Adding upstream version 2:8.2.2434.upstream/2%8.2.2434upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1349 insertions, 0 deletions

diff --git a/src/gui_dwrite.cpp b/src/gui_dwrite.cpp
new file mode 100644
index 0000000..83acdab
--- /dev/null
+++ b/src/gui_dwrite.cpp
@@ -0,0 +1,1349 @@
+/* vi:set ts=8 sts=4 sw=4 noet: */
+/*
+ * Author: MURAOKA Taro <koron.kaoriya@gmail.com>
+ *
+ * Contributors:
+ *  - Ken Takata
+ *  - Yasuhiro Matsumoto
+ *
+ * Copyright (C) 2013 MURAOKA Taro <koron.kaoriya@gmail.com>
+ * THIS FILE IS DISTRIBUTED UNDER THE VIM LICENSE.
+ */
+
+#define WIN32_LEAN_AND_MEAN
+
+#ifndef DYNAMIC_DIRECTX
+# if WINVER < 0x0600
+#  error WINVER must be 0x0600 or above to use DirectWrite(DirectX)
+# endif
+#endif
+
+#include <windows.h>
+#include <crtdbg.h>
+#include <assert.h>
+#include <math.h>
+#include <d2d1.h>
+#include <d2d1helper.h>
+
+// Disable these macros to compile with old VC and newer SDK (V8.1 or later).
+#if defined(_MSC_VER) && (_MSC_VER < 1700)
+# define _COM_Outptr_ __out
+# define _In_reads_(s)
+# define _In_reads_opt_(s)
+# define _Maybenull_
+# define _Out_writes_(s)
+# define _Out_writes_opt_(s)
+# define _Out_writes_to_(x, y)
+# define _Out_writes_to_opt_(x, y)
+# define _Outptr_
+#endif
+
+#ifdef FEAT_DIRECTX_COLOR_EMOJI
+# include <dwrite_2.h>
+#else
+# include <dwrite.h>
+#endif
+
+#include "gui_dwrite.h"
+
+#ifdef __MINGW32__
+# define __maybenull	SAL__maybenull
+# define __in		SAL__in
+# define __out		SAL__out
+#endif
+
+#if (defined(_MSC_VER) && (_MSC_VER >= 1700)) || (__cplusplus >= 201103L)
+# define FINAL final
+#else
+# define FINAL
+#endif
+
+#ifdef DYNAMIC_DIRECTX
+extern "C" HINSTANCE vimLoadLib(char *name);
+
+typedef int (WINAPI *PGETUSERDEFAULTLOCALENAME)(LPWSTR, int);
+typedef HRESULT (WINAPI *PD2D1CREATEFACTORY)(D2D1_FACTORY_TYPE,
+	REFIID, const D2D1_FACTORY_OPTIONS *, void **);
+typedef HRESULT (WINAPI *PDWRITECREATEFACTORY)(DWRITE_FACTORY_TYPE,
+	REFIID, IUnknown **);
+
+static HINSTANCE hD2D1DLL = NULL;
+static HINSTANCE hDWriteDLL = NULL;
+
+static PGETUSERDEFAULTLOCALENAME pGetUserDefaultLocaleName = NULL;
+static PD2D1CREATEFACTORY pD2D1CreateFactory = NULL;
+static PDWRITECREATEFACTORY pDWriteCreateFactory = NULL;
+
+#define GetUserDefaultLocaleName	(*pGetUserDefaultLocaleName)
+#define D2D1CreateFactory		(*pD2D1CreateFactory)
+#define DWriteCreateFactory		(*pDWriteCreateFactory)
+
+    static void
+unload(HINSTANCE &hinst)
+{
+    if (hinst != NULL)
+    {
+	FreeLibrary(hinst);
+	hinst = NULL;
+    }
+}
+#endif // DYNAMIC_DIRECTX
+
+template <class T> inline void SafeRelease(T **ppT)
+{
+    if (*ppT)
+    {
+	(*ppT)->Release();
+	*ppT = NULL;
+    }
+}
+
+    static DWRITE_PIXEL_GEOMETRY
+ToPixelGeometry(int value)
+{
+    switch (value)
+    {
+	default:
+	case 0:
+	    return DWRITE_PIXEL_GEOMETRY_FLAT;
+	case 1:
+	    return DWRITE_PIXEL_GEOMETRY_RGB;
+	case 2:
+	    return DWRITE_PIXEL_GEOMETRY_BGR;
+    }
+}
+
+    static int
+ToInt(DWRITE_PIXEL_GEOMETRY value)
+{
+    switch (value)
+    {
+	case DWRITE_PIXEL_GEOMETRY_FLAT:
+	    return 0;
+	case DWRITE_PIXEL_GEOMETRY_RGB:
+	    return 1;
+	case DWRITE_PIXEL_GEOMETRY_BGR:
+	    return 2;
+	default:
+	    return -1;
+    }
+}
+
+    static DWRITE_RENDERING_MODE
+ToRenderingMode(int value)
+{
+    switch (value)
+    {
+	default:
+	case 0:
+	    return DWRITE_RENDERING_MODE_DEFAULT;
+	case 1:
+	    return DWRITE_RENDERING_MODE_ALIASED;
+	case 2:
+	    return DWRITE_RENDERING_MODE_CLEARTYPE_GDI_CLASSIC;
+	case 3:
+	    return DWRITE_RENDERING_MODE_CLEARTYPE_GDI_NATURAL;
+	case 4:
+	    return DWRITE_RENDERING_MODE_CLEARTYPE_NATURAL;
+	case 5:
+	    return DWRITE_RENDERING_MODE_CLEARTYPE_NATURAL_SYMMETRIC;
+	case 6:
+	    return DWRITE_RENDERING_MODE_OUTLINE;
+    }
+}
+
+    static D2D1_TEXT_ANTIALIAS_MODE
+ToTextAntialiasMode(int value)
+{
+    switch (value)
+    {
+	default:
+	case 0:
+	    return D2D1_TEXT_ANTIALIAS_MODE_DEFAULT;
+	case 1:
+	    return D2D1_TEXT_ANTIALIAS_MODE_CLEARTYPE;
+	case 2:
+	    return D2D1_TEXT_ANTIALIAS_MODE_GRAYSCALE;
+	case 3:
+	    return D2D1_TEXT_ANTIALIAS_MODE_ALIASED;
+    }
+}
+
+    static int
+ToInt(DWRITE_RENDERING_MODE value)
+{
+    switch (value)
+    {
+	case DWRITE_RENDERING_MODE_DEFAULT:
+	    return 0;
+	case DWRITE_RENDERING_MODE_ALIASED:
+	    return 1;
+	case DWRITE_RENDERING_MODE_CLEARTYPE_GDI_CLASSIC:
+	    return 2;
+	case DWRITE_RENDERING_MODE_CLEARTYPE_GDI_NATURAL:
+	    return 3;
+	case DWRITE_RENDERING_MODE_CLEARTYPE_NATURAL:
