Modify the MDI manual test to allow multiple views of same document

- editing same document in different views is possible? yes
- resizing one QTextEdit calls QTextDocument::setTextWidth(), which
  affects the width in the other view too. You can resize either one,
  but you can't have two views with different layouts, of course.

Added a categorized log message in QTextDocument::setTextWidth()
for a sanity check.

Task-nunber: QTBUG-35688
Change-Id: I59c4d10143fda3a66b946237832274d67f9d9d45
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

src/gui/text/qtextdocument.cpp

@@ -11,6 +11,7 @@
 #include "qtexttable.h"
 #include "qtextlist.h"
 #include <qdebug.h>
+#include <qloggingcategory.h>
 #if QT_CONFIG(regularexpression)
 #include <qregularexpression.h>
 #endif
@@ -42,6 +43,8 @@
 
 QT_BEGIN_NAMESPACE
 
+Q_DECLARE_LOGGING_CATEGORY(lcLayout);
+
 using namespace Qt::StringLiterals;
 
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION unsigned int qt_int_sqrt(unsigned int n);
@@ -727,6 +730,8 @@ void QTextDocument::setTextWidth(qreal width)
 {
     Q_D(QTextDocument);
     QSizeF sz = d->pageSize;
+
+    qCDebug(lcLayout) << "page size" << sz << "-> width" << width;
     sz.setWidth(width);
     sz.setHeight(-1);
     setPageSize(sz);

tests/manual/examples/widgets/mainwindows/mdi/mainwindow.cpp

@@ -74,6 +74,12 @@ bool MainWindow::loadFile(const QString &fileName)
     return succeeded;
 }
 
+void MainWindow::newSubWindow()
+{
+    MdiChild *child = createMdiChild(static_cast<MdiChild *>(mdiArea->activeSubWindow()->widget()));
+    child->show();
+}
+
 static inline QString recentFilesKey() { return QStringLiteral("recentFileList"); }
 static inline QString fileKey() { return QStringLiteral("file"); }
 
@@ -201,6 +207,7 @@ void MainWindow::updateMenus()
 #ifndef QT_NO_CLIPBOARD
     pasteAct->setEnabled(hasMdiChild);
 #endif
+    newWindowAct->setEnabled(hasMdiChild);
     closeAct->setEnabled(hasMdiChild);
     closeAllAct->setEnabled(hasMdiChild);
     tileAct->setEnabled(hasMdiChild);
@@ -220,6 +227,7 @@ void MainWindow::updateMenus()
 void MainWindow::updateWindowMenu()
 {
     windowMenu->clear();
+    windowMenu->addAction(newWindowAct);
     windowMenu->addAction(closeAct);
     windowMenu->addAction(closeAllAct);
     windowMenu->addSeparator();
@@ -253,9 +261,9 @@ void MainWindow::updateWindowMenu()
     }
 }
 
-MdiChild *MainWindow::createMdiChild()
+MdiChild *MainWindow::createMdiChild(MdiChild *other)
 {
-    MdiChild *child = new MdiChild;
+    MdiChild *child = new MdiChild(other);
     mdiArea->addSubWindow(child);
 
 #ifndef QT_NO_CLIPBOARD
@@ -365,6 +373,11 @@ void MainWindow::createActions()
     windowMenu = menuBar()->addMenu(tr("&Window"));
     connect(windowMenu, &QMenu::aboutToShow, this, &MainWindow::updateWindowMenu);
 
+    newWindowAct = new QAction(tr("&New view"), this);
+    newWindowAct->setStatusTip(tr("Make another window viewing the same document"));
+    connect(newWindowAct, &QAction::triggered,
+            this, &MainWindow::newSubWindow);
+
     closeAct = new QAction(tr("Cl&ose"), this);
     closeAct->setStatusTip(tr("Close the active window"));
     connect(closeAct, &QAction::triggered,

tests/manual/examples/widgets/mainwindows/mdi/mainwindow.h

@@ -12,6 +12,7 @@ class QAction;
 class QMenu;
 class QMdiArea;
 class QMdiSubWindow;
+class QTextDocument;
 QT_END_NAMESPACE
 
 class MainWindow : public QMainWindow
@@ -41,8 +42,9 @@ private slots:
     void about();
     void updateMenus();
     void updateWindowMenu();
-    MdiChild *createMdiChild();
+    MdiChild *createMdiChild(MdiChild *other = nullptr);
     void switchLayoutDirection();
+    void newSubWindow();
 
 private:
     enum { MaxRecentFiles = 5 };
@@ -72,6 +74,7 @@ private:
     QAction *copyAct;
     QAction *pasteAct;
 #endif
+    QAction *newWindowAct;
     QAction *closeAct;
     QAction *closeAllAct;
     QAction *tileAct;

tests/manual/examples/widgets/mainwindows/mdi/mdichild.cpp

@@ -5,10 +5,18 @@
 
 #include "mdichild.h"
 
-MdiChild::MdiChild()
+MdiChild::MdiChild(MdiChild *other)
 {
     setAttribute(Qt::WA_DeleteOnClose);
-    isUntitled = true;
+    if (other) {
+        auto *doc = other->document();
+        setDocument(doc);
+        setWindowModified(other->isWindowModified());
+        connect(doc, &QTextDocument::contentsChanged,
+                this, &MdiChild::documentWasModified);
+        curFile = other->curFile;
+        setWindowTitle(userFriendlyCurrentFile() + "[*]");
+    }
 }
 
 void MdiChild::newFile()

tests/manual/examples/widgets/mainwindows/mdi/mdichild.h

@@ -11,7 +11,7 @@ class MdiChild : public QTextEdit
     Q_OBJECT
 
 public:
-    MdiChild();
+    MdiChild(MdiChild *other = nullptr);
 
     void newFile();
     bool loadFile(const QString &fileName);
@@ -33,7 +33,7 @@ private:
     QString strippedName(const QString &fullFileName);
 
     QString curFile;
-    bool isUntitled;
+    bool isUntitled = true;
 };
 
 #endif