content/common/page_zoom.cc

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include <cmath>
   6
   7 #include "content/public/common/page_zoom.h"
   8
   9 namespace content {
  10
  11 const double kMinimumZoomFactor = 0.25;
  12 const double kMaximumZoomFactor = 5.0;
  13 const double kEpsilon = 0.001;
  14 const double kTextSizeMultiplierRatio = 1.2;
  15
  16 bool ZoomValuesEqual(double value_a, double value_b) {
  17   return (std::fabs(value_a - value_b) <= kEpsilon);
  18 }
  19
  20 double ZoomLevelToZoomFactor(double zoom_level) {
  21   return std::pow(kTextSizeMultiplierRatio, zoom_level);
  22 }
  23
  24 double ZoomFactorToZoomLevel(double factor) {
  25   return std::log(factor) / std::log(kTextSizeMultiplierRatio);
  26 }
  27
  28 }  // namespace content