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/** \file screenshot.h */ // -*-c++-*-
// Copyright (C) 2009 Daniel Burrows
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program 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
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; see the file COPYING. If not, write to
// the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
// Boston, MA 02111-1307, USA.
#ifndef GTK_SCREENSHOT_CACHE_H
#define GTK_SCREENSHOT_CACHE_H
// GTK+ classes and functions relating to the screenshot cache.
#include <gdkmm/pixbuf.h>
#include <generic/apt/screenshot.h>
#include <memory>
namespace gui
{
// An abstract base class is qused here to simplify the header
// and avoid information leaks.
//
// Currently, the actual loading of screenshots takes place in a
// *foreground* thread. This is necessary because it's not clear
// that it's safe for a foreground thread to display a partial
// PixBuf while a background thread is possibly write()ing to it.
// In fact, it's probably *not* safe to do so.
/** \brief Handle to a package's screenshot.
*
* Internally, we cache the image buffers for the most recently
* acquired screenshots for reuse. When client code requests a
* screenshot, it either gets a previously acquired screenshot or
* gets a reference to a screenshot that's being loaded from the
* network.
*/
class cached_screenshot
{
sigc::signal<void, std::string> failed;
sigc::signal<void> prepared;
sigc::signal<void, int, int, int, int> updated;
sigc::signal<void> ready;
public:
cached_screenshot()
{
}
virtual ~cached_screenshot();
/** \brief Get the signal invoked when a screenshot can't be
* acquired.
*/
sigc::signal<void, std::string> &get_signal_failed() { return failed; }
/** \brief Get the signal invoked when we're ready to download a
* screenshot.
*
* Once this signal is invoked, the pixbuf has been created but
* isn't filled in yet. The client code can modify it in
* response to this signal.
*/
sigc::signal<void> &get_signal_prepared() { return prepared; }
/** \brief Get the signal invoked when a region of the screenshot
* is updated.
*
* The arguments are (x, y, width, height).
*/
sigc::signal<void, int, int, int, int> &get_signal_updated() { return updated; }
/** \brief Get the signal invoked when the image is ready to be
* displayed.
*
* In some corner cases, the image might have been changed to a
* newly allocated object since the last signal was emitted. The
* recipient should use get_screenshot() to ensure that the most
* recent image is being used.
*/
sigc::signal<void> &get_signal_ready() { return ready; }
/** \brief Get the screenshot associated with this handle, or
* return an invalid pointer if it's not available yet.
*/
virtual Glib::RefPtr<Gdk::Pixbuf> get_screenshot() = 0;
/** \brief Cancel downloading this screenshot, if possible. */
virtual void cancel() = 0;
};
/** \brief Retrieve the given screenshot. */
std::shared_ptr<cached_screenshot> get_screenshot(const aptitude::screenshot_key &key);
}
#endif // GTK_SCREENSHOT_CACHE_H
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