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, 34 insertions, 0 deletions

diff --git a/web/hitomezashi_web.h b/web/hitomezashi_web.h
new file mode 100644
index 0000000..5d4f523
--- /dev/null
+++ b/web/hitomezashi_web.h
@@ -0,0 +1,34 @@
+/** @file */
+#ifndef HITOMEZASHI_WEB_H
+#define HITOMEZASHI_WEB_H
+
+#include "emscripten.h"
+
+enum Hitomezashi_Web_Result {
+  Hitomezashi_Web_Result_Success = 0,
+  Hitomezashi_Web_Result_Err_Get_Params = 1,
+  Hitomezashi_Web_Result_Err_Sdl_Init = 2,
+  Hitomezashi_Web_Result_Err_State_Init = 3,
+};
+
+int hitomezashi_web(int x_pattern_len, int y_pattern_len, char *x_pattern,
+                    char *y_pattern, int gap, int line_thickness);
+
+/** Parse the URL query string and return the parameters thereof.
+ *
+ * This is implemented in JS with EM_JS, in order to access the query string.
+ * The friction of interoperation is the reason for turning the query string
+ * into a different string that the C code must parse to the actual values,
+ * rather than sending the data back individually with the correct types.
+ * That is probably possible, but it seems unpleasant.
+ *
+ * The query string's x_pattern, y_pattern, gap, and line_thickness are
+ * parsed. If not all of them are present, "i" is returned. If x_pattern or
+ * y_pattern in the query string have characters other than ASCII digits 0
+ * and 1, "i" is returned. Otherwise, the values are returned as a
+ * newline-delimited string in the order x_pattern, y_pattern, gap,
+ * line_thickness.
+ */
+char *hitomezashi_web_get_args(void);
+
+#endif // HITOMEZASHI_WEB_H