// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_NATIVE_THEME_NATIVE_THEME_H_
#define UI_NATIVE_THEME_NATIVE_THEME_H_

#include "base/observer_list.h"
#include "third_party/skia/include/core/SkColor.h"
#include "ui/gfx/native_widget_types.h"
#include "ui/native_theme/native_theme_export.h"

class SkCanvas;

namespace gfx {
class Rect;
class Size;
}

namespace ui {

class NativeThemeObserver;

// This class supports drawing UI controls (like buttons, text fields, lists,
// comboboxes, etc) that look like the native UI controls of the underlying
// platform, such as Windows or Linux. It also supplies default colors for
// dialog box backgrounds, etc., which are obtained from the system theme where
// possible.
//
// The supported control types are listed in the Part enum.  These parts can be
// in any state given by the State enum, where the actual definition of the
// state is part-specific. The supported colors are listed in the ColorId enum.
//
// Some parts require more information than simply the state in order to be
// drawn correctly, and this information is given to the Paint() method via the
// ExtraParams union.  Each part that requires more information has its own
// field in the union.
//
// NativeTheme also supports getting the default size of a given part with
// the GetPartSize() method.
class NATIVE_THEME_EXPORT NativeTheme {
 public:
  // The part to be painted / sized.
  enum Part {
    kComboboxArrow,
    kCheckbox,
    kInnerSpinButton,
    kMenuList,
    kMenuCheck,
    kMenuCheckBackground,
    kMenuPopupArrow,
    kMenuPopupBackground,
    kMenuPopupGutter,
    kMenuPopupSeparator,
    kMenuItemBackground,
    kProgressBar,
    kPushButton,
    kRadio,

    // The order of the arrow enums is important, do not change without also
    // changing the code in platform implementations.
    kScrollbarDownArrow,
    kScrollbarLeftArrow,
    kScrollbarRightArrow,
    kScrollbarUpArrow,

    kScrollbarHorizontalThumb,
    kScrollbarVerticalThumb,
    kScrollbarHorizontalTrack,
    kScrollbarVerticalTrack,
    kScrollbarHorizontalGripper,
    kScrollbarVerticalGripper,
    // The corner is drawn when there is both a horizontal and vertical
    // scrollbar.
    kScrollbarCorner,
    kSliderTrack,
    kSliderThumb,
    kTabPanelBackground,
    kTextField,
    kTrackbarThumb,
    kTrackbarTrack,
    kWindowResizeGripper,
    kMaxPart,
  };

  // The state of the part.
  enum State {
    // IDs defined as specific values for use in arrays.
    kDisabled = 0,
    kHovered  = 1,
    kNormal   = 2,
    kPressed  = 3,
    kNumStates = kPressed + 1,
  };

  // Each structure below holds extra information needed when painting a given
  // part.

  struct ButtonExtraParams {
    bool checked;
    bool indeterminate;  // Whether the button state is indeterminate.
    bool is_default;  // Whether the button is default button.
    bool is_focused;
    bool has_border;
    int classic_state;  // Used on Windows when uxtheme is not available.
    SkColor background_color;
  };

  struct InnerSpinButtonExtraParams {
    bool spin_up;
    bool read_only;
    int classic_state;  // Used on Windows when uxtheme is not available.
  };

  struct MenuArrowExtraParams {
    bool pointing_right;
    // Used for the disabled state to indicate if the item is both disabled and
    // selected.
    bool is_selected;
  };

  struct MenuCheckExtraParams {
    bool is_radio;
    // Used for the disabled state to indicate if the item is both disabled and
    // selected.
    bool is_selected;
  };

  struct MenuItemExtraParams {
    bool is_selected;
  };

  struct MenuListExtraParams {
    bool has_border;
    bool has_border_radius;
    int arrow_x;
    int arrow_y;
    SkColor background_color;
    int classic_state;  // Used on Windows when uxtheme is not available.
  };

  struct MenuBackgroundExtraParams {
    int corner_radius;
  };

  struct ProgressBarExtraParams {
    double animated_seconds;
    bool determinate;
    int value_rect_x;
    int value_rect_y;
    int value_rect_width;
    int value_rect_height;
  };

  struct ScrollbarArrowExtraParams {
    bool is_hovering;
  };

  struct ScrollbarTrackExtraParams {
    bool is_upper;
    int track_x;
    int track_y;
    int track_width;
    int track_height;
    int classic_state;  // Used on Windows when uxtheme is not available.
  };

  struct ScrollbarThumbExtraParams {
    bool is_hovering;
  };

  struct SliderExtraParams {
    bool vertical;
    bool in_drag;
  };

  struct TextFieldExtraParams {
    bool is_text_area;
    bool is_listbox;
    SkColor background_color;
    bool is_read_only;
    bool is_focused;
    bool fill_content_area;
    bool draw_edges;
    int classic_state;  // Used on Windows when uxtheme is not available.
  };

  struct TrackbarExtraParams {
    bool vertical;
    int classic_state;  // Used on Windows when uxtheme is not available.
  };

  union ExtraParams {
    ButtonExtraParams button;
    InnerSpinButtonExtraParams inner_spin;
    MenuArrowExtraParams menu_arrow;
    MenuCheckExtraParams menu_check;
    MenuItemExtraParams menu_item;
    MenuListExtraParams menu_list;
    MenuBackgroundExtraParams menu_background;
    ProgressBarExtraParams progress_bar;
    ScrollbarArrowExtraParams scrollbar_arrow;
    ScrollbarTrackExtraParams scrollbar_track;
    ScrollbarThumbExtraParams scrollbar_thumb;
    SliderExtraParams slider;
    TextFieldExtraParams text_field;
    TrackbarExtraParams trackbar;
  };

