Related: tdf#113076 vcl win DirectWrite: handle stretched text

Commit a51b7a1c (tdf#103831, tdf#100986:
Force using GDI when needed, 2017-03-03) noted that the DirectWrite text
renderer doesn't support stretched text, add support for this now by
setting a DirectWrite transform matrix that only does horizontal
scaling.

With this, tdf#113076 is kept fixed, but at the same time manually
stretched text keeps working. Previously the glyphs of the text had the
correct size and position, but the glyphs themselves where not streched,
but simply aligned to the left.

Change-Id: I8fe8e74d3edc0d71ed2f16fcce66c6f5009ed264
Reviewed-on: https://gerrit.libreoffice.org/71245Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

vcl/inc/win/DWriteTextRenderer.hxx

@@ -81,6 +81,18 @@ private:
     D2DTextAntiAliasMode meTextAntiAliasMode;
 };
 
+/// Sets and unsets the needed DirectWrite transform to support the font's horizontal scaling.
+class WinFontStretchGuard
+{
+public:
+    WinFontStretchGuard(ID2D1RenderTarget* pRenderTarget, float fHScale);
+    ~WinFontStretchGuard();
+
+private:
+    ID2D1RenderTarget* mpRenderTarget;
+    D2D1::Matrix3x2F maTransform;
+};
+
 #endif // INCLUDED_VCL_INC_WIN_DWRITERENDERER_HXX
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

vcl/inc/win/winlayout.hxx

@@ -151,6 +151,7 @@ public:
     ~WinFontInstance() override;
 
     bool hasHScale() const;
+    float getHScale() const;
 
     void SetGraphics(WinSalGraphics*);
     WinSalGraphics* GetGraphics() const { return m_pGraphics; }

vcl/win/gdi/DWriteTextRenderer.cxx

@@ -232,6 +232,10 @@ bool D2DWriteTextOutRenderer::performRender(GenericSalLayout const & rLayout, Sa
     if (!GetDWriteFaceFromHDC(hDC, &mpFontFace, &mlfEmHeight))
         return false;
 
+    const WinFontInstance& rWinFont = static_cast<const WinFontInstance&>(rLayout.GetFont());
+    float fHScale = rWinFont.getHScale();
+    WinFontStretchGuard aStretchGuard(mpRT, fHScale);
+
     tools::Rectangle bounds;
     bool succeeded = rLayout.GetBoundRect(bounds);
     if (succeeded)
@@ -258,9 +262,10 @@ bool D2DWriteTextOutRenderer::performRender(GenericSalLayout const & rLayout, Sa
         while (rLayout.GetNextGlyph(&pGlyph, aPos, nStart))
         {
             UINT16 glyphIndices[] = { pGlyph->m_aGlyphId };
-            FLOAT glyphAdvances[] = { static_cast<FLOAT>(pGlyph->m_nNewWidth) };
+            FLOAT glyphAdvances[] = { static_cast<FLOAT>(pGlyph->m_nNewWidth) / fHScale };
             DWRITE_GLYPH_OFFSET glyphOffsets[] = { { 0.0f, 0.0f }, };
-            D2D1_POINT_2F baseline = { static_cast<FLOAT>(aPos.X() - bounds.Left()), static_cast<FLOAT>(aPos.Y() - bounds.Top()) };
+            D2D1_POINT_2F baseline = { static_cast<FLOAT>(aPos.X() - bounds.Left()) / fHScale,
+                                       static_cast<FLOAT>(aPos.Y() - bounds.Top()) };
             DWRITE_GLYPH_RUN glyphs = {
                 mpFontFace,
                 mlfEmHeight,
@@ -379,6 +384,18 @@ bool D2DWriteTextOutRenderer::GetDWriteFaceFromHDC(HDC hDC, IDWriteFontFace ** p
     return succeeded;
 }
 
+WinFontStretchGuard::WinFontStretchGuard(ID2D1RenderTarget* pRenderTarget, float fHScale)
+    : mpRenderTarget(pRenderTarget)
+{
+    pRenderTarget->GetTransform(&maTransform);
+    if (fHScale == 1.0f)
+        return;
+
+    D2D1::Matrix3x2F aTransform
+        = maTransform * D2D1::Matrix3x2F::Scale(D2D1::Size(fHScale, 1.0f), D2D1::Point2F(0, 0));
+    mpRenderTarget->SetTransform(aTransform);
+}
 
+WinFontStretchGuard::~WinFontStretchGuard() { mpRenderTarget->SetTransform(maTransform); }
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

vcl/win/gdi/winlayout.cxx

@@ -116,10 +116,11 @@ bool WinFontInstance::CacheGlyphToAtlas(HDC hDC, HFONT hFont, int nGlyphIndex, S
     std::vector<float> aGlyphAdv(1);   // offsets between glyphs
     std::vector<DWRITE_GLYPH_OFFSET> aGlyphOffset(1, {0.0f, 0.0f});
     std::vector<int> aEnds(1); // end of each glyph box
+    float fHScale = getHScale();
     float totWidth = 0;
     {
         int overhang = aInkBoxes[0].Left();
-        int blackWidth = aInkBoxes[0].getWidth(); // width of non-AA pixels
+        int blackWidth = aInkBoxes[0].getWidth() * fHScale; // width of non-AA pixels
         aElement.maLeftOverhangs = overhang;
 
         aGlyphAdv[0] = blackWidth + aElement.getExtraSpace();
@@ -170,6 +171,7 @@ bool WinFontInstance::CacheGlyphToAtlas(HDC hDC, HFONT hFont, int nGlyphIndex, S
         0
     };
 
+    WinFontStretchGuard aStretchGuard(pRT, fHScale);
     pRT->BeginDraw();
     pRT->DrawGlyphRun(baseline, &glyphs, pBrush);
     HRESULT hResult = pRT->EndDraw();
@@ -314,6 +316,16 @@ bool WinFontInstance::hasHScale() const
     return nWidth != nHeight;
 }
 
+float WinFontInstance::getHScale() const
+{
+    const FontSelectPattern& rPattern = GetFontSelectPattern();
+    int nHeight(rPattern.mnHeight);
+    if (!nHeight)
+        return 1.0;
+    float nWidth(rPattern.mnWidth ? rPattern.mnWidth * GetAverageWidthFactor() : nHeight);
+    return nWidth / nHeight;
+}
+
 static hb_blob_t* getFontTable(hb_face_t* /*face*/, hb_tag_t nTableTag, void* pUserData)
 {
     sal_uLong nLength = 0;
@@ -460,9 +472,8 @@ void WinSalGraphics::DrawTextLayout(const GenericSalLayout& rLayout)
     const HFONT hLayoutFont = pWinFont->GetHFONT();
     bool bUseOpenGL = OpenGLHelper::isVCLOpenGLEnabled() && !mbPrinter;
 
-    // Our DirectWrite renderer is incomplete, skip it for non-horizontal or
-    // stretched text.
-    bool bForceGDI = rLayout.GetOrientation() || (pWinFont->hasHScale() && !bUseOpenGL);
+    // Our DirectWrite renderer is incomplete, skip it for non-horizontal text.
+    bool bForceGDI = rLayout.GetOrientation();
 
     if (!bUseOpenGL)
     {