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/* egg-frame-source.c
*
* Copyright (C) 2010-2016 Christian Hergert <christian@hergert.me>
*
* This file is free software; you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License as published by the Free
* Software Foundation; either version 2.1 of the License, or (at your option)
* any later version.
*
* This file 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 Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "animation/egg-frame-source.h"
typedef struct
{
GSource parent;
guint fps;
guint frame_count;
gint64 start_time;
} EggFrameSource;
static gboolean
egg_frame_source_prepare (GSource *source,
gint *timeout_)
{
EggFrameSource *fsource = (EggFrameSource *)(gpointer)source;
gint64 current_time;
guint elapsed_time;
guint new_frame_num;
guint frame_time;
current_time = g_source_get_time(source) / 1000;
elapsed_time = current_time - fsource->start_time;
new_frame_num = elapsed_time * fsource->fps / 1000;
/* If time has gone backwards or the time since the last frame is
* greater than the two frames worth then reset the time and do a
* frame now */
if (new_frame_num < fsource->frame_count ||
new_frame_num - fsource->frame_count > 2) {
/* Get the frame time rounded up to the nearest ms */
frame_time = (1000 + fsource->fps - 1) / fsource->fps;
/* Reset the start time */
fsource->start_time = current_time;
/* Move the start time as if one whole frame has elapsed */
fsource->start_time -= frame_time;
fsource->frame_count = 0;
*timeout_ = 0;
return TRUE;
} else if (new_frame_num > fsource->frame_count) {
*timeout_ = 0;
return TRUE;
} else {
*timeout_ = (fsource->frame_count + 1) * 1000 / fsource->fps - elapsed_time;
return FALSE;
}
}
static gboolean
egg_frame_source_check (GSource *source)
{
gint timeout_;
return egg_frame_source_prepare(source, &timeout_);
}
static gboolean
egg_frame_source_dispatch (GSource *source,
GSourceFunc source_func,
gpointer user_data)
{
EggFrameSource *fsource = (EggFrameSource *)(gpointer)source;
gboolean ret;
if ((ret = source_func(user_data)))
fsource->frame_count++;
return ret;
}
static GSourceFuncs source_funcs = {
egg_frame_source_prepare,
egg_frame_source_check,
egg_frame_source_dispatch,
};
/**
* egg_frame_source_add:
* @frames_per_sec: (in): Target frames per second.
* @callback: (in) (scope notified): A #GSourceFunc to execute.
* @user_data: (in): User data for @callback.
*
* Creates a new frame source that will execute when the timeout interval
* for the source has elapsed. The timing will try to synchronize based
* on the end time of the animation.
*
* Returns: A source id that can be removed with g_source_remove().
*/
guint
egg_frame_source_add (guint frames_per_sec,
GSourceFunc callback,
gpointer user_data)
{
EggFrameSource *fsource;
GSource *source;
guint ret;
g_return_val_if_fail (frames_per_sec > 0, 0);
g_return_val_if_fail (frames_per_sec <= 120, 0);
source = g_source_new(&source_funcs, sizeof(EggFrameSource));
fsource = (EggFrameSource *)(gpointer)source;
fsource->fps = frames_per_sec;
fsource->frame_count = 0;
fsource->start_time = g_get_monotonic_time() / 1000;
g_source_set_callback(source, callback, user_data, NULL);
g_source_set_name(source, "EggFrameSource");
ret = g_source_attach(source, NULL);
g_source_unref(source);
return ret;
}
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