add Windows IME support

vstgui/lib/ctexteditor.cpp

@@ -19,6 +19,7 @@
 #include "platform/iplatformtextinputclient.h"
 #include "platform/platformfactory.h"
 #include "platform/platform_macos.h"
+#include "platform/platform_win32.h"
 #include "controls/cbuttons.h"
 #include "controls/ctextedit.h"
 #include "animation/timingfunctions.h"
@@ -206,7 +207,8 @@ struct TextEditorView : public CView,
 						public TextEditorColorization::IEditorExt,
 						public IFocusDrawing,
 						public ViewEventListenerAdapter,
-						public ICocoaTextInputClient
+						public ICocoaTextInputClient,
+						public IIMETextInputClient
 {
 	TextEditorView (ITextEditorController* controller);
 	void beforeDelete () override;
@@ -331,6 +333,12 @@ struct TextEditorView : public CView,
 	std::u32string substringForRange (TextRange range, TextRange& actualRange) override;
 	size_t characterIndexForPoint (CPoint pos) override;
 
+	// IIMETextInputClient
+	bool ime_queryCharacterPosition (CharPosition& cp) override;
+	void ime_setMarkedText (const std::u32string& string) override;
+	void ime_insertText (const std::u32string& string) override;
+	void ime_unmarkText () override;
+
 private:
 	template<typename Proc>
 	bool callSTB (Proc proc) const;
@@ -662,6 +670,12 @@ void TextEditorView::takeFocus ()
 	{
 		cocoaFrame->setTextInputClient (this);
 	}
+#elif WINDOWS
+	auto pf = getFrame ()->getPlatformFrame ();
+	if (auto winFrame = dynamic_cast<IWin32PlatformFrame*> (pf))
+	{
+		winFrame->setTextInputClient (this);
+	}
 #endif
 }
 
@@ -677,6 +691,12 @@ void TextEditorView::looseFocus ()
 	{
 		cocoaFrame->setTextInputClient (nullptr);
 	}
+#elif WINDOWS
+	auto pf = getFrame ()->getPlatformFrame ();
+	if (auto winFrame = dynamic_cast<IWin32PlatformFrame*> (pf))
+	{
+		winFrame->setTextInputClient (nullptr);
+	}
 #endif
 }
 
@@ -3068,7 +3088,7 @@ size_t TextEditorView::characterIndexForPoint (CPoint pos)
 		pos.y -= md.style->lineSpacing;
 		if (pos.y >= 0.)
 		{
-			auto lineIndex = std::floor (pos.y / md.lineHeight);
+			auto lineIndex = static_cast<size_t> (std::floor (pos.y / md.lineHeight));
 			if (lineIndex < md.model.lines.size ())
 			{
 				pos.x += md.style->leftMargin;
@@ -3095,6 +3115,62 @@ size_t TextEditorView::characterIndexForPoint (CPoint pos)
 	return std::numeric_limits<size_t>::max ();
 }
 
+//------------------------------------------------------------------------
+// IIMETextInputClient
+//------------------------------------------------------------------------
+bool TextEditorView::ime_queryCharacterPosition (CharPosition& cp)
+{
+	auto it = findLine (md.model.lines.begin (), md.model.lines.end (), md.editState.cursor);
+	auto r = calculateLineRect (it);
+	if (static_cast<int> (it->range.start) != md.editState.cursor)
+	{
+		auto t = md.model.text.substr (it->range.start, md.editState.cursor - it->range.start);
+		auto nonSelectedText = convert (t);
+		replaceTabs (nonSelectedText, md.style->tabWidth, 0u);
+		auto str = getPlatformFactory ().createString (nonSelectedText.data ());
+		r.left += md.style->font->getFontPainter ()->getStringWidth (nullptr, str);
+		r.right = r.left;
+	}
+	r = translateToGlobal (r);
+	cp.position = r.getTopLeft ();
+	cp.lineHeight = md.lineHeight * getFrame ()->getScaleFactor ();
+	cp.documentRect = translateToGlobal (getVisibleViewSize ());
+	return true;
+}
+
+//------------------------------------------------------------------------
+void TextEditorView::ime_setMarkedText (const std::u32string& string)
+{
+	if (markedRange.length > 0)
+		deleteChars (markedRange.start, markedRange.length);
+	insertChars (md.editState.select_start, string.data (), string.size ());
+	markedRange.start = md.editState.select_start;
+	markedRange.length = string.size ();
+	md.editState.select_end = static_cast<int> (md.editState.select_start + string.size ());
+}
+
+//------------------------------------------------------------------------
+void TextEditorView::ime_insertText (const std::u32string& string)
+{
+	if (markedRange.length > 0)
+		deleteChars (markedRange.start, markedRange.length);
+	markedRange = {};
+	md.editState.select_start = md.editState.select_end = md.editState.cursor;
+	callSTB ([&] () {
+		stb_textedit_paste (this, &md.editState, string.data (),
+							static_cast<int32_t> (string.size ()));
+	});
+}
+
+//------------------------------------------------------------------------
+void TextEditorView::ime_unmarkText ()
+{
+	if (markedRange.length > 0)
+		deleteChars (markedRange.start, markedRange.length);
+	markedRange = {};
+	md.editState.select_start = md.editState.select_end = md.editState.cursor;
+}
+
 //------------------------------------------------------------------------
 //------------------------------------------------------------------------
 //------------------------------------------------------------------------

