linguist: preview QML files with translation

If a translation file corresponds to a Qml document, show a preview
of the qml document that contains the translations.

Knwon limitations:
- arguments in texts: "Hello %1"
	linguist can only see the runtime version of the string
	and fails to match it with an existing message in TS file.
- items in comboboxes:
	This needs a bit of more implementation (possibly next iterations),
	since combobox stores items in the "model" property,
	rather than "text". Also if implemented, it will not be
	available to .qml files, but only provides
	support for .ui.qml files. Since normal Qml files are opened
	in a frozen state (no interactions with the form, hence
	comboboxes cannot expand), to prevent executing operations
	of the Qml document whose logic is unknown to linguist.
- Qml item "ApplicationWindow" not supported:
	It needs a whole QQmlApplicationEngine. A normal QQuickWidget
	cannot contain it.
- Missing Qml plugins:
	if some required Qml plugins are missing, the document cannot
	be displayed. This patch contains some changes in the cmake file
	to add the Qml plugins in QtDeclarative as dependencies, so most
	used plugins are supported.

If due to the limitations above (or other limitations), a document
cannot be viewed reasonably, the user has always the choice to fall
back to the source code by toggling views->Preview Qml (then it
will be same as before).
Additionally, if there are some
errors in showing the Qml document (e.g., due to missing Qml
plugins), the editor automatically falls back to the source code.

Fixes: QTBUG-71161
Change-Id: I3dc4ac741b8be31ef96fd5bd9f5a13e1251a8ce1
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

Author: gongotar

CMakeLists.txt

@@ -21,7 +21,7 @@ endif()
 find_package(Qt6 ${PROJECT_VERSION} CONFIG REQUIRED COMPONENTS BuildInternals Core)
 find_package(Qt6 ${PROJECT_VERSION} QUIET CONFIG OPTIONAL_COMPONENTS
              DBus Network Xml Widgets Quick QuickWidgets Qml QmlLSPrivate
-             Sql PrintSupport OpenGL OpenGLWidgets ${optional_components})
+             Sql PrintSupport OpenGL OpenGLWidgets QuickLayouts ${optional_components})
 qt_internal_project_setup()
 
 qt_build_repo()

src/linguist/CMakeLists.txt

@@ -16,7 +16,7 @@ add_subdirectory(lupdate)
 add_subdirectory(lupdate-pro)
 if(QT_FEATURE_process AND QT_FEATURE_pushbutton AND QT_FEATURE_toolbutton
     AND QT_FEATURE_png AND QT_FEATURE_mdiarea AND QT_FEATURE_syntaxhighlighter
-    AND TARGET Qt::Widgets)
+    AND TARGET Qt::Widgets AND TARGET Qt::Quick)
     add_subdirectory(linguist)
 endif()
 

src/linguist/linguist/CMakeLists.txt

@@ -21,7 +21,8 @@ qt_internal_add_app(linguist
         batchtranslationdialog.cpp batchtranslationdialog.h
         errorsview.cpp errorsview.h
         finddialog.cpp finddialog.h finddialog.ui
-        formpreviewview.cpp formpreviewview.h
+        uiformpreviewview.cpp uiformpreviewview.h
+        qmlformpreviewview.h qmlformpreviewview.cpp
         globals.cpp globals.h
         main.cpp
         mainwindow.cpp mainwindow.h mainwindow.ui
@@ -52,6 +53,8 @@ qt_internal_add_app(linguist
         Qt::GuiPrivate
         Qt::UiToolsPrivate
         Qt::Widgets
+        Qt::QuickWidgets
+        Qt::QuickLayouts
 )
 
 qt_internal_extend_target(linguist CONDITION QT_FEATURE_printsupport
@@ -61,6 +64,48 @@ qt_internal_extend_target(linguist CONDITION QT_FEATURE_printsupport
         Qt::PrintSupport
 )
 
