Making a Control User Pane Theme-Compliant

Listing 3-5 shows a sample function, MyEditTextFrameControlUserPaneDrawProc , which, depending upon the presence of the Appearance Manager, branches between two functions, each of which draws a frame for an editable text field. In this example, the frame is defined as a control user pane. Before drawing, the MyEditTextFrameControlUserPaneDrawProc function calls the MyIsAppearancePresent function, described in Becoming a Client of the Appearance Manager , to determine whether the Appearance Manager is present.

MyEditTextFrameControlUserPaneDrawProc calls MyClassicEditTextFrameControlUserPaneDrawProc if the Appearance Manager is not present. MyClassicEditTextFrameControlUserPaneDrawProc first obtains the control rectangle, then supplies the control rectangle and a color to QuickDraw to draw the frame. However, an editable text frame drawn in this manner maintains a "fixed" look in any appearance and cannot adapt to a theme switch.

If the Appearance Manager is present, MyEditTextFrameControlUserPaneDrawProc calls the MyAppearanceSavvyEditTextFrameControlUserPaneDrawProc function. MyAppearanceSavvyEditTextFrameControlUserPaneDrawProc then passes the appropriate Appearance Manager constant for the drawing state (kThemeStateActive or kThemeStateInactive ) to the function DrawThemeEditTextFrame . DrawThemeEditTextFrame draws the frame appropriately for the activity state and the current theme. And, when a theme switch occurs, the frame automatically takes on a look consistent with the current theme.

Listing 3-5 Drawing a control user pane that is theme-compliant



 
static pascal void MyClassicEditTextFrameControlUserPaneDrawProc (

                                                    ControlHandle control,

                                                    SInt16 /* part */)

{

    Rect contrlRect = (**control).contrlRect;

    InsetRect (&contrlRect,-1,-1);

    // We're pre-Appearance Mgr here, so always draw in black...

    PenNormal ( );

    // unless the control part code value in contrlHilite indicates

    // that the control is inactive (or disabled); if so, draw in gray

    if ((**control).contrlHilite >= 254)

        PenPat (&(qd.gray));

    FrameRect (&contrlRect);

}



static pascal void MyAppearanceSavvyEditTextFrameControlUserPaneDrawProc (

                                                    ControlHandle control,

                                                    SInt16 /* part */)

{

    Rect contrlRect = (**control).contrlRect;

    DrawThemeEditTextFrame (&contrlRect,

        ((**control).contrlHilite < 254) ?

        kThemeStateActive : kThemeStateInactive);

}



static pascal void MyEditTextFrameControlUserPaneDrawProc (

                                                    ControlHandle control,

                                                    SInt16 part)

{

    OSStatus err = noErr;



    Boolean haveAppearance;



    if (!(err = MyIsAppearancePresent (&haveAppearance)))

    {

        if (haveAppearance)

            MyAppearanceSavvyEditTextFrameControlUserPaneDrawProc (control, part);

        else

            MyClassicEditTextFrameControlUserPaneDrawProc (control, part);

    }

}