Introduce QFontEngineDirectWrite

Make a font engine for subpixel positioned text on Windows Vista
(with platform update) and Windows 7. If selected during
configuration, the engine will be selected only when the hinting
preference of a font is set to None or Vertical hinting. The font
database uses most of the same logic but creates a direct write
font based on the LOGFONT rather than a GDI handle.

The engine is currently regarded as experimental, meaning that code
using it should do substantial testing to make sure it covers their
use cases.

Task-number: QTBUG-12678
Reviewed-by: Jiang Jiang

1 files changed, 185 insertions, 35 deletions

diff --git a/src/gui/text/qfontdatabase_win.cpp b/src/gui/text/qfontdatabase_win.cpp
index e2c5116..0bb1d8d 100644
--- a/src/gui/text/qfontdatabase_win.cpp
+++ b/src/gui/text/qfontdatabase_win.cpp
@@ -49,6 +49,11 @@
 #include "qabstractfileengine.h"
 #include "qendian.h"
 
+#if !defined(QT_NO_DIRECTWRITE)
+#  include "qsettings.h"
+#  include "qfontenginedirectwrite_p.h"
+#endif
+
 #ifdef Q_OS_WINCE
 #   include <QTemporaryFile>
 #endif
@@ -542,6 +547,65 @@ static void initFontInfo(QFontEngineWin *fe, const QFontDef &request, const QFon
     }
 }
 
+#if !defined(QT_NO_DIRECTWRITE)
+static void initFontInfo(QFontEngineDirectWrite *fe, const QFontDef &request,
+                         const QFontPrivate *fp, IDWriteFont *font)
+{
+    fe->fontDef = request;
+
+    IDWriteFontFamily *fontFamily = NULL;
+    HRESULT hr = font->GetFontFamily(&fontFamily);
+
+    IDWriteLocalizedStrings *familyNames = NULL;
+    if (SUCCEEDED(hr))
+        hr = fontFamily->GetFamilyNames(&familyNames);
+
+    UINT32 index = 0;
+    BOOL exists = false;
+
+    wchar_t localeName[LOCALE_NAME_MAX_LENGTH];
+
+    if (SUCCEEDED(hr)) {
+        int defaultLocaleSuccess = GetUserDefaultLocaleName(localeName, LOCALE_NAME_MAX_LENGTH);
+
+        if (defaultLocaleSuccess)
+            hr = familyNames->FindLocaleName(localeName, &index, &exists);
+
+        if (SUCCEEDED(hr) && !exists)
+            hr = familyNames->FindLocaleName(L"en-us", &index, &exists);
+    }
+
+    if (!exists)
+        index = 0;
+
+    UINT32 length = 0;
+    if (SUCCEEDED(hr))
+        hr = familyNames->GetStringLength(index, &length);
+
+    wchar_t *name = new (std::nothrow) wchar_t[length+1];
+    if (name == NULL)
+        hr = E_OUTOFMEMORY;
+
+    // Get the family name.
+    if (SUCCEEDED(hr))
+        hr = familyNames->GetString(index, name, length + 1);
+
+    if (SUCCEEDED(hr))
+        fe->fontDef.family = QString::fromWCharArray(name);
+
+    delete[] name;
+    if (familyNames != NULL)
+        familyNames->Release();
+
+    if (FAILED(hr))
+        qErrnoWarning(hr, "initFontInfo: Failed to get family name");
+
+    if (fe->fontDef.pointSize < 0)
+        fe->fontDef.pointSize = fe->fontDef.pixelSize * 72. / fp->dpi;
+    else if (fe->fontDef.pixelSize == -1)
+        fe->fontDef.pixelSize = qRound(fe->fontDef.pointSize * fp->dpi / 72.);
+}
+#endif
 
 static const char *other_tryFonts[] = {
     "Arial",
@@ -595,6 +659,14 @@ static const char *kr_tryFonts[] = {
 
 static const char **tryFonts = 0;
 
