Allow custom debug connectors

Expose a generic method for loading connector plugins in
QQmlDebuggingEnabler and don't insist on the two known ones when
actually loading them. This allows third-party connector plugins
to be loaded, for example to pass QML trace events to a generic
tracing library.

Change-Id: I4f66dfabdbd0c3aff3676f7e2591e0a6c42f8f7f
Reviewed-by: hjk <hjk@theqtcompany.com>
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

3 files changed, 36 insertions, 32 deletions

diff --git a/src/qml/debugger/qqmldebug.cpp b/src/qml/debugger/qqmldebug.cpp
index 64a951d53b..9276bd0544 100644
--- a/src/qml/debugger/qqmldebug.cpp
+++ b/src/qml/debugger/qqmldebug.cpp
@@ -134,22 +134,11 @@ void QQmlDebuggingEnabler::setServices(const QStringList &services)
  */
 bool QQmlDebuggingEnabler::startTcpDebugServer(int port, StartMode mode, const QString &hostName)
 {
-#ifndef QQML_NO_DEBUG_PROTOCOL
-    QQmlDebugConnector::setPluginKey(QLatin1String("QQmlDebugServer"));
-    QQmlDebugConnector *connector = QQmlDebugConnector::instance();
-    if (connector) {
-        QVariantHash configuration;
-        configuration[QLatin1String("portFrom")] = configuration[QLatin1String("portTo")] = port;
-        configuration[QLatin1String("block")] = (mode == WaitForClient);
-        configuration[QLatin1String("hostAddress")] = hostName;
-        return connector->open(configuration);
-    }
-#else
-    Q_UNUSED(port);
-    Q_UNUSED(mode);
-    Q_UNUSED(hostName);
-#endif
-    return false;
+    QVariantHash configuration;
+    configuration[QLatin1String("portFrom")] = configuration[QLatin1String("portTo")] = port;
+    configuration[QLatin1String("block")] = (mode == WaitForClient);
+    configuration[QLatin1String("hostAddress")] = hostName;
+    return startDebugConnector(QLatin1String("QQmlDebugServer"), configuration);
 }
 
 /*!
@@ -164,18 +153,33 @@ bool QQmlDebuggingEnabler::startTcpDebugServer(int port, StartMode mode, const Q
  */
 bool QQmlDebuggingEnabler::connectToLocalDebugger(const QString &socketFileName, StartMode mode)
 {
+    QVariantHash configuration;
+    configuration[QLatin1String("fileName")] = socketFileName;
+    configuration[QLatin1String("block")] = (mode == WaitForClient);
+    return startDebugConnector(QLatin1String("QQmlDebugServer"), configuration);
+}
+
+/*!
+ * \since 5.7
+ *
+ * Enables debugging for QML engines created after calling this function. A debug connector plugin
+ * specified by \a pluginName will be loaded and started using the given \a configuration. Supported
+ * configuration entries and their semantics depend on the plugin being loaded. You can only start
+ * one debug connector at a time. A debug connector may have already been started if the
+ * -qmljsdebugger= command line argument was given. This method returns \c true if a new debug
+ * connector was successfully started, or \c false otherwise.
+ */
+bool QQmlDebuggingEnabler::startDebugConnector(const QString &pluginName,
+                                               const QVariantHash &configuration)
+{
 #ifndef QQML_NO_DEBUG_PROTOCOL
-    QQmlDebugConnector::setPluginKey(QLatin1String("QQmlDebugServer"));
+    QQmlDebugConnector::setPluginKey(pluginName);
     QQmlDebugConnector *connector = QQmlDebugConnector::instance();
-    if (connector) {
-        QVariantHash configuration;
-        configuration[QLatin1String("fileName")] = socketFileName;
-        configuration[QLatin1String("block")] = (mode == WaitForClient);
+    if (connector)
         return connector->open(configuration);
-    }
 #else
-    Q_UNUSED(fileName);
-    Q_UNUSED(mode);
+    Q_UNUSED(pluginName);
+    Q_UNUSED(configuration);
 #endif
     return false;
 }
diff --git a/src/qml/debugger/qqmldebug.h b/src/qml/debugger/qqmldebug.h
index eebebefe62..660b9e4d46 100644
--- a/src/qml/debugger/qqmldebug.h
+++ b/src/qml/debugger/qqmldebug.h
@@ -42,6 +42,7 @@
 
 #include <QtQml/qtqmlglobal.h>
 #include <QtCore/qstring.h>
+#include <QtCore/qvariant.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -65,6 +66,8 @@ struct Q_QML_EXPORT QQmlDebuggingEnabler
                                     const QString &hostName = QString());
     static bool connectToLocalDebugger(const QString &socketFileName,
                                        StartMode mode = DoNotWaitForClient);
+    static bool startDebugConnector(const QString &pluginName,
+                                    const QVariantHash &configuration = QVariantHash());
 };
 
 // Execute code in constructor before first QQmlEngine is instantiated
diff --git a/src/qml/debugger/qqmldebugconnector.cpp b/src/qml/debugger/qqmldebugconnector.cpp
index 6edd28ea01..e6d1a218ad 100644
--- a/src/qml/debugger/qqmldebugconnector.cpp
+++ b/src/qml/debugger/qqmldebugconnector.cpp
@@ -127,18 +127,15 @@ QQmlDebugConnector *QQmlDebugConnector::instance()
     }
 
     if (!params->instance) {
-        const QString serverConnector = QStringLiteral("QQmlDebugServer");
-        const QString nativeConnector = QStringLiteral("QQmlNativeDebugConnector");
-        const bool isNative = params->arguments.startsWith(QLatin1String("native"));
         if (!params->pluginKey.isEmpty()) {
-            if (params->pluginKey == serverConnector || params->pluginKey == nativeConnector)
-                params->instance = loadQQmlDebugConnector(params->pluginKey);
-            else
-                return 0; // We cannot load anything else, yet
+            params->instance = loadQQmlDebugConnector(params->pluginKey);
         } else if (params->arguments.isEmpty()) {
             return 0; // no explicit class name given and no command line arguments
         } else {
-            params->instance = loadQQmlDebugConnector(isNative ? nativeConnector : serverConnector);
+            params->instance = loadQQmlDebugConnector(
+                        params->arguments.startsWith(QLatin1String("native")) ?
+                            QStringLiteral("QQmlNativeDebugConnector") :
+                            QStringLiteral("QQmlDebugServer"));
         }
 
         if (params->instance) {