+set(available_plugins "")
+
+set(plugin_targets
+    Qt::qtquickcontrols2plugin
+    Qt::qtquick2plugin
+    Qt::qtquickdialogsplugin
+    Qt::qtquickcontrols2universalstyleplugin
+    Qt::qtquickcontrols2basicstyleplugin
+    Qt::qtquickcontrols2fluentwinui3styleplugin
+    Qt::qtquickcontrols2fusionstyleplugin
+    Qt::qtquickcontrols2imaginestyleplugin
+    Qt::qtquickcontrols2iosstyleplugin
+    Qt::qtquickcontrols2macosstyleplugin
+    Qt::qtquickcontrols2materialstyleplugin
+    Qt::qtquicktemplates2plugin
+    Qt::qtquickcontrols2implplugin
+    Qt::qtquickdialogs2quickimplplugin
+    Qt::qtquickcontrols2universalstyleimplplugin
+    Qt::qtquickcontrols2basicstyleimplplugin
+    Qt::qtquickcontrols2fluentwinui3styleimplplugin
+    Qt::qtquickcontrols2fusionstyleimplplugin
+    Qt::qtquickcontrols2imaginestyleimplplugin
+    Qt::qtquickcontrols2iosstyleimplplugin
+    Qt::qtquickcontrols2macosstyleimplplugin
+    Qt::qtquickcontrols2materialstyleimplplugin
+    Qt::quickwindow
+)
+
+foreach(plugin ${plugin_targets})
+    if(TARGET ${plugin})
+        list(APPEND available_plugins ${plugin})
+    endif()
+endforeach()
+
+if (available_plugins)
+    if(BUILD_SHARED_LIBS)
+        add_dependencies(linguist ${available_plugins})
+    else()
+        qt_internal_extend_target(linguist LIBRARIES ${available_plugins})
+    endif()
+endif()
+
 qt_add_ui(linguist
     SOURCES
         batchtranslation.ui

src/linguist/linguist/mainwindow.cpp

@@ -11,7 +11,8 @@
 #include "batchtranslationdialog.h"
 #include "errorsview.h"
 #include "finddialog.h"
-#include "formpreviewview.h"
+#include "uiformpreviewview.h"
+#include "qmlformpreviewview.h"
 #include "globals.h"
 #include "messageeditor.h"
 #include "messagemodel.h"
@@ -73,6 +74,16 @@ enum Ending {
     End_Ellipsis
 };
 
+static bool hasUiFormPreview(const QString &fileName)
+{
+    return fileName.endsWith(".ui"_L1) || fileName.endsWith(".jui"_L1);
+}
+
+static bool hasQmlFormPreview(const QString &fileName, bool qmlPreviewChecked)
+{
+    return fileName.endsWith(QLatin1String(".qml")) && qmlPreviewChecked;
+}
+
 static QString leadingWhitespace(const QString &str)
 {
     int i = 0;
@@ -299,11 +310,6 @@ struct Validator
 
 static const int MessageMS = 2500;
 
-static bool hasFormPreview(const QString &fileName)
-{
-    return fileName.endsWith(".ui"_L1) || fileName.endsWith(".jui"_L1);
-}
-
 } // namespace
 
 QT_BEGIN_NAMESPACE
@@ -484,10 +490,12 @@ MainWindow::MainWindow()
     m_sourceAndFormDock->setWindowTitle(tr("Sources and Forms"));
     m_sourceAndFormView = new QStackedWidget(this);
     m_sourceAndFormDock->setWidget(m_sourceAndFormView);
-    m_formPreviewView = new FormPreviewView(0, m_dataModel);
+    m_uiFormPreviewView = new UiFormPreviewView(0, m_dataModel);
+    m_qmlFormPreviewView = new QmlFormPreviewView(m_dataModel);
     m_sourceCodeView = new SourceCodeView(0);
     m_sourceAndFormView->addWidget(m_sourceCodeView);
-    m_sourceAndFormView->addWidget(m_formPreviewView);
+    m_sourceAndFormView->addWidget(m_uiFormPreviewView);
+    m_sourceAndFormView->addWidget(m_qmlFormPreviewView);
 
     // Set up errors dock widget
     m_errorsDock = new QDockWidget(this);
@@ -684,7 +692,8 @@ void MainWindow::modelCountChanged()
     m_ui.actionFindNext->setEnabled(false);
     m_ui.actionFindPrev->setEnabled(false);
 
-    m_formPreviewView->setSourceContext(-1, 0);
+    m_uiFormPreviewView->setSourceContext(-1, 0);
+    m_qmlFormPreviewView->setSourceContext(-1, 0);
 }
 
 struct OpenedFile {
@@ -1662,8 +1671,11 @@ void MainWindow::translationChanged(const MultiDataIndex &index)
     updateDanger(index, true);
 
     MessageItem *m = m_dataModel->messageItem(index);
-    if (hasFormPreview(m->fileName()))
-        m_formPreviewView->setSourceContext(index.model(), m);
+    if (hasUiFormPreview(m->fileName()))
+        m_uiFormPreviewView->setSourceContext(index.model(), m);
+    else if (hasQmlFormPreview(m->fileName(), m_ui.actionQmlPreview->isChecked()))
+        if (!m_qmlFormPreviewView->setSourceContext(index.model(), m))
+            m_ui.actionQmlPreview->setChecked(false);
 }
 
