ui/base/layout.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 UI_BASE_LAYOUT_H_
   6 #define UI_BASE_LAYOUT_H_
   7
   8 #include <vector>
   9
  10 #include "build/build_config.h"
  11 #include "ui/base/ui_base_export.h"
  12 #include "ui/gfx/native_widget_types.h"
  13
  14 namespace ui {
  15
  16 // Supported UI scale factors for the platform. This is used as an index
  17 // into the array |kScaleFactorScales| which maps the enum value to a float.
  18 // SCALE_FACTOR_NONE is used for density independent resources such as
  19 // string, html/js files or an image that can be used for any scale factors
  20 // (such as wallpapers).
  21 enum ScaleFactor {
  22   SCALE_FACTOR_NONE = 0,
  23   SCALE_FACTOR_100P,
  24   SCALE_FACTOR_125P,
  25   SCALE_FACTOR_133P,
  26   SCALE_FACTOR_140P,
  27   SCALE_FACTOR_150P,
  28   SCALE_FACTOR_180P,
  29   SCALE_FACTOR_200P,
  30   SCALE_FACTOR_300P,
  31
  32   NUM_SCALE_FACTORS  // This always appears last.
  33 };
  34
  35 // Changes the value of GetSupportedScaleFactors() to |scale_factors|.
  36 // Use ScopedSetSupportedScaleFactors for unit tests as not to affect the
  37 // state of other tests.
  38 UI_BASE_EXPORT void SetSupportedScaleFactors(
  39     const std::vector<ScaleFactor>& scale_factors);
  40
  41 // Returns a vector with the scale factors which are supported by this
  42 // platform, in ascending order.
  43 UI_BASE_EXPORT const std::vector<ScaleFactor>& GetSupportedScaleFactors();
  44
  45 // Returns the actual image scale to be used for the scale factor passed in.
  46 // On Windows high dpi, this returns the dpi scale for the display.
  47 UI_BASE_EXPORT float GetImageScale(ScaleFactor scale_factor);
  48
  49 // Returns the supported ScaleFactor which most closely matches |scale|.
  50 // Converting from float to ScaleFactor is inefficient and should be done as
  51 // little as possible.
  52 // TODO(oshima): Make ScaleFactor a class and remove this.
  53 UI_BASE_EXPORT ScaleFactor GetSupportedScaleFactor(float image_scale);
  54
  55 // Returns the ScaleFactor used by |view|.
  56 UI_BASE_EXPORT ScaleFactor GetScaleFactorForNativeView(gfx::NativeView view);
  57
  58 // Returns true if |scale_factor| is supported by this platform.
  59 UI_BASE_EXPORT bool IsScaleFactorSupported(ScaleFactor scale_factor);
  60
  61 // Returns the scale factor closest to |scale| from the full list of factors.
  62 // Note that it does NOT rely on the list of supported scale factors.
  63 // Finding the closest match is inefficient and shouldn't be done frequently.
  64 UI_BASE_EXPORT ScaleFactor FindClosestScaleFactorUnsafe(float scale);
  65
  66 // Returns the image scale for the scale factor passed in.
  67 UI_BASE_EXPORT float GetScaleForScaleFactor(ScaleFactor scale_factor);
  68
  69 namespace test {
  70 // Class which changes the value of GetSupportedScaleFactors() to
  71 // |new_scale_factors| for the duration of its lifetime.
  72 class UI_BASE_EXPORT ScopedSetSupportedScaleFactors {
  73  public:
  74   explicit ScopedSetSupportedScaleFactors(
  75       const std::vector<ui::ScaleFactor>& new_scale_factors);
  76   ~ScopedSetSupportedScaleFactors();
  77
  78  private:
  79   std::vector<ui::ScaleFactor>* original_scale_factors_;
  80
  81   DISALLOW_COPY_AND_ASSIGN(ScopedSetSupportedScaleFactors);
  82 };
  83
  84 }  // namespace test
  85
  86 }  // namespace ui
  87
  88 #endif  // UI_BASE_LAYOUT_H_