1 | // Copyright 2011 Google Inc. All Rights Reserved. |
2 | // |
3 | // Use of this source code is governed by a BSD-style license |
4 | // that can be found in the COPYING file in the root of the source |
5 | // tree. An additional intellectual property rights grant can be found |
6 | // in the file PATENTS. All contributing project authors may |
7 | // be found in the AUTHORS file in the root of the source tree. |
8 | // ----------------------------------------------------------------------------- |
9 | // |
10 | // Internal header: WebP decoding parameters and custom IO on buffer |
11 | // |
12 | // Author: somnath@google.com (Somnath Banerjee) |
13 | |
14 | #ifndef WEBP_DEC_WEBPI_DEC_H_ |
15 | #define WEBP_DEC_WEBPI_DEC_H_ |
16 | |
17 | #ifdef __cplusplus |
18 | extern "C" { |
19 | #endif |
20 | |
21 | #include "src/utils/rescaler_utils.h" |
22 | #include "src/dec/vp8_dec.h" |
23 | |
24 | //------------------------------------------------------------------------------ |
25 | // WebPDecParams: Decoding output parameters. Transient internal object. |
26 | |
27 | typedef struct WebPDecParams WebPDecParams; |
28 | typedef int (*OutputFunc)(const VP8Io* const io, WebPDecParams* const p); |
29 | typedef int (*OutputAlphaFunc)(const VP8Io* const io, WebPDecParams* const p, |
30 | int expected_num_out_lines); |
31 | typedef int (*OutputRowFunc)(WebPDecParams* const p, int y_pos, |
32 | int max_out_lines); |
33 | |
34 | struct WebPDecParams { |
35 | WebPDecBuffer* output; // output buffer. |
36 | uint8_t* tmp_y, *tmp_u, *tmp_v; // cache for the fancy upsampler |
37 | // or used for tmp rescaling |
38 | |
39 | int last_y; // coordinate of the line that was last output |
40 | const WebPDecoderOptions* options; // if not NULL, use alt decoding features |
41 | |
42 | WebPRescaler* scaler_y, *scaler_u, *scaler_v, *scaler_a; // rescalers |
43 | void* memory; // overall scratch memory for the output work. |
44 | |
45 | OutputFunc emit; // output RGB or YUV samples |
46 | OutputAlphaFunc emit_alpha; // output alpha channel |
47 | OutputRowFunc emit_alpha_row; // output one line of rescaled alpha values |
48 | }; |
49 | |
50 | // Should be called first, before any use of the WebPDecParams object. |
51 | void WebPResetDecParams(WebPDecParams* const params); |
52 | |
53 | //------------------------------------------------------------------------------ |
54 | // Header parsing helpers |
55 | |
56 | // Structure storing a description of the RIFF headers. |
57 | typedef struct { |
58 | const uint8_t* data; // input buffer |
59 | size_t data_size; // input buffer size |
60 | int have_all_data; // true if all data is known to be available |
61 | size_t offset; // offset to main data chunk (VP8 or VP8L) |
62 | const uint8_t* alpha_data; // points to alpha chunk (if present) |
63 | size_t alpha_data_size; // alpha chunk size |
64 | size_t compressed_size; // VP8/VP8L compressed data size |
65 | size_t riff_size; // size of the riff payload (or 0 if absent) |
66 | int is_lossless; // true if a VP8L chunk is present |
67 | } ; |
68 | |
69 | // Skips over all valid chunks prior to the first VP8/VP8L frame header. |
70 | // Returns: VP8_STATUS_OK, VP8_STATUS_BITSTREAM_ERROR (invalid header/chunk), |
71 | // VP8_STATUS_NOT_ENOUGH_DATA (partial input) or VP8_STATUS_UNSUPPORTED_FEATURE |
72 | // in the case of non-decodable features (animation for instance). |
73 | // In 'headers', compressed_size, offset, alpha_data, alpha_size, and lossless |
74 | // fields are updated appropriately upon success. |
75 | VP8StatusCode (WebPHeaderStructure* const ); |
76 | |
77 | //------------------------------------------------------------------------------ |
78 | // Misc utils |
79 | |
80 | // Returns true if crop dimensions are within image bounds. |
81 | int WebPCheckCropDimensions(int image_width, int image_height, |
82 | int x, int y, int w, int h); |
83 | |
84 | // Initializes VP8Io with custom setup, io and teardown functions. The default |
85 | // hooks will use the supplied 'params' as io->opaque handle. |
86 | void WebPInitCustomIo(WebPDecParams* const params, VP8Io* const io); |
87 | |
88 | // Setup crop_xxx fields, mb_w and mb_h in io. 'src_colorspace' refers |
89 | // to the *compressed* format, not the output one. |
90 | int WebPIoInitFromOptions(const WebPDecoderOptions* const options, |
91 | VP8Io* const io, WEBP_CSP_MODE src_colorspace); |
92 | |
93 | //------------------------------------------------------------------------------ |
94 | // Internal functions regarding WebPDecBuffer memory (in buffer.c). |
95 | // Don't really need to be externally visible for now. |
96 | |
97 | // Prepare 'buffer' with the requested initial dimensions width/height. |
98 | // If no external storage is supplied, initializes buffer by allocating output |
99 | // memory and setting up the stride information. Validate the parameters. Return |
100 | // an error code in case of problem (no memory, or invalid stride / size / |
101 | // dimension / etc.). If *options is not NULL, also verify that the options' |
102 | // parameters are valid and apply them to the width/height dimensions of the |
103 | // output buffer. This takes cropping / scaling / rotation into account. |
104 | // Also incorporates the options->flip flag to flip the buffer parameters if |
105 | // needed. |
106 | VP8StatusCode WebPAllocateDecBuffer(int width, int height, |
107 | const WebPDecoderOptions* const options, |
108 | WebPDecBuffer* const buffer); |
109 | |
110 | // Flip buffer vertically by negating the various strides. |
111 | VP8StatusCode WebPFlipBuffer(WebPDecBuffer* const buffer); |
112 | |
113 | // Copy 'src' into 'dst' buffer, making sure 'dst' is not marked as owner of the |
114 | // memory (still held by 'src'). No pixels are copied. |
115 | void WebPCopyDecBuffer(const WebPDecBuffer* const src, |
116 | WebPDecBuffer* const dst); |
117 | |
118 | // Copy and transfer ownership from src to dst (beware of parameter order!) |
119 | void WebPGrabDecBuffer(WebPDecBuffer* const src, WebPDecBuffer* const dst); |
120 | |
121 | // Copy pixels from 'src' into a *preallocated* 'dst' buffer. Returns |
122 | // VP8_STATUS_INVALID_PARAM if the 'dst' is not set up correctly for the copy. |
123 | VP8StatusCode WebPCopyDecBufferPixels(const WebPDecBuffer* const src, |
124 | WebPDecBuffer* const dst); |
125 | |
126 | // Returns true if decoding will be slow with the current configuration |
127 | // and bitstream features. |
128 | int WebPAvoidSlowMemory(const WebPDecBuffer* const output, |
129 | const WebPBitstreamFeatures* const features); |
130 | |
131 | //------------------------------------------------------------------------------ |
132 | |
133 | #ifdef __cplusplus |
134 | } // extern "C" |
135 | #endif |
136 | |
137 | #endif // WEBP_DEC_WEBPI_DEC_H_ |
138 | |