Viewport, Platform: Fixed IME positioning for multi-viewport. Moved API from ImGuiIO to ImGuiPlatformIO. Because it is extremely unlikely to people redefined this API manually the moving-forward-breakage is ok. (#1542)

SDL2 ime support under Win32 never worked properly because of SDL interferences.

TODO.txt

@@ -261,7 +261,6 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - viewport: popup/tooltip glitches when appearing near the monitor limits (e.g. opening a menu).
  - viewport: platform: introduce getfocus/setfocus api, so e.g. focus flags can be honored, imgui-side ctrl-tab can focus os window, OS alt-tab can focus imgui window etc.
  - viewport: store per-viewport/monitor DPI in .ini file so an application reload or main window changing DPI on reload can be properly patched for.
- - viewport: IME positioning are wrong.
  - viewport: vulkan renderer implementation. 
  - viewport: need to clarify how to use GetMousePos() from a user point of view.
 

examples/imgui_impl_allegro5.cpp

@@ -199,10 +199,6 @@ bool ImGui_ImplAllegro5_Init(ALLEGRO_DISPLAY* display)
     io.KeyMap[ImGuiKey_Y] = ALLEGRO_KEY_Y;
     io.KeyMap[ImGuiKey_Z] = ALLEGRO_KEY_Z;
 
-#ifdef _WIN32
-    io.ImeWindowHandle = al_get_win_window_handle(g_Display);
-#endif
-
     return true;
 }
 

examples/imgui_impl_glfw.cpp

@@ -150,9 +150,6 @@ static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, Glfw
     io.SetClipboardTextFn = ImGui_ImplGlfw_SetClipboardText;
     io.GetClipboardTextFn = ImGui_ImplGlfw_GetClipboardText;
     io.ClipboardUserData = g_Window;
-#ifdef _WIN32
-    io.ImeWindowHandle = glfwGetWin32Window(g_Window);
-#endif
 
     g_MouseCursors[ImGuiMouseCursor_Arrow] = glfwCreateStandardCursor(GLFW_ARROW_CURSOR);
     g_MouseCursors[ImGuiMouseCursor_TextInput] = glfwCreateStandardCursor(GLFW_IBEAM_CURSOR);
@@ -500,7 +497,33 @@ static void ImGui_ImplGlfw_SwapBuffers(ImGuiViewport* viewport, void*)
         glfwSwapBuffers(data->Window);
 }
 
+//--------------------------------------------------------------------------------------------------------
+// IME (Input Method Editor) basic support for e.g. Asian language users
+//--------------------------------------------------------------------------------------------------------
+
+// We provide a Win32 implementation because this is such a common issue for IME users
+#if defined(_WIN32) && !defined(IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS) && !defined(__GNUC__)
+#define HAS_WIN32_IME   1
+#include <imm.h>
+#ifdef _MSC_VER
+#pragma comment(lib, "imm32")
+#endif
+static void ImGui_ImplWin32_SetImeInputPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    COMPOSITIONFORM cf = { CFS_FORCE_POSITION, { (LONG)(pos.x - viewport->Pos.x), (LONG)(pos.y - viewport->Pos.y) }, { 0, 0, 0, 0 } };
+    if (ImGuiViewportDataGlfw* data = (ImGuiViewportDataGlfw*)viewport->PlatformUserData)
+        if (HWND hwnd = glfwGetWin32Window(data->Window))
+            if (HIMC himc = ImmGetContext(hwnd))
+                ImmSetCompositionWindow(himc, &cf);
+}
+#else
+#define HAS_WIN32_IME   0
+#endif
+
+//--------------------------------------------------------------------------------------------------------
 // Vulkan support (the Vulkan renderer needs to call a platform-side support function to create the surface)
+//--------------------------------------------------------------------------------------------------------
+
 // Avoid including <vulkan.h> so we can build without it
 #if GLFW_HAS_VULKAN
 #ifndef VULKAN_H_
@@ -571,6 +594,9 @@ static void ImGui_ImplGlfw_InitPlatformInterface()
 #if GLFW_HAS_VULKAN
     platform_io.Platform_CreateVkSurface = ImGui_ImplGlfw_CreateVkSurface;
 #endif
+#if HAS_WIN32_IME
+    platform_io.Platform_SetImeInputPos = ImGui_ImplWin32_SetImeInputPos;
+#endif
 
