mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-11-23 21:01:08 +00:00
265e672179
# ignore-this-changeset --HG-- extra : amend_source : 4d301d3b0b8711c4692392aa76088ba7fd7d1022
115 lines
3.6 KiB
C++
115 lines
3.6 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
|
|
*
|
|
* 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/. */
|
|
|
|
#ifndef mozilla_image_FrameTimeout_h
|
|
#define mozilla_image_FrameTimeout_h
|
|
|
|
#include <stdint.h>
|
|
#include "mozilla/Assertions.h"
|
|
|
|
namespace mozilla {
|
|
namespace image {
|
|
|
|
/**
|
|
* FrameTimeout wraps a frame timeout value (measured in milliseconds) after
|
|
* first normalizing it. This normalization is necessary because some tools
|
|
* generate incorrect frame timeout values which we nevertheless have to
|
|
* support. For this reason, code that deals with frame timeouts should always
|
|
* use a FrameTimeout value rather than the raw value from the image header.
|
|
*/
|
|
struct FrameTimeout {
|
|
/**
|
|
* @return a FrameTimeout of zero. This should be used only for math
|
|
* involving FrameTimeout values. You can't obtain a zero FrameTimeout from
|
|
* FromRawMilliseconds().
|
|
*/
|
|
static FrameTimeout Zero() { return FrameTimeout(0); }
|
|
|
|
/// @return an infinite FrameTimeout.
|
|
static FrameTimeout Forever() { return FrameTimeout(-1); }
|
|
|
|
/// @return a FrameTimeout obtained by normalizing a raw timeout value.
|
|
static FrameTimeout FromRawMilliseconds(int32_t aRawMilliseconds) {
|
|
// Normalize all infinite timeouts to the same value.
|
|
if (aRawMilliseconds < 0) {
|
|
return FrameTimeout::Forever();
|
|
}
|
|
|
|
// Very small timeout values are problematic for two reasons: we don't want
|
|
// to burn energy redrawing animated images extremely fast, and broken tools
|
|
// generate these values when they actually want a "default" value, so such
|
|
// images won't play back right without normalization. For some context,
|
|
// see bug 890743, bug 125137, bug 139677, and bug 207059. The historical
|
|
// behavior of IE and Opera was:
|
|
// IE 6/Win:
|
|
// 10 - 50ms is normalized to 100ms.
|
|
// >50ms is used unnormalized.
|
|
// Opera 7 final/Win:
|
|
// 10ms is normalized to 100ms.
|
|
// >10ms is used unnormalized.
|
|
if (aRawMilliseconds >= 0 && aRawMilliseconds <= 10) {
|
|
return FrameTimeout(100);
|
|
}
|
|
|
|
// The provided timeout value is OK as-is.
|
|
return FrameTimeout(aRawMilliseconds);
|
|
}
|
|
|
|
bool operator==(const FrameTimeout& aOther) const {
|
|
return mTimeout == aOther.mTimeout;
|
|
}
|
|
|
|
bool operator!=(const FrameTimeout& aOther) const {
|
|
return !(*this == aOther);
|
|
}
|
|
|
|
FrameTimeout operator+(const FrameTimeout& aOther) {
|
|
if (*this == Forever() || aOther == Forever()) {
|
|
return Forever();
|
|
}
|
|
|
|
return FrameTimeout(mTimeout + aOther.mTimeout);
|
|
}
|
|
|
|
FrameTimeout& operator+=(const FrameTimeout& aOther) {
|
|
*this = *this + aOther;
|
|
return *this;
|
|
}
|
|
|
|
/**
|
|
* @return this FrameTimeout's value in milliseconds. Illegal to call on a
|
|
* an infinite FrameTimeout value.
|
|
*/
|
|
uint32_t AsMilliseconds() const {
|
|
if (*this == Forever()) {
|
|
MOZ_ASSERT_UNREACHABLE(
|
|
"Calling AsMilliseconds() on an infinite FrameTimeout");
|
|
return 100; // Fail to something sane.
|
|
}
|
|
|
|
return uint32_t(mTimeout);
|
|
}
|
|
|
|
/**
|
|
* @return this FrameTimeout value encoded so that non-negative values
|
|
* represent a timeout in milliseconds, and -1 represents an infinite
|
|
* timeout.
|
|
*
|
|
* XXX(seth): This is a backwards compatibility hack that should be removed.
|
|
*/
|
|
int32_t AsEncodedValueDeprecated() const { return mTimeout; }
|
|
|
|
private:
|
|
explicit FrameTimeout(int32_t aTimeout) : mTimeout(aTimeout) {}
|
|
|
|
int32_t mTimeout;
|
|
};
|
|
|
|
} // namespace image
|
|
} // namespace mozilla
|
|
|
|
#endif // mozilla_image_FrameTimeout_h
|