+	    return 4;
+	case DWRITE_RENDERING_MODE_CLEARTYPE_NATURAL_SYMMETRIC:
+	    return 5;
+	case DWRITE_RENDERING_MODE_OUTLINE:
+	    return 6;
+	default:
+	    return -1;
+    }
+}
+
+class FontCache {
+public:
+    struct Item {
+	HFONT              hFont;
+	IDWriteTextFormat* pTextFormat;
+	DWRITE_FONT_WEIGHT fontWeight;
+	DWRITE_FONT_STYLE  fontStyle;
+	Item() : hFont(NULL), pTextFormat(NULL) {}
+    };
+
+private:
+    int mSize;
+    Item *mItems;
+
+public:
+    FontCache(int size = 2) :
+	mSize(size),
+	mItems(new Item[size])
+    {
+    }
+
+    ~FontCache()
+    {
+	for (int i = 0; i < mSize; ++i)
+	    SafeRelease(&mItems[i].pTextFormat);
+	delete[] mItems;
+    }
+
+    bool get(HFONT hFont, Item &item)
+    {
+	int n = find(hFont);
+	if (n < 0)
+	    return false;
+	item = mItems[n];
+	slide(n);
+	return true;
+    }
+
+    void put(const Item& item)
+    {
+	int n = find(item.hFont);
+	if (n < 0)
+	    n = mSize - 1;
+	if (mItems[n].pTextFormat != item.pTextFormat)
+	{
+	    SafeRelease(&mItems[n].pTextFormat);
+	    if (item.pTextFormat != NULL)
+		item.pTextFormat->AddRef();
+	}
+	mItems[n] = item;
+	slide(n);
+    }
+
+private:
+    int find(HFONT hFont)
+    {
+	for (int i = 0; i < mSize; ++i)
+	{
+	    if (mItems[i].hFont == hFont)
+		return i;
+	}
+	return -1;
+    }
+
+    void slide(int nextTop)
+    {
+	if (nextTop == 0)
+	    return;
+	Item tmp = mItems[nextTop];
+	for (int i = nextTop - 1; i >= 0; --i)
+	    mItems[i + 1] = mItems[i];
+	mItems[0] = tmp;
+    }
+};
+
+enum DrawingMode {
+    DM_GDI = 0,
+    DM_DIRECTX = 1,
+    DM_INTEROP = 2,
+};
+
+struct DWriteContext {
+    HDC mHDC;
+    RECT mBindRect;
+    DrawingMode mDMode;
+    HDC mInteropHDC;
+    bool mDrawing;
+    bool mFallbackDC;
+
+    ID2D1Factory *mD2D1Factory;
+
+    ID2D1DCRenderTarget *mRT;
+    ID2D1GdiInteropRenderTarget *mGDIRT;
+    ID2D1SolidColorBrush *mBrush;
+    ID2D1Bitmap *mBitmap;
+
+    IDWriteFactory *mDWriteFactory;
+#ifdef FEAT_DIRECTX_COLOR_EMOJI
+    IDWriteFactory2 *mDWriteFactory2;
+#endif
+
+    IDWriteGdiInterop *mGdiInterop;
+    IDWriteRenderingParams *mRenderingParams;
+
+    FontCache mFontCache;
+    IDWriteTextFormat *mTextFormat;
+    DWRITE_FONT_WEIGHT mFontWeight;
+    DWRITE_FONT_STYLE mFontStyle;
+
+    D2D1_TEXT_ANTIALIAS_MODE mTextAntialiasMode;
+
+    // METHODS
+
+    DWriteContext();
+
+    virtual ~DWriteContext();
+
+    HRESULT CreateDeviceResources();
+
+    void DiscardDeviceResources();
+
+    HRESULT CreateTextFormatFromLOGFONT(const LOGFONTW &logFont,
+	    IDWriteTextFormat **ppTextFormat);
+
+    HRESULT SetFontByLOGFONT(const LOGFONTW &logFont);
+
+    void SetFont(HFONT hFont);
+
+    void Rebind();
+
+    void BindDC(HDC hdc, const RECT *rect);
+
+    HRESULT SetDrawingMode(DrawingMode mode);
+
+    ID2D1Brush* SolidBrush(COLORREF color);
+
+    void DrawText(const WCHAR *text, int len,
+	int x, int y, int w, int h, int cellWidth, COLORREF color,
+	UINT fuOptions, const RECT *lprc, const INT *lpDx);
+
+    void FillRect(const RECT *rc, COLORREF color);
+
+    void DrawLine(int x1, int y1, int x2, int y2, COLORREF color);
+
+    void SetPixel(int x, int y, COLORREF color);
+
+    void Scroll(int x, int y, const RECT *rc);
+
+    void Flush();
+
+    void SetRenderingParams(
+	    const DWriteRenderingParams *params);
+
+    DWriteRenderingParams *GetRenderingParams(
+	    DWriteRenderingParams *params);
+};
+
+class AdjustedGlyphRun : public DWRITE_GLYPH_RUN
+{
+private:
+    FLOAT &mAccum;
+    FLOAT mDelta;
+    FLOAT *mAdjustedAdvances;
+
+public:
+    AdjustedGlyphRun(
+	    const DWRITE_GLYPH_RUN *glyphRun,
+	    FLOAT cellWidth,
+	    FLOAT &accum) :
+	DWRITE_GLYPH_RUN(*glyphRun),
+	mAccum(accum),
+	mDelta(0.0f),
+	mAdjustedAdvances(new FLOAT[glyphRun->glyphCount])
+    {
+	assert(cellWidth != 0.0f);
+	for (UINT32 i = 0; i < glyphRun->glyphCount; ++i)
+	{
+	    FLOAT orig = glyphRun->glyphAdvances[i];
+	    FLOAT adjusted = adjustToCell(orig, cellWidth);
+	    mAdjustedAdvances[i] = adjusted;
+	    mDelta += adjusted - orig;
+	}
+	glyphAdvances = mAdjustedAdvances;
+    }
+
+    ~AdjustedGlyphRun()
+    {
+	mAccum += mDelta;
+	delete[] mAdjustedAdvances;
+    }
+
+    static FLOAT adjustToCell(FLOAT value, FLOAT cellWidth)
+    {
+	int cellCount = int(floor(value / cellWidth + 0.5f));
+	if (cellCount < 1)
+	    cellCount = 1;
+	return cellCount * cellWidth;
+    }
+};
+
+struct TextRendererContext {
+    // const fields.
