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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
commit36d22d82aa202bb199967e9512281e9a53db42c9 (patch)
tree105e8c98ddea1c1e4784a60a5a6410fa416be2de /gfx/layers/apz/src/DesktopFlingPhysics.h
parentInitial commit. (diff)
downloadfirefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz
firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip
Adding upstream version 115.7.0esr.upstream/115.7.0esr
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'gfx/layers/apz/src/DesktopFlingPhysics.h')
-rw-r--r--gfx/layers/apz/src/DesktopFlingPhysics.h67
1 files changed, 67 insertions, 0 deletions
diff --git a/gfx/layers/apz/src/DesktopFlingPhysics.h b/gfx/layers/apz/src/DesktopFlingPhysics.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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_layers_DesktopFlingPhysics_h_
+#define mozilla_layers_DesktopFlingPhysics_h_
+
+#include "AsyncPanZoomController.h"
+#include "Units.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/StaticPrefs_apz.h"
+
+namespace mozilla {
+namespace layers {
+
+class DesktopFlingPhysics {
+ public:
+ void Init(const ParentLayerPoint& aStartingVelocity,
+ float aPLPPI /* unused */) {
+ mVelocity = aStartingVelocity;
+ }
+ void Sample(const TimeDuration& aDelta, ParentLayerPoint* aOutVelocity,
+ ParentLayerPoint* aOutOffset) {
+ float friction = StaticPrefs::apz_fling_friction();
+ float threshold = StaticPrefs::apz_fling_stopped_threshold();
+
+ mVelocity = ParentLayerPoint(
+ ApplyFrictionOrCancel(mVelocity.x, aDelta, friction, threshold),
+ ApplyFrictionOrCancel(mVelocity.y, aDelta, friction, threshold));
+
+ *aOutVelocity = mVelocity;
+ *aOutOffset = mVelocity * aDelta.ToMilliseconds();
+ }
+
+ private:
+ /**
+ * Applies friction to the given velocity and returns the result, or
+ * returns zero if the velocity is too low.
+ * |aVelocity| is the incoming velocity.
+ * |aDelta| is the amount of time that has passed since the last time
+ * friction was applied.
+ * |aFriction| is the amount of friction to apply.
+ * |aThreshold| is the velocity below which the fling is cancelled.
+ */
+ static float ApplyFrictionOrCancel(float aVelocity,
+ const TimeDuration& aDelta,
+ float aFriction, float aThreshold) {
+ if (fabsf(aVelocity) <= aThreshold) {
+ // If the velocity is very low, just set it to 0 and stop the fling,
+ // otherwise we'll just asymptotically approach 0 and the user won't
+ // actually see any changes.
+ return 0.0f;
+ }
+
+ aVelocity *= pow(1.0f - aFriction, float(aDelta.ToMilliseconds()));
+ return aVelocity;
+ }
+
+ ParentLayerPoint mVelocity;
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif // mozilla_layers_DesktopFlingPhysics_h_