/src/libwebp/src/utils/rescaler_utils.h

Source
// Copyright 2012 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.
// -----------------------------------------------------------------------------
//
// Rescaling functions
//
// Author: Skal (pascal.massimino@gmail.com)

#ifndef WEBP_UTILS_RESCALER_UTILS_H_
#define WEBP_UTILS_RESCALER_UTILS_H_

#ifdef __cplusplus
extern "C" {
#endif

#include "src/utils/bounds_safety.h"
#include "src/webp/types.h"

WEBP_ASSUME_UNSAFE_INDEXABLE_ABI

#define WEBP_RESCALER_RFIX 32  // fixed-point precision for multiplies
#define WEBP_RESCALER_ONE (1ull << WEBP_RESCALER_RFIX)
#define WEBP_RESCALER_FRAC(x, y) \
  ((uint32_t)(((uint64_t)(x) << WEBP_RESCALER_RFIX) / (y)))

// Structure used for on-the-fly rescaling
typedef uint32_t rescaler_t;  // type for side-buffer
typedef struct WebPRescaler WebPRescaler;
struct WebPRescaler {
  int x_expand;               // true if we're expanding in the x direction
  int y_expand;               // true if we're expanding in the y direction
  int num_channels;           // bytes to jump between pixels
  uint32_t fx_scale;          // fixed-point scaling factors
  uint32_t fy_scale;          // ''
  uint32_t fxy_scale;         // ''
  int y_accum;                // vertical accumulator
  int y_add, y_sub;           // vertical increments
  int x_add, x_sub;           // horizontal increments
  int src_width, src_height;  // source dimensions
  int dst_width, dst_height;  // destination dimensions
  int src_y, dst_y;           // row counters for input and output
  uint8_t* dst;
  int dst_stride;
  // work buffer
  rescaler_t* WEBP_COUNTED_BY(dst_width* num_channels) irow;
  rescaler_t* WEBP_COUNTED_BY(dst_width* num_channels) frow;
};

// Initialize a rescaler given scratch area 'work' and dimensions of src & dst.
// Returns false in case of error.
int WebPRescalerInit(WebPRescaler* const rescaler, int src_width,
                     int src_height, uint8_t* const dst, int dst_width,
                     int dst_height, int dst_stride, int num_channels,
                     rescaler_t* const WEBP_COUNTED_BY(2ULL * dst_width *
                                                       num_channels) work);

// If either 'scaled_width' or 'scaled_height' (but not both) is 0 the value
// will be calculated preserving the aspect ratio, otherwise the values are
// left unmodified. Returns true on success, false if either value is 0 after
// performing the scaling calculation.
int WebPRescalerGetScaledDimensions(int src_width, int src_height,
                                    int* const scaled_width,
                                    int* const scaled_height);

// Returns the number of input lines needed next to produce one output line,
// considering that the maximum available input lines are 'max_num_lines'.
int WebPRescaleNeededLines(const WebPRescaler* const rescaler,
                           int max_num_lines);

// Import multiple rows over all channels, until at least one row is ready to
// be exported. Returns the actual number of lines that were imported.
int WebPRescalerImport(WebPRescaler* const rescaler, int num_rows,
                       const uint8_t* src, int src_stride);

// Export as many rows as possible. Return the numbers of rows written.
int WebPRescalerExport(WebPRescaler* const rescaler);

// Return true if input is finished
static WEBP_INLINE int WebPRescalerInputDone(
    const WebPRescaler* const rescaler) {
  return (rescaler->src_y >= rescaler->src_height);
}
// Return true if output is finished
static WEBP_INLINE int WebPRescalerOutputDone(
    const WebPRescaler* const rescaler) {
  return (rescaler->dst_y >= rescaler->dst_height);
}

// Return true if there are pending output rows ready.
static WEBP_INLINE int WebPRescalerHasPendingOutput(
    const WebPRescaler* const rescaler) {
  return !WebPRescalerOutputDone(rescaler) && (rescaler->y_accum <= 0);
}

