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:
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 fromNo 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()
Virtual destructor as for any base class.
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.
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.
void DrawHeaderButton(wxWindow* win, wxDC& dc, const wxRect& rect, int flags = 0)
Draw the header control button (used by wxListCtrl).
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.
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.
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()
Return the currently used renderer.
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()
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.
wxSplitterRenderParams GetSplitterParams(const wxWindow* win)
Get the splitter parameters, see wxSplitterRenderParams.
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(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* 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.