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_H_
15#define WEBP_DEC_WEBPI_H_
16
17#ifdef __cplusplus
18extern "C" {
19#endif
20
21#include "../utils/rescaler_utils.h"
22#include "./vp8_dec.h"
23
24//------------------------------------------------------------------------------
25// WebPDecParams: Decoding output parameters. Transient internal object.
26
27typedef struct WebPDecParams WebPDecParams;
28typedef int (*OutputFunc)(const VP8Io* const io, WebPDecParams* const p);
29typedef int (*OutputAlphaFunc)(const VP8Io* const io, WebPDecParams* const p,
30 int expected_num_out_lines);
31typedef int (*OutputRowFunc)(WebPDecParams* const p, int y_pos,
32 int max_out_lines);
33
34struct 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.
51void WebPResetDecParams(WebPDecParams* const params);
52
53//------------------------------------------------------------------------------
54// Header parsing helpers
55
56// Structure storing a description of the RIFF headers.
57typedef 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} WebPHeaderStructure;
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.
75VP8StatusCode WebPParseHeaders(WebPHeaderStructure* const headers);
76
77//------------------------------------------------------------------------------
78// Misc utils
79
80// Initializes VP8Io with custom setup, io and teardown functions. The default
81// hooks will use the supplied 'params' as io->opaque handle.
82void WebPInitCustomIo(WebPDecParams* const params, VP8Io* const io);
83
84// Setup crop_xxx fields, mb_w and mb_h in io. 'src_colorspace' refers
85// to the *compressed* format, not the output one.
86int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
87 VP8Io* const io, WEBP_CSP_MODE src_colorspace);
88
89//------------------------------------------------------------------------------
90// Internal functions regarding WebPDecBuffer memory (in buffer.c).
91// Don't really need to be externally visible for now.
92
93// Prepare 'buffer' with the requested initial dimensions width/height.
94// If no external storage is supplied, initializes buffer by allocating output
95// memory and setting up the stride information. Validate the parameters. Return
96// an error code in case of problem (no memory, or invalid stride / size /
97// dimension / etc.). If *options is not NULL, also verify that the options'
98// parameters are valid and apply them to the width/height dimensions of the
99// output buffer. This takes cropping / scaling / rotation into account.
100// Also incorporates the options->flip flag to flip the buffer parameters if
101// needed.
102VP8StatusCode WebPAllocateDecBuffer(int width, int height,
103 const WebPDecoderOptions* const options,
104 WebPDecBuffer* const buffer);
105
106// Flip buffer vertically by negating the various strides.
107VP8StatusCode WebPFlipBuffer(WebPDecBuffer* const buffer);
108
109// Copy 'src' into 'dst' buffer, making sure 'dst' is not marked as owner of the
110// memory (still held by 'src'). No pixels are copied.
111void WebPCopyDecBuffer(const WebPDecBuffer* const src,
112 WebPDecBuffer* const dst);
113
114// Copy and transfer ownership from src to dst (beware of parameter order!)
115void WebPGrabDecBuffer(WebPDecBuffer* const src, WebPDecBuffer* const dst);
116
117// Copy pixels from 'src' into a *preallocated* 'dst' buffer. Returns
118// VP8_STATUS_INVALID_PARAM if the 'dst' is not set up correctly for the copy.
119VP8StatusCode WebPCopyDecBufferPixels(const WebPDecBuffer* const src,
120 WebPDecBuffer* const dst);
121
122// Returns true if decoding will be slow with the current configuration
123// and bitstream features.
124int WebPAvoidSlowMemory(const WebPDecBuffer* const output,
125 const WebPBitstreamFeatures* const features);
126
127//------------------------------------------------------------------------------
128
129#ifdef __cplusplus
130} // extern "C"
131#endif
132
133#endif /* WEBP_DEC_WEBPI_H_ */
134