//------------------------------------------------------------------------------

#ifdef __cplusplus
}  // extern "C"
#endif

#endif  // WEBP_UTILS_RESCALER_UTILS_H_

Line	Count	Source
1		// Copyright 2012 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		// Rescaling functions
11		//
12		// Author: Skal (pascal.massimino@gmail.com)
13
14		#ifndef WEBP_UTILS_RESCALER_UTILS_H_
15		#define WEBP_UTILS_RESCALER_UTILS_H_
16
17		#ifdef __cplusplus
18		extern "C" {
19		#endif
20
21		#include "src/utils/bounds_safety.h"
22		#include "src/webp/types.h"
23
24		WEBP_ASSUME_UNSAFE_INDEXABLE_ABI
25
26	0	#define WEBP_RESCALER_RFIX 32 // fixed-point precision for multiplies
27	0	#define WEBP_RESCALER_ONE (1ull << WEBP_RESCALER_RFIX)
28		#define WEBP_RESCALER_FRAC(x, y) \
29	0	((uint32_t)(((uint64_t)(x) << WEBP_RESCALER_RFIX) / (y)))
30
31		// Structure used for on-the-fly rescaling
32		typedef uint32_t rescaler_t; // type for side-buffer
33		typedef struct WebPRescaler WebPRescaler;
34		struct WebPRescaler {
35		int x_expand; // true if we're expanding in the x direction
36		int y_expand; // true if we're expanding in the y direction
37		int num_channels; // bytes to jump between pixels
38		uint32_t fx_scale; // fixed-point scaling factors
39		uint32_t fy_scale; // ''
40		uint32_t fxy_scale; // ''
41		int y_accum; // vertical accumulator
42		int y_add, y_sub; // vertical increments
43		int x_add, x_sub; // horizontal increments
44		int src_width, src_height; // source dimensions
45		int dst_width, dst_height; // destination dimensions
46		int src_y, dst_y; // row counters for input and output
47		uint8_t* dst;
48		int dst_stride;
49		// work buffer
50		rescaler_t* WEBP_COUNTED_BY(dst_width* num_channels) irow;
51		rescaler_t* WEBP_COUNTED_BY(dst_width* num_channels) frow;
52		};
53
54		// Initialize a rescaler given scratch area 'work' and dimensions of src & dst.
55		// Returns false in case of error.
56		int WebPRescalerInit(WebPRescaler* const rescaler, int src_width,
57		int src_height, uint8_t* const dst, int dst_width,
58		int dst_height, int dst_stride, int num_channels,
59		rescaler_t* const WEBP_COUNTED_BY(2ULL * dst_width *
60		num_channels) work);
61
62		// If either 'scaled_width' or 'scaled_height' (but not both) is 0 the value
63		// will be calculated preserving the aspect ratio, otherwise the values are
64		// left unmodified. Returns true on success, false if either value is 0 after
65		// performing the scaling calculation.
66		int WebPRescalerGetScaledDimensions(int src_width, int src_height,
67		int* const scaled_width,
68		int* const scaled_height);
69
70		// Returns the number of input lines needed next to produce one output line,
71		// considering that the maximum available input lines are 'max_num_lines'.
72		int WebPRescaleNeededLines(const WebPRescaler* const rescaler,
73		int max_num_lines);
74
75		// Import multiple rows over all channels, until at least one row is ready to
76		// be exported. Returns the actual number of lines that were imported.
77		int WebPRescalerImport(WebPRescaler* const rescaler, int num_rows,
78		const uint8_t* src, int src_stride);
79
80		// Export as many rows as possible. Return the numbers of rows written.
81		int WebPRescalerExport(WebPRescaler* const rescaler);
82
83		// Return true if input is finished
84		static WEBP_INLINE int WebPRescalerInputDone(
85	0	const WebPRescaler* const rescaler) {
86	0	return (rescaler->src_y >= rescaler->src_height);
