Start the implementation of in-place recoding for images

Currently, with the graphics system raster, converting from images
to QPixmap often needs to allocate a new image to convert the right
format.

For example, for an image in ARGB32 of 10 mbytes, we need to allocate
a second image of 10 mbytes in ARGB32_PM to convert the source image
in the right format for pixmap.

This can create a hight peak of memory, and is a bit slower
than it should.

This patch introduce in-place conversion of images when they are
loaded with QPixmap::loadFromData().
The images are loaded in their default format by QImageReader,
and are then converted in-place, trying to reduce memory
allocations.

Reviewed-by: Samuel Rødal

4 files changed, 399 insertions, 95 deletions

diff --git a/src/gui/image/qimage.cpp b/src/gui/image/qimage.cpp
index adc2632..bb8a994 100644
--- a/src/gui/image/qimage.cpp
+++ b/src/gui/image/qimage.cpp
@@ -2274,6 +2274,8 @@ bool QImage::create(const QSize& size, int depth, int numColors, QImage::Endian
 
 typedef void (*Image_Converter)(QImageData *dest, const QImageData *src, Qt::ImageConversionFlags);
 
+typedef bool (*InPlace_Image_Converter)(QImageData *data, Qt::ImageConversionFlags);
+
 static void convert_ARGB_to_ARGB_PM(QImageData *dest, const QImageData *src, Qt::ImageConversionFlags)
 {
     Q_ASSERT(src->format == QImage::Format_ARGB32);
@@ -2298,6 +2300,169 @@ static void convert_ARGB_to_ARGB_PM(QImageData *dest, const QImageData *src, Qt:
     }
 }
 
