gecko-dev/layout/base/nsLayoutHistoryState.cpp
Jan Henning 0e575681dc Bug 1265818 - Part 2 - Add scriptable methods for getting and setting PresStates from JS. r=jst
This will allow the session store to store and restore scroll positions (and pinch zoom on Android) for past session history entries as well, whereas today only the scroll position of the current page is saved.

As a LayoutHistoryState saves its PresStates in a hash table that doesn't allow direct access to its contents if you don't already know the entry's key, we provide a function to iterate over all stored PresStates and retrieve their keys, which can then be used to get access to each individual PresState in turn. Since nsPresState is little more than a fancy struct and we don't want to have to turn it into a full-blown XPCOM-compatible interface, we just pass the scroll/zoom-related values we're interested in as in/out parameters from/to JS via the LayoutHistoryState.

We also require a helper method for initialising an SHEntry's LayoutHistoryState, since normally this doesn't happen until the PresShell wants to capture the history state in it. We on the other hand require a LayoutHistoryState to be present immediately after creation of a fresh SHEntry object, so we can feed it the session store data during history restoration.

MozReview-Commit-ID: FfZf8KDsVWl
***

--HG--
extra : rebase_source : 0b3f729bff3ac24680d6fe8a0fb796979886170b
2017-03-25 14:01:29 +01:00

161 lines
3.8 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */
/*
* container for information saved in session history when the document
* is not
*/
#include "nsILayoutHistoryState.h"
#include "nsWeakReference.h"
#include "nsClassHashtable.h"
#include "nsPresState.h"
#include "mozilla/Attributes.h"
class nsLayoutHistoryState final : public nsILayoutHistoryState,
public nsSupportsWeakReference
{
public:
nsLayoutHistoryState()
: mScrollPositionOnly(false)
{
}
NS_DECL_ISUPPORTS
NS_DECL_NSILAYOUTHISTORYSTATE
private:
~nsLayoutHistoryState() {}
bool mScrollPositionOnly;
nsClassHashtable<nsCStringHashKey,nsPresState> mStates;
};
already_AddRefed<nsILayoutHistoryState>
NS_NewLayoutHistoryState()
{
RefPtr<nsLayoutHistoryState> state = new nsLayoutHistoryState();
return state.forget();
}
NS_IMPL_ISUPPORTS(nsLayoutHistoryState,
nsILayoutHistoryState,
nsISupportsWeakReference)
NS_IMETHODIMP
nsLayoutHistoryState::GetHasStates(bool* aHasStates)
{
*aHasStates = HasStates();
return NS_OK;
}
NS_IMETHODIMP
nsLayoutHistoryState::GetKeys(uint32_t* aCount, char*** aKeys)
{
if (!HasStates()) {
return NS_ERROR_FAILURE;
}
char** keys =
static_cast<char**>(moz_xmalloc(sizeof(char*) * mStates.Count()));
*aCount = mStates.Count();
*aKeys = keys;
for (auto iter = mStates.Iter(); !iter.Done(); iter.Next()) {
*keys = ToNewCString(iter.Key());
keys++;
}
return NS_OK;
}
NS_IMETHODIMP
nsLayoutHistoryState::GetPresState(const nsACString& aKey,
float* aScrollX, float* aScrollY,
bool* aAllowScrollOriginDowngrade,
float* aRes, bool* aScaleToRes)
{
nsPresState* state = GetState(nsCString(aKey));
if (!state) {
return NS_ERROR_FAILURE;
}
*aScrollX = state->GetScrollPosition().x;
*aScrollY = state->GetScrollPosition().y;
*aAllowScrollOriginDowngrade = state->GetAllowScrollOriginDowngrade();
*aRes = state->GetResolution();
*aScaleToRes = state->GetScaleToResolution();
return NS_OK;
}
NS_IMETHODIMP
nsLayoutHistoryState::AddNewPresState(const nsACString& aKey,
float aScrollX, float aScrollY,
bool aAllowScrollOriginDowngrade,
float aRes, bool aScaleToRes)
{
nsPresState* newState = new nsPresState();
newState->SetScrollState(nsPoint(aScrollX, aScrollY));
newState->SetAllowScrollOriginDowngrade(aAllowScrollOriginDowngrade);
newState->SetResolution(aRes);
newState->SetScaleToResolution(aScaleToRes);
mStates.Put(nsCString(aKey), newState);
return NS_OK;
}
void
nsLayoutHistoryState::AddState(const nsCString& aStateKey, nsPresState* aState)
{
mStates.Put(aStateKey, aState);
}
nsPresState*
nsLayoutHistoryState::GetState(const nsCString& aKey)
{
nsPresState* state = nullptr;
bool entryExists = mStates.Get(aKey, &state);
if (entryExists && mScrollPositionOnly) {
// Ensure any state that shouldn't be restored is removed
state->ClearNonScrollState();
}
return state;
}
void
nsLayoutHistoryState::RemoveState(const nsCString& aKey)
{
mStates.Remove(aKey);
}
bool
nsLayoutHistoryState::HasStates()
{
return mStates.Count() != 0;
}
void
nsLayoutHistoryState::SetScrollPositionOnly(const bool aFlag)
{
mScrollPositionOnly = aFlag;
}
void
nsLayoutHistoryState::ResetScrollState()
{
for (auto iter = mStates.Iter(); !iter.Done(); iter.Next()) {
nsPresState* state = iter.UserData();
if (state) {
state->SetScrollState(nsPoint(0, 0));
}
}
}