WIP -- SkFont

include/core/SkFont.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkRefCnt.h"
+#include "SkScalar.h"
+
+class SkTypeface;
+
+enum SkTextEncoding {
+    kUTF8_SkTextEncoding,
+    kUTF16_SkTextEncoding,
+    kUTF32_SkTextEncoding,
+    kGlyphID_SkTextEncoding,
+};
+
+class SkFont : public SkRefCnt {
+public:
+    enum Flags {
+        /**
+         *  Us the system's automatic hinting mechanism to hint the typeface.

[bungeman-skia, 2014/03/26 16:23:40]

nit: s/Us/Use

[reed1, 2014/03/26 18:05:00]

Done.

+         *  If both bytecode and auto hints are specified, attempt to use the bytecodes first.
+         *  If that fails (e.g. there are no codes), then attempt to autohint.
+         */
+        kEnableAutoHints_Flag       = 1 << 0,
+
+        /**
+         *  If the typeface contains explicit bytecodes for hinting, use them.
+         *  If both bytecode and auto hints are specified, attempt to use the bytecodes first.

[bungeman-skia, 2014/03/26 16:23:40]

nit: semicolon at the end of this to link to the next sentence

[reed1, 2014/03/26 18:05:00]

Done.

+         *  If that fails (e.g. there are no codes), then attempt to autohint.
+         */
+        kEnableByteCodeHints_Flag   = 1 << 1,
+
+        /**
+         *  Use rounded metric values (e.g. advance).
+         *  If either auto or bytecode hinting was used, apply those results to the metrics of the
+         *  glyphs as well. If no hinting was applied, the metrics will just be rounded to the
+         *  nearest integer.
+         *
+         *  This applies to calls that return metrics (e.g. measureText) and to drawing the glyphs
+         *  (see SkCanvas drawText and drawPosText).
+         */
+        kUseNonlinearMetrics_Flag   = 1 << 2,
+
+        kVertical_Flag              = 1 << 3,
+        kEmbeddedBitmaps_Flag       = 1 << 4,
+        kGenA8FromLCD_Flag          = 1 << 5,
+        kLCD_Mask_Flag              = 1 << 6,

[bungeman-skia, 2014/03/26 16:23:40]

Since we're changing up all of this anyway, I'd like to avoid using 'LCD' here.
I'd prefer to refer to it as 'SurfaceDependentRendering' or something like that.

kAllAntialiasedLikeSurfaceDependentRendering
kEnableSurfaceDependentRendering

The idea is to make it obvious that these are just flags to enable the feature,
but that it's up to the SkDeviceProperties (or whatever we end up calling this
sort of thing in the Surface world) to specify the geometry. I'd like to avoid
the temptation to try to add a 'rgb vs bgr' flag here, or for anyone to confuse
kVertical with vertical subpixels. Also, this is an enabler, but only if
available. For example, on Mac it doesn't matter how much one asks for 'lcd' if
the user has it turned off in the system settings, there's no documented way to
get it.

This is also an area where the confusion about exploiting the geometry vs
specifying the geometry has bitten FontConfig. FontConfig allows one to specify
the actual geometry (rgb, bgr, vrgb, vbgr) on a per font basis, which is simply
silly. They should have simply had a per font setting for 'exploit or not,
possibly on a per-geometry basis' and allowed the system settings (for the
display) to indicate what the geometry actually is.

[reed1, 2014/03/26 18:05:00]

Trying yet another way to organize mask types...

+        kEmbolden_Flag              = 1 << 7,
+    };
+
+
+    SkTypeface* getTypeface() const { return fTypeface; }
+    SkScalar    getSize() const { return fSize; }
+    SkScalar    getScaleX() const { return fScaleX; }
+    SkScalar    getSkewX() const { return fSkewX; }
+    uint32_t    getFlags() const { return fFlags; }
+
+    int textToGlyphs(const void* text, size_t byteLength, SkTextEncoding,
+                     uint16_t glyphs[], int maxGlyphCount) const;
+
+    SkScalar measureText(const void* text, size_t byteLength, SkTextEncoding) const;
+
+    static SkFont* Create(SkTypeface*, SkScalar size, uint32_t flags);
+    static SkFont* Create(SkTypeface*, SkScalar size, SkScalar scaleX, SkScalar skewX,
+                          uint32_t flags);
+    static SkFont* Create(const SkFont&, SkScalar newSize);
+
+private:
+    enum {
+        kAllFlags = 0xFF,
+    };
+
+    SkFont(SkTypeface*, SkScalar size, SkScalar scaleX, SkScalar skewX, uint32_t flags);
+    virtual ~SkFont();
+
+    SkTypeface* fTypeface;
+    SkScalar    fSize;
+    SkScalar    fScaleX;
+    SkScalar    fSkewX;
+    uint32_t    fFlags;
+};
+