libreoffice/fpicker/source/win32/filepicker/PreviewCtrl.hxx

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 * This file is part of the LibreOffice project.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * This file incorporates work covered by the following license notice:
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements. See the NOTICE file distributed
 *   with this work for additional information regarding copyright
 *   ownership. The ASF licenses this file to you under the Apache
 *   License, Version 2.0 (the "License"); you may not use this file
 *   except in compliance with the License. You may obtain a copy of
 *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
 */

#ifndef INCLUDED_FPICKER_SOURCE_WIN32_FILEPICKER_PREVIEWCTRL_HXX
#define INCLUDED_FPICKER_SOURCE_WIN32_FILEPICKER_PREVIEWCTRL_HXX

#include <sal/types.h>
#include <rtl/ustring.hxx>

#include <comdef.h>

#include <memory>


// declaration


class CDimension
{
public:
    CDimension( ) :
        m_cx( 0 ),
        m_cy( 0 )
    {
    }

    CDimension( sal_Int32 cx, sal_Int32 cy ) :
        m_cx( cx ),
        m_cy( cy )
    {
    }

    sal_Int32 m_cx;
    sal_Int32 m_cy;
};


// we use OleInitialize here because we are calling
// some Ole functions to realize the picture preview
// and we expect to be called from the main thread
// so that there will be no problem calling
// OleInitialize (the main thread should be an STA)
// When OleInitialize should fail at worst the
// preview doesn't work


class CAutoOleInit
{
public:

    // used to communicate ole
    // initialization failures
    class COleInitException { };

    CAutoOleInit( )
    {
        HRESULT hr = OleInitialize( NULL );
        if ( FAILED( hr ) )
            throw COleInitException( );
    }

    ~CAutoOleInit( )
    {
        OleUninitialize( );
    }
};


// A simple file preview class to preview some
// common picture formats like *.gif, *jpg, etc.
// This class is not thread-safe and is
// implemented as singleton, because the class
// has only one static member to reconnect
// from callback functions
// we use a singleton-destroyer to get rid off
// the singleton instance, but this happens
// only on shutdown (unloading of the dll) -
// it's a question of taste (other solutions
// are possible)


class CFilePreview
{
public:
    // to ensure only one instance (singleton)
    static CFilePreview* createInstance(
        HWND aParent,
        POINT ulCorner,
        const CDimension& aSize,
        HINSTANCE hInstance,
        sal_Bool bShow = sal_True,
        sal_Bool bEnabled = sal_True );

    // sets the size of the preview window
    sal_Bool SAL_CALL setSize( const CDimension& aSize );

    // returns the CDimension of the preview
    sal_Bool SAL_CALL getSize( CDimension& theSize ) const;

    // sets the position of the upper left corner
    // of the preview window relative to the
    // upper left corner of the parent window
    sal_Bool SAL_CALL setPos( POINT ulCorner );

    // returns the current position of the preview
    // relative to the upper left corner of the
    // parent window
    sal_Bool SAL_CALL getPos( POINT& ulCorner ) const;

    // enables or disables the preview window
    // bEnable - true the window is enabled and updates its
    // view when update is called
    // bEnable - false the window shows itself in disabled
    // mode and does not update its view when update is
    // called
    void SAL_CALL enable( sal_Bool bEnable );

    // shows the preview window
    // possible values see SHOW_STATE
    sal_Bool SAL_CALL show( sal_Bool bShow );


    // if the preview is shown and enabled
    // preview of the given file will be shown
    // returns true on success or false if an error
    // occurred (the file in not there or not accessible etc.)
    virtual sal_Bool SAL_CALL update( const OUString& aFileName );

protected:
    // clients can create instances only through the static create method
    CFilePreview(
        HWND aParent,
        POINT ulCorner,
        const CDimension& aSize,
        HINSTANCE hInstance,
        sal_Bool bShow = sal_True,
        sal_Bool bEnabled = sal_True );

    // only the singleton destroyer class is allowed to delete the
    // singleton instance of this class
    virtual ~CFilePreview( );

    // we use the stl unique_ptr class as singleton destroyer
    typedef std::unique_ptr< CFilePreview > FILEPREVIEW_SINGLETON_DESTROYER_T;

protected:
    virtual void SAL_CALL onPaint( HWND hWnd, HDC hDC );

    sal_Bool loadFile( const OUString& aFileName );

private:
    CAutoOleInit m_autoOleInit;
    POINT        m_pt;
    CDimension   m_dim;
    HWND         m_hwnd;
    sal_Bool     m_bEnabled;
    IPicturePtr  m_IPicture;
    ATOM         m_atomPrevWndClass;
    HINSTANCE    m_hInstance;

    static LRESULT CALLBACK WndProc( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam );

    static CFilePreview* s_FilePreviewInst;
    static FILEPREVIEW_SINGLETON_DESTROYER_T s_SingletonDestroyer;

private:
    friend FILEPREVIEW_SINGLETON_DESTROYER_T;
};


#endif

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