reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2006 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #ifndef SkFontHost_DEFINED |
| 18 | #define SkFontHost_DEFINED |
| 19 | |
| 20 | #include "SkScalerContext.h" |
| 21 | #include "SkTypeface.h" |
| 22 | |
| 23 | class SkDescriptor; |
| 24 | class SkStream; |
| 25 | class SkWStream; |
| 26 | |
| 27 | /** \class SkFontHost |
| 28 | |
| 29 | This class is ported to each environment. It is responsible for bridging the gap |
| 30 | between SkTypeface and the resulting platform-specific instance of SkScalerContext. |
| 31 | */ |
| 32 | class SkFontHost { |
| 33 | public: |
| 34 | /** Return the closest matching typeface given either an existing family |
| 35 | (specified by a typeface in that family) or by a familyName, and a |
| 36 | requested style. |
| 37 | 1) If familyFace is null, use famillyName. |
| 38 | 2) If famillyName is null, use familyFace. |
| 39 | 3) If both are null, return the default font that best matches style |
| 40 | |
| 41 | NOTE: this does not return a new typeface, nor does it affect the |
| 42 | owner count of an existing one, so the caller is free to ignore the |
| 43 | return result, or just compare it against null. |
| 44 | */ |
| 45 | static SkTypeface* FindTypeface(const SkTypeface* familyFace, |
| 46 | const char famillyName[], |
| 47 | SkTypeface::Style style); |
| 48 | |
| 49 | /** Return the typeface associated with the uniqueID, or null if that ID |
| 50 | does not match any faces. |
| 51 | |
| 52 | NOTE: this does not return a new typeface, nor does it affect the |
| 53 | owner count of an existing one, so the caller is free to ignore the |
| 54 | return result, or just compare it against null. |
| 55 | */ |
| 56 | static SkTypeface* ResolveTypeface(uint32_t uniqueID); |
| 57 | |
| 58 | /** Return a new stream to read the font data, or null if the uniqueID does |
| 59 | not match an existing typeface. The caller must call CloseStream() when |
| 60 | it is finished reading the stream. |
| 61 | */ |
| 62 | static SkStream* OpenStream(uint32_t uniqueID); |
| 63 | |
| 64 | /** Call this when finished reading from the stream returned by OpenStream. |
| 65 | The caller should NOT try to delete the stream. |
| 66 | */ |
| 67 | static void CloseStream(uint32_t uniqueID, SkStream*); |
| 68 | |
| 69 | /** Return a new typeface given the data buffer (owned by the caller). |
| 70 | If the data does not represent a valid font, return null. The caller is |
| 71 | responsible for unref-ing the returned typeface (if it is not null). |
| 72 | */ |
| 73 | static SkTypeface* CreateTypeface(SkStream*); |
| 74 | |
| 75 | /////////////////////////////////////////////////////////////////////////// |
| 76 | |
| 77 | /** Write a unique identifier to the stream, so that the same typeface can |
| 78 | be retrieved with Deserialize(). |
| 79 | */ |
| 80 | static void Serialize(const SkTypeface*, SkWStream*); |
| 81 | |
| 82 | /** Given a stream created by Serialize(), return the corresponding typeface |
| 83 | or null if no match is found. |
| 84 | |
| 85 | NOTE: this does not return a new typeface, nor does it affect the |
| 86 | owner count of an existing one, so the caller is free to ignore the |
| 87 | return result, or just compare it against null. |
| 88 | */ |
| 89 | static SkTypeface* Deserialize(SkStream*); |
| 90 | |
| 91 | /////////////////////////////////////////////////////////////////////////// |
| 92 | |
| 93 | /** Return a subclass of SkScalarContext |
| 94 | */ |
| 95 | static SkScalerContext* CreateScalerContext(const SkDescriptor* desc); |
| 96 | |
| 97 | /** Return a scalercontext using the "fallback" font. If there is no designated |
| 98 | fallback, return null. |
| 99 | */ |
| 100 | static SkScalerContext* CreateFallbackScalerContext(const SkScalerContext::Rec&); |
| 101 | |
| 102 | /** Return the number of bytes (approx) that should be purged from the font |
| 103 | cache. The input parameter is the cache's estimate of how much as been |
| 104 | allocated by the cache so far. |
| 105 | To purge (basically) everything, return the input parameter. |
| 106 | To purge nothing, return 0 |
| 107 | */ |
| 108 | static size_t ShouldPurgeFontCache(size_t sizeAllocatedSoFar); |
| 109 | |
| 110 | /** Return SkScalerContext gamma flag, or 0, based on the paint that will be |
| 111 | used to draw something with antialiasing. |
| 112 | */ |
| 113 | static int ComputeGammaFlag(const SkPaint& paint); |
| 114 | |
| 115 | /** Return NULL or a pointer to 256 bytes for the black (table[0]) and |
| 116 | white (table[1]) gamma tables. |
| 117 | */ |
| 118 | static void GetGammaTables(const uint8_t* tables[2]); |
| 119 | }; |
| 120 | |
| 121 | #endif |
| 122 | |