Add support for rendering SVG data to the image provider

The image provider can already render SVG images supplied
as format_data due to using QImage as backend.
This unfortunately only works correctly as long as the SVG image is
not scaled, as the image provider ignores the requested_size parameter
for format_data, causing the SVG image to be first rendered at its default size
and then scaled at the bitmap level, resulting in a very blurry image.

As there does not appear to be any easy fix for this when working with
the format_data type add a new data type called format_svg_data that
properly renders the SVG image at requested size with QtSvgRenderer.

Also the documentation has been updated to include format_svg_data
and an example has been added.

docs/index.rst

@@ -380,6 +380,12 @@ The following constants have been added in PyOtherSide 1.3:
 **pyotherside.version**
     Version of PyOtherSide as string.
 
+.. versionadded:: 1.5.0
+
+The following constants have been added in PyOtherSide 1.5:
+
+**pyotherside.format_svg_data**
+    SVG image XML data
 
 
 Data Type Mapping
@@ -465,9 +471,11 @@ The image provider must return a tuple ``(data, size, format)``:
     pixel data in pixels.
 
 **format**
-    The pixel format of ``data`` (see `constants`_), or
+    The pixel format of ``data`` (see `constants`_),
     ``pyotherside.format_data`` if ``data`` contains an
-    encoded (PNG/JPEG) image instead of raw pixel data.
+    encoded (PNG/JPEG) image instead of raw pixel data
+    or ``pyotherside.format_svg_data`` if ``data`` contains 
+    SVG image XML data.
 
 In order to register the image provider with PyOtherSide for use
 as provider for ``image://python/`` URLs, the image provider function

examples/imageprovider_svg_data.py

@@ -0,0 +1,32 @@
+#
+# PyOtherSide: Asynchronous Python 3 Bindings for Qt 5
+# Copyright (c) 2011, 2013, Thomas Perl <m@thp.io>
+#
+# Permission to use, copy, modify, and/or distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+# FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+# OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+# PERFORMANCE OF THIS SOFTWARE.
+#
+
+import pyotherside
+
+import os
+
+def load_data(image_id, requested_size):
+    # If you return data in the format "pyotherside.format_svg_data" requested_size
+    # is is used as the target size when rendering the SVG image
+
+    # We use the image id to get name of the SVG file to render
+    with open(image_id, 'rb') as f:
+        svg_image_data = f.read()
+
+    return bytearray(svg_image_data), requested_size, pyotherside.format_svg_data
+
+pyotherside.set_image_provider(load_data)

examples/imageprovider_svg_data.qml

@@ -0,0 +1,41 @@
+
+/**
+ * PyOtherSide: Asynchronous Python 3 Bindings for Qt 5
+ * Copyright (c) 2011, 2013, Thomas Perl <m@thp.io>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ **/
+
+import QtQuick 2.0
+import io.thp.pyotherside 1.0
+
+Image {
+    id: image
+    width: 300
+    height: 300
+    sourceSize.width: 300
+    sourceSize.height: 300
+
+    Python {
+        Component.onCompleted: {
+            // Add the directory of this .qml file to the search path
+            addImportPath(Qt.resolvedUrl('.'));
+
+            importModule('imageprovider_svg_data', function () {
+                image.source = 'image://python/python_logo.svg';
+            });
+        }
+
+        onError: console.log('Python error: ' + traceback)
+    }
+}