+#if !defined(QT_NO_DIRECTWRITE)
+static QString fontNameSubstitute(const QString &familyName)
+{
+    QLatin1String key("HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows NT\\CurrentVersion\\"
+                      "FontSubstitutes");
+    return QSettings(key, QSettings::NativeFormat).value(familyName, familyName).toString();
+}
+#endif
 
 static inline HFONT systemFont()
 {
@@ -629,6 +701,15 @@ QFontEngine *loadEngine(int script, const QFontPrivate *fp, const QFontDef &requ
 
     HFONT hfont = 0;
 
+
+#if !defined(QT_NO_DIRECTWRITE)
+    bool useDirectWrite = (request.hintingPreference & QFont::PreferNoHinting)
+                       || (request.hintingPreference & QFont::PreferVerticalHinting);
+    IDWriteFont *directWriteFont = 0;
+#else
+    bool useDirectWrite = false;
+#endif
+
     if (fp->rawMode) {                        // will choose a stock font
         int f, deffnt = SYSTEM_FONT;
         QString fam = desc->family->name.toLower();
@@ -745,6 +826,7 @@ QFontEngine *loadEngine(int script, const QFontPrivate *fp, const QFontDef &requ
             fam = QLatin1String("Courier New");
 
         memcpy(lf.lfFaceName, fam.utf16(), sizeof(wchar_t) * qMin(fam.length() + 1, 32));  // 32 = Windows hard-coded
+
         hfont = CreateFontIndirect(&lf);
         if (!hfont)
             qErrnoWarning("QFontEngine::loadEngine: CreateFontIndirect failed");
@@ -759,52 +841,120 @@ QFontEngine *loadEngine(int script, const QFontPrivate *fp, const QFontDef &requ
         res = GetTextMetrics(hdc, &tm);
         avWidth = tm.tmAveCharWidth;
         ttf = tm.tmPitchAndFamily & TMPF_TRUETYPE;
-
         SelectObject(hdc, oldObj);
 
-        if (hfont && (!ttf || request.stretch != 100)) {
-            DeleteObject(hfont);
-            if (!res)
-                qErrnoWarning("QFontEngine::loadEngine: GetTextMetrics failed");
-            lf.lfWidth = avWidth * request.stretch/100;
-            hfont = CreateFontIndirect(&lf);
-            if (!hfont)
-                qErrnoWarning("QFontEngine::loadEngine: CreateFontIndirect with stretch failed");
-        }
+        if (!ttf || !useDirectWrite) {
+            useDirectWrite = false;
+
+            if (hfont && (!ttf || request.stretch != 100)) {
+                DeleteObject(hfont);
+                if (!res)
+                    qErrnoWarning("QFontEngine::loadEngine: GetTextMetrics failed");
+                lf.lfWidth = avWidth * request.stretch/100;
+                hfont = CreateFontIndirect(&lf);
+                if (!hfont)
+                    qErrnoWarning("QFontEngine::loadEngine: CreateFontIndirect with stretch failed");
+            }
 
 #ifndef Q_WS_WINCE
-        if (hfont == 0) {
-            hfont = (HFONT)GetStockObject(ANSI_VAR_FONT);
-            stockFont = true;
-        }
+            if (hfont == 0) {
+                hfont = (HFONT)GetStockObject(ANSI_VAR_FONT);
+                stockFont = true;
+            }
 #else
-        if (hfont == 0) {
-            hfont = (HFONT)GetStockObject(SYSTEM_FONT);
-            stockFont = true;
+            if (hfont == 0) {
+                hfont = (HFONT)GetStockObject(SYSTEM_FONT);
+                stockFont = true;
+            }
+#endif
+
+        }
+
+#if !defined(QT_NO_DIRECTWRITE)
+        else {
+            // Default to false for DirectWrite (and re-enable once/if everything
+            // turns out okay)
+            useDirectWrite = false;
+
+            QFontDatabasePrivate *db = privateDb();
+            if (db->directWriteFactory == 0) {
+                HRESULT hr = DWriteCreateFactory(
+                            DWRITE_FACTORY_TYPE_SHARED,
+                            __uuidof(IDWriteFactory),
+                            reinterpret_cast<IUnknown **>(&db->directWriteFactory)
+                            );
+                if (FAILED(hr)) {
+                    qErrnoWarning("QFontEngine::loadEngine: DWriteCreateFactory failed");
+                } else {
+                    hr = db->directWriteFactory->GetGdiInterop(&db->directWriteGdiInterop);
+                    if (FAILED(hr))
+                        qErrnoWarning("QFontEngine::loadEngine: GetGdiInterop failed");
+                }
+            }
+
+            if (db->directWriteGdiInterop != 0) {
+                QString nameSubstitute = fontNameSubstitute(QString::fromWCharArray(lf.lfFaceName));
+                memcpy(lf.lfFaceName, nameSubstitute.utf16(),
+                       sizeof(wchar_t) * qMin(nameSubstitute.length() + 1, LF_FACESIZE));
+
+                HRESULT hr = db->directWriteGdiInterop->CreateFontFromLOGFONT(
+                            &lf,
+                            &directWriteFont);
+                if (FAILED(hr)) {
+                    qErrnoWarning("QFontEngine::loadEngine: CreateFontFromLOGFONT failed "
+                                  "for %ls (0x%lx)",
+                                  lf.lfFaceName, hr);
+                } else {
+                    DeleteObject(hfont);
+                    useDirectWrite = true;
+                }
+            }
         }
 #endif
 
