WIP: testing IME text editing

This commit is a test for IME text editing.

For CJK text editing you may need to use a font that support
CHK characters like:

https://github.com/be5invis/Sarasa-Gothic

Currently on windows we receive no text editing events.

data/core/docview.lua

@@ -309,6 +309,29 @@ function DocView:on_text_input(text)
 end
 
 
+function DocView:draw_ime_text_editing(text, start, len)
+  local line, col = self.doc:get_selection()
+  local x, y = self:get_line_screen_position(line)
+  x = x + get_col_x_offset(line, col)
+  local default_font = self:get_font()
+  local subpixel_scale = default_font:subpixel_scale()
+  local tx, ty = subpixel_scale * x, y + self:get_line_text_y_offset()
+  renderer.draw_text_subpixel(default_font, text, tx, ty, style.text)
+end
+
+
+function DocView:on_ime_text_editing(text, start, len)
+  local line, col = self.doc:get_selection()
+  local x, y = self:get_line_screen_position(line)
+  x = x + get_col_x_offset(line, col)
+  local h = self:get_line_height()
+  local w = self:get_font():get_width(5)
+  system.set_ime_input_rect(x, y, w, h)
+
+  core.root_view:defer_draw(draw_ime_text_editing, self, text, start, len)
+end
+
+
 function DocView:update()
   -- scroll to make caret visible and reset blink timer if it moved
   local line, col = self.doc:get_selection()

data/core/init.lua

@@ -954,6 +954,9 @@ function core.on_event(type, ...)
     end
   elseif type == "focuslost" then
     core.root_view:on_focus_lost(...)
+  elseif type == "textediting" then
+    core.root_view:on_ime_text_editing(...)
+    did_keymap = keymap.on_key_pressed(...)
   elseif type == "quit" then
     core.quit()
   end

data/core/rootview.lua

@@ -1033,6 +1033,11 @@ function RootView:on_focus_lost(...)
 end
 
 
+function RootView:on_ime_text_editing(...)
+  core.active_view:on_ime_text_editing(...)
+end
+
+
 function RootView:interpolate_drag_overlay(overlay)
   self:move_towards(overlay, "x", overlay.to.x)
   self:move_towards(overlay, "y", overlay.to.y)

data/core/view.lua

@@ -102,6 +102,9 @@ function View:on_text_input(text)
   -- no-op
 end
 
+-- no-op
+View.on_ime_text_editing = View.on_text_input
+
 
 function View:on_mouse_wheel(y)
   if self.scrollable then

src/api/system.c

@@ -193,6 +193,14 @@ top:
       lua_pushstring(L, get_key_name(&e, buf));
       return 2;
 
+    case SDL_TEXTEDITING:
+      fprintf(stderr, "textediting: %s (%d, %d)\n", e.edit.text, e.edit.start, e.edit.length); fflush(stderr);
+      lua_pushstring(L, "textediting");
+      lua_pushstring(L, e.edit.text);
+      lua_pushnumber(L, e.edit.start);
+      lua_pushnumber(L, e.edit.length);
+      return 4;
+
     case SDL_TEXTINPUT:
       lua_pushstring(L, "textinput");
       lua_pushstring(L, e.text.text);
@@ -652,6 +660,16 @@ static int f_set_window_opacity(lua_State *L) {
 }
 
 
+static int f_set_ime_input_rect(lua_State *L) {
+  SDL_Rect r;
+  r.x = luaL_checkinteger(L, 1);
+  r.y = luaL_checkinteger(L, 2);
+  r.w = luaL_checkinteger(L, 3);
+  r.h = luaL_checkinteger(L, 4);
+  SDL_SetTextInputRect(&r);
+  return 0;
+}
+
 static const luaL_Reg lib[] = {
   { "poll_event",          f_poll_event          },
   { "wait_event",          f_wait_event          },
@@ -678,6 +696,7 @@ static const luaL_Reg lib[] = {
   { "exec",                f_exec                },
   { "fuzzy_match",         f_fuzzy_match         },
   { "set_window_opacity",  f_set_window_opacity  },
+  { "set_ime_input_rect",  f_set_ime_input_rect  },
   { NULL, NULL }
 };