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// Copyright 2011 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This file input format is based loosely on
// Tools/DumpRenderTree/ImageDiff.m
// The exact format of this tool's output to stdout is important, to match
// what the run-webkit-tests script expects.
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <cmath>
#include <map>
#include <string>
#include <vector>
#include "core/fxcrt/fx_memory.h"
#include "core/fxcrt/numerics/safe_conversions.h"
#include "testing/image_diff/image_diff_png.h"
#include "testing/utils/path_service.h"
#if BUILDFLAG(IS_WIN)
#include <windows.h>
#endif
// Return codes used by this utility.
constexpr int kStatusSame = 0;
constexpr int kStatusDifferent = 1;
constexpr int kStatusError = 2;
// Color codes.
constexpr uint32_t RGBA_RED = 0x000000ff;
constexpr uint32_t RGBA_ALPHA = 0xff000000;
class Image {
public:
Image() = default;
Image(const Image& image) = default;
Image& operator=(const Image& other) = default;
bool has_image() const { return w_ > 0 && h_ > 0; }
int w() const { return w_; }
int h() const { return h_; }
pdfium::span<const uint8_t> span() const { return data_; }
// Creates the image from the given filename on disk, and returns true on
// success.
bool CreateFromFilename(const std::string& path) {
return CreateFromFilenameImpl(path, /*reverse_byte_order=*/false);
}
// Same as CreateFromFilename(), but with BGRA instead of RGBA ordering.
bool CreateFromFilenameWithReverseByteOrder(const std::string& path) {
return CreateFromFilenameImpl(path, /*reverse_byte_order=*/true);
}
void Clear() {
w_ = h_ = 0;
data_.clear();
}
// Returns the RGBA value of the pixel at the given location
uint32_t pixel_at(int x, int y) const {
if (!pixel_in_bounds(x, y))
return 0;
return *reinterpret_cast<const uint32_t*>(&(data_[pixel_address(x, y)]));
}
void set_pixel_at(int x, int y, uint32_t color) {
if (!pixel_in_bounds(x, y))
return;
void* addr = &data_[pixel_address(x, y)];
*reinterpret_cast<uint32_t*>(addr) = color;
}
private:
bool CreateFromFilenameImpl(const std::string& path,
bool reverse_byte_order) {
FILE* f = fopen(path.c_str(), "rb");
if (!f)
return false;
std::vector<uint8_t> compressed;
const size_t kBufSize = 1024;
uint8_t buf[kBufSize];
size_t num_read = 0;
while ((num_read = fread(buf, 1, kBufSize, f)) > 0) {
compressed.insert(compressed.end(), buf, buf + num_read);
}
fclose(f);
data_ = image_diff_png::DecodePNG(compressed, reverse_byte_order, &w_, &h_);
if (data_.empty()) {
Clear();
return false;
}
return true;
}
bool pixel_in_bounds(int x, int y) const {
return x >= 0 && x < w_ && y >= 0 && y < h_;
}
size_t pixel_address(int x, int y) const { return (y * w_ + x) * 4; }
// Pixel dimensions of the image.
int w_ = 0;
int h_ = 0;
std::vector<uint8_t> data_;
};
float CalculateDifferencePercentage(const Image& actual, int pixels_different) {
// Like the WebKit ImageDiff tool, we define percentage different in terms
// of the size of the 'actual' bitmap.
float total_pixels =
static_cast<float>(actual.w()) * static_cast<float>(actual.h());
if (total_pixels == 0) {
// When the bitmap is empty, they are 100% different.
return 100.0f;
}
return 100.0f * pixels_different / total_pixels;
}
void CountImageSizeMismatchAsPixelDifference(const Image& baseline,
const Image& actual,
int* pixels_different) {
int w = std::min(baseline.w(), actual.w());
int h = std::min(baseline.h(), actual.h());
// Count pixels that are a difference in size as also being different.
int max_w = std::max(baseline.w(), actual.w());
int max_h = std::max(baseline.h(), actual.h());
// These pixels are off the right side, not including the lower right corner.