 // This and the following function operate directly on the messageitem,
@@ -1677,8 +1689,12 @@ void MainWindow::updateTranslation(const QStringList &translations)
         return;
 
     m->setTranslations(translations);
-    if (!m->fileName().isEmpty() && hasFormPreview(m->fileName()))
-        m_formPreviewView->setSourceContext(m_currentIndex.model(), m);
+    if (!m->fileName().isEmpty() && hasUiFormPreview(m->fileName()))
+        m_uiFormPreviewView->setSourceContext(m_currentIndex.model(), m);
+    else if (!m->fileName().isEmpty()
+             && hasQmlFormPreview(m->fileName(), m_ui.actionQmlPreview->isChecked()))
+        if (!m_qmlFormPreviewView->setSourceContext(m_currentIndex.model(), m))
+            m_ui.actionQmlPreview->setChecked(false);
     updateDanger(m_currentIndex, true);
 
     if (m->isFinished())
@@ -2083,8 +2099,9 @@ void MainWindow::setupMenuBar()
     connect(m_ui.actionDisplayGuesses, &QAction::triggered,
             m_phraseView, &PhraseView::toggleGuessing);
     connect(m_ui.actionStatistics, &QAction::triggered, this, &MainWindow::showStatistics);
-    connect(m_ui.actionVisualizeWhitespace, &QAction::triggered, this,
-            &MainWindow::toggleVisualizeWhitespace);
+    connect(m_ui.actionQmlPreview, &QAction::triggered, this, &MainWindow::toggleQmlPreview);
+    connect(m_ui.actionVisualizeWhitespace, &QAction::triggered,
+            this, &MainWindow::toggleVisualizeWhitespace);
     connect(m_ui.actionIncreaseZoom, &QAction::triggered,
             m_messageEditor, &MessageEditor::increaseFontSize);
     connect(m_ui.actionDecreaseZoom, &QAction::triggered,
@@ -2189,10 +2206,14 @@ void MainWindow::doUpdateLatestModel(int model)
 void MainWindow::updateSourceView(int model, MessageItem *item)
 {
     if (item && !item->fileName().isEmpty()) {
-        if (hasFormPreview(item->fileName())) {
-            m_sourceAndFormView->setCurrentWidget(m_formPreviewView);
-            m_formPreviewView->setSourceContext(model, item);
+        if (hasUiFormPreview(item->fileName())) {
+            m_sourceAndFormView->setCurrentWidget(m_uiFormPreviewView);
+            m_uiFormPreviewView->setSourceContext(model, item);
+        } else if (hasQmlFormPreview(item->fileName(), m_ui.actionQmlPreview->isChecked())
+                   && m_qmlFormPreviewView->setSourceContext(model, item)) {
+            m_sourceAndFormView->setCurrentWidget(m_qmlFormPreviewView);
         } else {
+            m_ui.actionQmlPreview->setChecked(false);
             m_sourceAndFormView->setCurrentWidget(m_sourceCodeView);
             QDir dir = QFileInfo(m_dataModel->srcFileName(model)).dir();
             QString fileName = QDir::cleanPath(dir.absoluteFilePath(item->fileName()));
@@ -2733,6 +2754,14 @@ void MainWindow::showStatistics()
     updateStatistics();
 }
 
+void MainWindow::toggleQmlPreview()
+{
+    if (m_ui.actionQmlPreview->isChecked())
+        m_sourceAndFormView->setCurrentWidget(m_qmlFormPreviewView);
+    else
+        m_sourceAndFormView->setCurrentWidget(m_sourceCodeView);
+}
+
 void MainWindow::toggleVisualizeWhitespace()
 {
     m_messageEditor->setVisualizeWhitespace(m_ui.actionVisualizeWhitespace->isChecked());

src/linguist/linguist/mainwindow.h

@@ -36,7 +36,8 @@ class QTreeView;
 class BatchTranslationDialog;
 class ErrorsView;
 class FocusWatcher;
-class FormPreviewView;
+class UiFormPreviewView;
+class QmlFormPreviewView;
 class MessageEditor;
 class PhraseView;
 class SourceCodeView;
@@ -129,6 +130,7 @@ private slots:
                   FindDialog::FindOptions options, int statusFilter);
     void revalidate();
     void showStatistics();
+    void toggleQmlPreview();
     void toggleVisualizeWhitespace();
     void onWhatsThis();
     void updatePhraseDicts();
@@ -193,7 +195,8 @@ private slots:
     PhraseView *m_phraseView;
     QStackedWidget *m_sourceAndFormView;
     SourceCodeView *m_sourceCodeView;
-    FormPreviewView *m_formPreviewView;
+    UiFormPreviewView *m_uiFormPreviewView;
+    QmlFormPreviewView *m_qmlFormPreviewView;
     ErrorsView *m_errorsView;
     QLabel *m_progressLabel;
     QLabel *m_modifiedLabel;

