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      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_export.h"
     12 #include "ui/gfx/native_widget_types.h"
     13 
     14 namespace ui {
     15 
     16 enum DisplayLayout {
     17   // The typical layout for e.g. Windows, Mac and Linux.
     18   LAYOUT_DESKTOP,
     19 
     20   // Layout optimized for touch.  Used e.g. for Windows 8 Metro mode.
     21   LAYOUT_TOUCH,
     22 };
     23 
     24 // Returns the display layout that should be used.  This could be used
     25 // e.g. to tweak hard-coded padding that's layout specific, or choose
     26 // the .pak file of theme resources to load.
     27 // WARNING: this is deprecated and will be nuked as soon as aura is the default
     28 // on windows.
     29 UI_EXPORT DisplayLayout GetDisplayLayout();
     30 
     31 // Supported UI scale factors for the platform. This is used as an index
     32 // into the array |kScaleFactorScales| which maps the enum value to a float.
     33 // SCALE_FACTOR_NONE is used for density independent resources such as
     34 // string, html/js files or an image that can be used for any scale factors
     35 // (such as wallpapers).
     36 enum ScaleFactor {
     37   SCALE_FACTOR_NONE = 0,
     38   SCALE_FACTOR_100P,
     39   SCALE_FACTOR_133P,
     40   SCALE_FACTOR_140P,
     41   SCALE_FACTOR_150P,
     42   SCALE_FACTOR_180P,
     43   SCALE_FACTOR_200P,
     44 
     45   NUM_SCALE_FACTORS  // This always appears last.
     46 };
     47 
     48 // Returns the float scale value for |scale_factor|.
     49 UI_EXPORT float GetScaleFactorScale(ScaleFactor scale_factor);
     50 
     51 // Returns the supported ScaleFactor which most closely matches |scale|.
     52 // Converting from float to ScaleFactor is inefficient and should be done as
     53 // little as possible.
     54 // TODO(oshima): Make ScaleFactor a class and remove this.
     55 UI_EXPORT ScaleFactor GetScaleFactorFromScale(float scale);
     56 
     57 // Returns the ScaleFactor used by |view|.
     58 UI_EXPORT ScaleFactor GetScaleFactorForNativeView(gfx::NativeView view);
     59 
     60 // Returns the maximum device scale factor supported by this platform.
     61 UI_EXPORT ScaleFactor GetMaxScaleFactor();
     62 
     63 // Returns a vector with the scale factors which are supported by this
     64 // platform, in ascending order.
     65 UI_EXPORT std::vector<ScaleFactor> GetSupportedScaleFactors();
     66 
     67 // Returns true if |scale_factor| is supported by this platform.
     68 UI_EXPORT bool IsScaleFactorSupported(ScaleFactor scale_factor);
     69 
     70 namespace test {
     71 
     72 // Changes the value of GetSupportedScaleFactors() to |scale_factors|.
     73 // Use ScopedSetSupportedScaleFactors for unit tests as not to affect the
     74 // state of other tests.
     75 UI_EXPORT void SetSupportedScaleFactors(
     76     const std::vector<ScaleFactor>& scale_factors);
     77 
     78 // Class which changes the value of GetSupportedScaleFactors() to
     79 // |new_scale_factors| for the duration of its lifetime.
     80 class UI_EXPORT ScopedSetSupportedScaleFactors {
     81  public:
     82   explicit ScopedSetSupportedScaleFactors(
     83       const std::vector<ui::ScaleFactor>& new_scale_factors);
     84   ~ScopedSetSupportedScaleFactors();
     85 
     86  private:
     87   const std::vector<ui::ScaleFactor> original_scale_factors_;
     88 
     89   DISALLOW_COPY_AND_ASSIGN(ScopedSetSupportedScaleFactors);
     90 };
     91 
     92 }  // namespace test
     93 
     94 }  // namespace ui
     95 
     96 #endif  // UI_BASE_LAYOUT_H_
     97