1 files changed, 16 insertions, 8 deletions
diff --git a/src/gui/painting/qprinter.cpp b/src/gui/painting/qprinter.cpp
index 6c309c7..154d90c 100644
--- a/src/gui/painting/qprinter.cpp
+++ b/src/gui/painting/qprinter.cpp
@@ -285,6 +285,10 @@ void QPrinterPrivate::addToManualSetList(QPrintEngine::PrintEnginePropertyKey ke
   the printProgram() function can be used to specify the command or utility
   to use instead of the system default.
 
+  Note that setting parameters like paper size and resolution on an
+  invalid printer is undefined. You can use QPrinter::isValid() to
+  verify this before changing any parameters.
+
   QPrinter supports a number of parameters, most of which can be
   changed by the end user through a \l{QPrintDialog}{print dialog}. In
   general, QPrinter passes these functions onto the underlying QPrintEngine.
@@ -740,7 +744,7 @@ void QPrinter::setOutputFormat(OutputFormat format)
 
 #ifndef QT_NO_PDF
     Q_D(QPrinter);
-    if (d->outputFormat == format)
+    if (d->validPrinter && d->outputFormat == format)
         return;
     d->outputFormat = format;
 
@@ -769,8 +773,8 @@ void QPrinter::setOutputFormat(OutputFormat format)
     if (def_engine)
         delete oldPrintEngine;
 
-    d->validPrinter = d->outputFormat == QPrinter::PdfFormat || d->outputFormat == QPrinter::PostScriptFormat;
-
+    if (d->outputFormat == QPrinter::PdfFormat || d->outputFormat == QPrinter::PostScriptFormat)
+        d->validPrinter = true;
 #else
     Q_UNUSED(format);
 #endif
@@ -830,11 +834,15 @@ void QPrinter::setPrinterName(const QString &name)
 #endif
 
     QList<QPrinterInfo> prnList = QPrinterInfo::availablePrinters();
-    d->validPrinter = false;
-    for (int i = 0; i < prnList.size(); ++i) {
-        if (prnList[i].printerName() == name) {
-            d->validPrinter = true;
-            break;
+    if (name.isEmpty()) {
+        d->validPrinter = d->outputFormat == QPrinter::PdfFormat || d->outputFormat == QPrinter::PostScriptFormat;
+    } else {
+        d->validPrinter = false;
+        for (int i = 0; i < prnList.size(); ++i) {
+            if (prnList[i].printerName() == name) {
+                d->validPrinter = true;
+                break;
+            }
         }
     }