examples/python_logo.svg

@@ -0,0 +1,113 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://web.resource.org/cc/"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:xlink="http://www.w3.org/1999/xlink"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   width="110.4211"
+   height="109.8461"
+   id="svg2169"
+   sodipodi:version="0.32"
+   inkscape:version="0.45.1"
+   version="1.0"
+   sodipodi:docbase="/home/bene/Desktop"
+   sodipodi:docname="dessin-1.svg"
+   inkscape:output_extension="org.inkscape.output.svg.inkscape">
+  <defs
+     id="defs2171">
+    <linearGradient
+       id="linearGradient11301"
+       inkscape:collect="always">
+      <stop
+         id="stop11303"
+         offset="0"
+         style="stop-color:#ffe052;stop-opacity:1" />
+      <stop
+         id="stop11305"
+         offset="1"
+         style="stop-color:#ffc331;stop-opacity:1" />
+    </linearGradient>
+    <linearGradient
+       gradientUnits="userSpaceOnUse"
+       y2="168.1012"
+       x2="147.77737"
+       y1="111.92053"
+       x1="89.136749"
+       id="linearGradient11307"
+       xlink:href="#linearGradient11301"
+       inkscape:collect="always" />
+    <linearGradient
+       id="linearGradient9515"
+       inkscape:collect="always">
+      <stop
+         id="stop9517"
+         offset="0"
+         style="stop-color:#387eb8;stop-opacity:1" />
+      <stop
+         id="stop9519"
+         offset="1"
+         style="stop-color:#366994;stop-opacity:1" />
+    </linearGradient>
+    <linearGradient
+       gradientUnits="userSpaceOnUse"
+       y2="131.85291"
+       x2="110.14919"
+       y1="77.070274"
+       x1="55.549179"
+       id="linearGradient9521"
+       xlink:href="#linearGradient9515"
+       inkscape:collect="always" />
+  </defs>
+  <sodipodi:namedview
+     id="base"
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1.0"
+     inkscape:pageopacity="0.0"
+     inkscape:pageshadow="2"
+     inkscape:zoom="0.24748737"
+     inkscape:cx="-260.46312"
+     inkscape:cy="316.02744"
+     inkscape:document-units="px"
+     inkscape:current-layer="layer1"
+     width="131.10236px"
+     height="184.25197px"
+     inkscape:window-width="872"
+     inkscape:window-height="624"
+     inkscape:window-x="5"
+     inkscape:window-y="48" />
+  <metadata
+     id="metadata2174">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+      </cc:Work>
+    </rdf:RDF>
+  </metadata>
+  <g
+     inkscape:label="Calque 1"
+     inkscape:groupmode="layer"
+     id="layer1"
+     transform="translate(-473.36088,-251.72485)">
+    <g
+       id="g1894"
+       transform="translate(428.42338,184.2561)">
+      <path
+         style="opacity:1;color:#000000;fill:url(#linearGradient9521);fill-opacity:1;fill-rule:nonzero;stroke:none;stroke-width:1;stroke-linecap:butt;stroke-linejoin:miter;marker:none;marker-start:none;marker-mid:none;marker-end:none;stroke-miterlimit:4;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1;visibility:visible;display:inline;overflow:visible"
+         d="M 99.75,67.46875 C 71.718268,67.468752 73.46875,79.625 73.46875,79.625 L 73.5,92.21875 L 100.25,92.21875 L 100.25,96 L 62.875,96 C 62.875,96 44.9375,93.965724 44.9375,122.25 C 44.937498,150.53427 60.59375,149.53125 60.59375,149.53125 L 69.9375,149.53125 L 69.9375,136.40625 C 69.9375,136.40625 69.433848,120.75 85.34375,120.75 C 101.25365,120.75 111.875,120.75 111.875,120.75 C 111.875,120.75 126.78125,120.99096 126.78125,106.34375 C 126.78125,91.696544 126.78125,82.125 126.78125,82.125 C 126.78125,82.124998 129.04443,67.46875 99.75,67.46875 z M 85,75.9375 C 87.661429,75.937498 89.8125,78.088571 89.8125,80.75 C 89.812502,83.411429 87.661429,85.5625 85,85.5625 C 82.338571,85.562502 80.1875,83.411429 80.1875,80.75 C 80.187498,78.088571 82.338571,75.9375 85,75.9375 z "
+         id="path8615" />
+      <path
+         id="path8620"
+         d="M 100.5461,177.31485 C 128.57784,177.31485 126.82735,165.1586 126.82735,165.1586 L 126.7961,152.56485 L 100.0461,152.56485 L 100.0461,148.7836 L 137.4211,148.7836 C 137.4211,148.7836 155.3586,150.81787 155.3586,122.53359 C 155.35861,94.249323 139.70235,95.252343 139.70235,95.252343 L 130.3586,95.252343 L 130.3586,108.37734 C 130.3586,108.37734 130.86226,124.03359 114.95235,124.03359 C 99.042448,124.03359 88.421098,124.03359 88.421098,124.03359 C 88.421098,124.03359 73.514848,123.79263 73.514848,138.43985 C 73.514848,153.08705 73.514848,162.6586 73.514848,162.6586 C 73.514848,162.6586 71.251668,177.31485 100.5461,177.31485 z M 115.2961,168.8461 C 112.63467,168.8461 110.4836,166.69503 110.4836,164.0336 C 110.4836,161.37217 112.63467,159.2211 115.2961,159.2211 C 117.95753,159.2211 120.1086,161.37217 120.1086,164.0336 C 120.10861,166.69503 117.95753,168.8461 115.2961,168.8461 z "
+         style="opacity:1;color:#000000;fill:url(#linearGradient11307);fill-opacity:1;fill-rule:nonzero;stroke:none;stroke-width:1;stroke-linecap:butt;stroke-linejoin:miter;marker:none;marker-start:none;marker-mid:none;marker-end:none;stroke-miterlimit:4;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1;visibility:visible;display:inline;overflow:visible" />
+    </g>
+  </g>
+</svg>

