dom/base/nsViewportInfo.h

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this
   3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 #ifndef nsViewportInfo_h___
   6 #define nsViewportInfo_h___
   7
   8 #include <stdint.h>
   9 #include "mozilla/Attributes.h"
  10 #include "Units.h"
  11
  12 namespace mozilla {
  13 namespace dom {
  14 enum class ViewportFitType : uint8_t {
  15   Auto,
  16   Contain,
  17   Cover,
  18 };
  19 }
  20 }  // namespace mozilla
  21
  22 /**
  23  * Default values for the nsViewportInfo class.
  24  */
  25 static const mozilla::LayoutDeviceToScreenScale kViewportMinScale(0.25f);
  26 static const mozilla::LayoutDeviceToScreenScale kViewportMaxScale(10.0f);
  27 static const mozilla::CSSIntSize kViewportMinSize(200, 40);
  28 static const mozilla::CSSIntSize kViewportMaxSize(10000, 10000);
  29
  30 /**
  31  * Information retrieved from the <meta name="viewport"> tag. See
  32  * Document::GetViewportInfo for more information on this functionality.
  33  */
  34 class MOZ_STACK_CLASS nsViewportInfo {
  35  public:
  36   enum class AutoSizeFlag {
  37     AutoSize,
  38     FixedSize,
  39   };
  40   enum class AutoScaleFlag {
  41     AutoScale,
  42     FixedScale,
  43   };
  44   enum class ZoomFlag {
  45     AllowZoom,
  46     DisallowZoom,
  47   };
  48   enum class ZoomBehaviour {
  49     Mobile,
  50     Desktop,  // disallows zooming out past default zoom
  51   };
  52   nsViewportInfo(const mozilla::ScreenIntSize& aDisplaySize,
  53                  const mozilla::CSSToScreenScale& aDefaultZoom,
  54                  ZoomFlag aZoomFlag, ZoomBehaviour aBehaviour)
  55       : mDefaultZoom(aDefaultZoom),
  56         mViewportFit(mozilla::dom::ViewportFitType::Auto),
  57         mDefaultZoomValid(true),
  58         mAutoSize(true),
  59         mAllowZoom(aZoomFlag == ZoomFlag::AllowZoom) {
  60     mSize = mozilla::ScreenSize(aDisplaySize) / mDefaultZoom;
  61     mozilla::CSSToLayoutDeviceScale pixelRatio(1.0f);
  62     if (aBehaviour == ZoomBehaviour::Desktop) {
  63       mMinZoom = aDefaultZoom;
  64     } else {
  65       mMinZoom = pixelRatio * kViewportMinScale;
  66     }
  67     mMaxZoom = pixelRatio * kViewportMaxScale;
  68     ConstrainViewportValues();
  69   }
  70
  71   nsViewportInfo(const mozilla::CSSToScreenScale& aDefaultZoom,
  72                  const mozilla::CSSToScreenScale& aMinZoom,
  73                  const mozilla::CSSToScreenScale& aMaxZoom,
  74                  const mozilla::CSSSize& aSize, AutoSizeFlag aAutoSizeFlag,
  75                  AutoScaleFlag aAutoScaleFlag, ZoomFlag aZoomFlag,
  76                  mozilla::dom::ViewportFitType aViewportFit)
  77       : mDefaultZoom(aDefaultZoom),
  78         mMinZoom(aMinZoom),
  79         mMaxZoom(aMaxZoom),
  80         mSize(aSize),
  81         mViewportFit(aViewportFit),
  82         mDefaultZoomValid(aAutoScaleFlag != AutoScaleFlag::AutoScale),
  83         mAutoSize(aAutoSizeFlag == AutoSizeFlag::AutoSize),
  84         mAllowZoom(aZoomFlag == ZoomFlag::AllowZoom) {
  85     ConstrainViewportValues();
  86   }
  87
  88   bool IsDefaultZoomValid() const { return mDefaultZoomValid; }
  89   mozilla::CSSToScreenScale GetDefaultZoom() const { return mDefaultZoom; }
  90   mozilla::CSSToScreenScale GetMinZoom() const { return mMinZoom; }
  91   mozilla::CSSToScreenScale GetMaxZoom() const { return mMaxZoom; }
  92
  93   mozilla::CSSSize GetSize() const { return mSize; }
  94
  95   bool IsAutoSizeEnabled() const { return mAutoSize; }
  96   bool IsZoomAllowed() const { return mAllowZoom; }
  97
  98   mozilla::dom::ViewportFitType GetViewportFit() const { return mViewportFit; }
  99
 100   enum {
 101     Auto = -1,
 102     ExtendToZoom = -2,
 103     DeviceSize = -3,  // for device-width or device-height
 104   };
 105   // MIN/MAX computations where one of the arguments is auto resolve to the
 106   // other argument. For instance, MIN(0.25, auto) = 0.25, and
 107   // MAX(5, auto) = 5.
 108   // https://drafts.csswg.org/css-device-adapt/#constraining-defs
 109   static const float& Max(const float& aA, const float& aB);
 110   static const float& Min(const float& aA, const float& aB);
 111
 112  private:
 113   /**
 114    * Constrain the viewport calculations from the
 115    * Document::GetViewportInfo() function in order to always return
 116    * sane minimum/maximum values.
 117    */
 118   void ConstrainViewportValues();
 119
 120   // Default zoom indicates the level at which the display is 'zoomed in'
 121   // initially for the user, upon loading of the page.
 122   mozilla::CSSToScreenScale mDefaultZoom;
 123
 124   // The minimum zoom level permitted by the page.
 125   mozilla::CSSToScreenScale mMinZoom;
 126
 127   // The maximum zoom level permitted by the page.
 128   mozilla::CSSToScreenScale mMaxZoom;
 129
 130   // The size of the viewport, specified by the <meta name="viewport"> tag.
 131   mozilla::CSSSize mSize;
 132
 133   // The value of the viewport-fit.
 134   mozilla::dom::ViewportFitType mViewportFit;
 135
 136   // If the default zoom was specified and was between the min and max
 137   // zoom values.
 138   // FIXME: Bug 1504362 - Unify this and mDefaultZoom into
 139   // Maybe<CSSToScreenScale>.
 140   bool mDefaultZoomValid;
 141
 142   // Whether or not we should automatically size the viewport to the device's
 143   // width. This is true if the document has been optimized for mobile, and
 144   // the width property of a specified <meta name="viewport"> tag is either
 145   // not specified, or is set to the special value 'device-width'.
 146   bool mAutoSize;
 147
 148   // Whether or not the user can zoom in and out on the page. Default is true.
 149   bool mAllowZoom;
 150 };
 151
 152 #endif