// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#ifndef LIB_JXL_IMAGE_H_
#define LIB_JXL_IMAGE_H_
// SIMD/multicore-friendly planar image representation with row accessors.
#if defined(ADDRESS_SANITIZER) ||
defined(MEMORY_SANITIZER) || \
defined(THREAD_SANITIZER)
#include <cinttypes>
// PRIu64
#endif
#include <jxl/memory_manager.h>
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <utility>
// std::move
#include "lib/jxl/base/compiler_specific.h"
#include "lib/jxl/base/status.h"
#include "lib/jxl/memory_manager_internal.h"
namespace jxl {
// DO NOT use PlaneBase outside of image.{h|cc}
namespace detail {
// Type-independent parts of Plane<> - reduces code duplication and facilitates
// moving member function implementations to cc file.
struct PlaneBase {
PlaneBase()
: xsize_(0),
ysize_(0),
orig_xsize_(0),
orig_ysize_(0),
bytes_per_row_(0),
sizeof_t_(0) {}
// Copy construction/assignment is forbidden to avoid inadvertent copies,
// which can be very expensive. Use CopyImageTo() instead.
PlaneBase(
const PlaneBase& other) =
delete;
PlaneBase&
operator=(
const PlaneBase& other) =
delete;
// Move constructor (required for returning Image from function)
PlaneBase(PlaneBase&& other) noexcept =
default;
// Move assignment (required for std::vector)
PlaneBase&
operator=(PlaneBase&& other) noexcept =
default;
~PlaneBase() =
default;
void Swap(PlaneBase& other);
// Useful for pre-allocating image with some padding for alignment purposes
// and later reporting the actual valid dimensions. May also be used to
// un-shrink the image. Caller is responsible for ensuring xsize/ysize are <=
// the original dimensions.
Status ShrinkTo(
const size_t xsize,
const size_t ysize) {
JXL_ENSURE(xsize <= orig_xsize_);
JXL_ENSURE(ysize <= orig_ysize_);
xsize_ =
static_cast<uint32_t>(xsize);
ysize_ =
static_cast<uint32_t>(ysize);
// NOTE: we can't recompute bytes_per_row for more compact storage and
// better locality because that would invalidate the image contents.
return true;
}
// How many pixels.
JXL_INLINE size_t xsize()
const {
return xsize_; }
JXL_INLINE size_t ysize()
const {
return ysize_; }
// NOTE: do not use this for copying rows - the valid xsize may be much less.
JXL_INLINE size_t bytes_per_row()
const {
return bytes_per_row_; }
JXL_INLINE JxlMemoryManager* memory_manager()
const {
return bytes_.memory_manager();
}
// Raw access to byte contents, for interfacing with other libraries.
// Unsigned char instead of char to avoid surprises (sign extension).
JXL_INLINE uint8_t* bytes() {
uint8_t* p = bytes_.address<uint8_t>();
return static_cast<uint8_t * JXL_RESTRICT>(JXL_ASSUME_ALIGNED(p, 64));
}
JXL_INLINE
const uint8_t* bytes()
const {
const uint8_t* p = bytes_.address<uint8_t>();
return static_cast<
const uint8_t * JXL_RESTRICT>(JXL_ASSUME_ALIGNED(p, 64));
}
protected:
PlaneBase(uint32_t xsize, uint32_t ysize, size_t sizeof_t);
Status Allocate(JxlMemoryManager* memory_manager, size_t pre_padding);
// Returns pointer to the start of a row.
JXL_INLINE
void* VoidRow(
const size_t y)
const {
JXL_DASSERT(y < ysize_);
uint8_t* row = bytes_.address<uint8_t>() + y * bytes_per_row_;
return JXL_ASSUME_ALIGNED(row, 64);
}
// (Members are non-const to enable assignment during move-assignment.)
uint32_t xsize_;
// In valid pixels, not including any padding.
uint32_t ysize_;
uint32_t orig_xsize_;
uint32_t orig_ysize_;
size_t bytes_per_row_;
// Includes padding.
AlignedMemory bytes_;
size_t sizeof_t_;
};
}
// namespace detail
// Single channel, aligned rows separated by padding. T must be POD.
//
// 'Single channel' (one 2D array per channel) simplifies vectorization
// (repeating the same operation on multiple adjacent components) without the
// complexity of a hybrid layout (8 R, 8 G, 8 B, ...). In particular, clients
// can easily iterate over all components in a row and Image requires no
// knowledge of the pixel format beyond the component type "T".
