dom/base/nsViewportInfo.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "nsViewportInfo.h"
   8 #include "mozilla/Assertions.h"
   9 #include <algorithm>
  10
  11 using namespace mozilla;
  12
  13 void nsViewportInfo::ConstrainViewportValues() {
  14   // Non-positive zoom factors can produce NaN or negative viewport sizes,
  15   // so we better be sure our constraints will produce positive zoom factors.
  16   MOZ_ASSERT(mMinZoom > CSSToScreenScale(0.0f), "zoom factor must be positive");
  17   MOZ_ASSERT(mMaxZoom > CSSToScreenScale(0.0f), "zoom factor must be positive");
  18
  19   if (mDefaultZoom > mMaxZoom) {
  20     mDefaultZoomValid = false;
  21     mDefaultZoom = mMaxZoom;
  22   }
  23   if (mDefaultZoom < mMinZoom) {
  24     mDefaultZoomValid = false;
  25     mDefaultZoom = mMinZoom;
  26   }
  27 }
  28
  29 static const float& MinOrMax(const float& aA, const float& aB,
  30                              const float& (*aMinOrMax)(const float&,
  31                                                        const float&)) {
  32   MOZ_ASSERT(aA != nsViewportInfo::kExtendToZoom &&
  33              aA != nsViewportInfo::kDeviceSize &&
  34              aB != nsViewportInfo::kExtendToZoom &&
  35              aB != nsViewportInfo::kDeviceSize);
  36   if (aA == nsViewportInfo::kAuto) {
  37     return aB;
  38   }
  39   if (aB == nsViewportInfo::kAuto) {
  40     return aA;
  41   }
  42   return aMinOrMax(aA, aB);
  43 }
  44
  45 // static
  46 const float& nsViewportInfo::Min(const float& aA, const float& aB) {
  47   return MinOrMax(aA, aB, std::min);
  48 }
  49
  50 // static
  51 const float& nsViewportInfo::Max(const float& aA, const float& aB) {
  52   return MinOrMax(aA, aB, std::max);
  53 }