/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include "math.h"
#include <array>
#include <cassert>
#include <functional>
#include <memory>
#include <stdlib.h>
#include <vector>
/*
* Provides a wrapper around libjpeg.
*/
namespace jpegutil {
class Transform;
class Plane;
inline int sgn(int val) { return (0 < val) - (val < 0); }
inline int min(int a, int b) { return a < b ? a : b; }
inline int max(int a, int b) { return a > b ? a : b; }
/**
* Represents a combined cropping and rotation transformation.
*
* The transformation maps the coordinates (orig_x, orig_y) and (one_x, one_y)
* in the input image to the origin and (output_width, output_height)
* respectively.
*/
class Transform {
public:
Transform(int orig_x, int orig_y, int one_x, int one_y);
static Transform ForCropFollowedByRotation(int cropLeft, int cropTop,
int cropRight, int cropBottom,
int rot90);
inline int output_width() const { return output_width_; }
inline int output_height() const { return output_height_; }
bool operator==(const Transform& other) const;
/**
* Transforms the input coordinates. Coordinates outside the cropped region
* are clamped to valid values.
*/
void Map(int x, int y, int* x_out, int* y_out) const;
private:
int output_width_;
int output_height_;
// The coordinates of the point to map the origin to.
const int orig_x_, orig_y_;
// The coordinates of the point to map the point (output_width(),
// output_height()) to.
const int one_x_, one_y_;
// A matrix for the rotational component.
int mat00_, mat01_;
int mat10_, mat11_;
};
/**
* Represents a model for accessing pixel data for a single plane of an image.
* Note that the actual data is not owned by this class, and the underlying
* data does not need to be stored in separate planes.
*/
struct Plane {
// The dimensions of this plane of the image
int width;
int height;
// A pointer to raw pixel data
const unsigned char* data;
// The difference in address between consecutive pixels in the same row
int pixel_stride;
// The difference in address between the start of consecutive rows
int row_stride;
};
/**
* Provides an interface for simultaneously reading a certain number of rows of
* an image plane as contiguous arrays, suitable for use with libjpeg.
*/
template <unsigned int ROWS>
class RowIterator {
public:
/**
* Creates a new RowIterator which will crop and rotate with the given
* transform.
*
* @param plane the plane to iterate over
* @param transform the transformation to map output values into the
* coordinate space of the plane
* @param row_length the length of the rows returned via LoadAt(). If this is
* longer than the width of the output (after applying the transform), then
* the right-most value is repeated.
*/
inline RowIterator(Plane plane, Transform transform, int row_length);
/**
* Returns an array of pointers into consecutive rows of contiguous image
* data starting at y. That is, samples within each row are contiguous.
* However, the individual arrays pointed-to may be separate.
* When the end of the image is reached, the last row of the image is
* repeated.
* The returned pointers are valid until the next call to LoadAt().
*/
inline const std::array<unsigned char*, ROWS> LoadAt(int y_base);
private:
Plane plane_;
Transform transform_;
// The length of a row, with padding to the next multiple of 64.
int padded_row_length_;
std::vector<unsigned char> buf_;
};
/**
* Compresses an image from YUV 420p to JPEG. Output is buffered in outBuf until
* capacity is reached, at which point flush(size_t) is called to write
* out the specified number of bytes from outBuf. Returns the number of bytes
* written, or -1 in case of an error.
*/
int Compress(int img_width, int img_height, RowIterator<16>& y_row_generator,
RowIterator<8>& cb_row_generator, RowIterator<8>& cr_row_generator,
unsigned char* out_buf, size_t out_buf_capacity,
std::function<void(size_t)> flush, int quality);
/**
* Compresses an image from YUV 420p to JPEG. Output is written into outBuf.
* Returns the number of bytes written, or -1 in case of an error.
*/
int Compress(
/** Input image dimensions */
int width, int height,
/** Y Plane */
unsigned char* yBuf, int yPStride, int yRStride,
/** Cb Plane */
unsigned char* cbBuf, int cbPStride, int cbRStride,
/** Cr Plane */
unsigned char* crBuf, int crPStride, int crRStride,
/** Output */
unsigned char* outBuf, size_t outBufCapacity,
/** Jpeg compression parameters */
int quality,
/** Crop */
int cropLeft, int cropTop, int cropRight, int cropBottom,
/** Rotation */
int rot90);
}
template <unsigned int ROWS>
jpegutil::RowIterator<ROWS>::RowIterator(Plane plane, Transform transform,
int row_length)
: plane_(plane), transform_(transform) {
padded_row_length_ = row_length;
buf_ = std::vector<unsigned char>(row_length * ROWS);
}
template <unsigned int ROWS>
const std::array<unsigned char*, ROWS> jpegutil::RowIterator<ROWS>::LoadAt(
int y_base) {
std::array<unsigned char*, ROWS> buf_ptrs;
for (int i = 0; i < ROWS; i++) {
buf_ptrs[i] = &buf_[padded_row_length_ * i];
}
if (plane_.width == 0 || plane_.height == 0) {
return buf_ptrs;
}
for (int i = 0; i < ROWS; i++) {
int y = i + y_base;
y = min(y, transform_.output_height() - 1);
int output_width = padded_row_length_;
output_width = min(output_width, transform_.output_width());
output_width = min(output_width, plane_.width);
// Each row in the output image will be copied into buf_ by gathering pixels
// along an axis-aligned line in the plane.
// The line is defined by (startX, startY) -> (endX, endY), computed via the
// current Transform.
int startX;
int startY;
transform_.Map(0, y, &startX, &startY);
int endX;
int endY;
transform_.Map(output_width - 1, y, &endX, &endY);
// Clamp (startX, startY) and (endX, endY) to the valid bounds of the plane.
startX = min(startX, plane_.width - 1);
startY = min(startY, plane_.height - 1);
endX = min(endX, plane_.width - 1);
endY = min(endY, plane_.height - 1);
startX = max(startX, 0);
startY = max(startY, 0);
endX = max(endX, 0);
endY = max(endY, 0);
// To reduce work inside the copy-loop, precompute the start, end, and
// stride relating the values to be gathered from plane_ into buf
// for this particular scan-line.
int dx = sgn(endX - startX);
int dy = sgn(endY - startY);
assert(dx == 0 || dy == 0);
// The index into plane_.data of (startX, startY)
int plane_start = startX * plane_.pixel_stride + startY * plane_.row_stride;
// The index into plane_.data of (endX, endY)
int plane_end = endX * plane_.pixel_stride + endY * plane_.row_stride;
// The stride, in terms of indices in plane_data, required to enumerate the
// samples between the start and end points.
int stride = dx * plane_.pixel_stride + dy * plane_.row_stride;
// In the degenerate-case of a 1x1 plane, startX and endX are equal, so
// stride would be 0, resulting in an infinite-loop. To avoid this case,
// use a stride of at-least 1.
if (stride == 0) {
stride = 1;
}
int outX = 0;
for (int idx = plane_start; idx >= min(plane_start, plane_end) &&
idx <= max(plane_start, plane_end);
idx += stride) {
buf_ptrs[i][outX] = plane_.data[idx];
outX++;
}
// Fill the remaining right-edge of the buffer by extending the last
// value.
unsigned char right_padding_value = buf_ptrs[i][outX - 1];
// TODO OPTIMIZE Use memset instead.
for (; outX < padded_row_length_; outX++) {
buf_ptrs[i][outX] = right_padding_value;
}
}
return buf_ptrs;
}