//
// 'Aligned' means each row is aligned to the L1 cache line size. This prevents
// false sharing between two threads operating on adjacent rows.
//
// 'Padding' is still relevant because vectors could potentially be larger than
// a cache line. By rounding up row sizes to the vector size, we allow
// reading/writing ALIGNED vectors whose first lane is a valid sample. This
// avoids needing a separate loop to handle remaining unaligned lanes.
//
// This image layout could also be achieved with a vector and a row accessor
// function, but a class wrapper with support for "deleter" allows wrapping
// existing memory allocated by clients without copying the pixels. It also
// provides convenient accessors for xsize/ysize, which shortens function
// argument lists. Supports move-construction so it can be stored in containers.
template <
typename ComponentType>
class Plane :
public detail::PlaneBase {
public:
using T = ComponentType;
static constexpr size_t kNumPlanes = 1;
Plane() =
default;
static StatusOr<Plane> Create(JxlMemoryManager* memory_manager,
const size_t xsize,
const size_t ysize,
const size_t pre_padding = 0) {
static_assert(
sizeof(T) == 1 ||
sizeof(T) == 2 ||
sizeof(T) == 4 ||
sizeof(T) == 8);
uint32_t xsize32 =
static_cast<uint32_t>(xsize);
uint32_t ysize32 =
static_cast<uint32_t>(ysize);
JXL_ENSURE(xsize32 == xsize);
JXL_ENSURE(ysize32 == ysize);
Plane plane(xsize32, ysize32,
sizeof(T));
JXL_RETURN_IF_ERROR(plane.Allocate(memory_manager, pre_padding));
return plane;
}
JXL_INLINE T* Row(
const size_t y) {
return static_cast<T*>(VoidRow(y)); }
// Returns pointer to const (see above).
JXL_INLINE
const T* Row(
const size_t y)
const {
return static_cast<
const T*>(VoidRow(y));
}
// Documents that the access is const.
JXL_INLINE
const T* ConstRow(
const size_t y)
const {
return static_cast<
const T*>(VoidRow(y));
}
// Returns number of pixels (some of which are padding) per row. Useful for
// computing other rows via pointer arithmetic. WARNING: this must
// NOT be used to determine xsize.
JXL_INLINE intptr_t PixelsPerRow()
const {
return static_cast<intptr_t>(bytes_per_row_ /
sizeof(T));
}
private:
Plane(uint32_t xsize, uint32_t ysize, size_t sizeof_t)
: detail::PlaneBase(xsize, ysize, sizeof_t) {}
};
using ImageSB = Plane<int8_t>;
using ImageB = Plane<uint8_t>;
using ImageS = Plane<int16_t>;
// signed integer or half-float
using ImageU = Plane<uint16_t>;
using ImageI = Plane<int32_t>;
using ImageF = Plane<
float>;
using ImageD = Plane<
double>;
// Currently, we abuse Image to either refer to an image that owns its storage
// or one that doesn't. In similar vein, we abuse Image* function parameters to
// either mean "assign to me" or "fill the provided image with data".
// Hopefully, the "assign to me" meaning will go away and most images in the
// codebase will not be backed by own storage. When this happens we can redesign
// Image to be a non-storage-holding view class and introduce BackedImage in
// those places that actually need it.
// NOTE: we can't use Image as a view because invariants are violated
// (alignment and the presence of padding before/after each "row").
// A bundle of 3 same-sized images. Typically constructed by moving from three
// rvalue references to Image. To overwrite an existing Image3 using
// single-channel producers, we also need access to Image*. Constructing
// temporary non-owning Image pointing to one plane of an existing Image3 risks
// dangling references, especially if the wrapper is moved. Therefore, we
// store an array of Image (which are compact enough that size is not a concern)
// and provide Plane+Row accessors.
template <
typename ComponentType>
class Image3 {
public:
using T = ComponentType;
using PlaneT = jxl::Plane<T>;
static constexpr size_t kNumPlanes = 3;
Image3() : planes_{PlaneT(), PlaneT(), PlaneT()} {}
// Copy construction/assignment is forbidden to avoid inadvertent copies,
// which can be very expensive. Use CopyImageTo instead.
