Add support for selecting the printer plugin via the env var

Task-number: QTBUG-57260
Change-Id: I046c8ce5af242cdc7efd23468bbe670d782bdfc0
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Andy Shaw <andy.shaw@qt.io>

1 files changed, 12 insertions, 2 deletions

diff --git a/src/printsupport/kernel/qplatformprintplugin.cpp b/src/printsupport/kernel/qplatformprintplugin.cpp
index 9bc4b61829..a80f369040 100644
--- a/src/printsupport/kernel/qplatformprintplugin.cpp
+++ b/src/printsupport/kernel/qplatformprintplugin.cpp
@@ -42,6 +42,7 @@
 #include "qprinterinfo.h"
 #include "private/qfactoryloader_p.h"
 #include <qcoreapplication.h>
+#include <qdebug.h>
 
 #ifndef QT_NO_PRINTER
 
@@ -79,8 +80,17 @@ QPlatformPrinterSupport *QPlatformPrinterSupportPlugin::get()
 {
     if (!printerSupport) {
         const QMultiMap<int, QString> keyMap = loader()->keyMap();
-        if (!keyMap.isEmpty())
-            printerSupport = qLoadPlugin<QPlatformPrinterSupport, QPlatformPrinterSupportPlugin>(loader(), keyMap.constBegin().value());
+        QMultiMap<int, QString>::const_iterator it = keyMap.cbegin();
+        if (!qEnvironmentVariableIsEmpty("QT_PRINTER_MODULE")) {
+            QString module = QString::fromLocal8Bit(qgetenv("QT_PRINTER_MODULE"));
+            QMultiMap<int, QString>::const_iterator it2 = std::find_if(keyMap.cbegin(), keyMap.cend(), [module](const QString &value){ return value == module; });
+            if (it2 == keyMap.cend())
+                qWarning() << "Unable to load printer plugin" << module;
+            else
+                it = it2;
+        }
+        if (it != keyMap.cend())
+            printerSupport = qLoadPlugin<QPlatformPrinterSupport, QPlatformPrinterSupportPlugin>(loader(), it.value());
         if (printerSupport)
             qAddPostRoutine(cleanupPrinterSupport);
     }