Add avatar support.

matrix/imageprovider.h

@@ -0,0 +1,28 @@
+#ifndef IMAGEPROVIDER_H
+#define IMAGEPROVIDER_H
+
+#include <QtQuick/QQuickImageProvider>
+#include <QtCore/QReadWriteLock>
+
+namespace QMatrixClient {
+    class Connection;
+}
+
+class ImageProvider: public QQuickImageProvider
+{
+    public:
+        explicit ImageProvider(QObject *parent = nullptr);
+
+        QImage requestImage(const QString& id, QSize* pSize,
+                              const QSize& requestedSize) override;
+
+        void setConnection(QMatrixClient::Connection* connection);
+
+        void initializeEngine(QQmlEngine *engine, const char *uri);
+
+    private:
+        QMatrixClient::Connection* m_connection;
+        QReadWriteLock m_lock;
+};
+
+#endif // IMAGEPROVIDER_H