+    COLORREF color;
+    FLOAT cellWidth;
+
+    // working fields.
+    FLOAT offsetX;
+};
+
+class TextRenderer FINAL : public IDWriteTextRenderer
+{
+public:
+    TextRenderer(
+	    DWriteContext* pDWC) :
+	cRefCount_(0),
+	pDWC_(pDWC)
+    {
+	AddRef();
+    }
+
+    // add "virtual" to avoid a compiler warning
+    virtual ~TextRenderer()
+    {
+    }
+
+    IFACEMETHOD(IsPixelSnappingDisabled)(
+	__maybenull void* clientDrawingContext,
+	__out BOOL* isDisabled)
+    {
+	*isDisabled = FALSE;
+	return S_OK;
+    }
+
+    IFACEMETHOD(GetCurrentTransform)(
+	__maybenull void* clientDrawingContext,
+	__out DWRITE_MATRIX* transform)
+    {
+	// forward the render target's transform
+	pDWC_->mRT->GetTransform(
+		reinterpret_cast<D2D1_MATRIX_3X2_F*>(transform));
+	return S_OK;
+    }
+
+    IFACEMETHOD(GetPixelsPerDip)(
+	__maybenull void* clientDrawingContext,
+	__out FLOAT* pixelsPerDip)
+    {
+	float dpiX, unused;
+	pDWC_->mRT->GetDpi(&dpiX, &unused);
+	*pixelsPerDip = dpiX / 96.0f;
+	return S_OK;
+    }
+
+    IFACEMETHOD(DrawUnderline)(
+	__maybenull void* clientDrawingContext,
+	FLOAT baselineOriginX,
+	FLOAT baselineOriginY,
+	__in DWRITE_UNDERLINE const* underline,
+	IUnknown* clientDrawingEffect)
+    {
+	return E_NOTIMPL;
+    }
+
+    IFACEMETHOD(DrawStrikethrough)(
+	__maybenull void* clientDrawingContext,
+	FLOAT baselineOriginX,
+	FLOAT baselineOriginY,
+	__in DWRITE_STRIKETHROUGH const* strikethrough,
+	IUnknown* clientDrawingEffect)
+    {
+	return E_NOTIMPL;
+    }
+
+    IFACEMETHOD(DrawInlineObject)(
+	__maybenull void* clientDrawingContext,
+	FLOAT originX,
+	FLOAT originY,
+	IDWriteInlineObject* inlineObject,
+	BOOL isSideways,
+	BOOL isRightToLeft,
+	IUnknown* clientDrawingEffect)
+    {
+	return E_NOTIMPL;
+    }
+
+    IFACEMETHOD(DrawGlyphRun)(
+	__maybenull void* clientDrawingContext,
+	FLOAT baselineOriginX,
+	FLOAT baselineOriginY,
+	DWRITE_MEASURING_MODE measuringMode,
+	__in DWRITE_GLYPH_RUN const* glyphRun,
+	__in DWRITE_GLYPH_RUN_DESCRIPTION const* glyphRunDescription,
+	IUnknown* clientDrawingEffect)
+    {
+	TextRendererContext *context =
+	    reinterpret_cast<TextRendererContext*>(clientDrawingContext);
+
+	AdjustedGlyphRun adjustedGlyphRun(glyphRun, context->cellWidth,
+		context->offsetX);
+
+#ifdef FEAT_DIRECTX_COLOR_EMOJI
+	if (pDWC_->mDWriteFactory2 != NULL)
+	{
+	    IDWriteColorGlyphRunEnumerator *enumerator = NULL;
+	    HRESULT hr = pDWC_->mDWriteFactory2->TranslateColorGlyphRun(
+		baselineOriginX + context->offsetX,
+		baselineOriginY,
+		&adjustedGlyphRun,
+		NULL,
+		DWRITE_MEASURING_MODE_GDI_NATURAL,
+		NULL,
+		0,
+		&enumerator);
+	    if (SUCCEEDED(hr))
+	    {
+		// Draw by IDWriteFactory2 for color emoji
+		BOOL hasRun = TRUE;
+		enumerator->MoveNext(&hasRun);
+		while (hasRun)
+		{
+		    const DWRITE_COLOR_GLYPH_RUN* colorGlyphRun;
+		    enumerator->GetCurrentRun(&colorGlyphRun);
+
+		    pDWC_->mBrush->SetColor(colorGlyphRun->runColor);
+		    pDWC_->mRT->DrawGlyphRun(
+			    D2D1::Point2F(
+				colorGlyphRun->baselineOriginX,
+				colorGlyphRun->baselineOriginY),
+			    &colorGlyphRun->glyphRun,
+			    pDWC_->mBrush,
+			    DWRITE_MEASURING_MODE_NATURAL);
+		    enumerator->MoveNext(&hasRun);
+		}
+		SafeRelease(&enumerator);
+		return S_OK;
+	    }
+	}
+#endif
+
+	// Draw by IDWriteFactory (without color emoji)
+	pDWC_->mRT->DrawGlyphRun(
+		D2D1::Point2F(
+		    baselineOriginX + context->offsetX,
+		    baselineOriginY),
+		&adjustedGlyphRun,
+		pDWC_->SolidBrush(context->color),
