diff -r 000000000000 -r 4f2f89ce4247 WebKitTools/DumpRenderTree/qt/ImageDiff.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WebKitTools/DumpRenderTree/qt/ImageDiff.cpp	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,146 @@
+/*
+    Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies)
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Library General Public
+    License as published by the Free Software Foundation; either
+    version 2 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Library General Public License for more details.
+
+    You should have received a copy of the GNU Library General Public License
+    along with this library; see the file COPYING.LIB.  If not, write to
+    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+    Boston, MA 02110-1301, USA.
+*/
+
+#include <QtCore/qmath.h>
+
+#include <QApplication>
+#include <QBuffer>
+#include <QByteArray>
+#include <QImage>
+#include <QStringList>
+
+#include <stdio.h>
+
+int main(int argc, char* argv[])
+{
+    QCoreApplication app(argc, argv);
+
+    qreal tolerance = 0;
+
+    QStringList args = app.arguments();
+    for (int i = 0; i < argc; ++i)
+        if (args[i] == "-t" || args[i] == "--tolerance")
+            tolerance = args[i + 1].toDouble();
+
+    char buffer[2048];
+    QImage actualImage;
+    QImage baselineImage;
+
+    while (fgets(buffer, sizeof(buffer), stdin)) {
+        // remove the CR
+        char* newLineCharacter = strchr(buffer, '\n');
+        if (newLineCharacter)
+            *newLineCharacter = '\0';
+
+        if (!strncmp("Content-Length: ", buffer, 16)) {
+            strtok(buffer, " ");
+            int imageSize = strtol(strtok(0, " "), 0, 10);
+
+            if (imageSize <= 0) {
+                fputs("error, image size must be specified.\n", stdout);
+            } else {
+                unsigned char buffer[2048];
+                QBuffer data;
+
+                // Read all the incoming chunks
+                data.open(QBuffer::WriteOnly);
+                while (imageSize > 0) {
+                    size_t bytesToRead = qMin(imageSize, 2048);
+                    size_t bytesRead = fread(buffer, 1, bytesToRead, stdin);
+                    data.write(reinterpret_cast<const char*>(buffer), bytesRead);
+                    imageSize -= static_cast<int>(bytesRead);
+                }
+
+                // Convert into QImage
+                QImage decodedImage;
+                decodedImage.loadFromData(data.data(), "PNG");
+                decodedImage.convertToFormat(QImage::Format_ARGB32);
+
+                // Place it in the right place
+                if (actualImage.isNull())
+                    actualImage = decodedImage;
+                else
+                    baselineImage = decodedImage;
+            }
+        }
+
+        if (!actualImage.isNull() && !baselineImage.isNull()) {
+
+            if (actualImage.size() != baselineImage.size()) {
+                fprintf(stderr, "error, test and reference image have different properties.\n");
+                fflush(stderr);
+            } else {
+
+                int w = actualImage.width();
+                int h = actualImage.height();
+                QImage diffImage(w, h, QImage::Format_ARGB32);
+
+                int count = 0;
+                qreal sum = 0;
+                qreal maxDistance = 0;
+
+                for (int x = 0; x < w; ++x)
+                    for (int y = 0; y < h; ++y) {
+                        QRgb pixel = actualImage.pixel(x, y);
+                        QRgb basePixel = baselineImage.pixel(x, y);
+                        qreal red = (qRed(pixel) - qRed(basePixel)) / static_cast<float>(qMax(255 - qRed(basePixel), qRed(basePixel)));
+                        qreal green = (qGreen(pixel) - qGreen(basePixel)) / static_cast<float>(qMax(255 - qGreen(basePixel), qGreen(basePixel)));
+                        qreal blue = (qBlue(pixel) - qBlue(basePixel)) / static_cast<float>(qMax(255 - qBlue(basePixel), qBlue(basePixel)));
+                        qreal alpha = (qAlpha(pixel) - qAlpha(basePixel)) / static_cast<float>(qMax(255 - qAlpha(basePixel), qAlpha(basePixel)));
+                        qreal distance = qSqrt(red * red + green * green + blue * blue + alpha * alpha) / 2.0f;
+                        int gray = distance * qreal(255);
+                        diffImage.setPixel(x, y, qRgb(gray, gray, gray));
+                        if (distance >= 1 / qreal(255)) {
+                            count++;
+                            sum += distance;
+                            maxDistance = qMax(maxDistance, distance);
+                        }
+                }
+
+                qreal difference = 0;
+                if (count)
+                    difference = 100 * sum / static_cast<qreal>(w * h);
+                if (difference <= tolerance) {
+                    difference = 0;
+                } else {
+                    difference = qRound(difference * 100) / 100;
+                    difference = qMax(difference, qreal(0.01));
+                }
+
+                if (!count) {
+                    fprintf(stdout, "diff: %01.2f%% passed\n", difference);
+                } else {
+                    QBuffer buffer;
+                    buffer.open(QBuffer::WriteOnly);
+                    diffImage.save(&buffer, "PNG");
+                    buffer.close();
+                    const QByteArray &data = buffer.data();
+                    printf("Content-Length: %lu\n", static_cast<unsigned long>(data.length()));
+                    fwrite(data.constData(), 1, data.length(), stdout);
+
+                    fprintf(stdout, "diff: %01.2f%% failed\n", difference);
+                }
+
+                fflush(stdout);
+            }
+        }
+    }
+
+    return 0;
+}