*pixels_different += (max_w - w) * h;
// These pixels are along the bottom, including the lower right corner.
*pixels_different += (max_h - h) * max_w;
}
struct UnpackedPixel {
explicit UnpackedPixel(uint32_t packed)
: red(packed & 0xff),
green((packed >> 8) & 0xff),
blue((packed >> 16) & 0xff),
alpha((packed >> 24) & 0xff) {}
uint8_t red;
uint8_t green;
uint8_t blue;
uint8_t alpha;
};
uint8_t ChannelDelta(uint8_t baseline_channel, uint8_t actual_channel) {
// No casts are necessary because arithmetic operators implicitly convert
// `uint8_t` to `int` first. The final delta is always in the range 0 to 255.
return std::abs(baseline_channel - actual_channel);
}
uint8_t MaxPixelPerChannelDelta(const UnpackedPixel& baseline_pixel,
const UnpackedPixel& actual_pixel) {
return std::max({ChannelDelta(baseline_pixel.red, actual_pixel.red),
ChannelDelta(baseline_pixel.green, actual_pixel.green),
ChannelDelta(baseline_pixel.blue, actual_pixel.blue),
ChannelDelta(baseline_pixel.alpha, actual_pixel.alpha)});
}
float PercentageDifferent(const Image& baseline,
const Image& actual,
uint8_t max_pixel_per_channel_delta) {
int w = std::min(baseline.w(), actual.w());
int h = std::min(baseline.h(), actual.h());
// Compute pixels different in the overlap.
int pixels_different = 0;
for (int y = 0; y < h; ++y) {
for (int x = 0; x < w; ++x) {
const uint32_t baseline_pixel = baseline.pixel_at(x, y);
const uint32_t actual_pixel = actual.pixel_at(x, y);
if (baseline_pixel == actual_pixel) {
continue;
}
if (MaxPixelPerChannelDelta(UnpackedPixel(baseline_pixel),
UnpackedPixel(actual_pixel)) >
max_pixel_per_channel_delta) {
++pixels_different;
}
}
}
CountImageSizeMismatchAsPixelDifference(baseline, actual, &pixels_different);
return CalculateDifferencePercentage(actual, pixels_different);
}
float HistogramPercentageDifferent(const Image& baseline, const Image& actual) {
// TODO(johnme): Consider using a joint histogram instead, as described in
// "Comparing Images Using Joint Histograms" by Pass & Zabih
// http://www.cs.cornell.edu/~rdz/papers/pz-jms99.pdf
int w = std::min(baseline.w(), actual.w());
int h = std::min(baseline.h(), actual.h());
// Count occurrences of each RGBA pixel value of baseline in the overlap.
std::map<uint32_t, int32_t> baseline_histogram;
for (int y = 0; y < h; ++y) {
for (int x = 0; x < w; ++x) {
// hash_map operator[] inserts a 0 (default constructor) if key not found.
++baseline_histogram[baseline.pixel_at(x, y)];
}
}
// Compute pixels different in the histogram of the overlap.