+		DWRITE_MEASURING_MODE_NATURAL);
+	return S_OK;
+    }
+
+public:
+    IFACEMETHOD_(unsigned long, AddRef) ()
+    {
+	return InterlockedIncrement(&cRefCount_);
+    }
+
+    IFACEMETHOD_(unsigned long, Release) ()
+    {
+	long newCount = InterlockedDecrement(&cRefCount_);
+
+	if (newCount == 0)
+	{
+	    delete this;
+	    return 0;
+	}
+	return newCount;
+    }
+
+    IFACEMETHOD(QueryInterface)(
+	IID const& riid,
+	void** ppvObject)
+    {
+	if (__uuidof(IDWriteTextRenderer) == riid)
+	{
+	    *ppvObject = this;
+	}
+	else if (__uuidof(IDWritePixelSnapping) == riid)
+	{
+	    *ppvObject = this;
+	}
+	else if (__uuidof(IUnknown) == riid)
+	{
+	    *ppvObject = this;
+	}
+	else
+	{
+	    *ppvObject = NULL;
+	    return E_FAIL;
+	}
+
+	return S_OK;
+    }
+
+private:
+    long cRefCount_;
+    DWriteContext* pDWC_;
+};
+
+DWriteContext::DWriteContext() :
+    mHDC(NULL),
+    mBindRect(),
+    mDMode(DM_GDI),
+    mInteropHDC(NULL),
+    mDrawing(false),
+    mFallbackDC(false),
+    mD2D1Factory(NULL),
+    mRT(NULL),
+    mGDIRT(NULL),
+    mBrush(NULL),
+    mBitmap(NULL),
+    mDWriteFactory(NULL),
+#ifdef FEAT_DIRECTX_COLOR_EMOJI
+    mDWriteFactory2(NULL),
+#endif
+    mGdiInterop(NULL),
+    mRenderingParams(NULL),
+    mFontCache(8),
+    mTextFormat(NULL),
+    mFontWeight(DWRITE_FONT_WEIGHT_NORMAL),
+    mFontStyle(DWRITE_FONT_STYLE_NORMAL),
+    mTextAntialiasMode(D2D1_TEXT_ANTIALIAS_MODE_DEFAULT)
+{
+    HRESULT hr;
+
+    hr = D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED,
+	    __uuidof(ID2D1Factory), NULL,
+	    reinterpret_cast<void**>(&mD2D1Factory));
+    _RPT2(_CRT_WARN, "D2D1CreateFactory: hr=%p p=%p\n", hr, mD2D1Factory);
+
+    if (SUCCEEDED(hr))
+    {
+	hr = DWriteCreateFactory(
+		DWRITE_FACTORY_TYPE_SHARED,
+		__uuidof(IDWriteFactory),
+		reinterpret_cast<IUnknown**>(&mDWriteFactory));
+	_RPT2(_CRT_WARN, "DWriteCreateFactory: hr=%p p=%p\n", hr,
+		mDWriteFactory);
+    }
+
+#ifdef FEAT_DIRECTX_COLOR_EMOJI
+    if (SUCCEEDED(hr))
+    {
+	DWriteCreateFactory(
+		DWRITE_FACTORY_TYPE_SHARED,
+		__uuidof(IDWriteFactory2),
+		reinterpret_cast<IUnknown**>(&mDWriteFactory2));
+	_RPT1(_CRT_WARN, "IDWriteFactory2: %s\n", SUCCEEDED(hr) ? "available" : "not available");
+    }
+#endif
+
+    if (SUCCEEDED(hr))
+    {
+	hr = mDWriteFactory->GetGdiInterop(&mGdiInterop);
+	_RPT2(_CRT_WARN, "GetGdiInterop: hr=%p p=%p\n", hr, mGdiInterop);
+    }
+
+    if (SUCCEEDED(hr))
+    {
+	hr = mDWriteFactory->CreateRenderingParams(&mRenderingParams);
+	_RPT2(_CRT_WARN, "CreateRenderingParams: hr=%p p=%p\n", hr,
+		mRenderingParams);
+    }
+}
+
+DWriteContext::~DWriteContext()
+{
+    SafeRelease(&mTextFormat);
+    SafeRelease(&mRenderingParams);
+    SafeRelease(&mGdiInterop);
+    SafeRelease(&mDWriteFactory);
+#ifdef FEAT_DIRECTX_COLOR_EMOJI
+    SafeRelease(&mDWriteFactory2);
+#endif
+    SafeRelease(&mBitmap);
+    SafeRelease(&mBrush);
+    SafeRelease(&mGDIRT);
+    SafeRelease(&mRT);
+    SafeRelease(&mD2D1Factory);
+}
+
+    HRESULT
+DWriteContext::CreateDeviceResources()
+{
+    HRESULT hr;
+
+    if (mRT != NULL)
+	return S_OK;
+
+    D2D1_RENDER_TARGET_PROPERTIES props = {
+	D2D1_RENDER_TARGET_TYPE_DEFAULT,
+	{ DXGI_FORMAT_B8G8R8A8_UNORM, D2D1_ALPHA_MODE_IGNORE },
+	0, 0,
+	D2D1_RENDER_TARGET_USAGE_GDI_COMPATIBLE,
+	D2D1_FEATURE_LEVEL_DEFAULT
+    };
+    hr = mD2D1Factory->CreateDCRenderTarget(&props, &mRT);
+    _RPT2(_CRT_WARN, "CreateDCRenderTarget: hr=%p p=%p\n", hr, mRT);
+
+    if (SUCCEEDED(hr))
+    {
+	// This always succeeds.
