Help: Cleanly separate different viewer backends

Removes the conditional compilation of the text browser vs web kit,
cleans up the code, and enables us to provide and test other backends
(WebEngine? Native?)
Adds runtime switch for testing the text browser variant by setting
environment variable QTC_FORCE_TEXTBROWSER (for now)

Change-Id: I8cc9bb373438d37c8194e433224314caa0b617bd
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/help/qtwebkithelpviewer.h

@@ -0,0 +1,165 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+****************************************************************************/
+
+#ifndef QTWEBKITHELPVIEWER_H
+#define QTWEBKITHELPVIEWER_H
+
+#include "helpviewer.h"
+
+#ifndef QT_NO_WEBKIT
+
+#include <QWebPage>
+#include <QWebView>
+
+namespace Help {
+namespace Internal {
+
+class HelpPage;
+class QtWebKitHelpWidget;
+
+class QtWebKitHelpViewer : public HelpViewer
+{
+    Q_OBJECT
+public:
+    explicit QtWebKitHelpViewer(qreal zoom, QWidget *parent = 0);
+    ~QtWebKitHelpViewer() { }
+
+    QFont viewerFont() const;
+    void setViewerFont(const QFont &font);
+
+    void scaleUp();
+    void scaleDown();
+    void resetScale();
+    qreal scale() const;
+
+    QString title() const;
+    void setTitle(const QString &title);
+
+    QUrl source() const;
+    void setSource(const QUrl &url);
+    void scrollToAnchor(const QString &anchor);
+    void highlightId(const QString &id);
+
+    void setHtml(const QString &html);
+
+    QString selectedText() const;
+    bool isForwardAvailable() const;
+    bool isBackwardAvailable() const;
+    void addBackHistoryItems(QMenu *backMenu);
+    void addForwardHistoryItems(QMenu *forwardMenu);
+    void setOpenInNewWindowActionVisible(bool visible);
+
+    bool findText(const QString &text, Core::FindFlags flags,
+        bool incremental, bool fromSearch, bool *wrapped = 0);
+
+    HelpPage *page() const;
+
+public slots:
+    void copy();
+    void stop();
+    void forward();
+    void backward();
+    void print(QPrinter *printer);
+
+private slots:
+    void goToBackHistoryItem();
+    void goToForwardHistoryItem();
+    void goToHistoryItem(bool forward);
+
+private:
+    QString m_oldHighlightId;
+    QString m_oldHighlightStyle;
+    QtWebKitHelpWidget *m_webView;
+};
+
+class QtWebKitHelpWidget : public QWebView
+{
+    Q_OBJECT
+
+public:
+    explicit QtWebKitHelpWidget(qreal zoom, QtWebKitHelpViewer *parent = 0);
+    ~QtWebKitHelpWidget();
+
+    void scaleUp();
+    void scaleDown();
+
+public slots:
+    void copy();
+
+signals:
+    void forwardAvailable(bool enabled);
+    void backwardAvailable(bool enabled);
+
+protected:
+    void keyPressEvent(QKeyEvent *e);
+    void wheelEvent(QWheelEvent *event);
+    void mousePressEvent(QMouseEvent *event);
+    void mouseReleaseEvent(QMouseEvent *event);
+
+private slots:
+    void actionChanged();
+    void slotNetworkReplyFinished(QNetworkReply *reply);
+
+private:
+    bool eventFilter(QObject *obj, QEvent *event);
+
+    QtWebKitHelpViewer *m_parent;
+};
+
+class HelpPage : public QWebPage
+{
+    Q_OBJECT
+public:
+    HelpPage(QObject *parent);
+
+protected:
+    virtual QWebPage *createWindow(QWebPage::WebWindowType);
+    virtual void triggerAction(WebAction action, bool checked = false);
+
+    virtual bool acceptNavigationRequest(QWebFrame *frame,
+        const QNetworkRequest &request, NavigationType type);
+
+private slots:
+    void onHandleUnsupportedContent(QNetworkReply *reply);
+
+private:
+    QUrl m_loadingUrl;
+    bool closeNewTabIfNeeded;
+
+    friend class Help::Internal::QtWebKitHelpWidget;
+    Qt::MouseButtons m_pressedButtons;
+    Qt::KeyboardModifiers m_keyboardModifiers;
+};
+
+}   // namespace Internal
+}   // namespace Help
+
+#endif // !QT_NO_WEBKIT
+
+#endif // QTWEBKITHELPVIEWER_H