content/public/common/page_zoom.h

   1 // Copyright (c) 2012 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 #ifndef CONTENT_PUBLIC_COMMON_PAGE_ZOOM_H_
   6 #define CONTENT_PUBLIC_COMMON_PAGE_ZOOM_H_
   7
   8 #include "content/common/content_export.h"
   9
  10 namespace content {
  11
  12 // This enum is the parameter to various text/page zoom commands so we know
  13 // what the specific zoom command is.
  14 enum PageZoom {
  15   PAGE_ZOOM_OUT   = -1,
  16   PAGE_ZOOM_RESET = 0,
  17   PAGE_ZOOM_IN    = 1,
  18 };
  19
  20 // The minimum zoom factor permitted for a page. This is an alternative to
  21 // WebView::minTextSizeMultiplier.
  22 CONTENT_EXPORT extern const double kMinimumZoomFactor;
  23
  24 // The maximum zoom factor permitted for a page. This is an alternative to
  25 // WebView::maxTextSizeMultiplier.
  26 CONTENT_EXPORT extern const double kMaximumZoomFactor;
  27
  28 // Epsilon value for comparing two floating-point zoom values. We don't use
  29 // std::numeric_limits<> because it is too precise for zoom values. Zoom
  30 // values lose precision due to factor/level conversions. A value of 0.001
  31 // is precise enough for zoom value comparisons.
  32 CONTENT_EXPORT extern const double kEpsilon;
  33
  34 // Test if two zoom values (either zoom factors or zoom levels) should be
  35 // considered equal.
  36 CONTENT_EXPORT bool ZoomValuesEqual(double value_a, double value_b);
  37
  38 // Converts between zoom factors and levels.
  39 CONTENT_EXPORT double ZoomLevelToZoomFactor(double zoom_level);
  40 CONTENT_EXPORT double ZoomFactorToZoomLevel(double factor);
  41
  42 }  // namespace content
  43
  44 #endif  // CONTENT_PUBLIC_COMMON_PAGE_ZOOM_H_