[ion/clipboard] Add support for web simulator

Wrote methods for accessing the system clipboard from the web
simulator, as the methods in SDL_Clipboard do not work when the video
device uses emscripten.

Change-Id: Ib2e66530a6b013eca0cf69fb52372e9e3a21c8bb

build/toolchain.emscripten.mak

@@ -77,6 +77,7 @@ _closure_call \
 _do_load \
 _do_load_from_lexer \
 _emscripten_sleep \
+_emscripten_sleep_with_yield \
 _fun_bc_call \
 _fun_builtin_1_call \
 _fun_builtin_var_call \
@@ -103,6 +104,14 @@ _mp_execute_bytecode \
 _mp_hal_input \
 _mp_import_name \
 _mp_parse_compile_execute \
+_get_clipboard_text \
+__ZN3Ion9Clipboard4readEPcm \
+__ZN9Clipboard10storedTextEv \
+__ZN11LayoutField18privateHandleEventEN3Ion6Events5EventE \
+__ZN11LayoutField11handleEventEN3Ion6Events5EventE \
+__ZN8TextArea18privateHandleEventEN3Ion6Events5EventE \
+__ZN8TextArea11handleEventEN3Ion6Events5EventE \
+__ZN15ExpressionField11handleEventEN3Ion6Events5EventE \
 _msleep
 
 EMTERPRETIFY_WHITELIST = $(foreach sym,$(EMSCRIPTEN_ASYNC_SYMBOLS),"$(sym)",)END

ion/src/simulator/Makefile

@@ -8,7 +8,6 @@ ion_src += $(addprefix ion/src/simulator/shared/, \
   dummy/serial_number.cpp \
   dummy/stack.cpp \
   dummy/usb.cpp \
-  clipboard.cpp \
   console_stdio.cpp:-consoledisplay \
   crc32.cpp \
   display.cpp:-headless \

ion/src/simulator/android/Makefile

@@ -6,6 +6,7 @@ ion_src += $(addprefix ion/src/simulator/android/src/cpp/, \
 ion_src += $(addprefix ion/src/simulator/shared/, \
   dummy/callback.cpp \
   dummy/language.cpp \
+  clipboard.cpp \
   haptics.cpp \
 )
 

ion/src/simulator/ios/Makefile

@@ -6,6 +6,7 @@ ion_src += $(addprefix ion/src/simulator/shared/, \
   apple/language.m \
   dummy/callback.cpp \
   dummy/haptics_enabled.cpp \
+  clipboard.cpp \
   haptics.cpp \
 )
 

ion/src/simulator/linux/Makefile

@@ -16,6 +16,7 @@ ion_src += $(addprefix ion/src/simulator/linux/, \
 ion_src += $(addprefix ion/src/simulator/shared/, \
   dummy/callback.cpp \
   dummy/haptics_enabled.cpp \
+  clipboard.cpp \
   collect_registers_x86_64.s \
   collect_registers.cpp \
   haptics.cpp \

ion/src/simulator/macos/Makefile

@@ -6,6 +6,7 @@ ion_src += $(addprefix ion/src/simulator/shared/, \
   apple/language.m \
   dummy/callback.cpp \
   dummy/haptics_enabled.cpp \
+  clipboard.cpp \
   collect_registers_x86_64.s \
   collect_registers.cpp \
   haptics.cpp \

ion/src/simulator/shared/clipboard.cpp

@@ -2,6 +2,9 @@
 #include <SDL.h>
 #include <string.h>
 
+/* This file implements the methods to access the system clipboard on all
+ * targets but the web simulator. */
+
 namespace Ion {
 
 void Clipboard::write(const char * text) {

ion/src/simulator/web/Makefile

@@ -15,6 +15,7 @@ LDFLAGS += --pre-js ion/src/simulator/web/preamble_env.js
 
 ion_src += $(addprefix ion/src/simulator/web/, \
   callback.cpp \
+  clipboard.cpp \
   helpers.cpp \
 )
 

