Inheritance diagram

Collaboration diagram

Description

A responder can be scrolled when its virtual region is larger than its real region.

Scroll bar control(SFZScrollBarControl) is a control bound with this scrollable responder to indicate the position of the scrollable information in its real region.

	Note
	In a scroll bar control, when the scrollable state of its bound responder is changed into the unscrollable state or vice versa, the scroll bar event[SFEVT_RESPONDER_SCROLLBAR] [SFXEvent(SFEVT_RESPONDER_SCROLLBAR, SFP16_SCROLLBAR_ENABLE, 0)] will occur.

	Note
	Information on whether or not the sate is scrollable currently can be obtained using the SFYScrollBarControl::IsScrollable function.

SFZScrollBarControl is implemented by adding the drawing function and the instance creation function on SFYScrollBarControl.

For more details, refer to SFYScrollBarControl.

Reference

SFYScrollBarControl

Member

Description

This constructor sets the type of this responder to "cscr".

Reference

SFYResponder::SetType | SFZScrollBarControl::CodeEnum | Type

Description

This destructor does nothing.

Description

This function will be called when the (SFEVT_RESPONDER_RENDER, SFP16_RENDER_REQUEST) event is received.

In case you want to perform your own drawing of this responder, override this function.

The default implementation is to draw this responder.

The method to darw a responder

In addition to overriding this virtual function, it is possible to define and implement the handler for drawing event(drawing handler)[XANDLER_DECLARE_VOIDRENDER], and register it into the responder. Then, the overridden virtual function will be called first, and next the drawing handlers registered into the responder will be booted up in the registered order. In almost all cases, the method to override this function is used to draw the responder since there is no need to declare and register the drawing handler.

Procedure of drawing a responder

The drawing handler will be booted up when the drawing event(SFEVT_RESPONDER_RENDER) occurs. And then the drawing handler draw the responder actually. The drawing event will be sent to only the responders including the region to be redrawn out of the redraw regions registered into the renderer using the SFYResponder::InvokeBackward function after the SFYResponder::Render function boots up the renderer. Here, the SFYResponder::Render function will be called at the following situations: At the end of the event loop At the applet start / resume or the end of a highest priority event handler In the callback, which is outside the event loop. If calling the SFYResponder::Render function with specifying "true" as an argument, the drawing event will be sent to all the responders to be actually displayed on the screen which are located below the responder in the responder tree, regardless of the registration of redraw region.

Internal Implementation

Internal implementation of the SFZScrollBarControl::HandleRenderRequest function is as follows:

/*protected virtual */Void SFZScrollBarControl::HandleRenderRequest(SFXGraphicsPtr graphics) const
{
    DrawTrack(graphics);
    DrawDecrement(graphics);
    DrawIncrement(graphics);
    DrawThumb(graphics);
    return;
}// SFZScrollBarControl::HandleRenderRequest //

Reference

SFYScrollBarControl::DrawTrack | SFYScrollBarControl::DrawDecrement | SFYScrollBarControl::DrawIncrement | SFYScrollBarControl::DrawThumb | SFYResponder::Invalidate | SFYResponder::Render | SFYResponder::InvokeBackward | Drawing Event[SFEVT_RESPONDER_RENDER] | Handler for the Drawing Event[XANDLER_DECLARE_VOIDRENDER] | Rendering | Event Loop | Responder Tree | Virtual Region | Real Region | Local Region

Argument

Return value

Description

This function creates a new instance of this responder class.

If succeeds, a not null pointer will be returned, and the "exception" argument is SFERR_NO_ERROR. If fails such as insufficient memory, a null pointer will be returned, and the "exception" argument holds the error value.

Example

The code to create a new instance of this responder class is as follows:

SFZScrollBarControlSmp _scrollbar;
SFCError error;

if ((_scrollbar = SFZScrollBarControl::NewInstance(&error)) != null) {

    ...
}