msarett | e16b04a | 2015-04-15 07:32:19 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2015 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 SkJpegCodec_DEFINED |
| 9 | #define SkJpegCodec_DEFINED |
| 10 | |
| 11 | #include "SkCodec.h" |
| 12 | #include "SkImageInfo.h" |
| 13 | #include "SkJpegDecoderMgr.h" |
| 14 | #include "SkJpegUtility.h" |
| 15 | #include "SkStream.h" |
| 16 | |
| 17 | extern "C" { |
| 18 | #include "jpeglib.h" |
| 19 | } |
| 20 | |
| 21 | /* |
| 22 | * |
| 23 | * This class implements the decoding for jpeg images |
| 24 | * |
| 25 | */ |
| 26 | class SkJpegCodec : public SkCodec { |
| 27 | public: |
| 28 | |
| 29 | /* |
| 30 | * Checks the start of the stream to see if the image is a jpeg |
| 31 | * Does not take ownership of the stream |
| 32 | */ |
| 33 | static bool IsJpeg(SkStream*); |
| 34 | |
| 35 | /* |
| 36 | * Assumes IsJpeg was called and returned true |
| 37 | * Creates a jpeg decoder |
| 38 | * Takes ownership of the stream |
| 39 | */ |
| 40 | static SkCodec* NewFromStream(SkStream*); |
| 41 | |
| 42 | protected: |
| 43 | |
| 44 | /* |
| 45 | * Recommend a set of destination dimensions given a requested scale |
| 46 | */ |
| 47 | SkISize onGetScaledDimensions(float desiredScale) const override; |
| 48 | |
| 49 | /* |
| 50 | * Initiates the jpeg decode |
| 51 | */ |
| 52 | Result onGetPixels(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes, const Options&, |
| 53 | SkPMColor*, int*) override; |
| 54 | |
| 55 | SkEncodedFormat onGetEncodedFormat() const override { |
| 56 | return kJPEG_SkEncodedFormat; |
| 57 | } |
| 58 | |
| 59 | private: |
| 60 | |
| 61 | /* |
| 62 | * Read enough of the stream to initialize the SkJpegCodec. |
| 63 | * Returns a bool representing success or failure. |
| 64 | * |
| 65 | * @param codecOut |
| 66 | * If this returns true, and codecOut was not NULL, |
| 67 | * codecOut will be set to a new SkJpegCodec. |
| 68 | * |
| 69 | * @param decoderMgrOut |
| 70 | * If this returns true, and codecOut was NULL, |
| 71 | * decoderMgrOut must be non-NULL and decoderMgrOut will be set to a new |
| 72 | * JpegDecoderMgr pointer. |
| 73 | * |
| 74 | * @param stream |
| 75 | * Deleted on failure. |
| 76 | * codecOut will take ownership of it in the case where we created a codec. |
| 77 | * Ownership is unchanged when we set decoderMgrOut. |
| 78 | * |
| 79 | */ |
| 80 | static bool ReadHeader(SkStream* stream, SkCodec** codecOut, |
| 81 | JpegDecoderMgr** decoderMgrOut); |
| 82 | |
| 83 | /* |
| 84 | * Creates an instance of the decoder |
| 85 | * Called only by NewFromStream |
| 86 | * |
| 87 | * @param srcInfo contains the source width and height |
| 88 | * @param stream the encoded image data |
| 89 | * @param decoderMgr holds decompress struct, src manager, and error manager |
| 90 | * takes ownership |
| 91 | */ |
| 92 | SkJpegCodec(const SkImageInfo& srcInfo, SkStream* stream, JpegDecoderMgr* decoderMgr); |
| 93 | |
| 94 | SkAutoTDelete<JpegDecoderMgr> fDecoderMgr; |
| 95 | |
| 96 | typedef SkCodec INHERITED; |
| 97 | }; |
| 98 | |
| 99 | #endif |