1 files changed, 94 insertions, 0 deletions
diff --git a/gfx/thebes/gfxFT2Utils.h b/gfx/thebes/gfxFT2Utils.h
new file mode 100644
index 000000000..35958bbf7
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+++ b/gfx/thebes/gfxFT2Utils.h
@@ -0,0 +1,94 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef GFX_FT2UTILS_H
+#define GFX_FT2UTILS_H
+
+#include "cairo-ft.h"
+#include "gfxFT2FontBase.h"
+#include "mozilla/Likely.h"
+
+// Rounding and truncation functions for a FreeType fixed point number 
+// (FT26Dot6) stored in a 32bit integer with high 26 bits for the integer
+// part and low 6 bits for the fractional part. 
+#define FLOAT_FROM_26_6(x) ((x) / 64.0)
+#define FLOAT_FROM_16_16(x) ((x) / 65536.0)
+#define ROUND_26_6_TO_INT(x) ((x) >= 0 ?  ((32 + (x)) >> 6) \
+                                       : -((32 - (x)) >> 6))
+
+typedef struct FT_FaceRec_* FT_Face;
+
+class gfxFT2LockedFace {
+public:
+    explicit gfxFT2LockedFace(gfxFT2FontBase *aFont) :
+        mGfxFont(aFont),
+        mFace(cairo_ft_scaled_font_lock_face(aFont->CairoScaledFont()))
+    { }
+    ~gfxFT2LockedFace()
+    {
+        if (mFace) {
+            cairo_ft_scaled_font_unlock_face(mGfxFont->CairoScaledFont());
+        }
+    }
+
+    FT_Face get() { return mFace; };
+
+    /**
+     * Get the glyph id for a Unicode character representable by a single
+     * glyph, or return zero if there is no such glyph.  This does no caching,
+     * so you probably want gfxFcFont::GetGlyph.
+     */
+    uint32_t GetGlyph(uint32_t aCharCode);
+    /**
+     * Returns 0 if there is no variation selector cmap subtable.
+     */
+    uint32_t GetUVSGlyph(uint32_t aCharCode, uint32_t aVariantSelector);
+
+    void GetMetrics(gfxFont::Metrics* aMetrics, uint32_t* aSpaceGlyph);
+
+    // A scale factor for use in converting horizontal metrics from font units
+    // to pixels.
+    gfxFloat XScale()
+    {
+        if (MOZ_UNLIKELY(!mFace))
+            return 0.0;
+
+        const FT_Size_Metrics& ftMetrics = mFace->size->metrics;
+
+        if (FT_IS_SCALABLE(mFace)) {
+            // Prefer FT_Size_Metrics::x_scale to x_ppem as x_ppem does not
+            // have subpixel accuracy.
+            //
+            // FT_Size_Metrics::x_scale is in 16.16 fixed point format.  Its
+            // (fractional) value is a factor that converts vertical metrics
+            // from design units to units of 1/64 pixels, so that the result
+            // may be interpreted as pixels in 26.6 fixed point format.
+            return FLOAT_FROM_26_6(FLOAT_FROM_16_16(ftMetrics.x_scale));
+        }
+
+        // Not scalable.
+        // FT_Size_Metrics doc says x_scale is "only relevant for scalable
+        // font formats".
+        return gfxFloat(ftMetrics.x_ppem) / gfxFloat(mFace->units_per_EM);
+    }
+
+protected:
+    /**
+     * Get extents for a simple character representable by a single glyph.
+     * The return value is the glyph id of that glyph or zero if no such glyph
+     * exists.  aExtents is only set when this returns a non-zero glyph id.
+     */
+    uint32_t GetCharExtents(char aChar, cairo_text_extents_t* aExtents);
+
+    typedef FT_UInt (*CharVariantFunction)(FT_Face  face,
+                                           FT_ULong charcode,
+                                           FT_ULong variantSelector);
+    CharVariantFunction FindCharVariantFunction();
+
+    RefPtr<gfxFT2FontBase> mGfxFont;
+    FT_Face mFace;
+};
+
+#endif /* GFX_FT2UTILS_H */