ion/src/simulator/web/clipboard.cpp

@@ -0,0 +1,87 @@
+#include <ion/clipboard.h>
+#include <emscripten.h>
+#include <SDL.h>
+#include <assert.h>
+#include <limits.h>
+#include <stdint.h>
+#include <string.h>
+
+enum class AsyncStatus : uint32_t {
+  Pending,
+  Success,
+  Failure
+};
+
+/* When using emscripten, the SDL_Clipboard methods do not interact with the
+ * system clipboard, but only with an internal buffer. We thus need to
+ * implement our own methods via the JavaScript API.
+ * However, we still call the SDL_Clipboard methods as a fallback to preserve
+ * the copy-paste feature in case of calls to set_clipboard_text and
+ * get_clipboard_text failing. */
+
+EM_JS(void, set_clipboard_text, (const char * text, AsyncStatus * status, AsyncStatus failure, AsyncStatus success), {
+  try {
+    navigator.clipboard.writeText(UTF8ToString(text)).then(
+      function () { HEAP32[status>>2] = success; },
+      function () { HEAP32[status>>2] = failure; }
+    );
+  } catch (error) {
+    console.error(error);
+    HEAP32[status>>2] = failure;
+  }
+});
+
+EM_JS(void, get_clipboard_text, (char * buffer, uint32_t bufferSize, AsyncStatus * status, AsyncStatus failure, AsyncStatus success), {
+  try {
+    navigator.clipboard.readText().then(
+      function(text) {
+        var lenghtBytes = Math.min(lengthBytesUTF8(text) + 1, bufferSize);
+        stringToUTF8(text, buffer, lenghtBytes);
+        HEAP32[status>>2] = success;
+      },
+      function(text) { HEAP32[status>>2] = failure; }
+    );
+  } catch (error) {
+    console.error(error);
+    HEAP32[status>>2] = failure;
+  }
+});
+
+namespace Ion {
+
+void Clipboard::write(const char * text) {
+  /* FIXME : Handle the error if need be. */
+  /* As the rest of the execution does not depend on the system clipboard being
+   * properly filled at this point, the call to set_clipboard_text does not
+   * need to be made synchronous. */
+  AsyncStatus lock;
+  set_clipboard_text(text, &lock, AsyncStatus::Failure, AsyncStatus::Success);
+  /* Store a local copy of the text in case the browser does not grant access
+   * to the clipboard. */
+  SDL_SetClipboardText(text);
+}
+
+void Clipboard::read(char * buffer, size_t bufferSize) {
+  AsyncStatus lock = AsyncStatus::Pending;
+  static_assert(sizeof(size_t) <= sizeof(uint32_t), "Cast from size_t to uint32_t may overflow.");
+  get_clipboard_text(buffer, static_cast<uint32_t>(bufferSize), &lock, AsyncStatus::Failure, AsyncStatus::Success);
+  while (lock == AsyncStatus::Pending) {
+    emscripten_sleep_with_yield(10);
+  }
+  if (lock == AsyncStatus::Success) {
+    return;
+  }
+  /* If the browser does not grant access to the clipboard, read from a local
+   * copy to at least maintain the basic copy-paste functionnality. */
+  if (!SDL_HasClipboardText()) {
+    buffer[0] = '\0';
+    return;
+  }
+  char * text = SDL_GetClipboardText();
+  if (text) {
+    strlcpy(buffer, text, bufferSize);
+    SDL_free(text);
+  }
+}
+
+}

ion/src/simulator/windows/Makefile

@@ -7,6 +7,7 @@ ion_src += $(addprefix ion/src/simulator/windows/, \
 ion_src += $(addprefix ion/src/simulator/shared/, \
   dummy/callback.cpp \
   dummy/haptics_enabled.cpp \
+  clipboard.cpp \
   haptics.cpp \
 )