+static bool convert_ARGB_to_ARGB_PM_inplace(QImageData *data, Qt::ImageConversionFlags)
+{
+    Q_ASSERT(data->format == QImage::Format_ARGB32);
+
+    const int pad = (data->bytes_per_line >> 2) - data->width;
+    QRgb *rgb_data = (QRgb *) data->data;
+
+    for (int i = 0; i < data->height; ++i) {
+        const QRgb *end = rgb_data + data->width;
+        while (rgb_data < end) {
+            *rgb_data = PREMUL(*rgb_data);
+            ++rgb_data;
+        }
+        rgb_data += pad;
+    }
+    data->format = QImage::Format_ARGB32_Premultiplied;
+    return true;
+}
+
+static bool convert_indexed8_to_ARGB_PM_inplace(QImageData *data, Qt::ImageConversionFlags)
+{
+    Q_ASSERT(data->format == QImage::Format_Indexed8);
+    const int depth = 32;
+
+    const int dst_bytes_per_line = ((data->width * depth + 31) >> 5) << 2;
+    const int nbytes = dst_bytes_per_line * data->height;
+    uchar *const newData = (uchar *)realloc(data->data, nbytes);
+    if (!newData)
+        return false;
+
+    data->data = newData;
+
+    // start converting from the end because the end image is bigger than the source
+    uchar *src_data = newData + data->nbytes; // end of src
+    quint32 *dest_data = (quint32 *) (newData + nbytes); // end of dest > end of src
+    const int width = data->width;
+    const int src_pad = data->bytes_per_line - width;
+    const int dest_pad = (dst_bytes_per_line >> 2) - width;
+
+    for (int i = 0; i < data->height; ++i) {
+        src_data -= src_pad;
+        dest_data -= dest_pad;
+        for (int pixI = 0; pixI < width; ++pixI) {
+            --src_data;
+            --dest_data;
+            const uint pixel = data->colortable[*src_data];
+            *dest_data = (quint32) PREMUL(pixel);
+        }
+    }
+
+    data->format = QImage::Format_ARGB32_Premultiplied;
+    data->bytes_per_line = dst_bytes_per_line;
+    data->depth = depth;
+    data->nbytes = nbytes;
+
+    return true;
+}
+
+static bool convert_indexed8_to_RGB_inplace(QImageData *data, Qt::ImageConversionFlags)
+{
+    Q_ASSERT(data->format == QImage::Format_Indexed8);
+    const int depth = 32;
+
+    const int dst_bytes_per_line = ((data->width * depth + 31) >> 5) << 2;
+    const int nbytes = dst_bytes_per_line * data->height;
+    uchar *const newData = (uchar *)realloc(data->data, nbytes);
+    if (!newData)
+        return false;
+
+    data->data = newData;
+
+    // start converting from the end because the end image is bigger than the source
+    uchar *src_data = newData + data->nbytes;
+    quint32 *dest_data = (quint32 *) (newData + nbytes);
+    const int width = data->width;
+    const int src_pad = data->bytes_per_line - width;
+    const int dest_pad = (dst_bytes_per_line >> 2) - width;
+
+    for (int i = 0; i < data->height; ++i) {
+        src_data -= src_pad;
+        dest_data -= dest_pad;
+        for (int pixI = 0; pixI < width; ++pixI) {
+            --src_data;
+            --dest_data;
+            *dest_data = (quint32) data->colortable[*src_data];
+        }
+    }
+
+    data->format = QImage::Format_RGB32;
+    data->bytes_per_line = dst_bytes_per_line;
+    data->depth = depth;
+    data->nbytes = nbytes;
+
+    return true;
+}
+
+static bool convert_indexed8_to_RGB16_inplace(QImageData *data, Qt::ImageConversionFlags)
+{
+    Q_ASSERT(data->format == QImage::Format_Indexed8);
+    const int depth = 16;
+
+    const int dst_bytes_per_line = ((data->width * depth + 31) >> 5) << 2;
+    const int nbytes = dst_bytes_per_line * data->height;
+    uchar *const newData = (uchar *)realloc(data->data, nbytes);
+    if (!newData)
+        return false;
+
+    data->data = newData;
+
+    // start converting from the end because the end image is bigger than the source
+    uchar *src_data = newData + data->nbytes;
+    quint16 *dest_data = (quint16 *) (newData + nbytes);
+    const int width = data->width;
+    const int src_pad = data->bytes_per_line - width;
+    const int dest_pad = (dst_bytes_per_line >> 1) - width;
+
+    for (int i = 0; i < data->height; ++i) {
+        src_data -= src_pad;
+        dest_data -= dest_pad;
+        for (int pixI = 0; pixI < width; ++pixI) {
+            --src_data;
+            --dest_data;
+            const uint pixel = data->colortable[*src_data];
+            *dest_data = qt_colorConvert<quint16, quint32>(pixel, 0);
+        }
+    }
+
+    data->format = QImage::Format_RGB16;
+    data->bytes_per_line = dst_bytes_per_line;
+    data->depth = depth;
+    data->nbytes = nbytes;
+
+    return true;
+}
+
+static bool convert_RGB_to_RGB16_inplace(QImageData *data, Qt::ImageConversionFlags)
+{
+    Q_ASSERT(data->format == QImage::Format_RGB32);
+    const int depth = 16;
+
+    const int dst_bytes_per_line = ((data->width * depth + 31) >> 5) << 2;
+    const int src_bytes_per_line = data->bytes_per_line;
+    quint32 *src_data = (quint32 *) data->data;
+    quint16 *dst_data = (quint16 *) data->data;
+
+    for (int i = 0; i < data->height; ++i) {
+        qt_memconvert(dst_data, src_data, data->width);
+        src_data = (quint32 *) (((char*)src_data) + src_bytes_per_line);
+        dst_data = (quint16 *) (((char*)dst_data) + dst_bytes_per_line);
+    }
+    data->format = QImage::Format_RGB16;
+    data->bytes_per_line = dst_bytes_per_line;
+    data->depth = depth;
+    data->nbytes = dst_bytes_per_line * data->height;
+    uchar *const newData = (uchar *)realloc(data->data, data->nbytes);
+    if (newData) {
+        data->data = newData;
+        return true;
+    } else {
+        return false;
+    }
+}
+
 static void convert_ARGB_PM_to_ARGB(QImageData *dest, const QImageData *src, Qt::ImageConversionFlags)
 {
     Q_ASSERT(src->format == QImage::Format_ARGB32_Premultiplied);
@@ -3447,6 +3612,103 @@ static const Image_Converter converter_map[QImage::NImageFormats][QImage::NImage
     } // Format_ARGB4444_Premultiplied
 };
 
