Long live QColorSpace and friends

Adds QColorSpace and QColorTransform classes,
and parsing of a common subset of ICC profiles
found in images, and also parses the ICC profiles
in PNG and JPEGs.

For backwards compatibility no automatic color
handling is done by this patch.

[ChangeLog][QtGui] A QColorSpace class has been added,
and color spaces are now parsed from PNG and JPEG images.
No automatic color space conversion is done however, and
applications must request it.

Change-Id: Ic09935f84640a716467fa3a9ed1e73c02daf3675
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>

5 files changed, 213 insertions, 11 deletions

diff --git a/src/gui/image/qimage.cpp b/src/gui/image/qimage.cpp
index 16de045cf0..204729b551 100644
--- a/src/gui/image/qimage.cpp
+++ b/src/gui/image/qimage.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2018 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtGui module of the Qt Toolkit.
@@ -38,8 +38,10 @@
 ****************************************************************************/
 
 #include "qimage.h"
-#include "qdatastream.h"
+
 #include "qbuffer.h"
+#include "qdatastream.h"
+#include "qcolortransform.h"
 #include "qmap.h"
 #include "qmatrix.h"
 #include "qtransform.h"
@@ -54,6 +56,7 @@
 #include <stdlib.h>
 #include <limits.h>
 #include <qpa/qplatformpixmap.h>
+#include <private/qcolortransform_p.h>
 #include <private/qdrawhelper_p.h>
 #include <private/qmemrotate_p.h>
 #include <private/qimagescale_p.h>
@@ -1098,6 +1101,7 @@ static void copyMetadata(QImageData *dst, const QImageData *src)
     dst->dpmy = src->dpmy;
     dst->devicePixelRatio = src->devicePixelRatio;
     dst->text = src->text;
+    dst->colorSpace = src->colorSpace;
 }
 
 /*!
@@ -4920,6 +4924,132 @@ QTransform QImage::trueMatrix(const QTransform &matrix, int w, int h)
     return matrix * QTransform().translate(-delta.x(), -delta.y());
 }
 
+/*!
+    \since 5.14
+
+    Sets the image color space to \a colorSpace without performing any conversions on image data.
+
+    \sa colorSpace()
+*/
+void QImage::setColorSpace(const QColorSpace &colorSpace)
+{
+    if (!d)
+        return;
+    if (d->colorSpace == colorSpace)
+        return;
+    if (!isDetached()) // Detach only if shared, not for read-only data.
+        detach();
+    d->colorSpace = colorSpace;
+}
+
+/*!
+    \since 5.14
+
+    Converts the image to \a colorSpace.
+
+    If the image has no valid color space, the method does nothing.
+
+    \sa convertedToColorSpace(), setColorSpace()
+*/
+void QImage::convertToColorSpace(const QColorSpace &colorSpace)
+{
+    if (!d)
+        return;
+    if (!d->colorSpace.isValid())
+        return;
+    if (!colorSpace.isValid()) {
+        qWarning() << "QImage::convertToColorSpace: Output colorspace is not valid";
+        return;
+    }
+    detach();
+    applyColorTransform(d->colorSpace.transformationToColorSpace(colorSpace));
+    d->colorSpace = colorSpace;
+}
+
+/*!
+    \since 5.14
+
+    Returns the image converted to \a colorSpace.
+
+    If the image has no valid color space, a null QImage is returned.
+
+    \sa convertToColorSpace()
+*/
+QImage QImage::convertedToColorSpace(const QColorSpace &colorSpace) const
+{
+    if (!d || !d->colorSpace.isValid() || !colorSpace.isValid())
+        return QImage();
+    QImage image = copy();
+    image.convertToColorSpace(colorSpace);
+    return image;
+}
+
+/*!
+    \since 5.14
+
+    Returns the color space of the image if a color space is defined.
+*/
+QColorSpace QImage::colorSpace() const
+{
+    if (!d)
+        return QColorSpace::Undefined;
+    return d->colorSpace;
+}
+
+/*!
+    \since 5.14
+
+    Applies the color transformation \a transform to all pixels in the image.
+*/
+void QImage::applyColorTransform(const QColorTransform &transform)
+{
+    QImage::Format oldFormat = format();
+    if (depth() > 32) {
+        if (format() != QImage::Format_RGBX64 && format() != QImage::Format_RGBA64
+                && format() != QImage::Format_RGBA64_Premultiplied)
+            *this = std::move(*this).convertToFormat(QImage::Format_RGBA64);
+    } else if (format() != QImage::Format_ARGB32 && format() != QImage::Format_RGB32
+                && format() != QImage::Format_ARGB32_Premultiplied) {
+        if (hasAlphaChannel())
+            *this = std::move(*this).convertToFormat(QImage::Format_ARGB32);
+        else
+            *this = std::move(*this).convertToFormat(QImage::Format_RGB32);
+    }
+
+    QColorTransformPrivate::TransformFlags flags = QColorTransformPrivate::Unpremultiplied;
+    switch (format()) {
+    case Format_ARGB32_Premultiplied:
+    case Format_RGBA64_Premultiplied:
+        flags = QColorTransformPrivate::Premultiplied;
+        break;
+    case Format_RGB32:
+    case Format_RGBX64:
+        flags = QColorTransformPrivate::InputOpaque;
+        break;
+    case Format_ARGB32:
+    case Format_RGBA64:
+        break;
+    default:
+        Q_UNREACHABLE();
+    }
+
+    if (depth() > 32) {
+        for (int i = 0; i < height(); ++i) {
+            QRgba64 *scanline = reinterpret_cast<QRgba64 *>(scanLine(i));
+            transform.d_func()->apply(scanline, scanline, width(), flags);
+        }
+    } else {
+        for (int i = 0; i < height(); ++i) {
+            QRgb *scanline = reinterpret_cast<QRgb *>(scanLine(i));
+            transform.d_func()->apply(scanline, scanline, width(), flags);
+        }
+    }
+
+    if (oldFormat != format())
+        *this = std::move(*this).convertToFormat(oldFormat);
+}
+
+
 bool QImageData::convertInPlace(QImage::Format newFormat, Qt::ImageConversionFlags flags)
 {
     if (format == newFormat)
diff --git a/src/gui/image/qimage.h b/src/gui/image/qimage.h
index 45f571807c..b09e69c839 100644
--- a/src/gui/image/qimage.h
+++ b/src/gui/image/qimage.h
@@ -61,9 +61,11 @@ Q_FORWARD_DECLARE_MUTABLE_CG_TYPE(CGImage);
 QT_BEGIN_NAMESPACE
 
