binary_str_to_ints(x_pattern_str, x_pattern_len);
+
+  char *y_pattern_str = strtok(NULL, "\n");
+  int y_pattern_len = strlen(y_pattern_str);
+  char *y_pattern =
+      hitomezashi_ascii_binary_str_to_ints(y_pattern_str, y_pattern_len);
+
+  int gap = strtol(strtok(NULL, "\n"), NULL, 0);
+  int line_thickness = strtol(strtok(NULL, "\n"), NULL, 0);
+
+  if (SDL_Init(SDL_INIT_VIDEO) != 0) {
+    return Hitomezashi_Web_Result_Err_Sdl_Init;
+  }
+
+  SDL_Window *window;
+  SDL_Renderer *renderer;
+  SDL_Texture *texture;
+
+  struct Hitomezashi_State state;
+  if (hitomezashi_state_init(&state, x_pattern_len, y_pattern_len, x_pattern,
+                             y_pattern, gap, line_thickness) != 0) {
+    return Hitomezashi_Web_Result_Err_State_Init;
+  }
+
+  // Stop SDL from capturing all input and stopping input elements from working
+  SDL_SetHint(SDL_HINT_EMSCRIPTEN_KEYBOARD_ELEMENT, "#canvas");
+  SDL_CreateWindowAndRenderer(state.output_width, state.output_height, 0,
+                              &window, &renderer);
+
+  hitomezashi_draw(&state);
+
+  texture = SDL_CreateTextureFromSurface(renderer, state.surface);
+  SDL_RenderClear(renderer);
+  SDL_RenderCopy(renderer, texture, NULL, NULL);
+  SDL_RenderPresent(renderer);
+
+  return Hitomezashi_Web_Result_Success;
+}
+
+EM_JS(char *, hitomezashi_web_get_args, (void), {
+  function validate_pattern(pattern) {
+    let valid = true;
+    for (let c of pattern) {
+      if (c != "0" && c != "1") {
+        valid = false;
+        break;
+      }
+    }
+    return valid;
+  }
+
+  let result_js = "";
+
+  let search_params = new URLSearchParams(window.location.search);
+
+  const x_pattern = search_params.get("x_pattern");
+  const y_pattern = search_params.get("y_pattern");
+  const gap = search_params.get("gap");
+  const line_thickness = search_params.get("line_thickness");
+
+  if (!(x_pattern && y_pattern && gap && line_thickness)) {
+    result_js = "i";
+  } else {
+    const patterns_are_valid =
+        validate_pattern(x_pattern) && validate_pattern(y_pattern);
+    if (!patterns_are_valid) {
+      result_js = "i";
+    } else {
+      result_js = x_pattern + "\n" + y_pattern + "\n" + gap + "\n" +
+                  line_thickness + "\n";
+    }
+  }
+
+  const result_length_bytes = lengthBytesUTF8(result_js) + 1;
+  let result_wasm_heap = _malloc(result_length_bytes);
+  stringToUTF8(result_js, result_wasm_heap, result_length_bytes);
+  return result_wasm_heap;
+})