Add IME text rendering

This shows the uncommitted text in a box in the bottom left corner.
This doesn't show the selection (defined by the start and length fields
in the event) yet, but this is already much better than it was on its
own, and I don't know how urgent the selection is since it's broken on
Windows anyway.

desktop_version/CMakeLists.txt

@@ -82,6 +82,7 @@ set(VVV_CXX_SRC
     src/Graphics.cpp
     src/GraphicsResources.cpp
     src/GraphicsUtil.cpp
+    src/IMERender.cpp
     src/Input.cpp
     src/KeyPoll.cpp
     src/Labclass.cpp

desktop_version/src/Graphics.cpp

@@ -12,6 +12,7 @@
 #include "FileSystemUtils.h"
 #include "Font.h"
 #include "GraphicsUtil.h"
+#include "IMERender.h"
 #include "Localization.h"
 #include "Map.h"
 #include "Maths.h"
@@ -3529,6 +3530,7 @@ void Graphics::get_stretch_info(SDL_Rect* rect)
 
 void Graphics::render(void)
 {
+    ime_render();
     draw_screenshot_border();
 
     if (gameScreen.badSignalEffect)
@@ -3541,10 +3543,12 @@ void Graphics::render(void)
 
     draw_window_background();
 
-    SDL_Rect rect;
-    get_stretch_info(&rect);
+    SDL_Rect stretch_info;
+    get_stretch_info(&stretch_info);
 
-    copy_texture(gameTexture, NULL, &rect, 0, NULL, flipmode ? SDL_FLIP_VERTICAL : SDL_FLIP_NONE);
+    ime_set_rect(&stretch_info);
+
+    copy_texture(gameTexture, NULL, &stretch_info, 0, NULL, flipmode ? SDL_FLIP_VERTICAL : SDL_FLIP_NONE);
 }
 
 void Graphics::renderwithscreeneffects(void)

desktop_version/src/IMERender.cpp

@@ -0,0 +1,57 @@
+#include <SDL.h>
+
+#include "Constants.h"
+#include "Font.h"
+#include "Graphics.h"
+#include "KeyPoll.h"
+
+static bool render_done = false;
+static SDL_Rect imebox;
+
+void ime_render(void)
+{
+    render_done = false;
+
+    if (!SDL_IsTextInputActive() || key.imebuffer == "")
+    {
+        return;
+    }
+
+    int fontheight = font::height(PR_FONT_LEVEL);
+    imebox.x = 8;
+    imebox.y = SCREEN_HEIGHT_PIXELS - 32 - fontheight;
+    imebox.w = font::len(PR_FONT_LEVEL, key.imebuffer.c_str()) + 1;
+    imebox.h = fontheight + 1;
+
+    SDL_Rect imebox_border = imebox;
+    imebox_border.x -= 1;
+    imebox_border.y -= 1;
+    imebox_border.w += 2;
+    imebox_border.h += 2;
+
+    graphics.fill_rect(&imebox_border, 128, 128, 128);
+    graphics.fill_rect(&imebox, 0, 0, 0);
+    font::print(PR_FONT_LEVEL | PR_CJK_LOW, imebox.x + 1, imebox.y + 1, key.imebuffer, 255, 255, 255);
+
+    render_done = true;
+}
+
+void ime_set_rect(SDL_Rect* stretch_info)
+{
+    if (!render_done)
+    {
+        return;
+    }
+
+    SDL_Rect imebox_scaled = imebox;
+    float x_scale = (float) stretch_info->w / SCREEN_WIDTH_PIXELS;
+    float y_scale = (float) stretch_info->h / SCREEN_HEIGHT_PIXELS;
+    imebox_scaled.x *= x_scale;
+    imebox_scaled.y *= y_scale;
+    imebox_scaled.w *= x_scale;
+    imebox_scaled.h *= y_scale;
+    imebox_scaled.x += stretch_info->x;
+    imebox_scaled.y += stretch_info->y;
+
+    SDL_SetTextInputRect(&imebox_scaled);
+}

desktop_version/src/IMERender.h

@@ -0,0 +1,7 @@
+#ifndef IMERENDER_H
+#define IMERENDER_H
+
+void ime_render(void);
+void ime_set_rect(SDL_Rect* stretch_info);
+
+#endif /* IMERENDER_H */