Image3(
const Image3& other) =
delete;
Image3&
operator=(
const Image3& other) =
delete;
Image3(Image3&& other) noexcept {
for (size_t i = 0; i < kNumPlanes; i++) {
planes_[i] = std::move(other.planes_[i]);
}
}
Image3&
operator=(Image3&& other) noexcept {
for (size_t i = 0; i < kNumPlanes; i++) {
planes_[i] = std::move(other.planes_[i]);
}
return *
this;
}
static StatusOr<Image3> Create(JxlMemoryManager* memory_manager,
const size_t xsize,
const size_t ysize) {
JXL_ASSIGN_OR_RETURN(PlaneT plane0,
PlaneT::Create(memory_manager, xsize, ysize));
JXL_ASSIGN_OR_RETURN(PlaneT plane1,
PlaneT::Create(memory_manager, xsize, ysize));
JXL_ASSIGN_OR_RETURN(PlaneT plane2,
PlaneT::Create(memory_manager, xsize, ysize));
return Image3(std::move(plane0), std::move(plane1), std::move(plane2));
}
// Returns row pointer; usage: PlaneRow(idx_plane, y)[x] = val.
JXL_INLINE T* PlaneRow(
const size_t c,
const size_t y) {
// Custom implementation instead of calling planes_[c].Row ensures only a
// single multiplication is needed for PlaneRow(0..2, y).
PlaneRowBoundsCheck(c, y);
const size_t row_offset = y * planes_[0].bytes_per_row();
void* row = planes_[c].bytes() + row_offset;
return static_cast<T * JXL_RESTRICT>(JXL_ASSUME_ALIGNED(row, 64));
}
// Returns const row pointer; usage: val = PlaneRow(idx_plane, y)[x].
JXL_INLINE
const T* PlaneRow(
const size_t c,
const size_t y)
const {
PlaneRowBoundsCheck(c, y);
const size_t row_offset = y * planes_[0].bytes_per_row();
const void* row = planes_[c].bytes() + row_offset;
return static_cast<
const T * JXL_RESTRICT>(JXL_ASSUME_ALIGNED(row, 64));
}
// Returns const row pointer, even if called from a non-const Image3.
JXL_INLINE
const T* ConstPlaneRow(
const size_t c,
const size_t y)
const {
PlaneRowBoundsCheck(c, y);
return PlaneRow(c, y);
}
JXL_INLINE
const PlaneT& Plane(size_t idx)
const {
return planes_[idx]; }
JXL_INLINE PlaneT& Plane(size_t idx) {
return planes_[idx]; }
void Swap(Image3& other) {
for (size_t c = 0; c < 3; ++c) {
other.planes_[c].Swap(planes_[c]);
}
}
// Useful for pre-allocating image with some padding for alignment purposes
// and later reporting the actual valid dimensions. May also be used to
// un-shrink the image. Caller is responsible for ensuring xsize/ysize are <=
// the original dimensions.
Status ShrinkTo(
const size_t xsize,
const size_t ysize) {
for (PlaneT& plane : planes_) {
JXL_RETURN_IF_ERROR(plane.ShrinkTo(xsize, ysize));
}
return true;
}
// Sizes of all three images are guaranteed to be equal.
JXL_INLINE JxlMemoryManager* memory_manager()
const {
return planes_[0].memory_manager();
}
JXL_INLINE size_t xsize()
const {
return planes_[0].xsize(); }
JXL_INLINE size_t ysize()
const {
return planes_[0].ysize(); }
// Returns offset [bytes] from one row to the next row of the same plane.
// WARNING: this must NOT be used to determine xsize, nor for copying rows -
// the valid xsize may be much less.
JXL_INLINE size_t bytes_per_row()
const {
return planes_[0].bytes_per_row(); }
// Returns number of pixels (some of which are padding) per row. Useful for
// computing other rows via pointer arithmetic. WARNING: this must NOT be used
// to determine xsize.
JXL_INLINE intptr_t PixelsPerRow()
const {
return planes_[0].PixelsPerRow(); }
private:
Image3(PlaneT&& plane0, PlaneT&& plane1, PlaneT&& plane2) {
planes_[0] = std::move(plane0);
planes_[1] = std::move(plane1);
planes_[2] = std::move(plane2);
}
void PlaneRowBoundsCheck(
const size_t c,
const size_t y)
const {
JXL_DASSERT(c < kNumPlanes && y < ysize());
}
PlaneT planes_[kNumPlanes];
};
using Image3B = Image3<uint8_t>;
using Image3S = Image3<int16_t>;
using Image3U = Image3<uint16_t>;
using Image3I = Image3<int32_t>;
using Image3F = Image3<
float>;
using Image3D = Image3<
double>;
}
// namespace jxl
#endif // LIB_JXL_IMAGE_H_