int pixels_different = 0;
for (int y = 0; y < h; ++y) {
for (int x = 0; x < w; ++x) {
uint32_t actual_rgba = actual.pixel_at(x, y);
auto it = baseline_histogram.find(actual_rgba);
if (it != baseline_histogram.end() && it->second > 0)
--it->second;
else
++pixels_different;
}
}
CountImageSizeMismatchAsPixelDifference(baseline, actual, &pixels_different);
return CalculateDifferencePercentage(actual, pixels_different);
}
void PrintHelp(const std::string& binary_name) {
fprintf(
stderr,
"Usage:\n"
" %s OPTIONS <compare_file> <reference_file>\n"
" Compares two files on disk, returning 0 when they are the same.\n"
" Passing \"--histogram\" additionally calculates a diff of the\n"
" RGBA value histograms (which is resistant to shifts in layout).\n"
" Passing \"--reverse-byte-order\" additionally assumes the\n"
" compare file has BGRA byte ordering.\n"
" Passing \"--fuzzy\" additionally allows individual pixels to\n"
" differ by at most 1 on each channel.\n\n"
" %s --diff <compare_file> <reference_file> <output_file>\n"
" Compares two files on disk, and if they differ, outputs an image\n"
" to <output_file> that visualizes the differing pixels as red\n"
" dots.\n\n"
" %s --subtract <compare_file> <reference_file> <output_file>\n"
" Compares two files on disk, and if they differ, outputs an image\n"
" to <output_file> that visualizes the difference as a scaled\n"
" subtraction of pixel values.\n",
binary_name.c_str(), binary_name.c_str(), binary_name.c_str());
}
int CompareImages(const std::string& binary_name,
const std::string& file1,
const std::string& file2,
bool compare_histograms,
bool reverse_byte_order,
uint8_t max_pixel_per_channel_delta) {
Image actual_image;
Image baseline_image;
bool actual_load_result =
reverse_byte_order
? actual_image.CreateFromFilenameWithReverseByteOrder(file1)
: actual_image.CreateFromFilename(file1);
if (!actual_load_result) {
fprintf(stderr, "%s: Unable to open file \"%s\"\n", binary_name.c_str(),
file1.c_str());
return kStatusError;
}
if (!baseline_image.CreateFromFilename(file2)) {
fprintf(stderr, "%s: Unable to open file \"%s\"\n", binary_name.c_str(),
file2.c_str());
return kStatusError;
}
if (compare_histograms) {
float percent = HistogramPercentageDifferent(actual_image, baseline_image);
const char* passed = percent > 0.0 ? "failed" : "passed";
printf("histogram diff: %01.2f%% %s\n", percent, passed);
}
const char* const diff_name = compare_histograms ? "exact diff" : "diff";
float percent = PercentageDifferent(actual_image, baseline_image,
max_pixel_per_channel_delta);
const char* const passed = percent > 0.0 ? "failed" : "passed";
printf("%s: %01.2f%% %s\n", diff_name, percent, passed);
if (percent > 0.0) {
// failure: The WebKit version also writes the difference image to
// stdout, which seems excessive for our needs.
return kStatusDifferent;
}
// success
return kStatusSame;
}
bool CreateImageDiff(const Image& image1, const Image& image2, Image* out) {
int w = std::min(image1.w(), image2.w());
int h = std::min(image1.h(), image2.h());
*out = Image(image1);
bool same = (image1.w() == image2.w()) && (image1.h() == image2.h());
// TODO(estade): do something with the extra pixels if the image sizes
// are different.
for (int y = 0; y < h; ++y) {
for (int x = 0; x < w; ++x) {
uint32_t base_pixel = image1.pixel_at(x, y);
if (base_pixel != image2.pixel_at(x, y)) {
// Set differing pixels red.
out->set_pixel_at(x, y, RGBA_RED | RGBA_ALPHA);
same = false;
} else {
// Set same pixels as faded.
