1 /*
2  * Copyright 2013 Google Inc.
3  *
4  * Use of this source code is governed by a BSD-style license that can be
5  * found in the LICENSE file.
6  */
7 
8 #ifndef SkPaintPriv_DEFINED
9 #define SkPaintPriv_DEFINED
10 
11 #include "SkPaint.h"
12 
13 class SkFont;
14 class SkReadBuffer;
15 class SkWriteBuffer;
16 
17 enum SkReadPaintResult {
18     kFailed_ReadPaint,
19     kSuccess_JustPaint,
20     kSuccess_PaintAndFont,
21 };
22 
23 class SkPaintPriv {
24 public:
25     enum ShaderOverrideOpacity {
26         kNone_ShaderOverrideOpacity,        //!< there is no overriding shader (bitmap or image)
27         kOpaque_ShaderOverrideOpacity,      //!< the overriding shader is opaque
28         kNotOpaque_ShaderOverrideOpacity,   //!< the overriding shader may not be opaque
29     };
30 
31     /**
32      *  Returns true if drawing with this paint (or nullptr) will ovewrite all affected pixels.
33      *
34      *  Note: returns conservative true, meaning it may return false even though the paint might
35      *        in fact overwrite its pixels.
36      */
37     static bool Overwrites(const SkPaint* paint, ShaderOverrideOpacity);
38 
39     static bool ShouldDither(const SkPaint&, SkColorType);
40 
41     /*
42      * The luminance color is used to determine which Gamma Canonical color to map to.  This is
43      * really only used by backends which want to cache glyph masks, and need some way to know if
44      * they need to generate new masks based off a given color.
45      */
46     static SkColor ComputeLuminanceColor(const SkPaint&);
47 
48     /** Serializes SkPaint into a buffer. A companion unflatten() call
49     can reconstitute the paint at a later time.
50 
51     @param buffer  SkWriteBuffer receiving the flattened SkPaint data
52     */
53     static void Flatten(const SkPaint& paint, SkWriteBuffer& buffer);
54 
55     /** Populates SkPaint, typically from a serialized stream, created by calling
56         flatten() at an earlier time.
57 
58         SkReadBuffer class is not public, so unflatten() cannot be meaningfully called
59         by the client.
60 
61         Older formats also stored font info in the serialized data. On success, this
62         returns if it deserialized just a paint, or both a font and paint. The font
63         param is optional.
64 
65         @param buffer  serialized data describing SkPaint content
66         @return        false if the buffer contains invalid data
67     */
68     static SkReadPaintResult Unflatten(SkPaint* paint, SkReadBuffer& buffer, SkFont* font);
69 
70 private:
71     static SkReadPaintResult Unflatten_PreV68(SkPaint* paint, SkReadBuffer& buffer, SkFont*);
72 };
73 
74 #endif
75