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52 lines
2.1 KiB
C++
52 lines
2.1 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_RelativeTo_h
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#define mozilla_RelativeTo_h
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#include <ostream>
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class nsIFrame;
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namespace mozilla {
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// A flag that can be used to annotate a frame to distinguish coordinates
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// relative to the viewport frame as being in layout or visual coordinates.
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enum class ViewportType { Layout, Visual };
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// A struct that combines a frame with a ViewportType annotation. The
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// combination completely describes what a set of coordinates is "relative to".
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// Notes on expected usage:
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// - The boundary between visual and layout coordinates is approximately
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// at the root content document (RCD)'s ViewportFrame, which we'll
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// call "RCD-VF".
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// - Coordinates relative to the RCD-VF's descendants (other than the
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// RCD's viewport scrollbar frames) should be in layout coordinates.
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// - Coordinates relative to the RCD-VF's ancestors should be in visual
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// coordinates (note that in an e10s setup, the RCD-VF doesn't
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// typically have in-process ancestors).
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// - Coordinates relative to the RCD-VF itself can be in either layout
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// or visual coordinates.
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struct RelativeTo {
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const nsIFrame* mFrame = nullptr;
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// Choose ViewportType::Layout as the default as this is what the vast
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// majority of layout code deals with.
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ViewportType mViewportType = ViewportType::Layout;
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bool operator==(const RelativeTo& aOther) const {
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return mFrame == aOther.mFrame && mViewportType == aOther.mViewportType;
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}
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friend std::ostream& operator<<(std::ostream& aOs, const RelativeTo& aR) {
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return aOs << "{" << aR.mFrame << ", "
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<< (aR.mViewportType == ViewportType::Visual ? "visual"
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: "layout")
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<< "}";
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}
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};
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} // namespace mozilla
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#endif // mozilla_RelativeTo_h
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