     ImGui_ImplGlfw_UpdateMonitors();
 

examples/imgui_impl_sdl2.cpp

@@ -170,13 +170,6 @@ bool    ImGui_ImplSDL2_Init(SDL_Window* window, void* sdl_gl_context)
     g_MouseCursors[ImGuiMouseCursor_ResizeNESW] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENESW);
     g_MouseCursors[ImGuiMouseCursor_ResizeNWSE] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENWSE);
 
-#ifdef _WIN32
-    SDL_SysWMinfo wmInfo;
-    SDL_VERSION(&wmInfo.version);
-    SDL_GetWindowWMInfo(window, &wmInfo);
-    io.ImeWindowHandle = wmInfo.info.win.window;
-#endif
-
     // Our mouse update function expect PlatformHandle to be filled for the main viewport
     ImGuiViewport* main_viewport = ImGui::GetMainViewport();
     main_viewport->PlatformHandle = (void*)window;

examples/imgui_impl_win32.cpp

@@ -76,8 +76,6 @@ bool    ImGui_ImplWin32_Init(void* hwnd)
     io.KeyMap[ImGuiKey_Y] = 'Y';
     io.KeyMap[ImGuiKey_Z] = 'Z';
 
-    io.ImeWindowHandle = g_hWnd;    
-
     return true;
 }
 
@@ -279,7 +277,7 @@ IMGUI_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hwnd, UINT msg, WPARAM wPa
     return 0;
 }
 
-// --------------------------------------------------------------------------------------------------------
+//--------------------------------------------------------------------------------------------------------
 // DPI handling
 // Those in theory should be simple calls but Windows has multiple ways to handle DPI, and most of them
 // require recent Windows versions at runtime or recent Windows SDK at compile-time. Neither we want to depend on.
@@ -370,9 +368,30 @@ float ImGui_ImplWin32_GetDpiScaleForRect(int x1, int y1, int x2, int y2)
     return ImGui_ImplWin32_GetDpiScaleForMonitor(monitor);
 }
 
-// --------------------------------------------------------------------------------------------------------
+//--------------------------------------------------------------------------------------------------------
+// IME (Input Method Editor) basic support for e.g. Asian language users
+//--------------------------------------------------------------------------------------------------------
+
+#if defined(_WIN32) && !defined(IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS) && !defined(__GNUC__)
+#define HAS_WIN32_IME   1
+#include <imm.h>
+#ifdef _MSC_VER
+#pragma comment(lib, "imm32")
+#endif
+static void ImGui_ImplWin32_SetImeInputPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    COMPOSITIONFORM cf = { CFS_FORCE_POSITION,{ (LONG)(pos.x - viewport->Pos.x), (LONG)(pos.y - viewport->Pos.y) },{ 0, 0, 0, 0 } };
+    if (HWND hwnd = (HWND)viewport->PlatformHandle)
+        if (HIMC himc = ImmGetContext(hwnd))
+            ImmSetCompositionWindow(himc, &cf);
+}
+#else
+#define HAS_WIN32_IME   0
+#endif
+
+//--------------------------------------------------------------------------------------------------------
 // Platform Windows
-// --------------------------------------------------------------------------------------------------------
+//--------------------------------------------------------------------------------------------------------
 
 struct ImGuiViewportDataWin32
 {
@@ -625,6 +644,9 @@ static void ImGui_ImplWin32_InitPlatformInterface()
     platform_io.Platform_SetWindowAlpha = ImGui_ImplWin32_SetWindowAlpha;
     platform_io.Platform_GetWindowDpiScale = ImGui_ImplWin32_GetWindowDpiScale;
     platform_io.Platform_OnChangedViewport = ImGui_ImplWin32_OnChangedViewport; // FIXME-DPI
+#if HAS_WIN32_IME
+    platform_io.Platform_SetImeInputPos = ImGui_ImplWin32_SetImeInputPos;
+#endif
 
     // Register main window handle (which is owned by the main application, not by us)
     ImGuiViewport* main_viewport = ImGui::GetMainViewport();

imgui.cpp

@@ -262,6 +262,8 @@
  Here is a change-log of API breaking changes, if you are using one of the functions listed, expect to have to fix some code.
  Also read releases logs https://github.com/ocornut/imgui/releases for more details.
 
