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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ui/gfx/delegated_ink_point.h"
#include <inttypes.h>
#include "base/strings/stringprintf.h"
#include "base/trace_event/trace_event.h"
#include "ui/gfx/delegated_ink_metadata.h"
namespace gfx {
bool DelegatedInkPoint::MatchesDelegatedInkMetadata(
const DelegatedInkMetadata* metadata) const {
if (!metadata) {
return false;
}
// The maximum difference allowed when comparing a DelegatedInkPoint |point_|
// to the |point_| on a DelegatedInkMetadata. Some precision loss can occur
// when moving between coordinate spaces in the browser and renderer,
// particularly when the device scale factor is not a whole number. This can
// result in a DelegatedInkMetadata and DelegatedInkPoint having been created
// from the same point, but having a very small difference. When this occurs,
// we can safely ignore that they are slightly different and use the point for
// a delegated ink trail anyway, since it is a very small difference and will
// only be visible for a single frame. The allowed difference is the square
// root of 2 - which is derived from the maximum allowed difference of 1px in
// each direction.
// TODO(crbug.com/338250110) Consider removing this tolerance.
constexpr float kEpsilon = 1.4143f;
TRACE_EVENT_INSTANT2("delegated_ink_trails",
"DelegatedInkPoint::MatchesDelegatedInkMetadata",
TRACE_EVENT_SCOPE_THREAD, "metadata",
metadata->ToString(), "point", ToString());
return timestamp_ == metadata->timestamp() &&
point_.IsWithinDistance(metadata->point(), kEpsilon);
}
std::string DelegatedInkPoint::ToString() const {
return base::StringPrintf("point: %s, timestamp: %" PRId64 ", pointer_id: %d",
point_.ToString().c_str(),
timestamp_.since_origin().InMicroseconds(),
pointer_id_);
}
} // namespace gfx
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