feat(editor): 增加MD文件预览功能

src/controls/settingsdialog.cpp

@@ -38,12 +38,13 @@
     auto shortcuts_window_jumptolineName = QObject::tr("Go to line");
     auto shortcuts_window_savepositionName = QObject::tr("Save cursor position");
     auto shortcuts_window_restorepositionName = QObject::tr("Reset cursor position");
     auto shortcuts_window_escapeName = QObject::tr("Exit");
     auto shortcuts_window_displayshortcutsName = QObject::tr("Display shortcuts");
     auto shortcuts_window_printName = QObject::tr("Print");
+    auto shortcuts_window_togglemarkdownpreviewName = QObject::tr("Toggle markdown preview");
     auto group_editorName = QObject::tr("Editor");
     auto shortcuts_editor_indentlineName = QObject::tr("Increase indent");
     auto shortcuts_editor_backindentlineName = QObject::tr("Decrease indent");
     auto shortcuts_editor_forwardcharName = QObject::tr("Forward character");
     auto shortcuts_editor_backwardcharName = QObject::tr("Backward character");
     auto shortcuts_editor_forwardwordName = QObject::tr("Forward word");

src/editor/editwrapper.cpp

@@ -4,9 +4,10 @@
 
 #include "editwrapper.h"
 #include "leftareaoftextedit.h"
+#include "markdownpreview.h"
 #include "drecentmanager.h"
 
 #include <unistd.h>
 
 #include <QCoreApplication>
 #include <QApplication>
@@ -15,9 +16,10 @@
 #include <QScroller>
 #include <QDebug>
 #include <QTimer>
 #include <QDir>
 #include <QFileInfo>
 #include <QEvent>
+#include <QSplitter>
 
 #include <DSettings>
 #include <DSettingsOption>
@@ -103,16 +105,41 @@
     m_pTextEdit->setAccessibleName("TextEditor");
     m_pBottomBar->setAccessibleName("EditorBottomBar");
     // Init layout and widgets.
-    QHBoxLayout *m_layout = new QHBoxLayout;
     m_pLeftAreaTextEdit = m_pTextEdit->getLeftAreaWidget();
-    m_layout->setContentsMargins(0, 0, 0, 0);
-    m_layout->setSpacing(0);
-    m_layout->addWidget(m_pLeftAreaTextEdit);
-    m_layout->addWidget(m_pTextEdit);
     m_pTextEdit->setWrapper(this);
 
+    // 编辑器容器：行号/标记区 + 文本编辑区，保持原有布局
+    QWidget *editorContainer = new QWidget(this);
+    QHBoxLayout *editorLayout = new QHBoxLayout(editorContainer);
+    editorLayout->setContentsMargins(0, 0, 0, 0);
+    editorLayout->setSpacing(0);
+    editorLayout->addWidget(m_pLeftAreaTextEdit);
+    editorLayout->addWidget(m_pTextEdit);
+
+    // 编辑区与 Markdown 预览分栏，默认只显示编辑区
+    m_pEditSplitter = new QSplitter(Qt::Horizontal, this);
+    m_pEditSplitter->setObjectName("EditSplitter");
+    m_pEditSplitter->setChildrenCollapsible(false);
+    m_pEditSplitter->setHandleWidth(1);
+    m_pEditSplitter->addWidget(editorContainer);
+    m_pEditSplitter->setStretchFactor(0, 1);
+
+    // Qt5 构建下预览不可用（QTextDocument::setMarkdown 需要 Qt >= 6.5）
+    if (MarkdownPreview::isSupported()) {
+        m_pMarkdownPreview = new MarkdownPreview(this);
+        m_pMarkdownPreview->setVisible(false);
+        m_pEditSplitter->addWidget(m_pMarkdownPreview);
+        m_pEditSplitter->setStretchFactor(1, 1);
+        // 编辑内容变化时实时刷新预览
+        connect(m_pTextEdit, &QPlainTextEdit::textChanged, this, [this]() {
+            if (m_pMarkdownPreview != nullptr && m_pMarkdownPreview->isVisible()) {
+                m_pMarkdownPreview->updatePreview(m_pTextEdit->toPlainText());
+            }
+        });
+    }
+
     QVBoxLayout *mainLayout = new QVBoxLayout;
-    mainLayout->addLayout(m_layout);
+    mainLayout->addWidget(m_pEditSplitter);
     mainLayout->addWidget(m_pBottomBar);
     mainLayout->setContentsMargins(0, 0, 0, 0);
     mainLayout->setSpacing(0);
@@ -780,6 +807,10 @@
     qDebug() << "EditWrapper updatePath, m_pTextEdit->setFilePath(file)";
     m_pTextEdit->setTruePath(qstrTruePath);
     qDebug() << "EditWrapper updatePath, m_pTextEdit->setTruePath(qstrTruePath)";
+    // Markdown 文件打开时自动显示可视化预览
+    if (m_pMarkdownPreview != nullptr) {
+        setMarkdownPreviewVisible(MarkdownPreview::isMarkdownFile(file));
+    }
 }
 