+static const InPlace_Image_Converter inplace_converter_map[QImage::NImageFormats][QImage::NImageFormats] =
+{
+    {
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    },
+    {
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    }, // Format_Mono
+    {
+       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    }, // Format_MonoLSB
+    {
+        0,
+        0,
+        0,
+        0,
+        0,
+        convert_indexed8_to_RGB_inplace,
+        convert_indexed8_to_ARGB_PM_inplace,
+        convert_indexed8_to_RGB16_inplace,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+    }, // Format_Indexed8
+    {
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        convert_RGB_to_RGB16_inplace,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+    }, // Format_ARGB32
+    {
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        convert_ARGB_to_ARGB_PM_inplace,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+    }, // Format_ARGB32
+    {
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    },  // Format_ARGB32_Premultiplied
+    {
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    }, // Format_RGB16
+    {
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    }, // Format_ARGB8565_Premultiplied
+    {
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    }, // Format_RGB666
+    {
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    }, // Format_ARGB6666_Premultiplied
+    {
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    }, // Format_RGB555
+    {
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    }, // Format_ARGB8555_Premultiplied
+    {
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    }, // Format_RGB888
+    {
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    }, // Format_RGB444
+    {
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+    } // Format_ARGB4444_Premultiplied
+};
+
 /*!
     Returns a copy of the image in the given \a format.
 
@@ -6276,6 +6538,18 @@ QTransform QImage::trueMatrix(const QTransform &matrix, int w, int h)
     return matrix * QTransform().translate(-delta.x(), -delta.y());
 }
 
+bool QImageData::convertInPlace(QImage::Format newFormat, Qt::ImageConversionFlags flags)
+{
+    if (format == newFormat)
+        return true;
+
+    const InPlace_Image_Converter *const converterPtr = &inplace_converter_map[format][newFormat];
+    InPlace_Image_Converter converter = *converterPtr;
+    if (converter)
+        return converter(this, flags);
+    else
+        return false;
+}
 
 /*!
     \typedef QImage::DataPtr
diff --git a/src/gui/image/qimage_p.h b/src/gui/image/qimage_p.h
index 0c19647..f1a0c47 100644
--- a/src/gui/image/qimage_p.h
+++ b/src/gui/image/qimage_p.h
@@ -96,6 +96,9 @@ struct Q_GUI_EXPORT QImageData {        // internal image data
 
     bool checkForAlphaPixels() const;
 
+    // Convert the image in-place, minimizing memory reallocation
+    // Return false if the conversion cannot be done in-place.
+    bool convertInPlace(QImage::Format newFormat, Qt::ImageConversionFlags);
 
 #ifndef QT_NO_IMAGE_TEXT
     QMap<QString, QString> text;
diff --git a/src/gui/image/qpixmap_raster.cpp b/src/gui/image/qpixmap_raster.cpp
index 4f32d2f..13c03a1 100644
--- a/src/gui/image/qpixmap_raster.cpp
+++ b/src/gui/image/qpixmap_raster.cpp
@@ -47,6 +47,9 @@
 
 #include "qbitmap.h"
 #include "qimage.h"
+#include <QBuffer>
+#include <QImageReader>
+#include <private/qsimd_p.h>
 #include <private/qwidget_p.h>
 #include <private/qdrawhelper_p.h>
 
@@ -127,104 +130,26 @@ void QRasterPixmapData::resize(int width, int height)
     setSerialNumber(image.serialNumber());
 }
 
