## wxRendererNative

First, a brief introduction to wxRenderer and why it is needed.

Usually wxWidgets uses the underlying low level GUI system to draw all the controls - this is what we mean when we say that it is a "native'' framework. However not all controls exist under all (or even any) platforms and in this case wxWidgets provides a default, generic, implementation of them written in wxWidgets itself.

These controls don't have the native appearance if only the standard line drawing and other graphics primitives are used, because the native appearance is different under different platforms while the lines are always drawn in the same way.

This is why we have renderers: wxRenderer is a class which virtualizes the drawing, i.e. it abstracts the drawing operations and allows you to draw say, a button, without caring about exactly how this is done. Of course, as we can draw the button differently in different renderers, this also allows us to emulate the native look and feel.

So the renderers work by exposing a large set of high-level drawing functions which are used by the generic controls. There is always a default global renderer but it may be changed or extended by the user, see Render sample.

All drawing functions take some standard parameters:

- win is the window being drawn. It is normally not used and when it is it should only be used as a generic wxWindow (in order to get its low level handle, for example), but you should not assume that it is of some given type as the same renderer function may be reused for drawing different kinds of control.
- dc is the wxDC to draw on. Only this device context should be used for drawing. It is not necessary to restore pens and brushes for it on function exit but, on the other hand, you shouldn't assume that it is in any specific state on function entry: the rendering functions should always prepare it.
- rect the bounding rectangle for the element to be drawn.
- flags the optional flags (none by default) which can be a combination of the `wxCONTROL_XXX` constants below.

Constants

The following rendering flags are defined:

    enum
    {
        wxCONTROL_DISABLED   = 0x00000001,  // control is disabled
        wxCONTROL_FOCUSED    = 0x00000002,  // currently has keyboard focus
        wxCONTROL_PRESSED    = 0x00000004,  // (button) is pressed
        wxCONTROL_ISDEFAULT  = 0x00000008,  // only applies to the buttons
        wxCONTROL_ISSUBMENU  = wxCONTROL_ISDEFAULT, // only for menu items
        wxCONTROL_EXPANDED   = wxCONTROL_ISDEFAULT, // only for the tree items
        wxCONTROL_CURRENT    = 0x00000010,  // mouse is currently over the control
        wxCONTROL_SELECTED   = 0x00000020,  // selected item in e.g. listbox
        wxCONTROL_CHECKED    = 0x00000040,  // (check/radio button) is checked
        wxCONTROL_CHECKABLE  = 0x00000080   // (menu) item can be checked
    };

Derived from

No base class

Include files

<wx/renderer.h>

Members

wxRendererNative::~wxRendererNative
wxRendererNative::DrawComboBoxDropButton
wxRendererNative::DrawDropArrow
wxRendererNative::DrawHeaderButton
wxRendererNative::DrawSplitterBorder
wxRendererNative::DrawSplitterSash
wxRendererNative::DrawTreeItemButton
wxRendererNative::Get
wxRendererNative::GetDefault
wxRendererNative::GetGeneric
wxRendererNative::GetSplitterParams
wxRendererNative::GetVersion
wxRendererNative::Load
wxRendererNative::Set

### wxRendererNative::~wxRendererNative

~wxRendererNative()

Virtual destructor as for any base class.

### wxRendererNative::DrawComboBoxDropButton

void DrawComboBoxDropButton(wxWindow *win, wxDC& dc, const wxRect& rect, int flags)

Draw a button like the one used by wxComboBox to show a drop down window. The usual appearance is a downwards pointing arrow.

flags may have the `wxCONTROL_PRESSED` or `wxCONTROL_CURRENT` bit set.

### wxRendererNative::DrawDropArrow

void DrawDropArrow(wxWindow *win, wxDC& dc, const wxRect& rect, int flags)

Draw a drop down arrow that is suitable for use outside a combo box. Arrow will have transparent background.

rect is not entirely filled by the arrow. Instead, you should use bounding rectangle of a drop down button which arrow matches the size you need. flags may have the `wxCONTROL_PRESSED` or `wxCONTROL_CURRENT` bit set.

### wxRendererNative::DrawHeaderButton

void DrawHeaderButton(wxWindow* win, wxDC& dc, const wxRect& rect, int flags = 0)

Draw the header control button (used by wxListCtrl).

### wxRendererNative::DrawSplitterBorder

void DrawSplitterBorder(wxWindow* win, wxDC& dc, const wxRect& rect, int flags = 0)

Draw the border for sash window: this border must be such that the sash drawn by DrawSash blends into it well.

### wxRendererNative::DrawSplitterSash

void DrawSplitterSash(wxWindow* win, wxDC& dc, const wxSize& size, wxCoord position, wxOrientation orient, int flags = 0)

Draw a sash. The orient parameter defines whether the sash should be vertical or horizontal and how the position should be interpreted.

### wxRendererNative::DrawTreeItemButton

void DrawTreeItemButton(wxWindow* win, wxDC& dc, const wxRect& rect, int flags = 0)

Draw the expanded/collapsed icon for a tree control item. To draw an expanded button the flags parameter must contain `wxCONTROL_EXPANDED` bit.

### wxRendererNative::Get

wxRendererNative& Get()

Return the currently used renderer.

### wxRendererNative::GetDefault

wxRendererNative& GetDefault()

Return the default (native) implementation for this platform -- this is also the one used by default but this may be changed by calling Set in which case the return value of this method may be different from the return value of Get.

### wxRendererNative::GetGeneric

wxRendererNative& GetGeneric()

Return the generic implementation of the renderer. Under some platforms, this is the default renderer implementation, others have platform-specific default renderer which can be retrieved by calling GetDefault.

### wxRendererNative::GetSplitterParams

wxSplitterRenderParams GetSplitterParams(const wxWindow* win)

Get the splitter parameters, see wxSplitterRenderParams.

### wxRendererNative::GetVersion

wxRendererVersion GetVersion() const

This function is used for version checking: Load refuses to load any shared libraries implementing an older or incompatible version.

The implementation of this method is always the same in all renderers (simply construct wxRendererVersion using the `wxRendererVersion::Current_XXX` values), but it has to be in the derived, not base, class, to detect mismatches between the renderers versions and so you have to implement it anew in all renderers.

### wxRendererNative::Load

wxRendererNative* Load(const wxString& name)

Load the renderer from the specified DLL, the returned pointer must be deleted by caller if not `NULL` when it is not used any more.

The name should be just the base name of the renderer and not the full name of the DLL file which is constructed differently (using wxDynamicLibrary::CanonicalizePluginName) on different systems.

### wxRendererNative::Set

wxRendererNative* Set(wxRendererNative* renderer)

Set the renderer to use, passing `NULL` reverts to using the default renderer (the global renderer must always exist).

Return the previous renderer used with Set() or `NULL` if none.