     }
-    QFontEngineWin *few = new QFontEngineWin(font_name, hfont, stockFont, lf);
-
-    if (preferClearTypeAA)
-        few->glyphFormat = QFontEngineGlyphCache::Raster_RGBMask;
-
-    // Also check for OpenType tables when using complex scripts
-    // ### TODO: This only works for scripts that require OpenType. More generally
-    // for scripts that do not require OpenType we should just look at the list of
-    // supported writing systems in the font's OS/2 table.
-    if (scriptRequiresOpenType(script)) {
-        HB_Face hbFace = few->harfbuzzFace();
-        if (!hbFace || !hbFace->supported_scripts[script]) {
-            FM_DEBUG("  OpenType support missing for script\n");
-            delete few;
-            return 0;
+
+    QFontEngine *fe = 0;
+    if (!useDirectWrite)  {
+        QFontEngineWin *few = new QFontEngineWin(font_name, hfont, stockFont, lf);
+        if (preferClearTypeAA)
+            few->glyphFormat = QFontEngineGlyphCache::Raster_RGBMask;
+
+        // Also check for OpenType tables when using complex scripts
+        // ### TODO: This only works for scripts that require OpenType. More generally
+        // for scripts that do not require OpenType we should just look at the list of
+        // supported writing systems in the font's OS/2 table.
+        if (scriptRequiresOpenType(script)) {
+            HB_Face hbFace = few->harfbuzzFace();
+            if (!hbFace || !hbFace->supported_scripts[script]) {
+                FM_DEBUG("  OpenType support missing for script\n");
+                delete few;
+                return 0;
+            }
         }
+
+        initFontInfo(few, request, fp);
+        fe = few;
     }
 
-    QFontEngine *fe = few;
-    initFontInfo(few, request, fp);
+#if !defined(QT_NO_DIRECTWRITE)
+    else {
+        QFontDatabasePrivate *db = privateDb();
+        QFontEngineDirectWrite *fedw = new QFontEngineDirectWrite(font_name,
+                                                                  db->directWriteFactory,
+                                                                  db->directWriteGdiInterop,
+                                                                  directWriteFont,
+                                                                  request.pixelSize);
+
+        initFontInfo(fedw, request, fp, directWriteFont);
+
+        fe = fedw;
+    }
+
+    if (directWriteFont != 0)
+        directWriteFont->Release();
+#endif
+
     if(script == QUnicodeTables::Common
        && !(request.styleStrategy & QFont::NoFontMerging)
        && !(desc->family->writingSystems[QFontDatabase::Symbol] & QtFontFamily::Supported)) {
@@ -836,7 +986,7 @@ QFontEngine *loadEngine(int script, const QFontPrivate *fp, const QFontDef &requ
                 list << QLatin1String(*tf);
             ++tf;
         }
-        QFontEngine *mfe = new QFontEngineMultiWin(few, list);
+        QFontEngine *mfe = new QFontEngineMultiWin(fe, list);
         mfe->fontDef = fe->fontDef;
         fe = mfe;
     }