src/qpython_imageprovider.cpp

@@ -22,6 +22,8 @@
 #include "ensure_gil_state.h"
 
 #include <QDebug>
+#include <QSvgRenderer>
+#include <QPainter>
 
 
 QPythonImageProvider::QPythonImageProvider()
@@ -109,7 +111,9 @@ QPythonImageProvider::requestImage(const QString &id, QSize *size, const QSize &
     }
 
     switch (format) {
-        case -1: /* pyotherside.format_data */
+        case PYOTHERSIDE_IMAGE_FORMAT_ENCODED: /* pyotherside.format_data */
+            break;
+        case PYOTHERSIDE_IMAGE_FORMAT_SVG: /* pyotherside.format_svg_data */
             break;
         case QImage::Format_Mono:
         case QImage::Format_MonoLSB:
@@ -141,7 +145,7 @@ QPythonImageProvider::requestImage(const QString &id, QSize *size, const QSize &
     // While we could re-pack the data to be aligned, we don't want to do that
     // for performance reasons.
     // If we're using 32-bit data (e.g. ARGB32), it will always be aligned.
-    if (format != -1 && bitsPerPixel != 32) {
+    if (format >= 0 && bitsPerPixel != 32) {
         if ((bitsPerPixel * width) % 32 != 0) {
             // If actualBytes > requiredBytes, we can check if there are enough
             // bytes to consider the data 32-bit aligned (from Python) and avoid
@@ -155,7 +159,7 @@ QPythonImageProvider::requestImage(const QString &id, QSize *size, const QSize &
         }
     }
 
-    if (format != -1 && requiredBytes > actualBytes) {
+    if (format >= 0 && requiredBytes > actualBytes) {
         qDebug() << "Format" << (enum QImage::Format)format <<
             "at size" << QSize(width, height) <<
             "requires at least" << requiredBytes <<
@@ -163,11 +167,72 @@ QPythonImageProvider::requestImage(const QString &id, QSize *size, const QSize &
         goto cleanup;
     }
 
+    if (format < 0) {
+        switch (format) {
+        case PYOTHERSIDE_IMAGE_FORMAT_ENCODED: {
+            // Pixel data is actually encoded image data that we need to decode
+            img.loadFromData((const unsigned char*)PyByteArray_AsString(pixels), PyByteArray_Size(pixels));
+            break;
+        }
+        case PYOTHERSIDE_IMAGE_FORMAT_SVG: {
+            // Convert the Python byte array to a QByteArray
+            QByteArray svgDataArray(PyByteArray_AsString(pixels), PyByteArray_Size(pixels));
 
