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// Copyright 2017 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Original code copyright 2014 Foxit Software Inc.
#include <vector>
#include "core/fxcrt/fx_coordinates.h"
#include "core/fxcrt/fx_memory_wrappers.h"
#include "core/fxcrt/fx_system.h"
#include "core/fxcrt/retain_ptr.h"
#include "core/fxcrt/unowned_ptr.h"
#include "core/fxge/dib/fx_dib.h"
#include "third_party/base/check_op.h"
#include "third_party/base/span.h"
class CFX_DIBBase;
class PauseIndicatorIface;
class ScanlineComposerIface;
class CStretchEngine {
static constexpr uint32_t kFixedPointBits = 16;
static constexpr uint32_t kFixedPointOne = 1 << kFixedPointBits;
static inline uint32_t FixedFromDouble(double d) {
return static_cast<uint32_t>(FXSYS_round(d * kFixedPointOne));
static inline uint32_t FixedFromFloat(float f) {
return static_cast<uint32_t>(FXSYS_roundf(f * kFixedPointOne));
static inline uint8_t PixelFromFixed(uint32_t fixed) {
return static_cast<uint8_t>(fixed >> kFixedPointBits);
struct PixelWeight {
static size_t TotalBytesForWeightCount(size_t weight_count);
void SetStartEnd(int src_start, int src_end, size_t weight_count) {
CHECK_LT(src_end - src_start, static_cast<int>(weight_count));
m_SrcStart = src_start;
m_SrcEnd = src_end;
uint32_t GetWeightForPosition(int position) const {
CHECK_GE(position, m_SrcStart);
CHECK_LE(position, m_SrcEnd);
return m_Weights[position - m_SrcStart];
void SetWeightForPosition(int position, uint32_t weight) {
CHECK_GE(position, m_SrcStart);
CHECK_LE(position, m_SrcEnd);
m_Weights[position - m_SrcStart] = weight;
// NOTE: relies on defined behaviour for unsigned overflow to
// decrement the previous position, as needed.
void RemoveLastWeightAndAdjust(uint32_t weight_change) {
CHECK_GT(m_SrcEnd, m_SrcStart);
m_Weights[m_SrcEnd - m_SrcStart] += weight_change;
int m_SrcStart;
int m_SrcEnd; // Note: inclusive, [0, -1] for empty range at 0.
uint32_t m_Weights[1]; // Not really 1, variable size.
class WeightTable {
// Accepts a negative `dest_len` argument, producing a "mirror
// image" of the result if `dest_len` is negative.
bool CalculateWeights(int dest_len,
int dest_min,
int dest_max,
int src_len,
int src_min,
int src_max,
const FXDIB_ResampleOptions& options);
const PixelWeight* GetPixelWeight(int pixel) const;
PixelWeight* GetPixelWeight(int pixel) {
return const_cast<PixelWeight*>(
static_cast<const WeightTable*>(this)->GetPixelWeight(pixel));
int m_DestMin = 0;
size_t m_ItemSizeBytes = 0;
size_t m_WeightTablesSizeBytes = 0;
std::vector<uint8_t, FxAllocAllocator<uint8_t>> m_WeightTables;
CStretchEngine(ScanlineComposerIface* pDestBitmap,
FXDIB_Format dest_format,
int dest_width,
int dest_height,
const FX_RECT& clip_rect,
const RetainPtr<const CFX_DIBBase>& pSrcBitmap,
const FXDIB_ResampleOptions& options);
bool Continue(PauseIndicatorIface* pPause);
bool StartStretchHorz();
bool ContinueStretchHorz(PauseIndicatorIface* pPause);
void StretchVert();
const FXDIB_ResampleOptions& GetResampleOptionsForTest() const {
return m_ResampleOptions;
enum class State : uint8_t { kInitial, kHorizontal, kVertical };
enum class TransformMethod : uint8_t {
const FXDIB_Format m_DestFormat;
const int m_DestBpp;
const int m_SrcBpp;
const bool m_bHasAlpha;
RetainPtr<const CFX_DIBBase> const m_pSource;
pdfium::span<const uint32_t> m_pSrcPalette;
const int m_SrcWidth;
const int m_SrcHeight;
UnownedPtr<ScanlineComposerIface> const m_pDestBitmap;
const int m_DestWidth;
const int m_DestHeight;
const FX_RECT m_DestClip;
std::vector<uint8_t, FxAllocAllocator<uint8_t>> m_DestScanline;
std::vector<uint8_t, FxAllocAllocator<uint8_t>> m_DestMaskScanline;
std::vector<uint8_t, FxAllocAllocator<uint8_t>> m_InterBuf;
std::vector<uint8_t, FxAllocAllocator<uint8_t>> m_ExtraAlphaBuf;
FX_RECT m_SrcClip;
int m_InterPitch;
int m_ExtraMaskPitch;
FXDIB_ResampleOptions m_ResampleOptions;
TransformMethod m_TransMethod;
State m_State = State::kInitial;
int m_CurRow;
WeightTable m_WeightTable;