 bool EditWrapper::isModified()
@@ -1482,6 +1513,27 @@
     return  m_pTextEdit->getFilePath();
 }
 
+void EditWrapper::setMarkdownPreviewVisible(bool visible)
+{
+    if (m_pMarkdownPreview == nullptr) {
+        return;
+    }
+    m_pMarkdownPreview->setVisible(visible);
+    if (visible) {
+        m_pMarkdownPreview->updatePreview(m_pTextEdit->toPlainText());
+        // 保证初次显示时左右分栏比例合理（编辑区 55% / 预览 45%）
+        if (m_pEditSplitter != nullptr && m_pEditSplitter->width() > 0) {
+            const int total = m_pEditSplitter->width();
+            m_pEditSplitter->setSizes({total * 55 / 100, total * 45 / 100});
+        }
+    }
+}
+
+bool EditWrapper::isMarkdownPreviewVisible() const
+{
+    return m_pMarkdownPreview != nullptr && m_pMarkdownPreview->isVisible();
+}
+
 TextEdit *EditWrapper::textEditor()
 {
     qDebug() << "EditWrapper textEditor";

src/editor/editwrapper.h

@@ -26,6 +26,8 @@
 #include <KSyntaxHighlighting/Theme>
 
 class Window;
+class MarkdownPreview;
+class QSplitter;
 class EditWrapper : public QWidget
 {
     Q_OBJECT
@@ -108,6 +110,10 @@ class EditWrapper : public QWidget
     Window *window();
     void updateHighlighterAll();
 
+    // Markdown 可视化预览开关（Qt5 构建下预览不可用，调用无效果）
+    void setMarkdownPreviewVisible(bool visible);
+    bool isMarkdownPreviewVisible() const;
+
     //get and set m_tModifiedDateTime
     QDateTime getLastModifiedTime() const;
     void setLastModifiedTime(const QString &time);
@@ -175,6 +181,10 @@ public slots:
     BottomBar *m_pBottomBar = nullptr;
     //
     WarningNotices *m_pWaringNotices = nullptr;
+    //
+    MarkdownPreview *m_pMarkdownPreview = nullptr;
+    // 编辑区与 Markdown 预览的分栏容器
+    QSplitter *m_pEditSplitter = nullptr;
 
     QDateTime m_tModifiedDateTime;
     //退出

src/editor/markdownpreview.cpp

@@ -0,0 +1,65 @@
+// SPDX-FileCopyrightText: 2026 UnionTech Software Technology Co., Ltd.
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "markdownpreview.h"
+
+#include <QFileInfo>
+#include <QTextDocument>
+#include <QUrl>
+
+MarkdownPreview::MarkdownPreview(QWidget *parent)
+    : QTextBrowser(parent)
+{
+    setAccessibleName("MarkdownPreviewView");
+    setFrameShape(QFrame::NoFrame);
+    setOpenLinks(false);
+    setOpenExternalLinks(false);
+    setReadOnly(true);
+}
+
+bool MarkdownPreview::isSupported()
+{
+#if QT_VERSION >= QT_VERSION_CHECK(6, 5, 0)
+    return true;
+#else
+    return false;
+#endif
+}
+
+bool MarkdownPreview::isMarkdownFile(const QString &filePath)
+{
+    const QString suffix = QFileInfo(filePath).suffix().toLower();
+    return suffix == QStringLiteral("md") || suffix == QStringLiteral("markdown");
+}
+
+void MarkdownPreview::updatePreview(const QString &markdown)
+{
+#if QT_VERSION >= QT_VERSION_CHECK(6, 5, 0)
+    QTextDocument *newDoc = new QTextDocument(this);
+    // 主题无关的基础样式：标题分级 + 等宽代码，颜色随应用调色板自适应
+    newDoc->setDefaultStyleSheet(QStringLiteral(
+        "h1 { font-size: 26px; font-weight: 600; }"
+        "h2 { font-size: 22px; font-weight: 600; }"
+        "h3 { font-size: 19px; font-weight: 600; }"
+        "h4 { font-size: 16px; font-weight: 600; }"
+        "h5 { font-size: 14px; font-weight: 600; }"
+        "h6 { font-size: 13px; font-weight: 600; }"
+        "code, pre { font-family: 'monospace'; }"
+        "blockquote { margin-left: 16px; }"));
+    newDoc->setMarkdown(markdown);
+
+    // setDocument 会接管新文档（父对象为 this）并释放上一份文档，无需手动 delete
+    setDocument(newDoc);
+#else
+    Q_UNUSED(markdown)
+    setPlainText(markdown);
+#endif
+}
+
+void MarkdownPreview::doSetSource(const QUrl &url, QTextDocument::ResourceType type)
+{
+    Q_UNUSED(url)
+    Q_UNUSED(type)
+    // 预览只读，不进行链接跳转
+}

