Move image_diff code into testing/image_diff/
It is not actually a sample program to demonstrate how to use PDFium
APIs. It is more of a test utility program.
Remove header include dependency from samples/ to core/, to set a good
example.
Change-Id: Idd5d567c82314bcf0e4a7bec8a3210e7d57226ee
Reviewed-on: https://pdfium-review.googlesource.com/6871
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/testing/image_diff/image_diff.cpp b/testing/image_diff/image_diff.cpp
new file mode 100644
index 0000000..806e0c8
--- /dev/null
+++ b/testing/image_diff/image_diff.cpp
@@ -0,0 +1,336 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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 <assert.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <algorithm>
+#include <iostream>
+#include <map>
+#include <string>
+#include <vector>
+
+#include "core/fxcrt/fx_memory.h"
+#include "testing/image_diff/image_diff_png.h"
+#include "third_party/base/logging.h"
+#include "third_party/base/numerics/safe_conversions.h"
+
+#if defined(OS_WIN)
+#include <windows.h>
+#endif
+
+// Return codes used by this utility.
+static const int kStatusSame = 0;
+static const int kStatusDifferent = 1;
+static const int kStatusError = 2;
+
+// Color codes.
+static const uint32_t RGBA_RED = 0x000000ff;
+static const uint32_t RGBA_ALPHA = 0xff000000;
+
+class Image {
+ public:
+ Image() : w_(0), h_(0) {}
+ Image(const Image& image) : w_(image.w_), h_(image.h_), data_(image.data_) {}
+
+ bool has_image() const { return w_ > 0 && h_ > 0; }
+ int w() const { return w_; }
+ int h() const { return h_; }
+ const unsigned char* data() const { return &data_.front(); }
+
+ // Creates the image from the given filename on disk, and returns true on
+ // success.
+ bool CreateFromFilename(const std::string& path) {
+ FILE* f = fopen(path.c_str(), "rb");
+ if (!f)
+ return false;
+
+ std::vector<unsigned char> compressed;
+ const size_t kBufSize = 1024;
+ unsigned char 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);
+
+ if (!image_diff_png::DecodePNG(compressed.data(), compressed.size(), &data_,
+ &w_, &h_)) {
+ Clear();
+ return false;
+ }
+ return 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 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_;
+ int h_;
+
+ std::vector<unsigned char> 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;
+}
+
+float PercentageDifferent(const Image& baseline, const Image& actual) {
+ 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) {
+ if (baseline.pixel_at(x, y) != actual.pixel_at(x, y))
+ ++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 occurences 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() {
+ fprintf(
+ stderr,
+ "Usage:\n"
+ " image_diff [--histogram] <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"
+ " image_diff --diff <compare file> <reference file> <output file>\n"
+ " Compares two files on disk, outputs an image that visualizes the\n"
+ " difference to <output file>\n");
+}
+
+int CompareImages(const std::string& file1,
+ const std::string& file2,
+ bool compare_histograms) {
+ Image actual_image;
+ Image baseline_image;
+
+ if (!actual_image.CreateFromFilename(file1)) {
+ fprintf(stderr, "image_diff: Unable to open file \"%s\"\n", file1.c_str());
+ return kStatusError;
+ }
+ if (!baseline_image.CreateFromFilename(file2)) {
+ fprintf(stderr, "image_diff: Unable to open file \"%s\"\n", 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);
+ 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;
+}
+
+int DiffImages(const std::string& file1,
+ const std::string& file2,
+ const std::string& out_file) {
+ Image actual_image;
+ Image baseline_image;
+
+ if (!actual_image.CreateFromFilename(file1)) {
+ fprintf(stderr, "image_diff: Unable to open file \"%s\"\n", file1.c_str());
+ return kStatusError;
+ }
+ if (!baseline_image.CreateFromFilename(file2)) {
+ fprintf(stderr, "image_diff: Unable to open file \"%s\"\n", file2.c_str());
+ return kStatusError;
+ }
+
+ Image diff_image;
+ bool same = CreateImageDiff(baseline_image, actual_image, &diff_image);
+ if (same)
+ return kStatusSame;
+
+ std::vector<unsigned char> png_encoding;
+ image_diff_png::EncodeRGBAPNG(diff_image.data(), diff_image.w(),
+ diff_image.h(), diff_image.w() * 4,
+ &png_encoding);
+
+ 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[]) {
+ FXMEM_InitializePartitionAlloc();
+
+ bool histograms = false;
+ bool produce_diff_image = false;
+ std::string filename1;
+ std::string filename2;
+ std::string diff_filename;
+
+ 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;
+ }
+ }
+ if (i < argc)
+ filename1 = argv[i++];
+ if (i < argc)
+ filename2 = argv[i++];
+ if (i < argc)
+ diff_filename = argv[i++];
+
+ if (produce_diff_image) {
+ if (!diff_filename.empty()) {
+ return DiffImages(filename1, filename2, diff_filename);
+ }
+ } else if (!filename2.empty()) {
+ return CompareImages(filename1, filename2, histograms);
+ }
+
+ PrintHelp();
+ return kStatusError;
+}