+ - 2018/XX/XX (1.XX) - Moved IME support functions from io.ImeSetInputScreenPosFn, io.ImeWindowHandle to the PlatformIO api.
+
  - 2018/04/09 (1.61) - IM_DELETE() helper function added in 1.60 doesn't clear the input _pointer_ reference, more consistent with expectation and allows passing r-value.
  - 2018/03/20 (1.60) - Renamed io.WantMoveMouse to io.WantSetMousePos for consistency and ease of understanding (was added in 1.52, _not_ used by core and only honored by some binding ahead of merging the Nav branch).
  - 2018/03/12 (1.60) - Removed ImGuiCol_CloseButton, ImGuiCol_CloseButtonActive, ImGuiCol_CloseButtonHovered as the closing cross uses regular button colors now.
@@ -617,10 +619,7 @@
     Otherwise you can convert yourself to UTF-8 or load text data from file already saved as UTF-8.
 
     Text input: it is up to your application to pass the right character code by calling 
-    io.AddInputCharacter(). The applications in examples/ are doing that. For languages relying 
-    on an Input Method Editor (IME), on Windows you can copy the Hwnd of your application in the
-    io.ImeWindowHandle field. The default implementation of io.ImeSetInputScreenPosFn() will set
-    your Microsoft IME position correctly.
+    io.AddInputCharacter(). The applications in examples/ are doing that. 
 
  Q: How can I use the drawing facilities without an ImGui window? (using ImDrawList API)
  A: - You can create a dummy window. Call SetNextWindowBgAlpha(0.0f), call Begin() with NoTitleBar|NoResize|NoMove|NoScrollbar|NoSavedSettings|NoInputs flags. 
@@ -771,7 +770,6 @@ static void             SetCurrentViewport(ImGuiViewportP* viewport);
 
 static const char*      GetClipboardTextFn_DefaultImpl(void* user_data);
 static void             SetClipboardTextFn_DefaultImpl(void* user_data, const char* text);
-static void             ImeSetInputScreenPosFn_DefaultImpl(int x, int y);
 
 //-----------------------------------------------------------------------------
 // Context
@@ -907,8 +905,6 @@ ImGuiIO::ImGuiIO()
     GetClipboardTextFn = GetClipboardTextFn_DefaultImpl;   // Platform dependent default implementations
     SetClipboardTextFn = SetClipboardTextFn_DefaultImpl;
     ClipboardUserData = NULL;
-    ImeSetInputScreenPosFn = ImeSetInputScreenPosFn_DefaultImpl;
-    ImeWindowHandle = NULL;
 
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
     RenderDrawListsFn = NULL;
@@ -3924,7 +3920,8 @@ void ImGui::NewFrame()
 
     g.MouseCursor = ImGuiMouseCursor_Arrow;
     g.WantCaptureMouseNextFrame = g.WantCaptureKeyboardNextFrame = g.WantTextInputNextFrame = -1;
-    g.OsImePosRequest = ImVec2(1.0f, 1.0f); // OS Input Method Editor showing on top-left of our window by default
+    g.PlatformImePos = ImVec2(1.0f, 1.0f); // OS Input Method Editor showing on top-left of our window by default
+    g.PlatformImePosViewport = NULL;
 
     // Mouse wheel scrolling, scale
     if (g.HoveredWindow && !g.HoveredWindow->Collapsed && (g.IO.MouseWheel != 0.0f || g.IO.MouseWheelH != 0.0f))
@@ -4464,10 +4461,11 @@ void ImGui::EndFrame()
         return;
 
