Page Speed Optimization Libraries  1.7.30.1
net/instaweb/rewriter/public/image_data_lookup.h
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00001 /*
00002  * Copyright 2011 Google Inc.
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *      http:///www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 
00018 
00019 #ifndef NET_INSTAWEB_REWRITER_PUBLIC_IMAGE_DATA_LOOKUP_H_
00020 #define NET_INSTAWEB_REWRITER_PUBLIC_IMAGE_DATA_LOOKUP_H_
00021 
00022 #include <cstddef>
00023 #include "net/instaweb/util/public/basictypes.h"
00024 #include "net/instaweb/util/public/string_util.h"
00025 
00026 namespace net_instaweb {
00027 
00031 
00033 inline int CharToInt(char c) {
00034   uint8 uc = static_cast<uint8>(c);
00035   return static_cast<int>(uc);
00036 }
00037 
00038 inline int JpegIntAtPosition(const StringPiece& buf, size_t pos) {
00039   return (CharToInt(buf[pos]) << 8) |
00040          (CharToInt(buf[pos + 1]));
00041 }
00042 
00043 inline int GifIntAtPosition(const StringPiece& buf, size_t pos) {
00044   return (CharToInt(buf[pos + 1]) << 8) |
00045          (CharToInt(buf[pos]));
00046 }
00047 
00048 inline int PngIntAtPosition(const StringPiece& buf, size_t pos) {
00049   return (CharToInt(buf[pos    ]) << 24) |
00050          (CharToInt(buf[pos + 1]) << 16) |
00051          (CharToInt(buf[pos + 2]) << 8) |
00052          (CharToInt(buf[pos + 3]));
00053 }
00054 
00055 inline bool PngSectionIdIs(const char* hdr,
00056                            const StringPiece& buf, size_t pos) {
00057   return ((buf[pos + 4] == hdr[0]) &&
00058           (buf[pos + 5] == hdr[1]) &&
00059           (buf[pos + 6] == hdr[2]) &&
00060           (buf[pos + 7] == hdr[3]));
00061 }
00062 
00063 namespace ImageHeaders {
00065   extern const char kPngHeader[];
00066   extern const size_t kPngHeaderLength;
00067   extern const char kPngIHDR[];
00068   extern const size_t kPngIHDRLength;
00069   extern const size_t kIHDRDataStart;
00070   extern const size_t kPngIntSize;
00071 
00072   extern const char kGifHeader[];
00073   extern const size_t kGifHeaderLength;
00074   extern const size_t kGifDimStart;
00075   extern const size_t kGifIntSize;
00076 
00077   extern const size_t kJpegIntSize;
00078 }  
00079 
00080 }  
00081 
00082 #endif  ///< NET_INSTAWEB_REWRITER_PUBLIC_IMAGE_DATA_LOOKUP_H_
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