Add QmlImageProvider to allow asynchronous access to images.

Setting an image source to image://providerid/imageid will pass the
request for imageid to the provider registered for providerid.
QmlImageProvider::request() is run in a low priority thread, so the
main thread is not blocked while the image is loaded/rendered.

Reviewed-by: Aaron Kennedy

4 files changed, 135 insertions, 0 deletions

diff --git a/examples/declarative/imageprovider/imageprovider.pro b/examples/declarative/imageprovider/imageprovider.pro
new file mode 100644
index 0000000..60423ab
--- /dev/null
+++ b/examples/declarative/imageprovider/imageprovider.pro
@@ -0,0 +1,9 @@
+TEMPLATE = app
+TARGET = imageprovider
+DEPENDPATH += .
+INCLUDEPATH += .
+QT += declarative
+
+# Input
+SOURCES += main.cpp
+RESOURCES += imageprovider.qrc
diff --git a/examples/declarative/imageprovider/imageprovider.qrc b/examples/declarative/imageprovider/imageprovider.qrc
new file mode 100644
index 0000000..17e9301
--- /dev/null
+++ b/examples/declarative/imageprovider/imageprovider.qrc
@@ -0,0 +1,5 @@
+<!DOCTYPE RCC><RCC version="1.0">
+<qresource>
+    <file>view.qml</file>
+</qresource>
+</RCC>
diff --git a/examples/declarative/imageprovider/main.cpp b/examples/declarative/imageprovider/main.cpp
new file mode 100644
index 0000000..718e9bb
--- /dev/null
+++ b/examples/declarative/imageprovider/main.cpp
@@ -0,0 +1,99 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the demonstration applications of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QApplication>
+
+#include <qmlengine.h>
+#include <qmlcontext.h>
+#include <qml.h>
+#include <qmlgraphicsitem.h>
+#include <qmlimageprovider.h>
+#include <qmlview.h>
+#include <QImage>
+#include <QPainter>
+
+/*
+   This example illustrates using a QmlImageProvider to serve
+   images asynchronously.
+*/
+
+//![0]
+class ColorImageProvider : public QmlImageProvider
+{
+public:
+    // This is run in a low priority thread.
+    QImage request(const QString &id) {
+        QImage image(100, 50, QImage::Format_RGB32);
+        image.fill(QColor(id).rgba());
+        QPainter p(&image);
+        p.setPen(Qt::black);
+        p.drawText(QRectF(0,0,100,50),Qt::AlignCenter,id);
+        return image;
+    }
+};
+
+int main(int argc, char ** argv)
+{
+    QApplication app(argc, argv);
+
+    QmlView view;
+    view.setUrl(QUrl("qrc:view.qml"));
+
+    view.engine()->addImageProvider("colors", new ColorImageProvider);
+
+    QStringList dataList;
+    dataList.append("image://colors/red");
+    dataList.append("image://colors/green");
+    dataList.append("image://colors/blue");
+    dataList.append("image://colors/brown");
+    dataList.append("image://colors/orange");
+    dataList.append("image://colors/purple");
+    dataList.append("image://colors/yellow");
+
+    QmlContext *ctxt = view.rootContext();
+    ctxt->setContextProperty("myModel", QVariant::fromValue(dataList));
+
+    view.execute();
+    view.show();
+
+    return app.exec();
+}
+//![0]
diff --git a/examples/declarative/imageprovider/view.qml b/examples/declarative/imageprovider/view.qml
new file mode 100644
index 0000000..2ab729d
--- /dev/null
+++ b/examples/declarative/imageprovider/view.qml
@@ -0,0 +1,22 @@
+import Qt 4.6
+//![0]
+ListView {
+    width: 100
+    height: 100
+    anchors.fill: parent
+    model: myModel
+    delegate: Component {
+        Item {
+            width: 100
+            height: 50
+            Text {
+                text: "Loading..."
+                anchors.centerIn: parent
+            }
+            Image {
+                source: modelData
+            }
+        }
+    }
+}
+//![0]