1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/layout/base/DisplayListClipState.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,250 @@
1.4 +/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
1.5 + * This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#ifndef DISPLAYLISTCLIPSTATE_H_
1.10 +#define DISPLAYLISTCLIPSTATE_H_
1.11 +
1.12 +#include "DisplayItemClip.h"
1.13 +
1.14 +#include "mozilla/DebugOnly.h"
1.15 +
1.16 +class nsIFrame;
1.17 +class nsDisplayListBuilder;
1.18 +
1.19 +namespace mozilla {
1.20 +
1.21 +/**
1.22 + * All clip coordinates are in appunits relative to the reference frame
1.23 + * for the display item we're building.
1.24 + */
1.25 +class DisplayListClipState {
1.26 +public:
1.27 + DisplayListClipState()
1.28 + : mClipContentDescendants(nullptr)
1.29 + , mClipContainingBlockDescendants(nullptr)
1.30 + , mCurrentCombinedClip(nullptr)
1.31 + {}
1.32 +
1.33 + /**
1.34 + * Returns intersection of mClipContainingBlockDescendants and
1.35 + * mClipContentDescendants, allocated on aBuilder's arena.
1.36 + */
1.37 + const DisplayItemClip* GetCurrentCombinedClip(nsDisplayListBuilder* aBuilder);
1.38 +
1.39 + const DisplayItemClip* GetClipForContainingBlockDescendants() const
1.40 + {
1.41 + return mClipContainingBlockDescendants;
1.42 + }
1.43 + const DisplayItemClip* GetClipForContentDescendants() const
1.44 + {
1.45 + return mClipContentDescendants;
1.46 + }
1.47 +
1.48 + class AutoSaveRestore;
1.49 + friend class AutoSaveRestore;
1.50 +
1.51 + class AutoClipContainingBlockDescendantsToContentBox;
1.52 + friend class AutoClipContainingBlockDescendantsToContentBox;
1.53 +
1.54 + class AutoClipMultiple;
1.55 + friend class AutoClipMultiple;
1.56 +
1.57 + enum {
1.58 + ASSUME_DRAWING_RESTRICTED_TO_CONTENT_RECT = 0x01
1.59 + };
1.60 +
1.61 +private:
1.62 + void SetClipForContainingBlockDescendants(const DisplayItemClip* aClip)
1.63 + {
1.64 + mClipContainingBlockDescendants = aClip;
1.65 + mCurrentCombinedClip = nullptr;
1.66 + }
1.67 +
1.68 + void Clear()
1.69 + {
1.70 + mClipContentDescendants = nullptr;
1.71 + mClipContainingBlockDescendants = nullptr;
1.72 + mCurrentCombinedClip = nullptr;
1.73 + }
1.74 +
1.75 + /**
1.76 + * Intersects the given clip rect (with optional aRadii) with the current
1.77 + * mClipContainingBlockDescendants and sets mClipContainingBlockDescendants to
1.78 + * the result, stored in aClipOnStack.
1.79 + */
1.80 + void ClipContainingBlockDescendants(const nsRect& aRect,
1.81 + const nscoord* aRadii,
1.82 + DisplayItemClip& aClipOnStack);
1.83 +
1.84 + void ClipContentDescendants(const nsRect& aRect,
1.85 + const nscoord* aRadii,
1.86 + DisplayItemClip& aClipOnStack);
1.87 +
1.88 + /**
1.89 + * Clips containing-block descendants to the frame's content-box,
1.90 + * taking border-radius into account.
1.91 + * If aFlags contains ASSUME_DRAWING_RESTRICTED_TO_CONTENT_RECT then
1.92 + * we assume display items will not draw outside the content rect, so
1.93 + * clipping is only required if there is a border-radius. This is an
1.94 + * optimization to reduce the amount of clipping required.
1.95 + */
1.96 + void ClipContainingBlockDescendantsToContentBox(nsDisplayListBuilder* aBuilder,
1.97 + nsIFrame* aFrame,
1.98 + DisplayItemClip& aClipOnStack,
1.99 + uint32_t aFlags);
1.100 +
1.101 + /**
1.102 + * All content descendants (i.e. following placeholder frames to their
1.103 + * out-of-flows if necessary) should be clipped by mClipContentDescendants.
1.104 + * Null if no clipping applies.
1.105 + */
1.106 + const DisplayItemClip* mClipContentDescendants;
1.107 + /**
1.108 + * All containing-block descendants (i.e. frame descendants), including
1.109 + * display items for the current frame, should be clipped by
1.110 + * mClipContainingBlockDescendants.
1.111 + * Null if no clipping applies.
1.112 + */
1.113 + const DisplayItemClip* mClipContainingBlockDescendants;
1.114 + /**
1.115 + * The intersection of mClipContentDescendants and
1.116 + * mClipContainingBlockDescendants.
1.117 + * Allocated in the nsDisplayListBuilder arena. Null if none has been
1.118 + * allocated or both mClipContentDescendants and mClipContainingBlockDescendants
1.119 + * are null.
1.120 + */
1.121 + const DisplayItemClip* mCurrentCombinedClip;
1.122 +};
1.123 +
1.124 +/**
1.125 + * A class to automatically save and restore the current clip state. Also
1.126 + * offers methods for modifying the clip state. Only one modification is allowed
1.127 + * to be in scope at a time using one of these objects; multiple modifications
1.128 + * require nested objects. The interface is written this way to prevent
1.129 + * dangling pointers to DisplayItemClips.