+	mRT->QueryInterface(
+		__uuidof(ID2D1GdiInteropRenderTarget),
+		reinterpret_cast<void**>(&mGDIRT));
+	_RPT1(_CRT_WARN, "GdiInteropRenderTarget: p=%p\n", mGDIRT);
+    }
+
+    if (SUCCEEDED(hr))
+    {
+	hr = mRT->CreateSolidColorBrush(
+		D2D1::ColorF(D2D1::ColorF::Black),
+		&mBrush);
+	_RPT2(_CRT_WARN, "CreateSolidColorBrush: hr=%p p=%p\n", hr, mBrush);
+    }
+
+    if (SUCCEEDED(hr))
+	Rebind();
+
+    return hr;
+}
+
+    void
+DWriteContext::DiscardDeviceResources()
+{
+    SafeRelease(&mBitmap);
+    SafeRelease(&mBrush);
+    SafeRelease(&mGDIRT);
+    SafeRelease(&mRT);
+}
+
+    HRESULT
+DWriteContext::CreateTextFormatFromLOGFONT(const LOGFONTW &logFont,
+	IDWriteTextFormat **ppTextFormat)
+{
+    // Most of this function is copied from: https://github.com/Microsoft/Windows-classic-samples/blob/master/Samples/Win7Samples/multimedia/DirectWrite/RenderTest/TextHelpers.cpp
+    HRESULT hr = S_OK;
+    IDWriteTextFormat *pTextFormat = NULL;
+
+    IDWriteFont *font = NULL;
+    IDWriteFontFamily *fontFamily = NULL;
+    IDWriteLocalizedStrings *localizedFamilyNames = NULL;
+    float fontSize = 0;
+
+    if (SUCCEEDED(hr))
+    {
+	hr = mGdiInterop->CreateFontFromLOGFONT(&logFont, &font);
+    }
+
+    // Get the font family to which this font belongs.
+    if (SUCCEEDED(hr))
+    {
+	hr = font->GetFontFamily(&fontFamily);
+    }
+
+    // Get the family names. This returns an object that encapsulates one or
+    // more names with the same meaning but in different languages.
+    if (SUCCEEDED(hr))
+    {
+	hr = fontFamily->GetFamilyNames(&localizedFamilyNames);
+    }
+
+    // Get the family name at index zero. If we were going to display the name
+    // we'd want to try to find one that matched the use locale, but for
+    // purposes of creating a text format object any language will do.
+
+    wchar_t familyName[100];
+    if (SUCCEEDED(hr))
+    {
+	hr = localizedFamilyNames->GetString(0, familyName,
+		ARRAYSIZE(familyName));
+    }
+
+    if (SUCCEEDED(hr))
+    {
+	// Use lfHeight of the LOGFONT as font size.
+	fontSize = float(logFont.lfHeight);
+
+	if (fontSize < 0)
+	{
+	    // Negative lfHeight represents the size of the em unit.
+	    fontSize = -fontSize;
+	}
+	else
+	{
+	    // Positive lfHeight represents the cell height (ascent +
+	    // descent).
+	    DWRITE_FONT_METRICS fontMetrics;
+	    font->GetMetrics(&fontMetrics);
+
+	    // Convert the cell height (ascent + descent) from design units
+	    // to ems.
+	    float cellHeight = static_cast<float>(
+		    fontMetrics.ascent + fontMetrics.descent)
+		/ fontMetrics.designUnitsPerEm;
+
+	    // Divide the font size by the cell height to get the font em
+	    // size.
+	    fontSize /= cellHeight;
+	}
+    }
+
+    // The text format includes a locale name. Ideally, this would be the
+    // language of the text, which may or may not be the same as the primary
+    // language of the user. However, for our purposes the user locale will do.
+    wchar_t localeName[LOCALE_NAME_MAX_LENGTH];
+    if (SUCCEEDED(hr))
+    {
+	if (GetUserDefaultLocaleName(localeName, LOCALE_NAME_MAX_LENGTH) == 0)
+	    hr = HRESULT_FROM_WIN32(GetLastError());
+    }
+
+    if (SUCCEEDED(hr))
+    {
+	// Create the text format object.