     // Notify OS when our Input Method Editor cursor has moved (e.g. CJK inputs using Microsoft IME)
-    if (g.IO.ImeSetInputScreenPosFn && ImLengthSqr(g.OsImePosRequest - g.OsImePosSet) > 0.0001f)
+    if (g.PlatformIO.Platform_SetImeInputPos && g.PlatformImePosViewport != NULL && ImLengthSqr(g.PlatformImePos - g.PlatformImeLastPos) > 0.0001f)
     {
-        g.IO.ImeSetInputScreenPosFn((int)g.OsImePosRequest.x, (int)g.OsImePosRequest.y);
-        g.OsImePosSet = g.OsImePosRequest;
+        g.PlatformIO.Platform_SetImeInputPos(g.PlatformImePosViewport, g.PlatformImePos);
+        g.PlatformImeLastPos = g.PlatformImePos;
+        g.PlatformImePosViewport = NULL;
     }
 
     // Hide implicit "Debug" window if it hasn't been used
@@ -11316,7 +11314,10 @@ bool ImGui::InputTextEx(const char* label, char* buf, int buf_size, const ImVec2
 
         // Notify OS of text input position for advanced IME (-1 x offset so that Windows IME can cover our cursor. Bit of an extra nicety.)
         if (is_editable)
-            g.OsImePosRequest = ImVec2(cursor_screen_pos.x - 1, cursor_screen_pos.y - g.FontSize);
+        {
+            g.PlatformImePos = ImVec2(cursor_screen_pos.x - 1, cursor_screen_pos.y - g.FontSize);
+            g.PlatformImePosViewport = window->Viewport;
+        }
     }
     else
     {
@@ -14027,34 +14028,6 @@ static void SetClipboardTextFn_DefaultImpl(void*, const char* text)
 
 #endif
 
-// Win32 API IME support (for Asian languages, etc.)
-#if defined(_WIN32) && !defined(__GNUC__) && !defined(IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS)
-
-#include <imm.h>
-#ifdef _MSC_VER
-#pragma comment(lib, "imm32")
-#endif
-
-static void ImeSetInputScreenPosFn_DefaultImpl(int x, int y)
-{
-    // Notify OS Input Method Editor of text input position
-    if (HWND hwnd = (HWND)GImGui->IO.ImeWindowHandle)
-        if (HIMC himc = ImmGetContext(hwnd))
-        {
-            COMPOSITIONFORM cf;
-            cf.ptCurrentPos.x = x;
-            cf.ptCurrentPos.y = y;
-            cf.dwStyle = CFS_FORCE_POSITION;
-            ImmSetCompositionWindow(himc, &cf);
-        }
-}
-
-#else
-
-static void ImeSetInputScreenPosFn_DefaultImpl(int, int) {}
-
-#endif
-
 //-----------------------------------------------------------------------------
 // HELP
 //-----------------------------------------------------------------------------

imgui.h

@@ -1059,11 +1059,6 @@ struct ImGuiIO
     void        (*SetClipboardTextFn)(void* user_data, const char* text);
     void*       ClipboardUserData;
 
-    // Optional: notify OS Input Method Editor of the screen position of your cursor for text input position (e.g. when using Japanese/Chinese IME in Windows)
-    // (default to use native imm32 api on Windows)
-    void        (*ImeSetInputScreenPosFn)(int x, int y);
-    void*       ImeWindowHandle;            // (Windows) Set this to your HWND to get automatic IME cursor positioning.
-
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
     // [OBSOLETE] Rendering function, will be automatically called in Render(). Please call your rendering function yourself now! You can obtain the ImDrawData* by calling ImGui::GetDrawData() after Render().
     // See example applications if you are unsure of how to implement this.
@@ -1896,7 +1891,7 @@ struct ImGuiPlatformIO
     // Input - Back-end interface/functions + Monitor List
     //------------------------------------------------------------------
 