  // Return the size of the part.
  virtual gfx::Size GetPartSize(Part part,
                                State state,
                                const ExtraParams& extra) const = 0;

  // Paint the part to the canvas.
  virtual void Paint(SkCanvas* canvas,
                     Part part,
                     State state,
                     const gfx::Rect& rect,
                     const ExtraParams& extra) const = 0;

  // Paint part during state transition, used for overlay scrollbar state
  // transition animation.
  virtual void PaintStateTransition(SkCanvas* canvas,
                                    Part part,
                                    State startState,
                                    State endState,
                                    double progress,
                                    const gfx::Rect& rect) const { }

  // Supports theme specific colors.
  void SetScrollbarColors(unsigned inactive_color,
                          unsigned active_color,
                          unsigned track_color);

  // Colors for GetSystemColor().
  enum ColorId {
    // Windows
    kColorId_WindowBackground,
    // Dialogs
    kColorId_DialogBackground,
    // FocusableBorder
    kColorId_FocusedBorderColor,
    kColorId_UnfocusedBorderColor,
    // Button
    kColorId_ButtonBackgroundColor,
    kColorId_ButtonEnabledColor,
    kColorId_ButtonDisabledColor,
    kColorId_ButtonHighlightColor,
    kColorId_ButtonHoverColor,
    kColorId_ButtonHoverBackgroundColor,
    kColorId_BlueButtonEnabledColor,
    kColorId_BlueButtonDisabledColor,
    kColorId_BlueButtonPressedColor,
    kColorId_BlueButtonHoverColor,
    kColorId_BlueButtonShadowColor,
    // MenuItem
    kColorId_EnabledMenuItemForegroundColor,
    kColorId_DisabledMenuItemForegroundColor,
    kColorId_DisabledEmphasizedMenuItemForegroundColor,
    kColorId_SelectedMenuItemForegroundColor,
    kColorId_FocusedMenuItemBackgroundColor,
    kColorId_HoverMenuItemBackgroundColor,
    kColorId_MenuSeparatorColor,
    kColorId_MenuBackgroundColor,
    kColorId_MenuBorderColor,
    // MenuButton - buttons in wrench menu
    kColorId_EnabledMenuButtonBorderColor,
    kColorId_FocusedMenuButtonBorderColor,
    kColorId_HoverMenuButtonBorderColor,
    // Label
    kColorId_LabelEnabledColor,
    kColorId_LabelDisabledColor,
    kColorId_LabelBackgroundColor,
    // Textfield
    kColorId_TextfieldDefaultColor,
    kColorId_TextfieldDefaultBackground,
    kColorId_TextfieldReadOnlyColor,
    kColorId_TextfieldReadOnlyBackground,
    kColorId_TextfieldSelectionColor,
    kColorId_TextfieldSelectionBackgroundFocused,
    // Tooltip
    kColorId_TooltipBackground,
    kColorId_TooltipText,
    // Tree
    kColorId_TreeBackground,
    kColorId_TreeText,
    kColorId_TreeSelectedText,
    kColorId_TreeSelectedTextUnfocused,
    kColorId_TreeSelectionBackgroundFocused,
    kColorId_TreeSelectionBackgroundUnfocused,
    kColorId_TreeArrow,
    // Table
    kColorId_TableBackground,
    kColorId_TableText,
    kColorId_TableSelectedText,
    kColorId_TableSelectedTextUnfocused,
    kColorId_TableSelectionBackgroundFocused,
    kColorId_TableSelectionBackgroundUnfocused,
    kColorId_TableGroupingIndicatorColor,
    // Results Tables, such as the chrome omnibox.
    kColorId_ResultsTableNormalBackground,
    kColorId_ResultsTableHoveredBackground,
    kColorId_ResultsTableSelectedBackground,
    kColorId_ResultsTableNormalText,
    kColorId_ResultsTableHoveredText,
    kColorId_ResultsTableSelectedText,
    kColorId_ResultsTableNormalDimmedText,
    kColorId_ResultsTableHoveredDimmedText,
    kColorId_ResultsTableSelectedDimmedText,
    kColorId_ResultsTableNormalUrl,
    kColorId_ResultsTableHoveredUrl,
    kColorId_ResultsTableSelectedUrl,
    kColorId_ResultsTableNormalDivider,
    kColorId_ResultsTableHoveredDivider,
    kColorId_ResultsTableSelectedDivider,
    // TODO(benrg): move other hardcoded colors here.

    kColorId_NumColors,
  };

  // Return a color from the system theme.
  virtual SkColor GetSystemColor(ColorId color_id) const = 0;

  // Returns a shared instance of the native theme.
  // The returned object should not be deleted by the caller.  This function
  // is not thread safe and should only be called from the UI thread.
  // Each port of NativeTheme should provide its own implementation of this
  // function, returning the port's subclass.
  static NativeTheme* instance();

  // Add or remove observers to be notified when the native theme changes.
  void AddObserver(NativeThemeObserver* observer);
  void RemoveObserver(NativeThemeObserver* observer);

  // Notify observers of native theme changes.
  void NotifyObservers();

 protected:
  NativeTheme();
  virtual ~NativeTheme();

  unsigned int thumb_inactive_color_;
  unsigned int thumb_active_color_;
  unsigned int track_color_;

 private:
  // Observers to notify when the native theme changes.
  ObserverList<NativeThemeObserver> native_theme_observers_;

  DISALLOW_COPY_AND_ASSIGN(NativeTheme);
};

}  // namespace ui

#endif  // UI_NATIVE_THEME_NATIVE_THEME_H_