+	hr = mDWriteFactory->CreateTextFormat(
+		familyName,
+		NULL, // no custom font collection
+		font->GetWeight(),
+		font->GetStyle(),
+		font->GetStretch(),
+		fontSize,
+		localeName,
+		&pTextFormat);
+    }
+
+    if (SUCCEEDED(hr))
+	hr = pTextFormat->SetTextAlignment(DWRITE_TEXT_ALIGNMENT_LEADING);
+
+    if (SUCCEEDED(hr))
+	hr = pTextFormat->SetParagraphAlignment(
+		DWRITE_PARAGRAPH_ALIGNMENT_FAR);
+
+    if (SUCCEEDED(hr))
+	hr = pTextFormat->SetWordWrapping(DWRITE_WORD_WRAPPING_NO_WRAP);
+
+    SafeRelease(&localizedFamilyNames);
+    SafeRelease(&fontFamily);
+    SafeRelease(&font);
+
+    if (SUCCEEDED(hr))
+	*ppTextFormat = pTextFormat;
+    else
+	SafeRelease(&pTextFormat);
+
+    return hr;
+}
+
+    HRESULT
+DWriteContext::SetFontByLOGFONT(const LOGFONTW &logFont)
+{
+    HRESULT hr = S_OK;
+    IDWriteTextFormat *pTextFormat = NULL;
+
+    hr = CreateTextFormatFromLOGFONT(logFont, &pTextFormat);
+
+    if (SUCCEEDED(hr))
+    {
+	SafeRelease(&mTextFormat);
+	mTextFormat = pTextFormat;
+	mFontWeight = static_cast<DWRITE_FONT_WEIGHT>(logFont.lfWeight);
+	mFontStyle = logFont.lfItalic ? DWRITE_FONT_STYLE_ITALIC
+	    : DWRITE_FONT_STYLE_NORMAL;
+    }
+
+    return hr;
+}
+
+    void
+DWriteContext::SetFont(HFONT hFont)
+{
+    FontCache::Item item;
+    if (mFontCache.get(hFont, item))
+    {
+	if (item.pTextFormat != NULL)
+	{
+	    item.pTextFormat->AddRef();
+	    SafeRelease(&mTextFormat);
+	    mTextFormat = item.pTextFormat;
+	    mFontWeight = item.fontWeight;
+	    mFontStyle = item.fontStyle;
+	    mFallbackDC = false;
+	}
+	else
+	    mFallbackDC = true;
+	return;
+    }
+
+    HRESULT hr = E_FAIL;
+    LOGFONTW lf;
+    if (GetObjectW(hFont, sizeof(lf), &lf))
+	hr = SetFontByLOGFONT(lf);
+
+    item.hFont = hFont;
+    if (SUCCEEDED(hr))
+    {
+	item.pTextFormat = mTextFormat;
+	item.fontWeight = mFontWeight;
+	item.fontStyle = mFontStyle;
+	mFallbackDC = false;
+    }
+    else
+	mFallbackDC = true;
+    mFontCache.put(item);
+}
+
+    void
+DWriteContext::Rebind()
+{
+    SafeRelease(&mBitmap);
+
+    mRT->BindDC(mHDC, &mBindRect);
+    mRT->SetTransform(D2D1::IdentityMatrix());
+
+    D2D1_BITMAP_PROPERTIES props = {
+	{DXGI_FORMAT_B8G8R8A8_UNORM, D2D1_ALPHA_MODE_IGNORE},
+	96.0f, 96.0f
+    };
+    mRT->CreateBitmap(
+	    D2D1::SizeU(mBindRect.right - mBindRect.left,
+		mBindRect.bottom - mBindRect.top),
+	    props, &mBitmap);
+}
+
+    void
+DWriteContext::BindDC(HDC hdc, const RECT *rect)
+{
+    mHDC = hdc;
+    mBindRect = *rect;
+
+    if (mRT == NULL)
+	CreateDeviceResources();
+    else
+    {
+	Flush();
+	Rebind();
+    }
+}
+
+extern "C" void redraw_later_clear(void);
+
+    HRESULT
+DWriteContext::SetDrawingMode(DrawingMode mode)
+{
+    HRESULT hr = S_OK;
+
+    switch (mode)
+    {
+	default:
+	case DM_GDI:
+	    if (mInteropHDC != NULL)
+	    {
+		mGDIRT->ReleaseDC(NULL);
+		mInteropHDC = NULL;
+	    }
+	    if (mDrawing)
+	    {
+		hr = mRT->EndDraw();
+		if (hr == (HRESULT)D2DERR_RECREATE_TARGET)
+		{
+		    hr = S_OK;
+		    DiscardDeviceResources();
+		    CreateDeviceResources();
+		    redraw_later_clear();
+		}
+		mDrawing = false;
+	    }
+	    break;
+
+	case DM_DIRECTX:
+	    if (mInteropHDC != NULL)
+	    {
+		mGDIRT->ReleaseDC(NULL);
+		mInteropHDC = NULL;
+	    }
+	    else if (mDrawing == false)
+	    {
+		CreateDeviceResources();
+		mRT->BeginDraw();
+		mDrawing = true;
+	    }
+	    break;
+
+	case DM_INTEROP:
+	    if (mDrawing == false)
+	    {
+		CreateDeviceResources();
+		mRT->BeginDraw();
+		mDrawing = true;
+	    }
+	    if (mInteropHDC == NULL)
+		hr = mGDIRT->GetDC(D2D1_DC_INITIALIZE_MODE_COPY, &mInteropHDC);
+	    break;
+    }
+    mDMode = mode;
+    return hr;
+}
+
+    ID2D1Brush*
+DWriteContext::SolidBrush(COLORREF color)
+{
+    mBrush->SetColor(D2D1::ColorF(UINT32(GetRValue(color)) << 16 |
+		UINT32(GetGValue(color)) << 8 | UINT32(GetBValue(color))));
+    return mBrush;
+}
+
+    void
+DWriteContext::DrawText(const WCHAR *text, int len,
+	int x, int y, int w, int h, int cellWidth, COLORREF color,
+	UINT fuOptions, const RECT *lprc, const INT *lpDx)
+{
+    if (mFallbackDC)
+    {
+	// Fall back to GDI rendering.
