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
18extern "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
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// Returns true if crop dimensions are within image bounds.
81int 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.
86void 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.
90int 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.
106VP8StatusCode WebPAllocateDecBuffer(int width, int height,
107 const WebPDecoderOptions* const options,
108 WebPDecBuffer* const buffer);
109
110// Flip buffer vertically by negating the various strides.
111VP8StatusCode 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.
115void WebPCopyDecBuffer(const WebPDecBuffer* const src,
116 WebPDecBuffer* const dst);
117
118// Copy and transfer ownership from src to dst (beware of parameter order!)
119void 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.
123VP8StatusCode 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.
128int 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