uint32_t alpha = base_pixel & RGBA_ALPHA;
uint32_t new_pixel = base_pixel - ((alpha / 2) & RGBA_ALPHA);
out->set_pixel_at(x, y, new_pixel);
}
}
}
return same;
}
bool SubtractImages(const Image& image1, const Image& image2, Image* out) {
int w = std::min(image1.w(), image2.w());
int h = std::min(image1.h(), image2.h());
*out = Image(image1);
bool same = (image1.w() == image2.w()) && (image1.h() == image2.h());
for (int y = 0; y < h; ++y) {
for (int x = 0; x < w; ++x) {
uint32_t pixel1 = image1.pixel_at(x, y);
int32_t r1 = pixel1 & 0xff;
int32_t g1 = (pixel1 >> 8) & 0xff;
int32_t b1 = (pixel1 >> 16) & 0xff;
uint32_t pixel2 = image2.pixel_at(x, y);
int32_t r2 = pixel2 & 0xff;
int32_t g2 = (pixel2 >> 8) & 0xff;
int32_t b2 = (pixel2 >> 16) & 0xff;
int32_t delta_r = r1 - r2;
int32_t delta_g = g1 - g2;
int32_t delta_b = b1 - b2;
same &= (delta_r == 0 && delta_g == 0 && delta_b == 0);
delta_r = std::clamp(128 + delta_r * 8, 0, 255);
delta_g = std::clamp(128 + delta_g * 8, 0, 255);
delta_b = std::clamp(128 + delta_b * 8, 0, 255);
uint32_t new_pixel = RGBA_ALPHA;
new_pixel |= delta_r;
new_pixel |= (delta_g << 8);
new_pixel |= (delta_b << 16);
out->set_pixel_at(x, y, new_pixel);
}
}
return same;
}
int DiffImages(const std::string& binary_name,
const std::string& file1,
const std::string& file2,
const std::string& out_file,
bool do_subtraction,
bool reverse_byte_order) {
Image actual_image;
Image baseline_image;
bool actual_load_result =
reverse_byte_order
? actual_image.CreateFromFilenameWithReverseByteOrder(file1)
: actual_image.CreateFromFilename(file1);
if (!actual_load_result) {
fprintf(stderr, "%s: Unable to open file \"%s\"\n", binary_name.c_str(),
file1.c_str());
return kStatusError;
}
if (!baseline_image.CreateFromFilename(file2)) {
fprintf(stderr, "%s: Unable to open file \"%s\"\n", binary_name.c_str(),
file2.c_str());
return kStatusError;
}
Image diff_image;
bool same = do_subtraction
? SubtractImages(baseline_image, actual_image, &diff_image)
: CreateImageDiff(baseline_image, actual_image, &diff_image);
if (same)
return kStatusSame;
std::vector<uint8_t> png_encoding = image_diff_png::EncodeRGBAPNG(
diff_image.span(), diff_image.w(), diff_image.h(), diff_image.w() * 4);
if (png_encoding.empty())
return kStatusError;
FILE* f = fopen(out_file.c_str(), "wb");
if (!f)
return kStatusError;
size_t size = png_encoding.size();
char* ptr = reinterpret_cast<char*>(&png_encoding.front());
if (fwrite(ptr, 1, size, f) != size)
return kStatusError;
return kStatusDifferent;
}
int main(int argc, const char* argv[]) {
FX_InitializeMemoryAllocators();
bool histograms = false;
bool produce_diff_image = false;
bool produce_image_subtraction = false;
bool reverse_byte_order = false;
uint8_t max_pixel_per_channel_delta = 0;
std::string filename1;
std::string filename2;
std::string diff_filename;
// Strip the path from the first arg
const char* last_separator = strrchr(argv[0], PATH_SEPARATOR);
std::string binary_name = last_separator ? last_separator + 1 : argv[0];
int i;
for (i = 1; i < argc; ++i) {
const char* arg = argv[i];
if (strstr(arg, "--") != arg)
break;
if (strcmp(arg, "--histogram") == 0) {
histograms = true;
} else if (strcmp(arg, "--diff") == 0) {
produce_diff_image = true;
} else if (strcmp(arg, "--subtract") == 0) {
produce_image_subtraction = true;
} else if (strcmp(arg, "--reverse-byte-order") == 0) {
reverse_byte_order = true;
} else if (strcmp(arg, "--fuzzy") == 0) {
max_pixel_per_channel_delta = 1;
}
}
if (i < argc)
filename1 = argv[i++];
if (i < argc)
filename2 = argv[i++];
if (i < argc)
diff_filename = argv[i++];
if (produce_diff_image || produce_image_subtraction) {
if (!diff_filename.empty()) {
return DiffImages(binary_name, filename1, filename2, diff_filename,
produce_image_subtraction, reverse_byte_order);
}
} else if (!filename2.empty()) {
return CompareImages(binary_name, filename1, filename2, histograms,
reverse_byte_order, max_pixel_per_channel_delta);
}
PrintHelp(binary_name);
return kStatusError;
}