 
+class QColorSpace;
+class QColorTransform;
 class QIODevice;
-class QStringList;
 class QMatrix;
+class QStringList;
 class QTransform;
 class QVariant;
 template <class T> class QList;
@@ -296,6 +298,12 @@ public:
 #endif
     void invertPixels(InvertMode = InvertRgb);
 
+    QColorSpace colorSpace() const;
+    QImage convertedToColorSpace(const QColorSpace &) const;
+    void convertToColorSpace(const QColorSpace &);
+    void setColorSpace(const QColorSpace &);
+
+    void applyColorTransform(const QColorTransform &transform);
 
     bool load(QIODevice *device, const char* format);
     bool load(const QString &fileName, const char *format = nullptr);
diff --git a/src/gui/image/qimage_conversions.cpp b/src/gui/image/qimage_conversions.cpp
index 82ffb8af8b..837ac88470 100644
--- a/src/gui/image/qimage_conversions.cpp
+++ b/src/gui/image/qimage_conversions.cpp
@@ -39,7 +39,7 @@
 
 #include <private/qdrawhelper_p.h>
 #include <private/qguiapplication_p.h>
-#include <private/qcolorprofile_p.h>
+#include <private/qcolortrclut_p.h>
 #include <private/qendian_p.h>
 #include <private/qsimd_p.h>
 #include <private/qimage_p.h>
@@ -100,7 +100,7 @@ const uchar *qt_get_bitflip_array()
 
 void qGamma_correct_back_to_linear_cs(QImage *image)
 {
-    const QColorProfile *cp = QGuiApplicationPrivate::instance()->colorProfileForA32Text();
+    const QColorTrcLut *cp = QGuiApplicationPrivate::instance()->colorProfileForA32Text();
     if (!cp)
         return;
     // gamma correct the pixels back to linear color space...
diff --git a/src/gui/image/qimage_p.h b/src/gui/image/qimage_p.h
index de12a313e8..a599fc17c9 100644
--- a/src/gui/image/qimage_p.h
+++ b/src/gui/image/qimage_p.h
@@ -51,7 +51,9 @@
 // We mean it.
 //
 
+#include <QtGui/qcolorspace.h>
 #include <QtGui/private/qtguiglobal_p.h>
+#include <QtGui/qimage.h>
 #include <QtCore/private/qnumeric_p.h>
 
 #include <QMap>
@@ -106,6 +108,8 @@ struct Q_GUI_EXPORT QImageData {        // internal image data
 
     QPaintEngine *paintEngine;
 
+    QColorSpace colorSpace;
+
     struct ImageSizeParameters {
         qsizetype bytesPerLine;
         qsizetype totalSize;
diff --git a/src/gui/image/qpnghandler.cpp b/src/gui/image/qpnghandler.cpp
index 3655c39326..066261620b 100644
--- a/src/gui/image/qpnghandler.cpp
+++ b/src/gui/image/qpnghandler.cpp
@@ -42,6 +42,7 @@
 
 #ifndef QT_NO_IMAGEFORMAT_PNG
 #include <qcoreapplication.h>
+#include <qdebug.h>
 #include <qiodevice.h>
 #include <qimage.h>
 #include <qlist.h>
@@ -50,6 +51,10 @@
 
 #include <private/qimage_p.h> // for qt_getImageText
 
+#include <qcolorspace.h>
+#include <private/qcolorspace_p.h>
+#include <private/qicc_p.h>
+
 #include <png.h>
 #include <pngconf.h>
 