+	HRESULT hr = SetDrawingMode(DM_INTEROP);
+	if (SUCCEEDED(hr))
+	{
+	    HGDIOBJ hFont = ::GetCurrentObject(mHDC, OBJ_FONT);
+	    HGDIOBJ hOldFont = ::SelectObject(mInteropHDC, hFont);
+	    ::SetTextColor(mInteropHDC, color);
+	    ::SetBkMode(mInteropHDC, ::GetBkMode(mHDC));
+	    ::ExtTextOutW(mInteropHDC, x, y, fuOptions, lprc, text, len, lpDx);
+	    ::SelectObject(mInteropHDC, hOldFont);
+	}
+	return;
+    }
+
+    HRESULT hr;
+    IDWriteTextLayout *textLayout = NULL;
+
+    SetDrawingMode(DM_DIRECTX);
+
+    hr = mDWriteFactory->CreateTextLayout(text, len, mTextFormat,
+	    FLOAT(w), FLOAT(h), &textLayout);
+
+    if (SUCCEEDED(hr))
+    {
+	DWRITE_TEXT_RANGE textRange = { 0, UINT32(len) };
+	textLayout->SetFontWeight(mFontWeight, textRange);
+	textLayout->SetFontStyle(mFontStyle, textRange);
+
+	TextRenderer renderer(this);
+	TextRendererContext context = { color, FLOAT(cellWidth), 0.0f };
+	textLayout->Draw(&context, &renderer, FLOAT(x), FLOAT(y));
+    }
+
+    SafeRelease(&textLayout);
+}
+
+    void
+DWriteContext::FillRect(const RECT *rc, COLORREF color)
+{
+    if (mDMode == DM_INTEROP)
+    {
+	// GDI functions are used before this call.  Keep using GDI.
+	// (Switching to Direct2D causes terrible slowdown.)
+	HBRUSH hbr = ::CreateSolidBrush(color);
+	::FillRect(mInteropHDC, rc, hbr);
+	::DeleteObject(HGDIOBJ(hbr));
+    }
+    else
+    {
+	SetDrawingMode(DM_DIRECTX);
+	mRT->FillRectangle(
+		D2D1::RectF(FLOAT(rc->left), FLOAT(rc->top),
+		    FLOAT(rc->right), FLOAT(rc->bottom)),
+		SolidBrush(color));
+    }
+}
+
+    void
+DWriteContext::DrawLine(int x1, int y1, int x2, int y2, COLORREF color)
+{
+    if (mDMode == DM_INTEROP)
+    {
+	// GDI functions are used before this call.  Keep using GDI.
+	// (Switching to Direct2D causes terrible slowdown.)
+	HPEN hpen = ::CreatePen(PS_SOLID, 1, color);
+	HGDIOBJ old_pen = ::SelectObject(mInteropHDC, HGDIOBJ(hpen));
+	::MoveToEx(mInteropHDC, x1, y1, NULL);
+	::LineTo(mInteropHDC, x2, y2);
+	::SelectObject(mInteropHDC, old_pen);
+	::DeleteObject(HGDIOBJ(hpen));
+    }
+    else
+    {
+	SetDrawingMode(DM_DIRECTX);
+	mRT->DrawLine(
+		D2D1::Point2F(FLOAT(x1), FLOAT(y1) + 0.5f),
+		D2D1::Point2F(FLOAT(x2), FLOAT(y2) + 0.5f),
+		SolidBrush(color));
+    }
+}
+
+    void
+DWriteContext::SetPixel(int x, int y, COLORREF color)
+{
+    if (mDMode == DM_INTEROP)
+    {
+	// GDI functions are used before this call.  Keep using GDI.
+	// (Switching to Direct2D causes terrible slowdown.)
+	::SetPixel(mInteropHDC, x, y, color);
+    }
+    else
+    {
+	SetDrawingMode(DM_DIRECTX);
+	// Direct2D doesn't have SetPixel API.  Use DrawLine instead.
+	mRT->DrawLine(
+		D2D1::Point2F(FLOAT(x), FLOAT(y) + 0.5f),
+		D2D1::Point2F(FLOAT(x+1), FLOAT(y) + 0.5f),
+		SolidBrush(color));
+    }
+}
+
+    void
+DWriteContext::Scroll(int x, int y, const RECT *rc)
+{
+    SetDrawingMode(DM_DIRECTX);
+    mRT->Flush();
+
+    D2D1_RECT_U srcRect;
+    D2D1_POINT_2U destPoint;
+    if (x >= 0)
+    {
+	srcRect.left = rc->left;
+	srcRect.right = rc->right - x;
+	destPoint.x = rc->left + x;
+    }
+    else
+    {
+	srcRect.left = rc->left - x;
+	srcRect.right = rc->right;
+	destPoint.x = rc->left;
+    }
+    if (y >= 0)
+    {
+	srcRect.top = rc->top;
+	srcRect.bottom = rc->bottom - y;
+	destPoint.y = rc->top + y;
+    }
+    else
+    {
+	srcRect.top = rc->top - y;
+	srcRect.bottom = rc->bottom;
+	destPoint.y = rc->top;
+    }
+    mBitmap->CopyFromRenderTarget(&destPoint, mRT, &srcRect);
+
+    D2D1_RECT_F destRect = {
+	    FLOAT(destPoint.x), FLOAT(destPoint.y),
+	    FLOAT(destPoint.x + srcRect.right - srcRect.left),
+	    FLOAT(destPoint.y + srcRect.bottom - srcRect.top)
+    };
+    mRT->DrawBitmap(mBitmap, destRect, 1.0F,
+	    D2D1_BITMAP_INTERPOLATION_MODE_NEAREST_NEIGHBOR, destRect);
+}
+
+    void
+DWriteContext::Flush()
+{
+    SetDrawingMode(DM_GDI);
+}
+
+    void
+DWriteContext::SetRenderingParams(
+	const DWriteRenderingParams *params)
+{
+    if (mDWriteFactory == NULL)
+	return;
+
+    IDWriteRenderingParams *renderingParams = NULL;
+    D2D1_TEXT_ANTIALIAS_MODE textAntialiasMode =
+	D2D1_TEXT_ANTIALIAS_MODE_DEFAULT;
+    HRESULT hr;
+    if (params != NULL)
+    {
+	hr = mDWriteFactory->CreateCustomRenderingParams(params->gamma,
+		params->enhancedContrast, params->clearTypeLevel,
+		ToPixelGeometry(params->pixelGeometry),
+		ToRenderingMode(params->renderingMode), &renderingParams);
+	textAntialiasMode = ToTextAntialiasMode(params->textAntialiasMode);
+    }
+    else
+	hr = mDWriteFactory->CreateRenderingParams(&renderingParams);
+    if (SUCCEEDED(hr) && renderingParams != NULL)
+    {
+	SafeRelease(&mRenderingParams);
+	mRenderingParams = renderingParams;
+	mTextAntialiasMode = textAntialiasMode;
+
+	Flush();
+	mRT->SetTextRenderingParams(mRenderingParams);
+	mRT->SetTextAntialiasMode(mTextAntialiasMode);
+    }
+}
+
+    DWriteRenderingParams *
+DWriteContext::GetRenderingParams(
+	DWriteRenderingParams *params)
+{
+    if (params != NULL && mRenderingParams != NULL)
+    {
+	params->gamma = mRenderingParams->GetGamma();
+	params->enhancedContrast = mRenderingParams->GetEnhancedContrast();
+	params->clearTypeLevel = mRenderingParams->GetClearTypeLevel();
+	params->pixelGeometry = ToInt(mRenderingParams->GetPixelGeometry());
+	params->renderingMode = ToInt(mRenderingParams->GetRenderingMode());
+	params->textAntialiasMode = mTextAntialiasMode;
+    }
+    return params;
+}
+
+////////////////////////////////////////////////////////////////////////////
+// PUBLIC C INTERFACES
+
+    void
+DWrite_Init(void)
+{
+#ifdef DYNAMIC_DIRECTX
+    // Load libraries.