+bool QRasterPixmapData::fromData(const uchar *buffer, uint len, const char *format,
+                      Qt::ImageConversionFlags flags)
+{
+    QByteArray a = QByteArray::fromRawData(reinterpret_cast<const char *>(buffer), len);
+    QBuffer b(&a);
+    b.open(QIODevice::ReadOnly);
+    QImage image = QImageReader(&b, format).read();
+    if (image.isNull())
+        return false;
+
+    createPixmapForImage(image, flags, /* inplace = */true);
+    return !isNull();
+}
+
 void QRasterPixmapData::fromImage(const QImage &sourceImage,
                                   Qt::ImageConversionFlags flags)
 {
     Q_UNUSED(flags);
-
-#ifdef Q_WS_QWS
-    QImage::Format format;
-    if (pixelType() == BitmapType) {
-        format = QImage::Format_Mono;
-    } else {
-        format = QScreen::instance()->pixelFormat();
-        if (format == QImage::Format_Invalid)
-            format = QImage::Format_ARGB32_Premultiplied;
-        else if (format == QImage::Format_Indexed8) // currently not supported
-            format = QImage::Format_RGB444;
-    }
-
-    if (sourceImage.hasAlphaChannel()
-        && ((flags & Qt::NoOpaqueDetection)
-            || const_cast<QImage &>(sourceImage).data_ptr()->checkForAlphaPixels())) {
-        switch (format) {
-            case QImage::Format_RGB16:
-                format = QImage::Format_ARGB8565_Premultiplied;
-                break;
-            case QImage::Format_RGB666:
-                format = QImage::Format_ARGB6666_Premultiplied;
-                break;
-            case QImage::Format_RGB555:
-                format = QImage::Format_ARGB8555_Premultiplied;
-                break;
-            case QImage::Format_RGB444:
-                format = QImage::Format_ARGB4444_Premultiplied;
-                break;
-            default:
-                format = QImage::Format_ARGB32_Premultiplied;
-                break;
-        }
-    } else if (format == QImage::Format_Invalid) {
-        format = QImage::Format_ARGB32_Premultiplied;
-    }
-
-    image = sourceImage.convertToFormat(format);
-#else
-    if (pixelType() == BitmapType) {
-        image = sourceImage.convertToFormat(QImage::Format_MonoLSB);
-    } else {
-        if (sourceImage.depth() == 1) {
-            image = sourceImage.hasAlphaChannel()
-                    ? sourceImage.convertToFormat(QImage::Format_ARGB32_Premultiplied)
-                    : sourceImage.convertToFormat(QImage::Format_RGB32);
-        } else {
-
-            QImage::Format opaqueFormat = QNativeImage::systemFormat();
-            QImage::Format alphaFormat = QImage::Format_ARGB32_Premultiplied;
-
-#ifndef QT_HAVE_NEON
-            switch (opaqueFormat) {
-            case QImage::Format_RGB16:
-                alphaFormat = QImage::Format_ARGB8565_Premultiplied;
-                break;
-            default: // We don't care about the others...
-                break;
-            }
-#endif
-
-            if (!sourceImage.hasAlphaChannel()) {
-                image = sourceImage.convertToFormat(opaqueFormat);
-            } else if ((flags & Qt::NoOpaqueDetection) == 0
-                       && !const_cast<QImage &>(sourceImage).data_ptr()->checkForAlphaPixels())
-            {
-                // image has alpha format but is really opaque, so try to do a
-                // more efficient conversion
-                if (sourceImage.format() == QImage::Format_ARGB32
-                    || sourceImage.format() == QImage::Format_ARGB32_Premultiplied)
-                {
-                    QImage rgbImage(sourceImage.bits(), sourceImage.width(), sourceImage.height(),
-                                    QImage::Format_RGB32);
-                    image = rgbImage.convertToFormat(opaqueFormat);
-                    image.detach();
-                } else {
-                    image = sourceImage.convertToFormat(opaqueFormat);
-                }
-            } else {
-                image = sourceImage.convertToFormat(alphaFormat);
-            }
-        }
-    }
-#endif
-    if (image.d) {
-        w = image.d->width;
-        h = image.d->height;
-        d = image.d->depth;
-    } else {
-        w = h = d = 0;
-    }
-    is_null = (w <= 0 || h <= 0);
-
-    setSerialNumber(image.serialNumber());
+    QImage image = sourceImage;
+    createPixmapForImage(image, flags, /* inplace = */false);
 }
 
 // from qwindowsurface.cpp
@@ -253,7 +178,7 @@ void QRasterPixmapData::fill(const QColor &color)
         if (alpha != 255) {
             if (!image.hasAlphaChannel()) {
                 QImage::Format toFormat;
-#ifndef QT_HAVE_NEON
+#if !(defined(QT_HAVE_NEON) || defined(QT_ALWAYS_HAVE_SSE2))
                 if (image.format() == QImage::Format_RGB16)
                     toFormat = QImage::Format_ARGB8565_Premultiplied;
                 else if (image.format() == QImage::Format_RGB666)
@@ -411,6 +336,105 @@ int QRasterPixmapData::metric(QPaintDevice::PaintDeviceMetric metric) const
     return 0;
 }
 