@@ -96,9 +101,16 @@ public:
         ReadingEnd,
         Error
     };
+    // Defines the order of how the various ways of setting colorspace overrides eachother:
+    enum ColorSpaceState {
+        Undefined = 0,
+        GammaChrm = 1, // gAMA+cHRM chunks
+        Srgb = 2,      // sRGB chunk
+        Icc = 3        // iCCP chunk
+    };
 
     QPngHandlerPrivate(QPngHandler *qq)
-        : gamma(0.0), fileGamma(0.0), quality(50), compression(50), png_ptr(0), info_ptr(0), end_info(0), state(Ready), q(qq)
+        : gamma(0.0), fileGamma(0.0), quality(50), compression(50), colorSpaceState(Undefined), png_ptr(0), info_ptr(0), end_info(0), state(Ready), q(qq)
     { }
 
     float gamma;
@@ -108,6 +120,8 @@ public:
     QString description;
     QSize scaledSize;
     QStringList readTexts;
+    QColorSpace colorSpace;
+    ColorSpaceState colorSpaceState;
 
     png_struct *png_ptr;
     png_info *info_ptr;
@@ -226,11 +240,8 @@ void qpiw_flush_fn(png_structp /* png_ptr */)
 }
 
 static
-void setup_qt(QImage& image, png_structp png_ptr, png_infop info_ptr, QSize scaledSize, bool *doScaledRead, float screen_gamma=0.0, float file_gamma=0.0)
+void setup_qt(QImage& image, png_structp png_ptr, png_infop info_ptr, QSize scaledSize, bool *doScaledRead)
 {
-    if (screen_gamma != 0.0 && file_gamma != 0.0)
-        png_set_gamma(png_ptr, 1.0f / screen_gamma, file_gamma);
-
     png_uint_32 width;
     png_uint_32 height;
     int bit_depth;
@@ -585,10 +596,45 @@ bool QPngHandlerPrivate::readPngHeader()
 
     readPngTexts(info_ptr);
 
+#ifdef PNG_iCCP_SUPPORTED
+    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_iCCP)) {
+        png_charp name = nullptr;
+        int compressionType = 0;
+#if (PNG_LIBPNG_VER < 10500)
+        png_charp profileData = nullptr;
+#else
+        png_bytep profileData = nullptr;
+#endif
+        png_uint_32 profLen;
+        png_get_iCCP(png_ptr, info_ptr, &name, &compressionType, &profileData, &profLen);
+        if (!QIcc::fromIccProfile(QByteArray::fromRawData((const char *)profileData, profLen), &colorSpace)) {
+            qWarning() << "QPngHandler: Failed to parse ICC profile";
+        } else {
+            colorSpaceState = Icc;
+        }
+    }
+#endif
+    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sRGB)) {
+        int rendering_intent = -1;
+        png_get_sRGB(png_ptr, info_ptr, &rendering_intent);
+        // We don't actually care about the rendering_intent, just that it is valid
+        if (rendering_intent >= 0 && rendering_intent <= 3 && colorSpaceState <= Srgb) {
+            colorSpace = QColorSpace::SRgb;
+            colorSpaceState = Srgb;
+        }
+    }
     if (png_get_valid(png_ptr, info_ptr, PNG_INFO_gAMA)) {
         double file_gamma = 0.0;
         png_get_gAMA(png_ptr, info_ptr, &file_gamma);
         fileGamma = file_gamma;
+        if (fileGamma > 0.0f && colorSpaceState <= GammaChrm) {
+            QColorSpacePrivate *csPrivate = colorSpace.d_func();
+            csPrivate->gamut = QColorSpace::Gamut::SRgb;
+            csPrivate->transferFunction = QColorSpace::TransferFunction::Gamma;
+            csPrivate->gamma = fileGamma;
+            csPrivate->initialize();
+            colorSpaceState = GammaChrm;
+        }
     }
 
     state = ReadHeader;
@@ -613,8 +659,19 @@ bool QPngHandlerPrivate::readPngImage(QImage *outImage)
         return false;
     }
 
+    if (gamma != 0.0 && fileGamma != 0.0) {
+        // This configuration forces gamma correction and
+        // thus changes the output colorspace
+        png_set_gamma(png_ptr, 1.0f / gamma, fileGamma);
+        QColorSpacePrivate *csPrivate = colorSpace.d_func();
+        csPrivate->transferFunction = QColorSpace::TransferFunction::Gamma;
+        csPrivate->gamma = gamma;
+        csPrivate->initialize();
+        colorSpaceState = GammaChrm;
+    }
+
     bool doScaledRead = false;
-    setup_qt(*outImage, png_ptr, info_ptr, scaledSize, &doScaledRead, gamma, fileGamma);
+    setup_qt(*outImage, png_ptr, info_ptr, scaledSize, &doScaledRead);
 
     if (outImage->isNull()) {
         png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
@@ -683,6 +740,9 @@ bool QPngHandlerPrivate::readPngImage(QImage *outImage)
     if (scaledSize.isValid() && outImage->size() != scaledSize)
         *outImage = outImage->scaled(scaledSize, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
 
+    if (colorSpaceState > Undefined && colorSpace.isValid())
+        outImage->setColorSpace(colorSpace);
+
     return true;
 }