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/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
* 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/. */
package org.mozilla.gecko.gfx;
/**
* A class used to schedule a callback to occur when the next frame is drawn.
* Subclasses must redefine the internalRun method, not the run method.
*/
public abstract class RenderTask {
/**
* Whether to run the task after the render, or before.
*/
public final boolean runAfter;
/**
* Time when this task has first run, in ns. Useful for tasks which run for a specific duration.
*/
private long mStartTime;
/**
* Whether we should initialise mStartTime on the next frame run.
*/
private boolean mResetStartTime = true;
/**
* The callback to run on each frame. timeDelta is the time elapsed since
* the last call, in nanoseconds. Returns true if it should continue
* running, or false if it should be removed from the task queue. Returning
* true implicitly schedules a redraw.
*
* This method first initializes the start time if resetStartTime has been invoked,
* then calls internalRun.
*
* Note : subclasses should override internalRun.
*
* @param timeDelta the time between the beginning of last frame and the beginning of this frame, in ns.
* @param currentFrameStartTime the startTime of the current frame, in ns.
* @return true if animation should be run at the next frame, false otherwise
* @see RenderTask#internalRun(long, long)
*/
public final boolean run(long timeDelta, long currentFrameStartTime) {
if (mResetStartTime) {
mStartTime = currentFrameStartTime;
mResetStartTime = false;
}
return internalRun(timeDelta, currentFrameStartTime);
}
/**
* Abstract method to be overridden by subclasses.
* @param timeDelta the time between the beginning of last frame and the beginning of this frame, in ns
* @param currentFrameStartTime the startTime of the current frame, in ns.
* @return true if animation should be run at the next frame, false otherwise
*/
protected abstract boolean internalRun(long timeDelta, long currentFrameStartTime);
public RenderTask(boolean aRunAfter) {
runAfter = aRunAfter;
}
/**
* Get the start time of this task.
* It is the start time of the first frame this task was run on.
* @return the start time in ns
*/
public long getStartTime() {
return mStartTime;
}
/**
* Schedule a reset of the recorded start time next time {@link RenderTask#run(long, long)} is run.
* @see RenderTask#getStartTime()
*/
public void resetStartTime() {
mResetStartTime = true;
}
}
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