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      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
     29