src/linguist/linguist/mainwindow.ui

@@ -97,6 +97,7 @@
     </widget>
     <addaction name="actionResetSorting"/>
     <addaction name="actionDisplayGuesses"/>
+    <addaction name="actionQmlPreview"/>
     <addaction name="actionLengthVariants"/>
     <addaction name="actionVisualizeWhitespace"/>
     <addaction name="separator"/>
@@ -645,6 +646,23 @@
     <enum>QAction::NoRole</enum>
    </property>
   </action>
+  <action name="actionQmlPreview">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="checked">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>&amp;QML preview</string>
+   </property>
+   <property name="whatsThis">
+    <string>Display a preview of QML documents.</string>
+   </property>
+   <property name="menuRole">
+    <enum>QAction::NoRole</enum>
+   </property>
+  </action>
   <action name="actionManual">
    <property name="text">
     <string>&amp;Manual</string>

src/linguist/linguist/qmlformpreviewview.cpp

@@ -0,0 +1,110 @@
+// Copyright (C) 2025 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#include "qmlformpreviewview.h"
+
+#include "messagemodel.h"
+
+#include <QDir>
+#include <QQuickWidget>
+#include <QApplication>
+#include <QVBoxLayout>
+#include <QQuickItem>
+#include <QHash>
+#include <QMessageBox>
+
+using namespace Qt::Literals::StringLiterals;
+
+namespace {
+
+void traverseQml(QObject *obj, QHash<QString, QList<QObject *>> &targets)
+{
+    if (obj) {
+        if (QVariant text = obj->property("text"); text.isValid()) {
+            if (auto itr = targets.find(text.toString()); itr != targets.end()) {
+                itr->append(obj);
+                return;
+            }
+        }
+        for (QObject *child : obj->children())
+            traverseQml(child, targets);
+    }
+}
+
+void matchSources(QQuickItem *root, QHash<QString, QList<QObject *>> &targets)
+{
+    traverseQml(root, targets);
+}
+
+ContextItem *getContext(const DataModel *m, const QString &contextName)
+{
+    for (int i = 0; i < m->contextCount(); i++)
+        if (auto ctx = m->contextItem(i); ctx->context() == contextName)
+            return ctx;
+    Q_UNREACHABLE_RETURN(nullptr);
+}
+
+QHash<QString, QList<QObject *>> extractSources(const DataModel *m, const QString &contextName)
+{
+    QHash<QString, QList<QObject *>> t;
+    ContextItem *ctx = getContext(m, contextName);
+    for (int j = 0; j < ctx->messageCount(); j++)
+        t[ctx->messageItem(j)->text()] = {};
+    return t;
+}
+} // namespace
+
+QT_BEGIN_NAMESPACE
+
+QmlFormPreviewView::QmlFormPreviewView(MultiDataModel *dataModel)
+    : QQuickWidget(0), m_dataModel(dataModel) {}
+
+bool QmlFormPreviewView::setSourceContext(int model, MessageItem *messageItem)
+{
+    if (model < 0 || !messageItem) {
+        m_lastModel = -1;
+        return true;
+    }
+    const QDir dir = QFileInfo(m_dataModel->srcFileName(model)).dir();
+    const QString fileName = QDir::cleanPath(dir.absoluteFilePath(messageItem->fileName()));
+    if (m_lastFormName != fileName) {
+        m_lastFormName = fileName;
+
+        setAttribute(Qt::WA_TransparentForMouseEvents, !fileName.endsWith(".ui.qml"_L1));
+
+        setSource(QUrl::fromLocalFile(fileName));
+        if (!errors().empty()) {
+            QString errs;
+            for (const auto &error : errors())
+                errs += error.toString() + "\n"_L1;
+            QMessageBox::warning(this, tr("Qt Linguist"),
+                                 tr("Error loading QML file: %1").arg(errs));
+            m_lastError = true;
+            return false;
+        }
+
+        m_targets = extractSources(m_dataModel->model(model), messageItem->context());
+        matchSources(rootObject(), m_targets);
+
+        setResizeMode(SizeViewToRootObject);
+        show();
+    } else if (m_lastError) {
+        return false;
+    }
+    if (m_lastModel != model) {
+        ContextItem *ctx = getContext(m_dataModel->model(model), messageItem->context());
+        for (int i = 0; i < ctx->messageCount(); i++) {
+            MessageItem *message = ctx->messageItem(i);
+            for (QObject *item : std::as_const(m_targets[message->text()]))
+                item->setProperty("text", message->translation());
+        }
+        m_lastModel = model;
+    } else {
+        for (QObject *item : std::as_const(m_targets[messageItem->text()]))
+            item->setProperty("text", messageItem->translation());
+    }
+    m_lastError = false;
+    return true;
+}
+
+QT_END_NAMESPACE