libkf5kio-dev 5.44.0-0ubuntu1 / usr / include / KF5 / KIOWidgets / kio / previewjob.h

// -*- c++ -*-
/*  This file is part of the KDE libraries
    Copyright (C) 2000 David Faure <faure@kde.org>
                  2000 Carsten Pfeiffer <pfeiffer@kde.org>
                  2001 Malte Starostik <malte.starostik@t-online.de>

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to
    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
    Boston, MA 02110-1301, USA.
*/

#ifndef KIO_PREVIEWJOB_H
#define KIO_PREVIEWJOB_H

#include "kiowidgets_export.h"
#include <kfileitem.h>
#include <kio/job.h>

class QPixmap;

namespace KIO
{
class PreviewJobPrivate;
/*!
 * @class KIO::PreviewJob previewjob.h <KIO/PreviewJob>
 *
 * This class catches a preview (thumbnail) for files.
 * @short KIO Job to get a thumbnail picture
 */
class KIOWIDGETS_EXPORT PreviewJob : public KIO::Job
{
    Q_OBJECT
public:
    /**
     * Specifies the type of scaling that is applied to the generated preview.
     * @since 4.7
     */
    enum ScaleType {
        /**
         * The original size of the preview will be returned. Most previews
         * will return a size of 256 x 256 pixels.
         */
        Unscaled,
        /**
         * The preview will be scaled to the size specified when constructing
         * the PreviewJob. The aspect ratio will be kept.
         */
        Scaled,
        /**
         * The preview will be scaled to the size specified when constructing
         * the PreviewJob. The result will be cached for later use. Per default
         * ScaledAndCached is set.
         */
        ScaledAndCached
    };

#ifndef KIOWIDGETS_NO_DEPRECATED
    /**
     * Creates a new PreviewJob.
     * @param items a list of files to create previews for
     * @param width the desired width
     * @param height the desired height, 0 to use the @p width
     * @param iconSize the size of the mimetype icon to overlay over the
     * preview or zero to not overlay an icon. This has no effect if the
     * preview plugin that will be used doesn't use icon overlays.
     * @param iconAlpha transparency to use for the icon overlay
     * @param scale if the image is to be scaled to the requested size or
     * returned in its original size
     * @param save if the image should be cached for later use
     * @param enabledPlugins If non-zero, this points to a list containing
     * the names of the plugins that may be used. If enabledPlugins is zero
     * all available plugins are used.
     *
     * @deprecated Use PreviewJob(const KFileItemList&, const QSize&, const QStringList*) in combination
     *             with the setter-methods instead. Note that the semantics of
     *             \p enabledPlugins has been slightly changed.
     */
    KIOWIDGETS_DEPRECATED PreviewJob(const KFileItemList &items, int width, int height,
                                     int iconSize, int iconAlpha, bool scale, bool save,
                                     const QStringList *enabledPlugins);
#endif

    /**
     * @param items          List of files to create previews for.
     * @param size           Desired size of the preview.
     * @param enabledPlugins If non-zero it defines the list of plugins that
     *                       are considered for generating the preview. If
     *                       enabledPlugins is zero the plugins specified in the
     *                       KConfigGroup "PreviewSettings" are used.
     * @since 4.7
     */
    PreviewJob(const KFileItemList &items,
               const QSize &size,
               const QStringList *enabledPlugins = nullptr);

    virtual ~PreviewJob();

    /**
     * Sets the size of the MIME-type icon which overlays the preview. If zero
     * is passed no overlay will be shown at all. The setting has no effect if
     * the preview plugin that will be used does not use icon overlays. Per
     * default the size is set to 0.
     * @since 4.7
     */
    void setOverlayIconSize(int size);

    /**
     * @return The size of the MIME-type icon which overlays the preview.
     * @see PreviewJob::setOverlayIconSize()
     * @since 4.7
     */
    int overlayIconSize() const;

    /**
     * Sets the alpha-value for the MIME-type icon which overlays the preview.
     * The alpha-value may range from 0 (= fully transparent) to 255 (= opaque).
     * Per default the value is set to 70.
     * @see PreviewJob::setOverlayIconSize()
     * @since 4.7
     */
    void setOverlayIconAlpha(int alpha);

    /**
     * @return The alpha-value for the MIME-type icon which overlays the preview.
     *         Per default 70 is returned.
     * @see PreviewJob::setOverlayIconAlpha()
     * @since 4.7
     */
    int overlayIconAlpha() const;

    /**
     * Sets the scale type for the generated preview. Per default
     * PreviewJob::ScaledAndCached is set.
     * @see PreviewJob::ScaleType
     * @since 4.7
     */
    void setScaleType(ScaleType type);

    /**
     * @return The scale type for the generated preview.
     * @see PreviewJob::ScaleType
     * @since 4.7
     */
    ScaleType scaleType() const;

    /**
     * Removes an item from preview processing. Use this if you passed
     * an item to filePreview and want to delete it now.
     *
     * @param url the url of the item that should be removed from the preview queue
     */
    void removeItem(const QUrl &url);

    /**
     * If @p ignoreSize is true, then the preview is always
     * generated regardless of the settings
     **/
    void setIgnoreMaximumSize(bool ignoreSize = true);

    /**
     * Sets the sequence index given to the thumb creators.
     * Use the sequence index, it is possible to create alternative
     * icons for the same item. For example it may allow iterating through
     * the items of a directory, or the frames of a video.
     *
     * @since 4.3
     **/
    void setSequenceIndex(int index);