-    if (format == -1) {
+            // Load the SVG data to the SVG renderer
-        // Pixel data is actually encoded image data that we need to decode
+            QSvgRenderer renderer(svgDataArray);
-        img.loadFromData((const unsigned char*)PyByteArray_AsString(pixels),
+
-                PyByteArray_Size(pixels));
+            // Handle width, height or both not being set
+            if (width < 0 && height < 0) {
+                // Both Width and Height have not been set - use the defaults from the SVG data
+                // (each SVG image has a default size)
+                // NOTE: we get a -1,-1 requestedSize only if sourceSize is not set at all,
+                //       if either width or height is set then the other one is 0, not -1
+                width = renderer.defaultSize().width();
+                height = renderer.defaultSize().height();
+            } else { // At least width or height is valid
+                if (width <= 0) {
+                    // Width is not set, use default width scaled according to height to keep
+                    // aspect ratio
+                    if (renderer.defaultSize().height() != 0) {  // Protect from division by zero
+                        width = (float)renderer.defaultSize().width()*((float)height/(float)renderer.defaultSize().height());
+                    }
+                }
+
+                if (height <= 0) {
+                    // Height is not set, use default height scaled according to width to keep
+                    // aspect ratio
+                    if (renderer.defaultSize().width() != 0) {  // Protect from division by zero
+                        height = (float)renderer.defaultSize().height()*((float)width/(float)renderer.defaultSize().width());
+                    }
+                }
+            }
+
+            // The pixel data is actually SVG image data that we need to render at correct size
+            //
+            // Note: according to the QImage and QPainter documentation the optimal QImage
+            // format for drawing is Format_ARGB32_Premultiplied
+            img = QImage(width, height, QImage::Format_ARGB32_Premultiplied);
+
+            // According to the documentation an empty QImage needs to be "flushed" before
+            // being used with QPainter to prevent rendering artifacts from showing up
+            img.fill(Qt::transparent);
+
+            // Convert the Python byte array to a QByteArray
+            QByteArray svgDataArray(PyByteArray_AsString(pixels), PyByteArray_Size(pixels));
+
+            // Load the SVG data to the SVG renderer
+            QSvgRenderer renderer(svgDataArray);
+
+            // Paints the rendered SVG to the QImage instance
+            QPainter painter(&img);
+            renderer.render(&painter);
+            break;
+        }
+        default:
+            qWarning() << "Unknown format" << format <<
+                "has been specified and will not be handled.";
+            break;
+        }
     } else {
         // Need to keep a reference to the byte array object, as it contains
         // the backing store data for the QImage.

src/qpython_priv.cpp

@@ -454,7 +454,8 @@ PyOtherSide_init()
     PyModule_AddIntConstant(pyotherside, "format_rgb444", QImage::Format_RGB444);
 
     // Custom constant - pixels are to be interpreted as encoded image file data
-    PyModule_AddIntConstant(pyotherside, "format_data", -1);
+    PyModule_AddIntConstant(pyotherside, "format_data", PYOTHERSIDE_IMAGE_FORMAT_ENCODED);
+    PyModule_AddIntConstant(pyotherside, "format_svg_data", PYOTHERSIDE_IMAGE_FORMAT_SVG);
 
     // Version of PyOtherSide (new in 1.3)
     PyModule_AddStringConstant(pyotherside, "version", PYOTHERSIDE_VERSION);

src/qpython_priv.h

@@ -28,6 +28,10 @@
 #include <QVariant>
 #include <QString>
 
+enum PyOtherSideImageFormat {
+    PYOTHERSIDE_IMAGE_FORMAT_ENCODED = -1,
+    PYOTHERSIDE_IMAGE_FORMAT_SVG = -2,
+};
 
 class QPythonPriv : public QObject {
     Q_OBJECT

src/src.pro

@@ -8,7 +8,7 @@ PLUGIN_IMPORT_PATH = io/thp/pyotherside
 
 TEMPLATE = lib
 CONFIG += qt plugin
-QT += qml quick
+QT += qml quick svg
 
 target.path = $$[QT_INSTALL_QML]/$$PLUGIN_IMPORT_PATH
 INSTALLS += target