Differ between vertical and no hinting on Windows

Symmetric text rendering seems to be the equivalent to no hinting
at all since it does subpixel antialiasing in both horizontal and vertical
directions. Let people select non-symmetric, natural rendering as well,
by setting vertical hinting on the font. This is the mode used for many
UI elements in newer versions of Windows (like the title bar of windows
etc.)

[ChangeLog][Windows] Added differentiation between vertical hinting and
no hinting in DirectWrite font engine.

Task-number: QTBUG-48546
Change-Id: I2f75ae2d16fdf26706587d92da43daf29afbbcf2
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>

3 files changed, 15 insertions, 5 deletions

diff --git a/src/plugins/platforms/windows/qwindowsfontdatabase.cpp b/src/plugins/platforms/windows/qwindowsfontdatabase.cpp
index 334c6a9407..8a2fbe1f6d 100644
--- a/src/plugins/platforms/windows/qwindowsfontdatabase.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontdatabase.cpp
@@ -1239,11 +1239,13 @@ QT_WARNING_POP
 
         fontFile->Release();
 
-        fontEngine = new QWindowsFontEngineDirectWrite(directWriteFontFace, pixelSize,
+        fontEngine = new QWindowsFontEngineDirectWrite(directWriteFontFace,
+                                                       pixelSize,
                                                        fontEngineData);
 
         // Get font family from font data
         fontEngine->fontDef.family = font.familyName();
+        fontEngine->fontDef.hintingPreference = hintingPreference;
 
         directWriteFontFace->Release();
     }
diff --git a/src/plugins/platforms/windows/qwindowsfontengine.cpp b/src/plugins/platforms/windows/qwindowsfontengine.cpp
index 4a799af44e..30417f7cee 100644
--- a/src/plugins/platforms/windows/qwindowsfontengine.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontengine.cpp
@@ -1362,6 +1362,7 @@ QFontEngine *QWindowsMultiFontEngine::loadEngine(int at)
                 if (fontEngine->fontDef.style > QFont::StyleNormal)
                     fedw->fontDef.style = fontEngine->fontDef.style;
                 fedw->fontDef.family = fam;
+                fedw->fontDef.hintingPreference = fontEngine->fontDef.hintingPreference;
                 return fedw;
             } else {
                 qErrnoWarning("%s: CreateFontFace failed", __FUNCTION__);
@@ -1379,6 +1380,7 @@ QFontEngine *QWindowsMultiFontEngine::loadEngine(int at)
     if (fontEngine->fontDef.style > QFont::StyleNormal)
         fe->fontDef.style = fontEngine->fontDef.style;
     fe->fontDef.family = fam;
+    fe->fontDef.hintingPreference = fontEngine->fontDef.hintingPreference;
     return fe;
 }
 
diff --git a/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp b/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp
index 75449e22ed..593ac7d810 100644
--- a/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontenginedirectwrite.cpp
@@ -196,8 +196,8 @@ namespace {
 */
 
 QWindowsFontEngineDirectWrite::QWindowsFontEngineDirectWrite(IDWriteFontFace *directWriteFontFace,
-                                               qreal pixelSize,
-                                               const QSharedPointer<QWindowsFontEngineData> &d)
+                                                             qreal pixelSize,
+                                                             const QSharedPointer<QWindowsFontEngineData> &d)
     : QFontEngine(DirectWrite)
     , m_fontEngineData(d)
     , m_directWriteFontFace(directWriteFontFace)
@@ -547,12 +547,17 @@ QImage QWindowsFontEngineDirectWrite::imageForGlyph(glyph_t t,
     transform.m21 = xform.m21();
     transform.m22 = xform.m22();
 
+    DWRITE_RENDERING_MODE renderMode =
+             fontDef.hintingPreference == QFont::PreferNoHinting
+                ? DWRITE_RENDERING_MODE_CLEARTYPE_NATURAL_SYMMETRIC
+                : DWRITE_RENDERING_MODE_CLEARTYPE_NATURAL;
+
     IDWriteGlyphRunAnalysis *glyphAnalysis = NULL;
     HRESULT hr = m_fontEngineData->directWriteFactory->CreateGlyphRunAnalysis(
                 &glyphRun,
                 1.0f,
                 &transform,
-                DWRITE_RENDERING_MODE_CLEARTYPE_NATURAL_SYMMETRIC,
+                renderMode,
                 DWRITE_MEASURING_MODE_NATURAL,
                 0.0, 0.0,
                 &glyphAnalysis
@@ -626,7 +631,8 @@ QImage QWindowsFontEngineDirectWrite::alphaRGBMapForGlyph(glyph_t t,
 QFontEngine *QWindowsFontEngineDirectWrite::cloneWithSize(qreal pixelSize) const
 {
     QFontEngine *fontEngine = new QWindowsFontEngineDirectWrite(m_directWriteFontFace,
-                                                                pixelSize, m_fontEngineData);
+                                                                pixelSize,
+                                                                m_fontEngineData);
 
     fontEngine->fontDef = fontDef;
     fontEngine->fontDef.pixelSize = pixelSize;