vstgui/lib/platform/iplatformtextinputclient.h

@@ -32,5 +32,24 @@ struct ICocoaTextInputClient
 	virtual ~ICocoaTextInputClient () noexcept = default;
 };
 
+//------------------------------------------------------------------------
+struct IIMETextInputClient
+{
+	struct CharPosition
+	{
+		uint32_t characterPosition;
+		CPoint position;
+		double lineHeight;
+		CRect documentRect;
+	};
+
+	virtual bool ime_queryCharacterPosition (CharPosition& cp) = 0;
+	virtual void ime_setMarkedText (const std::u32string& string) = 0;
+	virtual void ime_insertText (const std::u32string& string) = 0;
+	virtual void ime_unmarkText () = 0;
+
+	virtual ~IIMETextInputClient () noexcept = default;
+};
+
 //------------------------------------------------------------------------
 } // VSTGUI

vstgui/lib/platform/platform_win32.h

@@ -15,12 +15,15 @@
 //-----------------------------------------------------------------------------
 namespace VSTGUI {
 
+struct IIMETextInputClient;
+
 //-----------------------------------------------------------------------------
 // extens IPlatformFrame on Microsoft Windows
 class IWin32PlatformFrame
 {
 public:
 	virtual HWND getHWND () const = 0;
+	virtual void setTextInputClient (IIMETextInputClient* client) = 0;
 };
 
 //-----------------------------------------------------------------------------

vstgui/lib/platform/win32/win32frame.cpp

@@ -8,6 +8,7 @@
 
 #include <commctrl.h>
 #include <cmath>
+#include <codecvt>
 #include <windowsx.h>
 #include "direct2d/d2dbitmap.h"
 #include "direct2d/d2dgraphicspath.h"
@@ -20,6 +21,7 @@
 #include "win32dragging.h"
 #include "win32directcomposition.h"
 #include "win32viewlayer.h"
+#include "../iplatformtextinputclient.h"
 #include "../common/genericoptionmenu.h"
 #include "../common/generictextedit.h"
 #include "../../cdropsource.h"
@@ -37,6 +39,7 @@
 // windows libraries VSTGUI depends on
 #ifdef _MSC_VER
 #pragma comment(lib, "Shlwapi.lib")
+#pragma comment(lib, "Imm32.lib")
 #endif
 
 namespace VSTGUI {
@@ -738,6 +741,24 @@ static void setupMouseEventFromWParam (MouseEvent& event, WPARAM wParam)
 		event.modifiers.add (ModifierKey::Super);
 }
 
