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/* -*- 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/. */
#ifndef mozilla_StyleStructContext_h
#define mozilla_StyleStructContext_h
#include "CounterStyleManager.h"
#include "mozilla/LookAndFeel.h"
#include "nsPresContext.h"
class nsDeviceContext;
/**
* Construction context for style structs.
*
* Certain Gecko style structs have historically taken an nsPresContext
* argument in their constructor, which is used to compute various things. This
* makes Gecko style structs document-specific (which Servo style structs are
* not), and means that the initial values for style-structs cannot be shared
* across the entire runtime (as is the case in Servo).
*
* We'd like to remove this constraint so that Gecko can get the benefits of the
* Servo model, and so that Gecko aligns better with the Servo style system when
* using it. Unfortunately, this may require a fair amount of work, especially
* related to text zoom.
*
* So as an intermediate step, we define a reduced API set of "things that are
* needed when constructing style structs". This just wraps and forwards to an
* nsPresContext in the Gecko case, and returns some default not-always-correct
* values in the Servo case. We can then focus on reducing this API surface to
* zero, at which point this can be removed.
*
* We don't put the type in namespace mozilla, since we expect it to be
* temporary, and the namespacing would clutter up nsStyleStruct.h.
*/
#ifdef MOZ_STYLO
#define SERVO_DEFAULT(default_val) { if (!mPresContext) { return default_val; } }
#else
#define SERVO_DEFAULT(default_val) { MOZ_ASSERT(mPresContext); }
#endif
class StyleStructContext {
public:
MOZ_IMPLICIT StyleStructContext(nsPresContext* aPresContext)
: mPresContext(aPresContext) { MOZ_ASSERT(aPresContext); }
static StyleStructContext ServoContext() { return StyleStructContext(); }
// XXXbholley: Need to make text zoom work with stylo. This probably means
// moving the zoom handling out of computed values and into a post-
// computation.
float TextZoom()
{
SERVO_DEFAULT(1.0);
return mPresContext->TextZoom();
}
const nsFont* GetDefaultFont(uint8_t aFontID)
{
// NB: The servo case only differ from the default case in terms of which
// font pref cache gets used. The distinction is probably unnecessary.
SERVO_DEFAULT(mozilla::StaticPresData::Get()->
GetDefaultFont(aFontID, GetLanguageFromCharset()));
return mPresContext->GetDefaultFont(aFontID, GetLanguageFromCharset());
}
uint32_t GetBidi()
{
SERVO_DEFAULT(0);
return mPresContext->GetBidi();
}
int32_t AppUnitsPerDevPixel();
nscoord DevPixelsToAppUnits(int32_t aPixels)
{
return NSIntPixelsToAppUnits(aPixels, AppUnitsPerDevPixel());
}
typedef mozilla::LookAndFeel LookAndFeel;
nscolor DefaultColor()
{
SERVO_DEFAULT(LookAndFeel::GetColor(LookAndFeel::eColorID_WindowForeground,
NS_RGB(0x00, 0x00, 0x00)));
return mPresContext->DefaultColor();
}
mozilla::CounterStyle* BuildCounterStyle(const nsSubstring& aName)
{
SERVO_DEFAULT(mozilla::CounterStyleManager::GetBuiltinStyle(NS_STYLE_LIST_STYLE_DISC));
return mPresContext->CounterStyleManager()->BuildCounterStyle(aName);
}
nsIAtom* GetLanguageFromCharset() const
{
SERVO_DEFAULT(nsGkAtoms::x_western);
return mPresContext->GetLanguageFromCharset();
}
already_AddRefed<nsIAtom> GetContentLanguage() const
{
SERVO_DEFAULT(do_AddRef(nsGkAtoms::x_western));
return mPresContext->GetContentLanguage();
}
private:
nsDeviceContext* DeviceContext()
{
SERVO_DEFAULT(HackilyFindSomeDeviceContext());
return mPresContext->DeviceContext();
}
nsDeviceContext* HackilyFindSomeDeviceContext();
StyleStructContext() : mPresContext(nullptr) {}
nsPresContext* mPresContext;
};
#undef SERVO_DEFAULT
#endif // mozilla_StyleStructContext_h
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