    /**
     * Returns the currently set sequence index
     *
     * @since 4.3
     **/
    int sequenceIndex() const;

    /**
     * Returns a list of all available preview plugins. The list
     * contains the basenames of the plugins' .desktop files (no path,
     * no .desktop).
     * @return the list of all available plugins
     */
    static QStringList availablePlugins();

    /**
     * Returns a list of plugins that should be enabled by default, which is all plugins
     * Minus the plugins specified in an internal blacklist
     * @return the list of plugins that should be enabled by default
     * @since 5.40
     */
    static QStringList defaultPlugins();

    /**
     * Returns a list of all supported MIME types. The list can
     * contain entries like text/ * (without the space).
     * @return the list of mime types
     */
    static QStringList supportedMimeTypes();

    /**
     * Returns the default "maximum file size", in bytes, used by PreviewJob.
     * This is useful for applications providing a GUI for letting the user change the size.
     * @since 4.1
     * @deprecated PreviewJob uses different maximum file sizes dependent on the URL since 4.5.
     *             The returned file size is only valid for local URLs.
     */
#ifndef KIOWIDGETS_NO_DEPRECATED
    KIOWIDGETS_DEPRECATED static KIO::filesize_t maximumFileSize();
#endif

Q_SIGNALS:
    /**
     * Emitted when a thumbnail picture for @p item has been successfully
     * retrieved.
     * @param item the file of the preview
     * @param preview the preview image
     */
    void gotPreview(const KFileItem &item, const QPixmap &preview);
    /**
     * Emitted when a thumbnail for @p item could not be created,
     * either because a ThumbCreator for its MIME type does not
     * exist, or because something went wrong.
     * @param item the file that failed
     */
    void failed(const KFileItem &item);

protected Q_SLOTS:
    void slotResult(KJob *job) Q_DECL_OVERRIDE;

private:
    Q_PRIVATE_SLOT(d_func(), void startPreview())
    Q_PRIVATE_SLOT(d_func(), void slotThumbData(KIO::Job *, const QByteArray &))
    Q_DECLARE_PRIVATE(PreviewJob)
};

#ifndef KIOWIDGETS_NO_DEPRECATED
/**
 * Creates a PreviewJob to generate or retrieve a preview image
 * for the given URL.
 *
 * @param items files to get previews for
 * @param width the maximum width to use
 * @param height the maximum height to use, if this is 0, the same
 * value as width is used.
 * @param iconSize the size of the mimetype icon to overlay over the
 * preview or zero to not overlay an icon. This has no effect if the
 * preview plugin that will be used doesn't use icon overlays.
 * @param iconAlpha transparency to use for the icon overlay
 * @param scale if the image is to be scaled to the requested size or
 * returned in its original size
 * @param save if the image should be cached for later use
 * @param enabledPlugins if non-zero, this points to a list containing
 * the names of the plugins that may be used.
 * @return the new PreviewJob
 * @see PreviewJob::availablePlugins()
 * @deprecated Use KIO::filePreview(const KFileItemList&, const QSize&, const QStringList*) in combination
 *             with the setter-methods instead. Note that the semantics of
 *             \p enabledPlugins has been slightly changed.
 */
KIOWIDGETS_DEPRECATED_EXPORT PreviewJob *filePreview(const KFileItemList &items, int width, int height = 0, int iconSize = 0, int iconAlpha = 70, bool scale = true, bool save = true, const QStringList *enabledPlugins = nullptr);   // KDE5: use enums instead of bool scale + bool save

/**
 * Creates a PreviewJob to generate or retrieve a preview image
 * for the given URL.
 *
 * @param items files to get previews for
 * @param width the maximum width to use
 * @param height the maximum height to use, if this is 0, the same
 * value as width is used.
 * @param iconSize the size of the mimetype icon to overlay over the
 * preview or zero to not overlay an icon. This has no effect if the
 * preview plugin that will be used doesn't use icon overlays.
 * @param iconAlpha transparency to use for the icon overlay
 * @param scale if the image is to be scaled to the requested size or
 * returned in its original size
 * @param save if the image should be cached for later use
 * @param enabledPlugins if non-zero, this points to a list containing
 * the names of the plugins that may be used.
 * @return the new PreviewJob
 * @see PreviewJob::availablePlugins()
 * @deprecated Use KIO::filePreview(const KFileItemList&, const QSize&, const QStringList*) in combination
 *             with the setter-methods instead. Note that the semantics of
 *             \p enabledPlugins has been slightly changed.
 */
KIOWIDGETS_DEPRECATED_EXPORT PreviewJob *filePreview(const QList<QUrl> &items, int width, int height = 0, int iconSize = 0, int iconAlpha = 70, bool scale = true, bool save = true, const QStringList *enabledPlugins = nullptr);
#endif

/**
 * Creates a PreviewJob to generate a preview image for the given items.
 * @param items          List of files to create previews for.
 * @param size           Desired size of the preview.
 * @param enabledPlugins If non-zero it defines the list of plugins that
 *                       are considered for generating the preview. If
 *                       enabledPlugins is zero the plugins specified in the
 *                       KConfigGroup "PreviewSettings" are used.
 * @since 4.7
 */
KIOWIDGETS_EXPORT PreviewJob *filePreview(const KFileItemList &items, const QSize &size, const QStringList *enabledPlugins = nullptr);
}

#endif