- SlateCore\SlotBase.h
class SLATECORE_API FSlotBase // widget槽位, 每个槽位可拥有一个widget实例
{
FORCEINLINE_DEBUGGABLE void AttachWidget( const TSharedRef& InWidget )
{
Widget = InWidget;
}
/**
* Access the widget in the current slot.
* There will always be a widget in the slot; sometimes it is
* the SNullWidget instance.
*/
FORCEINLINE_DEBUGGABLE const TSharedRef& GetWidget() const
{
return Widget;
}
/**
* Remove the widget from its current slot.
* The removed widget is returned so that operations could be performed on it.
* If the null widget was being stored, an invalid shared ptr is returned instead.
*/
const TSharedPtr DetachWidget();
private:
/**
*
* Widget IS NOW PRIVATE!
*
*/
TSharedRef Widget;
};
template
class TSlotBase : public FSlotBase；
问题列表:
- 为何要TSlotBase，FSlotBase的子类是否拥有更多的槽位属性.
- SlateCore\Public\Widgets\DeclarativeSyntaxSupport.h
该文件时为了实现声明式编写ui而定义一些宏和类，声明式语法如下
//The Maximize/Minimize button is only displayed when not in Immersive mode.
SNew( SEditorViewportToolBarButton )
.Cursor( EMouseCursor::Default )
.ButtonType( EUserInterfaceActionType::ToggleButton )
.IsChecked( ViewportRef, &SLevelViewport::IsMaximized )
.OnClicked( ViewportRef, &SLevelViewport::OnToggleMaximize )
.Visibility( ViewportRef, &SLevelViewport::GetMaximizeToggleVisibility )
.Image( "LevelViewportToolBar.Maximize" )
.ToolTipText( LOCTEXT("Maximize_ToolTip", "Maximizes or restores this viewport") )
宏定义：
/**
* Slate widgets are constructed through SNew and SAssignNew.
* e.g.
*
* TSharedRef MyButton = SNew(SButton);
* or
* TSharedPtr MyButton;
* SAssignNew( MyButton, SButton );
*
* Using SNew and SAssignNew ensures that widgets are populated
*/
#define SNew( WidgetType, ... ) \
MakeTDecl( #WidgetType, __FILE__, __LINE__, RequiredArgs::MakeRequiredArgs(__VA_ARGS__) ) <<= TYPENAME_OUTSIDE_TEMPLATE WidgetType::FArguments()
#define SAssignNew( ExposeAs, WidgetType, ... ) \
MakeTDecl( #WidgetType, __FILE__, __LINE__, RequiredArgs::MakeRequiredArgs(__VA_ARGS__) ) . Expose( ExposeAs ) <<= TYPENAME_OUTSIDE_TEMPLATE WidgetType::FArguments()
其中每种类型的Widget都有自己的WidgetType::FArguments，作为初始化新实例的参数。
TDecl封装了构造Widget实例和初始化操作:
/**
* Utility class used during widget instantiation.
* Performs widget allocation and construction.
* Ensures that debug info is set correctly.
* Returns TSharedRef to widget.
*
* @see SNew
* @see SAssignNew
*/
template
struct TDecl
{
TDecl( const ANSICHAR* InType, const ANSICHAR* InFile, int32 OnLine, RequiredArgsPayloadType&& InRequiredArgs )
: _Widget( TWidgetAllocator::IsDerived >::PrivateAllocateWidget() )
, _RequiredArgs(InRequiredArgs)
{
_Widget->SetDebugInfo( InType, InFile, OnLine );
}
/**
* Initialize OutVarToInit with the widget that is being constructed.
* @see SAssignNew
*/
template
TDecl& Expose( TSharedPtr& OutVarToInit )
{
OutVarToInit = _Widget;
return *this;
}
/**
* Initialize OutVarToInit with the widget that is being constructed.
* @see SAssignNew
*/
template
TDecl& Expose( TSharedRef& OutVarToInit )
{
OutVarToInit = _Widget;
return *this;
}
/**
* Initialize a WEAK OutVarToInit with the widget that is being constructed.
* @see SAssignNew
*/
template
TDecl& Expose( TWeakPtr& OutVarToInit )
{
OutVarToInit = _Widget;
return *this;
}
/**
* Complete widget construction from InArgs.
*
* @param InArgs NamedArguments from which to construct the widget.
*
* @return A reference to the widget that we constructed.
*/
// 注意：该重载函数在宏中的应用.
TSharedRef operator<<=( const typename WidgetType::FArguments& InArgs ) const
{
//@todo UMG: This should be removed in favor of all widgets calling their superclass construct.
_Widget->SWidgetConstruct(
InArgs._ToolTipText,
InArgs._ToolTip ,
InArgs._Cursor ,
InArgs._IsEnabled ,
InArgs._Visibility,
InArgs._RenderTransform,
InArgs._RenderTransformPivot,
InArgs._Tag,
InArgs._ForceVolatile,
InArgs._Clipping,
InArgs.MetaData );
// 这里传递用户自定义类的参数, 和 FArguments的参数
_RequiredArgs.CallConstruct(_Widget, InArgs);
return _Widget;
}
const TSharedRef _Widget;
RequiredArgsPayloadType& _RequiredArgs;
};
- SlateCore\Public\Widgets\IToolTip.h
工具提示接口, 目前还不知道如何使用。
/**
* Interface for tool tips.
*/
class IToolTip
{
public:
/**
* Gets the widget that this tool tip represents.
*
* @return The tool tip widget.
*/
virtual TSharedRef AsWidget( ) = 0;
/**
* Gets the tool tip's content widget.
*
* @return The content widget.
*/
virtual TSharedRef GetContentWidget( ) = 0;
/**
* Sets the tool tip's content widget.
*
* @param InContentWidget The new content widget to set.
*/
virtual void SetContentWidget( const TSharedRef& InContentWidget ) = 0;
/**
* Checks whether this tool tip has no content to display right now.
*
* @return true if the tool tip has no content to display, false otherwise.
*/
virtual bool IsEmpty( ) const = 0;
/**
* Checks whether this tool tip can be made interactive by the user (by holding Ctrl).
*
* @return true if it is an interactive tool tip, false otherwise.
*/
virtual bool IsInteractive( ) const = 0;
/**
* Called when the tooltip widget is about to be requested for opening.
*/
virtual void OnOpening( ) = 0;
/**
* Called when the tooltip widget is closed and the tooltip is no longer needed.
*/
virtual void OnClosed( ) = 0;
public:
/** Virtual destructor. */
virtual ~IToolTip( ) { }
};