87	0	} Unexecuted instantiation: webp_dec.c:WebPRescalerInputDone Unexecuted instantiation: rescaler_utils.c:WebPRescalerInputDone Unexecuted instantiation: buffer_dec.c:WebPRescalerInputDone Unexecuted instantiation: frame_dec.c:WebPRescalerInputDone Unexecuted instantiation: io_dec.c:WebPRescalerInputDone Unexecuted instantiation: vp8_dec.c:WebPRescalerInputDone Unexecuted instantiation: vp8l_dec.c:WebPRescalerInputDone Unexecuted instantiation: dec.c:WebPRescalerInputDone Unexecuted instantiation: lossless.c:WebPRescalerInputDone Unexecuted instantiation: rescaler.c:WebPRescalerInputDone Unexecuted instantiation: dec_sse2.c:WebPRescalerInputDone Unexecuted instantiation: rescaler_sse2.c:WebPRescalerInputDone Unexecuted instantiation: dec_sse41.c:WebPRescalerInputDone Unexecuted instantiation: alpha_dec.c:WebPRescalerInputDone Unexecuted instantiation: quant_dec.c:WebPRescalerInputDone Unexecuted instantiation: tree_dec.c:WebPRescalerInputDone Unexecuted instantiation: picture_rescale_enc.c:WebPRescalerInputDone
88		// Return true if output is finished
89		static WEBP_INLINE int WebPRescalerOutputDone(
90	0	const WebPRescaler* const rescaler) {
91	0	return (rescaler->dst_y >= rescaler->dst_height);
92	0	} Unexecuted instantiation: webp_dec.c:WebPRescalerOutputDone Unexecuted instantiation: rescaler_utils.c:WebPRescalerOutputDone Unexecuted instantiation: buffer_dec.c:WebPRescalerOutputDone Unexecuted instantiation: frame_dec.c:WebPRescalerOutputDone Unexecuted instantiation: io_dec.c:WebPRescalerOutputDone Unexecuted instantiation: vp8_dec.c:WebPRescalerOutputDone Unexecuted instantiation: vp8l_dec.c:WebPRescalerOutputDone Unexecuted instantiation: dec.c:WebPRescalerOutputDone Unexecuted instantiation: lossless.c:WebPRescalerOutputDone Unexecuted instantiation: rescaler.c:WebPRescalerOutputDone Unexecuted instantiation: dec_sse2.c:WebPRescalerOutputDone Unexecuted instantiation: rescaler_sse2.c:WebPRescalerOutputDone Unexecuted instantiation: dec_sse41.c:WebPRescalerOutputDone Unexecuted instantiation: alpha_dec.c:WebPRescalerOutputDone Unexecuted instantiation: quant_dec.c:WebPRescalerOutputDone Unexecuted instantiation: tree_dec.c:WebPRescalerOutputDone Unexecuted instantiation: picture_rescale_enc.c:WebPRescalerOutputDone
93
94		// Return true if there are pending output rows ready.
95		static WEBP_INLINE int WebPRescalerHasPendingOutput(
96	0	const WebPRescaler* const rescaler) {
97	0	return !WebPRescalerOutputDone(rescaler) && (rescaler->y_accum <= 0);
98	0	} Unexecuted instantiation: webp_dec.c:WebPRescalerHasPendingOutput Unexecuted instantiation: rescaler_utils.c:WebPRescalerHasPendingOutput Unexecuted instantiation: buffer_dec.c:WebPRescalerHasPendingOutput Unexecuted instantiation: frame_dec.c:WebPRescalerHasPendingOutput Unexecuted instantiation: io_dec.c:WebPRescalerHasPendingOutput Unexecuted instantiation: vp8_dec.c:WebPRescalerHasPendingOutput Unexecuted instantiation: vp8l_dec.c:WebPRescalerHasPendingOutput Unexecuted instantiation: dec.c:WebPRescalerHasPendingOutput Unexecuted instantiation: lossless.c:WebPRescalerHasPendingOutput Unexecuted instantiation: rescaler.c:WebPRescalerHasPendingOutput Unexecuted instantiation: dec_sse2.c:WebPRescalerHasPendingOutput Unexecuted instantiation: rescaler_sse2.c:WebPRescalerHasPendingOutput Unexecuted instantiation: dec_sse41.c:WebPRescalerHasPendingOutput Unexecuted instantiation: alpha_dec.c:WebPRescalerHasPendingOutput Unexecuted instantiation: quant_dec.c:WebPRescalerHasPendingOutput Unexecuted instantiation: tree_dec.c:WebPRescalerHasPendingOutput Unexecuted instantiation: picture_rescale_enc.c:WebPRescalerHasPendingOutput
99
100		//------------------------------------------------------------------------------
101
102		#ifdef __cplusplus
103		} // extern "C"
104		#endif
105
106		#endif // WEBP_UTILS_RESCALER_UTILS_H_

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Created: 2026-02-14 06:26