Example 4.8. Implement the HandleRender() not to draw the "Hello World" string

// handler for redrawing full screen
Bool helloworld::HandleRender(SFXEventConstRef event)
{
    // here describe full screen redrawing when an applet starts or resumes

    SFXGraphicsPtr graphics;
    Bool      result(false);

    if (IsRenderable()) {  // if screen can be redrawn (i.e., if no highest priority event handler is registered)

        // get SFXGraphics instance
        if ((graphics = SFXGraphics::GetInstance()) != null) {

            // fill screen in white
            // get screen with SFXGraphics::GetDeviceRectangle() 
            // SFXRGBColor(0xFF, 0xFF, 0xFF, 0x00) represents white color
            graphics->ClearRectangle(graphics->GetDeviceRectangle(), SFXRGBColor(0xFF, 0xFF, 0xFF, 0x00));

            // call SFXGraphics::Update() to redraw screen
            // * screen will not be redrawn or updated if line below is NOT described
            graphics->Update();

            result = true;  // set result to "true" since screen is redrawn
        }
    }

    return result; // return "true" if screen has been redrawn, otherwise return "false"
}

	HandleRender() function
	The full screen has to be redrawn when an applet starts or resumes. The HandleRender() function will be automatically called at these timings. In the above example, the SFCApplication::HandleRender virtual function is overridden to fill the screen in white when this applet starts or resumes.

	Return value of the HandleRender() function
	The HandleRender() function will return "true" if the device screen is redrawn. Otherwise it will return "false".

	"graphics->Update();"
	When the full screen redrawing handler of SFCApplication::HandleRender is overridden, the screen will not be redrawn unless the SFXGraphics::Update function is called. Therefore, you have to describe the "graphics->Update();" statement at the end of the drawing processing.

Example 4.9. Draw() function

// Draw() function is a normal drawing function, which is called in the key handler("OnKey()" function)
Void Draw(Void)
{
    // fill screen in white and draw "Hello World" in black

    // get SFXGraphics instance
    SFXGraphicsPtr graphics = SFXGraphics::GetInstance();

    // clear screen
    // get rectangular screen coordinates by SFXGraphics::GetDeviceRectangle function
    // SFXRGBColor(0xFF, 0xFF, 0xFF, 0x00) defines white
    graphics->FillRectangle(SFXGraphics::GetDeviceRectangle(),
                               SFXRGBColor(0xFF, 0xFF, 0xFF, 0x00));

    // draw "Hello World" in screen
    graphics->DrawText("Hello World", SFXGraphics::GetDeviceRectangle(),
                          SFXRGBColor(0x00, 0x00, 0x00, 0x00));

    // call SFXGraphics::Update() to redraw screen
    // * screen will not be redrawn or updated if line below is NOT described
    graphics->Update();

    // * there is no need to return "true" or "false" in Draw() function
}

	Return value of the Draw() function
	Unlike the HandleRender() function, the Draw() function does not have to return "true" nor "false" as a return value.

"graphics->Update();"

In the Draw() function, the screen will not be redrawn unless the SFXGraphics::Update function is called. Therefore, you have to describe the "graphics->Update();" statement at the end of the drawing processing. However, when the responder region is drawn in the SFY applet, there is no need to describe the "graphics->Update();" statement since it will be executed automatically inside the renderer.

Example 4.10. Customize the key handler "OnKey()"

// key handler
Bool helloworld::OnKey(UInt16 key)
{
    // processing for key events
    switch (key) {

        case AVK_SELECT: // when SELECT key is pressed 

            Terminate(); // terminate application

            return true;

        // *** following are added
        case AVK_1:      // when "1" key is pressed

            Draw();      // call Draw() function

            return true; // return "true" since key event is handled
    }

    return false;  // return "false" since key event is NOT handled
}

	Return value of key handler
	The key handler returns "true" if it handles an event, otherwise it returns "false".