savegame ex.: revamp the way print() works

Basically, instead of re-creating QTextStreams all the time, create it
once, in main(), and then pass it to print() alongside the int
indentation.

Also fix a hard-coded indentation value that should have been relative
to the caller's indentation level.

Pick-to: 6.5 6.2
Task-number: QTBUG-108857
Change-Id: I811447295c9c3fdef23f61aff31ebe82941eb3b4
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

examples/corelib/serialization/savegame/character.cpp

@@ -77,12 +77,12 @@ QJsonObject Character::toJson() const
 }
 //! [toJson]
 
-void Character::print(int indentation) const
+void Character::print(QTextStream &s, int indentation) const
 {
     const QString indent(indentation * 2, ' ');
-    QTextStream(stdout) << indent << "Name:\t" << mName << "\n";
-    QTextStream(stdout) << indent << "Level:\t" << mLevel << "\n";
+    const QString className = QMetaEnum::fromType<ClassType>().valueToKey(mClassType);
 
-    QString className = QMetaEnum::fromType<ClassType>().valueToKey(mClassType);
-    QTextStream(stdout) << indent << "Class:\t" << className << "\n";
+    s << indent << "Name:\t" << mName << "\n"
+      << indent << "Level:\t" << mLevel << "\n"
+      << indent << "Class:\t" << className << "\n";
 }

examples/corelib/serialization/savegame/character.h

@@ -8,6 +8,8 @@
 #include <QObject>
 #include <QString>
 
+QT_FORWARD_DECLARE_CLASS(QTextStream)
+
 //! [0]
 class Character
 {
@@ -34,7 +36,7 @@ public:
     static Character fromJson(const QJsonObject &json);
     QJsonObject toJson() const;
 
-    void print(int indentation = 0) const;
+    void print(QTextStream &s, int indentation = 0) const;
 private:
     QString mName;
     int mLevel = 0;

examples/corelib/serialization/savegame/doc/src/savegame.qdoc

@@ -35,7 +35,9 @@
     subclasses, for example), other patterns may be more suitable. See the
     \l{xml/dombookmarks} and \l{xml/streambookmarks} examples for XML, and the
     implementation of \l QListWidgetItem::read() and \l QListWidgetItem::write()
-    for idiomatic QDataStream serialization.
+    for idiomatic QDataStream serialization. The \c{print()} functions in this example
+    are good examples of QTextStream serialization, even though they, of course, lack
+    the deserialization side.
 
     \snippet serialization/savegame/character.h 0
 

examples/corelib/serialization/savegame/game.cpp

@@ -140,13 +140,13 @@ QJsonObject Game::toJson() const
 }
 //! [toJson]
 
-void Game::print(int indentation) const
+void Game::print(QTextStream &s, int indentation) const
 {
     const QString indent(indentation * 2, ' ');
-    QTextStream(stdout) << indent << "Player\n";
-    mPlayer.print(indentation + 1);
+    s << indent << "Player\n";
+    mPlayer.print(s, indentation + 1);
 
-    QTextStream(stdout) << indent << "Levels\n";
+    s << indent << "Levels\n";
     for (const Level &level : mLevels)
-        level.print(indentation + 1);
+        level.print(s, indentation + 1);
 }

examples/corelib/serialization/savegame/game.h

@@ -10,6 +10,8 @@
 #include <QJsonObject>
 #include <QList>
 
+QT_FORWARD_DECLARE_CLASS(QTextStream)
+
 //! [0]
 class Game
 {
@@ -28,7 +30,7 @@ public:
     void read(const QJsonObject &json);
     QJsonObject toJson() const;
 
-    void print(int indentation = 0) const;
+    void print(QTextStream &s, int indentation = 0) const;
 private:
     Character mPlayer;
     QList<Level> mLevels;

examples/corelib/serialization/savegame/level.cpp

@@ -57,12 +57,12 @@ QJsonObject Level::toJson() const
 }
 //! [toJson]
 
-void Level::print(int indentation) const
+void Level::print(QTextStream &s, int indentation) const
 {
     const QString indent(indentation * 2, ' ');
-    QTextStream(stdout) << indent << "Name:\t" << mName << "\n";
 
-    QTextStream(stdout) << indent << "NPCs:\n";
+    s << indent << "Name:\t" << mName << "\n"
+      << indent << "NPCs:\n";
     for (const Character &character : mNpcs)
-        character.print(2);
+        character.print(s, indentation + 1);
 }

examples/corelib/serialization/savegame/level.h

@@ -9,6 +9,8 @@
 #include <QJsonObject>
 #include <QList>
 
+QT_FORWARD_DECLARE_CLASS(QTextStream)
+
 //! [0]
 class Level
 {
@@ -24,7 +26,7 @@ public:
     static Level fromJson(const QJsonObject &json);
     QJsonObject toJson() const;
 
-    void print(int indentation = 0) const;
+    void print(QTextStream &s, int indentation = 0) const;
 private:
     QString mName;
     QList<Character> mNpcs;

examples/corelib/serialization/savegame/main.cpp

@@ -29,8 +29,9 @@ int main(int argc, char *argv[])
     // Game is played; changes are made...
 //! [0]
 //! [1]
-    QTextStream(stdout) << "Game ended in the following state:\n";
-    game.print();
+    QTextStream s(stdout);
+    s << "Game ended in the following state:\n";
+    game.print(s);
     if (!game.saveGame(json ? Game::Json : Game::Binary))
         return 1;