+//------------------------------------------------------------------------
+static std::u32string convert (std::wstring_view s)
+{
+	std::string bytes;
+	bytes.reserve (s.size () * 2);
+
+	for (const char16_t c : s)
+	{
+		bytes.push_back (static_cast<char> (c / 256));
+		bytes.push_back (static_cast<char> (c % 256));
+	}
+
+#pragma warning(disable : 4996) // deprecated
+	std::wstring_convert<std::codecvt_utf16<char32_t>, char32_t> convert;
+	return convert.from_bytes (bytes);
+#pragma warning(3 : 4996) // deprecated
+}
+
 //-----------------------------------------------------------------------------
 LONG_PTR WINAPI Win32Frame::proc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 {
@@ -946,10 +967,90 @@ LONG_PTR WINAPI Win32Frame::proc (HWND hwnd, UINT message, WPARAM wParam, LPARAM
 			}
 			break;
 		}
+		case WM_IME_STARTCOMPOSITION:
+		{
+			if (!textInputClient)
+				break;
+			return 0;
+		}
+		case WM_IME_ENDCOMPOSITION:
+		{
+			if (!textInputClient)
+				break;
+			textInputClient->ime_unmarkText ();
+			return 0;
+		}
+		case WM_IME_COMPOSITION:
+		{
+			if (!textInputClient)
+				break;
+
+			static constexpr auto getCompositionString = [] (auto context, auto which) {
+				auto requiredBytes = ImmGetCompositionStringW (context, which, nullptr, 0);
+				if (requiredBytes > 0)
+				{
+					std::wstring str;
+					str.resize (requiredBytes / sizeof (char16_t));
+					if (ImmGetCompositionStringW (context, which, str.data (), requiredBytes) ==
+						requiredBytes)
+					{
+						return str;
+					}
+				}
+				return std::wstring ();
+			};
+
+			if (auto immContext = ImmGetContext (hwnd))
+			{
+				if (lParam & GCS_RESULTSTR)
+				{
+					auto str = getCompositionString (immContext, GCS_RESULTSTR);
+					auto u32str = convert (str);
+					textInputClient->ime_insertText (u32str);
+				}
+				if (lParam & GCS_COMPSTR)
+				{
+					auto str = getCompositionString (immContext, GCS_COMPSTR);
+					auto u32str = convert (str);
+					textInputClient->ime_setMarkedText (u32str);
+				}
+				ImmReleaseContext (hwnd, immContext);
+			}
+			break;
+		}
+		case WM_IME_REQUEST:
+		{
+			if (!textInputClient)
+				break;
+			if (wParam == IMR_QUERYCHARPOSITION)
+			{
+				IIMETextInputClient::CharPosition cp {};
+				if (textInputClient->ime_queryCharacterPosition (cp))
+				{
+					auto charPos = reinterpret_cast<IMECHARPOSITION*> (lParam);
+					charPos->dwSize = sizeof (IMECHARPOSITION);
+					charPos->cLineHeight = static_cast<UINT> (std::ceil (cp.lineHeight));
+					charPos->pt = {static_cast<INT> (cp.position.x),
+								   static_cast<INT> (cp.position.y)};
+					charPos->dwCharPos = cp.characterPosition;
+					charPos->rcDocument.left = static_cast<LONG> (cp.documentRect.left);
+					charPos->rcDocument.top = static_cast<LONG> (cp.documentRect.top);
+					charPos->rcDocument.right = static_cast<LONG> (cp.documentRect.right);
+					charPos->rcDocument.bottom = static_cast<LONG> (cp.documentRect.bottom);
+					MapWindowPoints (hwnd, nullptr, &charPos->pt, 1);
+					MapWindowRect (hwnd, nullptr, &charPos->rcDocument);
+					return 1;
+				}
+			}
+			break;
+		}
 	}
 	return DefWindowProc (hwnd, message, wParam, lParam);
 }
 
+//------------------------------------------------------------------------
+void Win32Frame::setTextInputClient (IIMETextInputClient* client) { textInputClient = client; }
+
 //-----------------------------------------------------------------------------
 Optional<UTF8String> Win32Frame::convertCurrentKeyEventToText ()
 {

vstgui/lib/platform/win32/win32frame.h

@@ -22,6 +22,8 @@ class Win32Frame final : public IPlatformFrame, public IWin32PlatformFrame
 	~Win32Frame () noexcept;
 
 	HWND getHWND () const override { return windowHandle; }
+	void setTextInputClient (IIMETextInputClient* client) override;
+
 	HWND getPlatformWindow () const { return windowHandle; }
 	HWND getParentPlatformWindow () const { return parentWindow; }
 	HWND getOuterWindow () const;
@@ -85,6 +87,7 @@ class Win32Frame final : public IPlatformFrame, public IWin32PlatformFrame
 	PlatformGraphicsDeviceContextPtr legacyDrawDevice;
 	Optional<MSG> currentEvent;
 	ViewLayers viewLayers;
+	IIMETextInputClient* textInputClient {nullptr};
 
 	bool inPaint;
 	bool mouseInside;