-    // Platform functions (e.g. Win32, GLFW, SDL2)
+    // (Optional) Platform functions (e.g. Win32, GLFW, SDL2)
     void    (*Platform_CreateWindow)(ImGuiViewport* vp);                    // Create a new platform window for the given viewport
     void    (*Platform_DestroyWindow)(ImGuiViewport* vp);
     void    (*Platform_ShowWindow)(ImGuiViewport* vp);                      // Newly created windows are initially hidden so SetWindowPos/Size/Title can be called on them first
@@ -1910,16 +1905,17 @@ struct ImGuiPlatformIO
     void    (*Platform_SwapBuffers)(ImGuiViewport* vp, void* render_arg);   // (Optional) Call Present/SwapBuffers (platform side)
     float   (*Platform_GetWindowDpiScale)(ImGuiViewport* vp);               // (Optional) DPI handling: Return DPI scale for this viewport. 1.0f = 96 DPI. (FIXME-DPI)
     void    (*Platform_OnChangedViewport)(ImGuiViewport* vp);               // (Optional) DPI handling: Called during Begin() every time the viewport we are outputting into changes, so back-end has a chance to swap fonts to adjust style.
+    void    (*Platform_SetImeInputPos)(ImGuiViewport* vp, ImVec2 pos);      // (Optional) Set IME (Input Method Editor, e.g. for Asian languages) input position, so text preview appears over the imgui input box.
     int     (*Platform_CreateVkSurface)(ImGuiViewport* vp, ImU64 vk_inst, const void* vk_allocators, ImU64* out_vk_surface); // (Optional) For Renderer to call into Platform code
 
-    // Renderer functions (e.g. DirectX, OpenGL3, Vulkan)
+    // (Optional) Renderer functions (e.g. DirectX, OpenGL3, Vulkan)
     void    (*Renderer_CreateWindow)(ImGuiViewport* vp);                    // Create swap chains, frame buffers etc.
     void    (*Renderer_DestroyWindow)(ImGuiViewport* vp);
     void    (*Renderer_SetWindowSize)(ImGuiViewport* vp, ImVec2 size);      // Resize swap chain, frame buffers etc.
     void    (*Renderer_RenderWindow)(ImGuiViewport* vp, void* render_arg);  // (Optional) Clear targets, Render viewport->DrawData
     void    (*Renderer_SwapBuffers)(ImGuiViewport* vp, void* render_arg);   // (Optional) Call Present/SwapBuffers (renderer side)
 
-    // List of monitors (updated by: app/back-end, used by: imgui to clamp popups/tooltips within same monitor and not have them straddle monitors)
+    // (Optional) List of monitors (updated by: app/back-end, used by: imgui to clamp popups/tooltips within same monitor and not have them straddle monitors)
     ImVector<ImGuiPlatformMonitor>  Monitors;
 
     //------------------------------------------------------------------

imgui_internal.h

@@ -715,7 +715,10 @@ struct ImGuiContext
     ImVec2                  ScrollbarClickDeltaToGrabCenter;    // Distance between mouse and center of grab box, normalized in parent space. Use storage?
     int                     TooltipOverrideCount;
     ImVector<char>          PrivateClipboard;                   // If no custom clipboard handler is defined
-    ImVec2                  OsImePosRequest, OsImePosSet;       // Cursor position request & last passed to the OS Input Method Editor
+
+    // Platform support
+    ImVec2                  PlatformImePos, PlatformImeLastPos; // Cursor position request & last passed to the OS Input Method Editor
+    ImGuiViewport*          PlatformImePosViewport;
 
     // Settings
     bool                           SettingsLoaded;
@@ -822,7 +825,8 @@ struct ImGuiContext
         DragSpeedScaleFast = 10.0f;
         ScrollbarClickDeltaToGrabCenter = ImVec2(0.0f, 0.0f);
         TooltipOverrideCount = 0;
-        OsImePosRequest = OsImePosSet = ImVec2(-1.0f, -1.0f);
+        PlatformImePos = PlatformImeLastPos = ImVec2(FLT_MAX, FLT_MAX);
+        PlatformImePosViewport = 0;
 
         SettingsLoaded = false;
         SettingsDirtyTimer = 0.0f;