1.130 + */
1.131 +class DisplayListClipState::AutoSaveRestore {
1.132 +public:
1.133 + AutoSaveRestore(nsDisplayListBuilder* aBuilder);
1.134 + void Restore()
1.135 + {
1.136 + mState = mSavedState;
1.137 + mRestored = true;
1.138 + }
1.139 + ~AutoSaveRestore()
1.140 + {
1.141 + mState = mSavedState;
1.142 + }
1.143 +
1.144 + void Clear()
1.145 + {
1.146 + NS_ASSERTION(!mRestored, "Already restored!");
1.147 + mState.Clear();
1.148 + mClipUsed = false;
1.149 + }
1.150 +
1.151 + /**
1.152 + * Intersects the given clip rect (with optional aRadii) with the current
1.153 + * mClipContainingBlockDescendants and sets mClipContainingBlockDescendants to
1.154 + * the result, stored in aClipOnStack.
1.155 + */
1.156 + void ClipContainingBlockDescendants(const nsRect& aRect,
1.157 + const nscoord* aRadii = nullptr)
1.158 + {
1.159 + NS_ASSERTION(!mRestored, "Already restored!");
1.160 + NS_ASSERTION(!mClipUsed, "mClip already used");
1.161 + mClipUsed = true;
1.162 + mState.ClipContainingBlockDescendants(aRect, aRadii, mClip);
1.163 + }
1.164 +
1.165 + void ClipContentDescendants(const nsRect& aRect,
1.166 + const nscoord* aRadii = nullptr)
1.167 + {
1.168 + NS_ASSERTION(!mRestored, "Already restored!");
1.169 + NS_ASSERTION(!mClipUsed, "mClip already used");
1.170 + mClipUsed = true;
1.171 + mState.ClipContentDescendants(aRect, aRadii, mClip);
1.172 + }
1.173 +
1.174 + /**
1.175 + * Clips containing-block descendants to the frame's content-box,
1.176 + * taking border-radius into account.
1.177 + * If aFlags contains ASSUME_DRAWING_RESTRICTED_TO_CONTENT_RECT then
1.178 + * we assume display items will not draw outside the content rect, so
1.179 + * clipping is only required if there is a border-radius. This is an
1.180 + * optimization to reduce the amount of clipping required.
1.181 + */
1.182 + void ClipContainingBlockDescendantsToContentBox(nsDisplayListBuilder* aBuilder,
1.183 + nsIFrame* aFrame,
1.184 + uint32_t aFlags = 0)
1.185 + {
1.186 + NS_ASSERTION(!mRestored, "Already restored!");
1.187 + NS_ASSERTION(!mClipUsed, "mClip already used");
1.188 + mClipUsed = true;
1.189 + mState.ClipContainingBlockDescendantsToContentBox(aBuilder, aFrame, mClip, aFlags);
1.190 + }
1.191 +
1.192 +protected:
1.193 + DisplayListClipState& mState;
1.194 + DisplayListClipState mSavedState;
1.195 + DisplayItemClip mClip;
1.196 + DebugOnly<bool> mClipUsed;
1.197 + DebugOnly<bool> mRestored;
1.198 +};
1.199 +
1.200 +class DisplayListClipState::AutoClipContainingBlockDescendantsToContentBox : public AutoSaveRestore {
1.201 +public:
1.202 + AutoClipContainingBlockDescendantsToContentBox(nsDisplayListBuilder* aBuilder,
1.203 + nsIFrame* aFrame,
1.204 + uint32_t aFlags = 0)
1.205 + : AutoSaveRestore(aBuilder)
1.206 + {
1.207 + mClipUsed = true;
1.208 + mState.ClipContainingBlockDescendantsToContentBox(aBuilder, aFrame, mClip, aFlags);
1.209 + }
1.210 +};
1.211 +
1.212 +/**
1.213 + * Do not use this outside of nsFrame::BuildDisplayListForChild, use
1.214 + * multiple AutoSaveRestores instead. We provide this class just to ensure
1.215 + * BuildDisplayListForChild is as efficient as possible.
1.216 + */
1.217 +class DisplayListClipState::AutoClipMultiple : public AutoSaveRestore {
1.218 +public:
1.219 + AutoClipMultiple(nsDisplayListBuilder* aBuilder)
1.220 + : AutoSaveRestore(aBuilder)
1.221 + , mExtraClipUsed(false)
1.222 + {}
1.223 +
1.224 + /**
1.225 + * *aClip must survive longer than this object. Be careful!!!
1.226 + */
1.227 + void SetClipForContainingBlockDescendants(const DisplayItemClip* aClip)
1.228 + {
1.229 + mState.SetClipForContainingBlockDescendants(aClip);
1.230 + }
1.231 +
1.232 + /**
1.233 + * Intersects the given clip rect (with optional aRadii) with the current
1.234 + * mClipContainingBlockDescendants and sets mClipContainingBlockDescendants to
1.235 + * the result, stored in aClipOnStack.
1.236 + */
1.237 + void ClipContainingBlockDescendantsExtra(const nsRect& aRect,
1.238 + const nscoord* aRadii)
1.239 + {
1.240 + NS_ASSERTION(!mRestored, "Already restored!");
1.241 + NS_ASSERTION(!mExtraClipUsed, "mExtraClip already used");
1.242 + mExtraClipUsed = true;
1.243 + mState.ClipContainingBlockDescendants(aRect, aRadii, mExtraClip);
1.244 + }
1.245 +
1.246 +protected:
1.247 + DisplayItemClip mExtraClip;
1.248 + DebugOnly<bool> mExtraClipUsed;
1.249 +};
1.250 +
1.251 +}
1.252 +
1.253 +#endif /* DISPLAYLISTCLIPSTATE_H_ */