+    hD2D1DLL = vimLoadLib(const_cast<char*>("d2d1.dll"));
+    hDWriteDLL = vimLoadLib(const_cast<char*>("dwrite.dll"));
+    if (hD2D1DLL == NULL || hDWriteDLL == NULL)
+    {
+	DWrite_Final();
+	return;
+    }
+    // Get address of procedures.
+    pGetUserDefaultLocaleName = (PGETUSERDEFAULTLOCALENAME)GetProcAddress(
+	    GetModuleHandle("kernel32.dll"), "GetUserDefaultLocaleName");
+    pD2D1CreateFactory = (PD2D1CREATEFACTORY)GetProcAddress(hD2D1DLL,
+	    "D2D1CreateFactory");
+    pDWriteCreateFactory = (PDWRITECREATEFACTORY)GetProcAddress(hDWriteDLL,
+	    "DWriteCreateFactory");
+#endif
+}
+
+    void
+DWrite_Final(void)
+{
+#ifdef DYNAMIC_DIRECTX
+    pGetUserDefaultLocaleName = NULL;
+    pD2D1CreateFactory = NULL;
+    pDWriteCreateFactory = NULL;
+    unload(hDWriteDLL);
+    unload(hD2D1DLL);
+#endif
+}
+
+    DWriteContext *
+DWriteContext_Open(void)
+{
+#ifdef DYNAMIC_DIRECTX
+    if (pGetUserDefaultLocaleName == NULL || pD2D1CreateFactory == NULL
+	    || pDWriteCreateFactory == NULL)
+	return NULL;
+#endif
+    return new DWriteContext();
+}
+
+    void
+DWriteContext_BindDC(DWriteContext *ctx, HDC hdc, const RECT *rect)
+{
+    if (ctx != NULL)
+	ctx->BindDC(hdc, rect);
+}
+
+    void
+DWriteContext_SetFont(DWriteContext *ctx, HFONT hFont)
+{
+    if (ctx != NULL)
+	ctx->SetFont(hFont);
+}
+
+    void
+DWriteContext_DrawText(
+	DWriteContext *ctx,
+	const WCHAR *text,
+	int len,
+	int x,
+	int y,
+	int w,
+	int h,
+	int cellWidth,
+	COLORREF color,
+	UINT fuOptions,
+	const RECT *lprc,
+	const INT *lpDx)
+{
+    if (ctx != NULL)
+	ctx->DrawText(text, len, x, y, w, h, cellWidth, color,
+		fuOptions, lprc, lpDx);
+}
+
+    void
+DWriteContext_FillRect(DWriteContext *ctx, const RECT *rc, COLORREF color)
+{
+    if (ctx != NULL)
+	ctx->FillRect(rc, color);
+}
+
+    void
+DWriteContext_DrawLine(DWriteContext *ctx, int x1, int y1, int x2, int y2,
+	COLORREF color)
+{
+    if (ctx != NULL)
+	ctx->DrawLine(x1, y1, x2, y2, color);
+}
+
+    void
+DWriteContext_SetPixel(DWriteContext *ctx, int x, int y, COLORREF color)
+{
+    if (ctx != NULL)
+	ctx->SetPixel(x, y, color);
+}
+
+    void
+DWriteContext_Scroll(DWriteContext *ctx, int x, int y, const RECT *rc)
+{
+    if (ctx != NULL)
+	ctx->Scroll(x, y, rc);
+}
+
+    void
+DWriteContext_Flush(DWriteContext *ctx)
+{
+    if (ctx != NULL)
+	ctx->Flush();
+}
+
+    void
+DWriteContext_Close(DWriteContext *ctx)
+{
+    delete ctx;
+}
+
+    void
+DWriteContext_SetRenderingParams(
+	DWriteContext *ctx,
+	const DWriteRenderingParams *params)
+{
+    if (ctx != NULL)
+	ctx->SetRenderingParams(params);
+}
+
+    DWriteRenderingParams *
+DWriteContext_GetRenderingParams(
+	DWriteContext *ctx,
+	DWriteRenderingParams *params)
+{
+    if (ctx != NULL)
+	return ctx->GetRenderingParams(params);
+    else
+	return NULL;
+}