src/editor/markdownpreview.h

@@ -0,0 +1,37 @@
+// SPDX-FileCopyrightText: 2026 UnionTech Software Technology Co., Ltd.
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef MARKDOWNPREVIEW_H
+#define MARKDOWNPREVIEW_H
+
+#include <QTextBrowser>
+
+/**
+ * @brief Markdown 可视化预览控件
+ *
+ * 将 markdown 文本实时渲染为富文本展示，基于 QTextDocument::setMarkdown（Qt >= 6.5）。
+ * Qt5 构建下预览功能整体禁用（isSupported() 返回 false）。
+ */
+class MarkdownPreview : public QTextBrowser
+{
+    Q_OBJECT
+
+public:
+    explicit MarkdownPreview(QWidget *parent = nullptr);
+
+    // 当前构建是否支持 markdown 预览（需要 Qt >= 6.5）
+    static bool isSupported();
+
+    // 是否为可预览的 markdown 文件（.md / .markdown）
+    static bool isMarkdownFile(const QString &filePath);
+
+    // 以 markdown 内容刷新预览
+    void updatePreview(const QString &markdown);
+
+protected:
+    // 预览为只读展示，忽略超链接跳转
+    void doSetSource(const QUrl &url, QTextDocument::ResourceType type = QTextDocument::UnknownResource) override;
+};
+
+#endif // MARKDOWNPREVIEW_H

src/resources/settings.json

@@ -238,6 +238,12 @@
                             "name": "Print",
                             "type": "keySequenceEdit",
                             "default":  "Ctrl+P"
+                        },
+                        {
+                            "key": "togglemarkdownpreview",
+                            "name": "Toggle markdown preview",
+                            "type": "keySequenceEdit",
+                            "default":  "Ctrl+Shift+M"
                         }
                     ]
                 },

src/resources/settings.json.in

@@ -238,6 +238,12 @@
                             "name": "Print",
                             "type": "keySequenceEdit",
                             "default":  "Ctrl+P"
+                        },
+                        {
+                            "key": "togglemarkdownpreview",
+                            "name": "Toggle markdown preview",
+                            "type": "keySequenceEdit",
+                            "default":  "Ctrl+Shift+M"
                         }
                     ]
                 },

src/widgets/window.cpp

@@ -4,6 +4,7 @@
 
 #include "window.h"
 #include "pathsettintwgt.h"
+#include "../editor/markdownpreview.h"
 #include <DTitlebar>
 #include <DAnchors>
 #include <DSettingsWidgetFactory>
@@ -477,6 +478,8 @@ void Window::updateSaveAsFileName(QString strOldFilePath, QString strNewFilePath
 
     m_wrappers.remove(strOldFilePath);
     m_wrappers.insert(strNewFilePath, wrapper);
+    // 另存为可能改变文件类型，刷新 Markdown 预览开关状态
+    updateMarkdownPreviewActionState();
     qDebug() << "updateSaveAsFileName end";
 }
 