+void QRasterPixmapData::createPixmapForImage(QImage &sourceImage, Qt::ImageConversionFlags flags, bool inPlace)
+{
+    QImage::Format format;
+#ifdef Q_WS_QWS
+    if (pixelType() == BitmapType) {
+        format = QImage::Format_Mono;
+    } else {
+        format = QScreen::instance()->pixelFormat();
+        if (format == QImage::Format_Invalid)
+            format = QImage::Format_ARGB32_Premultiplied;
+        else if (format == QImage::Format_Indexed8) // currently not supported
+            format = QImage::Format_RGB444;
+    }
+
+    if (sourceImage.hasAlphaChannel()
+        && ((flags & Qt::NoOpaqueDetection)
+            || const_cast<QImage &>(sourceImage).data_ptr()->checkForAlphaPixels())) {
+        switch (format) {
+            case QImage::Format_RGB16:
+                format = QImage::Format_ARGB8565_Premultiplied;
+                break;
+            case QImage::Format_RGB666:
+                format = QImage::Format_ARGB6666_Premultiplied;
+                break;
+            case QImage::Format_RGB555:
+                format = QImage::Format_ARGB8555_Premultiplied;
+                break;
+            case QImage::Format_RGB444:
+                format = QImage::Format_ARGB4444_Premultiplied;
+                break;
+            default:
+                format = QImage::Format_ARGB32_Premultiplied;
+                break;
+        }
+    } else if (format == QImage::Format_Invalid) {
+        format = QImage::Format_ARGB32_Premultiplied;
+    }
+#else
+    if (pixelType() == BitmapType) {
+        format = QImage::Format_MonoLSB;
+    } else {
+        if (sourceImage.depth() == 1) {
+            format = sourceImage.hasAlphaChannel()
+                    ? QImage::Format_ARGB32_Premultiplied
+                    : QImage::Format_RGB32;
+        } else {
+            QImage::Format opaqueFormat = QNativeImage::systemFormat();
+            QImage::Format alphaFormat = QImage::Format_ARGB32_Premultiplied;
+
+#if !defined(QT_HAVE_NEON) && !defined(QT_ALWAYS_HAVE_SSE2)
+            switch (opaqueFormat) {
+            case QImage::Format_RGB16:
+                alphaFormat = QImage::Format_ARGB8565_Premultiplied;
+                break;
+            default: // We don't care about the others...
+                break;
+            }
+#endif
+
+            if (!sourceImage.hasAlphaChannel()) {
+                format = opaqueFormat;
+            } else if ((flags & Qt::NoOpaqueDetection) == 0
+                       && !const_cast<QImage &>(sourceImage).data_ptr()->checkForAlphaPixels())
+            {
+                // image has alpha format but is really opaque, so try to do a
+                // more efficient conversion
+                if (sourceImage.format() == QImage::Format_ARGB32
+                    || sourceImage.format() == QImage::Format_ARGB32_Premultiplied)
+                {
+                    if (!inPlace)
+                        sourceImage.detach();
+                    sourceImage.d->format = QImage::Format_RGB32;
+                }
+                format = opaqueFormat;
+            } else {
+                format = alphaFormat;
+            }
+        }
+    }
+#endif
+
+    if (inPlace && sourceImage.d->convertInPlace(format, flags)) {
+        image = sourceImage;
+    } else {
+        image = sourceImage.convertToFormat(format);
+    }
+
+    if (image.d) {
+        w = image.d->width;
+        h = image.d->height;
+        d = image.d->depth;
+    } else {
+        w = h = d = 0;
+    }
+    is_null = (w <= 0 || h <= 0);
+
+    setSerialNumber(image.serialNumber());
+}
+
 QImage* QRasterPixmapData::buffer()
 {
     return &image;
diff --git a/src/gui/image/qpixmap_raster_p.h b/src/gui/image/qpixmap_raster_p.h
index 6cdd3d7..d7e3f85 100644
--- a/src/gui/image/qpixmap_raster_p.h
+++ b/src/gui/image/qpixmap_raster_p.h
@@ -72,6 +72,7 @@ public:
 
     void resize(int width, int height);
     void fromFile(const QString &filename, Qt::ImageConversionFlags flags);
+    bool fromData(const uchar *buffer, uint len, const char *format, Qt::ImageConversionFlags flags);
     void fromImage(const QImage &image, Qt::ImageConversionFlags flags);
 
     bool scroll(int dx, int dy, const QRect &rect);
@@ -85,6 +86,8 @@ public:
 
 protected:
     int metric(QPaintDevice::PaintDeviceMetric metric) const;
+    void createPixmapForImage(QImage &sourceImage, Qt::ImageConversionFlags flags, bool inPlace);
+    void setImage(const QImage &image);
     QImage image;
 
 private: