libwebp-0.6.0-rc1

third_party/libwebp/dec/webpi.h

-// Copyright 2011 Google Inc. All Rights Reserved.
-//
-// Use of this source code is governed by a BSD-style license
-// that can be found in the COPYING file in the root of the source
-// tree. An additional intellectual property rights grant can be found
-// in the file PATENTS. All contributing project authors may
-// be found in the AUTHORS file in the root of the source tree.
-// -----------------------------------------------------------------------------
-//
-// Internal header: WebP decoding parameters and custom IO on buffer
-//
-// Author: somnath@google.com (Somnath Banerjee)
-
-#ifndef WEBP_DEC_WEBPI_H_
-#define WEBP_DEC_WEBPI_H_
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#include "../utils/rescaler.h"
-#include "./decode_vp8.h"
-
-//------------------------------------------------------------------------------
-// WebPDecParams: Decoding output parameters. Transient internal object.
-
-typedef struct WebPDecParams WebPDecParams;
-typedef int (*OutputFunc)(const VP8Io* const io, WebPDecParams* const p);
-typedef int (*OutputAlphaFunc)(const VP8Io* const io, WebPDecParams* const p,
-                               int expected_num_out_lines);
-typedef int (*OutputRowFunc)(WebPDecParams* const p, int y_pos,
-                             int max_out_lines);
-
-struct WebPDecParams {
-  WebPDecBuffer* output;             // output buffer.
-  uint8_t* tmp_y, *tmp_u, *tmp_v;    // cache for the fancy upsampler
-                                     // or used for tmp rescaling
-
-  int last_y;                 // coordinate of the line that was last output
-  const WebPDecoderOptions* options;  // if not NULL, use alt decoding features
-  // rescalers
-  WebPRescaler scaler_y, scaler_u, scaler_v, scaler_a;
-  void* memory;                  // overall scratch memory for the output work.
-
-  OutputFunc emit;               // output RGB or YUV samples
-  OutputAlphaFunc emit_alpha;    // output alpha channel
-  OutputRowFunc emit_alpha_row;  // output one line of rescaled alpha values
-
-  WebPDecBuffer* final_output;   // In case the user supplied a slow-memory
-                                 // output, we decode image in temporary buffer
-                                 // (this::output) and copy it here.
-  WebPDecBuffer tmp_buffer;      // this::output will point to this one in case
-                                 // of slow memory.
-};
-
-// Should be called first, before any use of the WebPDecParams object.
-void WebPResetDecParams(WebPDecParams* const params);
-
-// Delete all memory (after an error occurred, for instance)
-void WebPFreeDecParams(WebPDecParams* const params);
-
-//------------------------------------------------------------------------------
-// Header parsing helpers
-
-// Structure storing a description of the RIFF headers.
-typedef struct {
-  const uint8_t* data;         // input buffer
-  size_t data_size;            // input buffer size
-  int have_all_data;           // true if all data is known to be available
-  size_t offset;               // offset to main data chunk (VP8 or VP8L)
-  const uint8_t* alpha_data;   // points to alpha chunk (if present)
-  size_t alpha_data_size;      // alpha chunk size
-  size_t compressed_size;      // VP8/VP8L compressed data size
-  size_t riff_size;            // size of the riff payload (or 0 if absent)
-  int is_lossless;             // true if a VP8L chunk is present
-} WebPHeaderStructure;
-
-// Skips over all valid chunks prior to the first VP8/VP8L frame header.
-// Returns: VP8_STATUS_OK, VP8_STATUS_BITSTREAM_ERROR (invalid header/chunk),
-// VP8_STATUS_NOT_ENOUGH_DATA (partial input) or VP8_STATUS_UNSUPPORTED_FEATURE
-// in the case of non-decodable features (animation for instance).
-// In 'headers', compressed_size, offset, alpha_data, alpha_size, and lossless
-// fields are updated appropriately upon success.
-VP8StatusCode WebPParseHeaders(WebPHeaderStructure* const headers);
-
-//------------------------------------------------------------------------------
-// Misc utils
-
-// Initializes VP8Io with custom setup, io and teardown functions. The default
-// hooks will use the supplied 'params' as io->opaque handle.
-void WebPInitCustomIo(WebPDecParams* const params, VP8Io* const io);
-
-// Setup crop_xxx fields, mb_w and mb_h in io. 'src_colorspace' refers
-// to the *compressed* format, not the output one.
-int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
-                          VP8Io* const io, WEBP_CSP_MODE src_colorspace);
-
-//------------------------------------------------------------------------------
-// Internal functions regarding WebPDecBuffer memory (in buffer.c).
-// Don't really need to be externally visible for now.
-
-// Prepare 'buffer' with the requested initial dimensions width/height.
-// If no external storage is supplied, initializes buffer by allocating output
-// memory and setting up the stride information. Validate the parameters. Return
-// an error code in case of problem (no memory, or invalid stride / size /
-// dimension / etc.). If *options is not NULL, also verify that the options'
-// parameters are valid and apply them to the width/height dimensions of the
-// output buffer. This takes cropping / scaling / rotation into account.
-// Also incorporates the options->flip flag to flip the buffer parameters if
-// needed.
-VP8StatusCode WebPAllocateDecBuffer(int width, int height,
-                                    const WebPDecoderOptions* const options,
-                                    WebPDecBuffer* const buffer);
-
-// Flip buffer vertically by negating the various strides.
-VP8StatusCode WebPFlipBuffer(WebPDecBuffer* const buffer);
-
-// Copy 'src' into 'dst' buffer, making sure 'dst' is not marked as owner of the
-// memory (still held by 'src'). No pixels are copied.
-void WebPCopyDecBuffer(const WebPDecBuffer* const src,
-                       WebPDecBuffer* const dst);
-
-// Copy and transfer ownership from src to dst (beware of parameter order!)
-void WebPGrabDecBuffer(WebPDecBuffer* const src, WebPDecBuffer* const dst);
-
-// Copy pixels from 'src' into a *preallocated* 'dst' buffer. Returns
-// VP8_STATUS_INVALID_PARAM if the 'dst' is not set up correctly for the copy.
-VP8StatusCode WebPCopyDecBufferPixels(const WebPDecBuffer* const src,
-                                      WebPDecBuffer* const dst);
-
-// Returns true if decoding will be slow with the current configuration
-// and bitstream features.
-int WebPAvoidSlowMemory(const WebPDecBuffer* const output,
-                        const WebPBitstreamFeatures* const features);
-
-//------------------------------------------------------------------------------
-
-#ifdef __cplusplus
-}    // extern "C"
-#endif
-
-#endif  /* WEBP_DEC_WEBPI_H_ */