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// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CC_INPUT_MAIN_THREAD_SCROLLING_REASON_H_
#define CC_INPUT_MAIN_THREAD_SCROLLING_REASON_H_
namespace cc {
// Ensure this stays in sync with MainThreadScrollingReason in histograms.xml.
// When adding a new MainThreadScrollingReason, make sure the corresponding
// [MainThread/Compositor]CanSetScrollReasons function is also updated.
struct MainThreadScrollingReason {
// Non-transient scrolling reasons.
enum : uint32_t { kNotScrollingOnMain = 0 };
enum : uint32_t { kHasBackgroundAttachmentFixedObjects = 1 << 0 };
enum : uint32_t { kHasNonLayerViewportConstrainedObjects = 1 << 1 };
enum : uint32_t { kThreadedScrollingDisabled = 1 << 2 };
enum : uint32_t { kScrollbarScrolling = 1 << 3 };
enum : uint32_t { kPageOverlay = 1 << 4 };
enum : uint32_t { kAnimatingScrollOnMainThread = 1 << 13 };
// Transient scrolling reasons. These are computed for each scroll begin.
enum : uint32_t { kNonFastScrollableRegion = 1 << 5 };
enum : uint32_t { kEventHandlers = 1 << 6 };
enum : uint32_t { kFailedHitTest = 1 << 7 };
enum : uint32_t { kNoScrollingLayer = 1 << 8 };
enum : uint32_t { kNotScrollable = 1 << 9 };
enum : uint32_t { kContinuingMainThreadScroll = 1 << 10 };
enum : uint32_t { kNonInvertibleTransform = 1 << 11 };
enum : uint32_t { kPageBasedScrolling = 1 << 12 };
// The number of flags in this struct (excluding itself).
enum : uint32_t { kMainThreadScrollingReasonCount = 15 };
// Returns true if the given MainThreadScrollingReason can be set by the main
// thread.
static bool MainThreadCanSetScrollReasons(uint32_t reasons) {
uint32_t reasons_set_by_main_thread =
kNotScrollingOnMain | kHasBackgroundAttachmentFixedObjects |
kHasNonLayerViewportConstrainedObjects | kThreadedScrollingDisabled |
kScrollbarScrolling | kPageOverlay | kAnimatingScrollOnMainThread;
return (reasons & reasons_set_by_main_thread) == reasons;
}
// Returns true if the given MainThreadScrollingReason can be set by the
// compositor.
static bool CompositorCanSetScrollReasons(uint32_t reasons) {
uint32_t reasons_set_by_compositor =
kNonFastScrollableRegion | kEventHandlers | kFailedHitTest |
kNoScrollingLayer | kNotScrollable | kContinuingMainThreadScroll |
kNonInvertibleTransform | kPageBasedScrolling;
return (reasons & reasons_set_by_compositor) == reasons;
}
};
} // namespace cc
#endif // CC_INPUT_MAIN_THREAD_SCROLLING_REASON_H_
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