tor-browser

nsViewportInfo.h (5579B)

---

/* 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 nsViewportInfo_h___
#define nsViewportInfo_h___

#include <stdint.h>

#include <algorithm>

#include "Units.h"
#include "mozilla/Attributes.h"
#include "mozilla/StaticPrefs_apz.h"

namespace mozilla::dom {
enum class ViewportFitType : uint8_t {
 Auto,
 Contain,
 Cover,
};
}  // namespace mozilla::dom

/**
* Default values for the nsViewportInfo class.
*/
static const mozilla::CSSIntSize kViewportMinSize(200, 40);
static const mozilla::CSSIntSize kViewportMaxSize(10000, 10000);

inline mozilla::LayoutDeviceToScreenScale ViewportMinScale() {
 return mozilla::LayoutDeviceToScreenScale(
     std::max(mozilla::StaticPrefs::apz_min_zoom(), 0.1f));
}

inline mozilla::LayoutDeviceToScreenScale ViewportMaxScale() {
 return mozilla::LayoutDeviceToScreenScale(
     std::min(mozilla::StaticPrefs::apz_max_zoom(), 100.0f));
}

/**
* Information retrieved from the <meta name="viewport"> tag. See
* Document::GetViewportInfo for more information on this functionality.
*/
class MOZ_STACK_CLASS nsViewportInfo {
public:
 enum class AutoSizeFlag {
   AutoSize,
   FixedSize,
 };
 enum class AutoScaleFlag {
   AutoScale,
   FixedScale,
 };
 enum class ZoomFlag {
   AllowZoom,
   DisallowZoom,
 };
 enum class ZoomBehaviour {
   Mobile,
   Desktop,  // disallows zooming out past default zoom
 };
 nsViewportInfo(const mozilla::ScreenIntSize& aDisplaySize,
                const mozilla::CSSToScreenScale& aDefaultZoom,
                ZoomFlag aZoomFlag, ZoomBehaviour aBehaviour,
                AutoScaleFlag aAutoScaleFlag = AutoScaleFlag::FixedScale)
     : mDefaultZoom(aDefaultZoom),
       mViewportFit(mozilla::dom::ViewportFitType::Auto),
       mDefaultZoomValid(aAutoScaleFlag != AutoScaleFlag::AutoScale),
       mAutoSize(true),
       mAllowZoom(aZoomFlag == ZoomFlag::AllowZoom) {
   mSize = mozilla::ScreenSize(aDisplaySize) / mDefaultZoom;
   mozilla::CSSToLayoutDeviceScale pixelRatio(1.0f);
   if (aBehaviour == ZoomBehaviour::Desktop) {
     mMinZoom = aDefaultZoom;
   } else {
     mMinZoom = pixelRatio * ViewportMinScale();
   }
   mMaxZoom = pixelRatio * ViewportMaxScale();
   ConstrainViewportValues();
 }

 nsViewportInfo(const mozilla::CSSToScreenScale& aDefaultZoom,
                const mozilla::CSSToScreenScale& aMinZoom,
                const mozilla::CSSToScreenScale& aMaxZoom,
                const mozilla::CSSSize& aSize, AutoSizeFlag aAutoSizeFlag,
                AutoScaleFlag aAutoScaleFlag, ZoomFlag aZoomFlag,
                mozilla::dom::ViewportFitType aViewportFit)
     : mDefaultZoom(aDefaultZoom),
       mMinZoom(aMinZoom),
       mMaxZoom(aMaxZoom),
       mSize(aSize),
       mViewportFit(aViewportFit),
       mDefaultZoomValid(aAutoScaleFlag != AutoScaleFlag::AutoScale),
       mAutoSize(aAutoSizeFlag == AutoSizeFlag::AutoSize),
       mAllowZoom(aZoomFlag == ZoomFlag::AllowZoom) {
   ConstrainViewportValues();
 }

 bool IsDefaultZoomValid() const { return mDefaultZoomValid; }
 mozilla::CSSToScreenScale GetDefaultZoom() const { return mDefaultZoom; }
 mozilla::CSSToScreenScale GetMinZoom() const { return mMinZoom; }
 mozilla::CSSToScreenScale GetMaxZoom() const { return mMaxZoom; }

 mozilla::CSSSize GetSize() const { return mSize; }

 bool IsAutoSizeEnabled() const { return mAutoSize; }
 bool IsZoomAllowed() const { return mAllowZoom; }

 mozilla::dom::ViewportFitType GetViewportFit() const { return mViewportFit; }

 static constexpr float kAuto = -1.0f;
 static constexpr float kExtendToZoom = -2.0f;
 static constexpr float kDeviceSize =
     -3.0f;  // for device-width or device-height

 // MIN/MAX computations where one of the arguments is auto resolve to the
 // other argument. For instance, MIN(0.25, auto) = 0.25, and
 // MAX(5, auto) = 5.
 // https://drafts.csswg.org/css-device-adapt/#constraining-defs
 static const float& Max(const float& aA, const float& aB);
 static const float& Min(const float& aA, const float& aB);

private:
 /**
  * Constrain the viewport calculations from the
  * Document::GetViewportInfo() function in order to always return
  * sane minimum/maximum values.
  */
 void ConstrainViewportValues();

 // Default zoom indicates the level at which the display is 'zoomed in'
 // initially for the user, upon loading of the page.
 mozilla::CSSToScreenScale mDefaultZoom;

 // The minimum zoom level permitted by the page.
 mozilla::CSSToScreenScale mMinZoom;

 // The maximum zoom level permitted by the page.
 mozilla::CSSToScreenScale mMaxZoom;

 // The size of the viewport, specified by the <meta name="viewport"> tag.
 mozilla::CSSSize mSize;

 // The value of the viewport-fit.
 mozilla::dom::ViewportFitType mViewportFit;

 // If the default zoom was specified and was between the min and max
 // zoom values.
 // FIXME: Bug 1504362 - Unify this and mDefaultZoom into
 // Maybe<CSSToScreenScale>.
 bool mDefaultZoomValid;

 // Whether or not we should automatically size the viewport to the device's
 // width. This is true if the document has been optimized for mobile, and
 // the width property of a specified <meta name="viewport"> tag is either
 // not specified, or is set to the special value 'device-width'.
 bool mAutoSize;

 // Whether or not the user can zoom in and out on the page. Default is true.
 bool mAllowZoom;
};

#endif