@@ -539,6 +542,11 @@ void Window::initTitlebar()
     saveAsAction->setObjectName("SaveAs");
     QAction *printAction(new QAction(tr("Print"), this));
     printAction->setObjectName("Print");
+    QAction *markdownPreviewAction(new QAction(tr("Markdown preview"), this));
+    markdownPreviewAction->setObjectName("MarkdownPreview");
+    markdownPreviewAction->setCheckable(true);
+    markdownPreviewAction->setEnabled(false);
+    m_markdownPreviewAction = markdownPreviewAction;
     QAction *switchThemeAction(new QAction(tr("Switch theme"), this));
     switchThemeAction->setObjectName("SwitchTheme");
     QAction *settingAction(new QAction(tr("Settings"), this));
@@ -557,6 +565,7 @@ void Window::initTitlebar()
     m_menu->addAction(saveAction);
     m_menu->addAction(saveAsAction);
     m_menu->addAction(printAction);
+    m_menu->addAction(markdownPreviewAction);
     //此接口不可删除，预留的编辑器内部主题选择接口
     //m_menu->addAction(switchThemeAction);
     m_menu->addSeparator();
@@ -627,6 +636,7 @@ void Window::initTitlebar()
     connect(saveAction, &QAction::triggered, this, &Window::saveFile);
     connect(saveAsAction, &QAction::triggered, this, &Window::saveAsFile);
     connect(printAction, &QAction::triggered, this, &Window::popupPrintDialog);
+    connect(markdownPreviewAction, &QAction::triggered, this, &Window::toggleMarkdownPreview);
     connect(settingAction, &QAction::triggered, this, &Window::popupSettingsDialog);
     connect(switchThemeAction, &QAction::triggered, this, &Window::popupThemePanel);
     qDebug() << "initTitlebar end";
@@ -3553,6 +3563,9 @@ void Window::handleCurrentChanged(const int &index)
         currentWrapper()->bottomBar()->show();
         currentWrapper()->bottomBar()->updateSize(BottomBar::defaultHeight(), false);
     }
+
+    // 同步 Markdown 预览菜单项状态（可用性 + 勾选状态）
+    updateMarkdownPreviewActionState();
     qDebug() << "handleCurrentChanged end";
 }
 
@@ -4515,6 +4528,9 @@ void Window::keyPressEvent(QKeyEvent *e)
     } else if (key == Utils::getKeyshortcutFromKeymap(m_settings, "window", "print")) {
         qDebug() << "key press event popup print dialog";
         popupPrintDialog();
+    } else if (key == Utils::getKeyshortcutFromKeymap(m_settings, "window", "togglemarkdownpreview")) {
+        qDebug() << "key press event toggle markdown preview";
+        toggleMarkdownPreview();
     } else {
         qDebug() << "key press event post event to window widget";
         // Post event to window widget if match Alt+0 ~ Alt+9
@@ -4654,6 +4670,29 @@ void Window::setPrintEnabled(bool enabled)
     }
 }
 
+void Window::toggleMarkdownPreview()
+{
+    EditWrapper *wrapper = currentWrapper();
+    if (wrapper == nullptr || !MarkdownPreview::isSupported()
+            || !MarkdownPreview::isMarkdownFile(wrapper->filePath())) {
+        return;
+    }
+    wrapper->setMarkdownPreviewVisible(!wrapper->isMarkdownPreviewVisible());
+    updateMarkdownPreviewActionState();
+}
+
+void Window::updateMarkdownPreviewActionState()
+{
+    if (m_markdownPreviewAction == nullptr) {
+        return;
+    }
+    EditWrapper *wrapper = currentWrapper();
+    const bool isMarkdown = (wrapper != nullptr) && MarkdownPreview::isSupported()
+            && MarkdownPreview::isMarkdownFile(wrapper->filePath());
+    m_markdownPreviewAction->setEnabled(isMarkdown);
+    m_markdownPreviewAction->setChecked(isMarkdown && wrapper->isMarkdownPreviewVisible());
+}
+
 QStackedWidget *Window::getStackedWgt()
 {
     qDebug() << "get stacked wgt";

src/widgets/window.h

@@ -102,6 +102,8 @@ class Window : public DMainWindow
     void popupThemePanel();
 
     void toggleFullscreen();
+    // Markdown 可视化预览开关（仅当前文件为 markdown 时可用）
+    void toggleMarkdownPreview();
 
     void remberPositionSave();
     void remberPositionRestore();
@@ -287,6 +289,11 @@ public Q_SLOTS:
     bool m_bBatchAddingPendingTabs = false;       // 批量添加 pending 标签页期间，阻止 handleCurrentChanged 触发加载
 
     DMenu *m_menu {nullptr};
+    // Markdown 预览开关菜单项，状态随当前标签页同步
+    QAction *m_markdownPreviewAction {nullptr};
+
+    // 刷新 Markdown 预览开关的可用性与勾选状态
+    void updateMarkdownPreviewActionState();
 
     QStringList m_closeFileHistory;