/* $Id: ttkScroll.c,v 1.5.4.1 2008/08/19 14:48:00 jenglish Exp $ * * Copyright 2004, Joe English * * Support routines for scrollable widgets. * * (This is sort of half-baked; needs some work) * * Scrollable interface: * * + 'first' is controlled by [xy]view widget command * and other scrolling commands like 'see'; * + 'total' depends on widget contents; * + 'last' depends on first, total, and widget size. * * Choreography (typical usage): * * 1. User adjusts scrollbar, scrollbar widget calls its -command * 2. Scrollbar -command invokes the scrollee [xy]view widget method * 3. TtkScrollviewCommand calls TtkScrollTo(), which updates * 'first' and schedules a redisplay. * 4. Once the scrollee knows 'total' and 'last' (typically in * the LayoutProc), call TtkScrolled(h,first,last,total) to * synchronize the scrollbar. * 5. The scrollee -[xy]scrollcommand is called (in an idle callback) * 6. Which calls the scrollbar 'set' method and redisplays the scrollbar. * * If the scrollee has internal scrolling (e.g., a 'see' method), * it should TtkScrollTo() directly (step 2). * * If the widget value changes, it should call TtkScrolled() (step 4). * (This usually happens automatically when the widget is redisplayed). * * If the scrollee's -[xy]scrollcommand changes, it should call * TtkScrollbarUpdateRequired, which will invoke step (5) (@@@ Fix this) */ #include #include "ttkTheme.h" #include "ttkWidget.h" /* Private data: */ #define SCROLL_UPDATE_PENDING (0x1) #define SCROLL_UPDATE_REQUIRED (0x2) struct ScrollHandleRec { unsigned flags; WidgetCore *corePtr; Scrollable *scrollPtr; }; /* TtkCreateScrollHandle -- * Initialize scroll handle. */ ScrollHandle TtkCreateScrollHandle(WidgetCore *corePtr, Scrollable *scrollPtr) { ScrollHandle h = (ScrollHandle)ckalloc(sizeof(*h)); h->flags = 0; h->corePtr = corePtr; h->scrollPtr = scrollPtr; scrollPtr->first = 0; scrollPtr->last = 1; scrollPtr->total = 1; return h; } /* UpdateScrollbar -- * Call the -scrollcommand callback to sync the scrollbar. * Returns: Whatever the -scrollcommand does. */ static int UpdateScrollbar(Tcl_Interp *interp, ScrollHandle h) { Scrollable *s = h->scrollPtr; WidgetCore *corePtr = h->corePtr; char arg1[TCL_DOUBLE_SPACE + 2]; char arg2[TCL_DOUBLE_SPACE + 2]; int code; h->flags &= ~SCROLL_UPDATE_REQUIRED; if (s->scrollCmd == NULL) { return TCL_OK; } arg1[0] = arg2[0] = ' '; Tcl_PrintDouble(interp, (double)s->first / s->total, arg1+1); Tcl_PrintDouble(interp, (double)s->last / s->total, arg2+1); Tcl_Preserve(corePtr); code = Tcl_VarEval(interp, s->scrollCmd, arg1, arg2, NULL); if (WidgetDestroyed(corePtr)) { Tcl_Release(corePtr); return TCL_ERROR; } Tcl_Release(corePtr); if (code != TCL_OK && !Tcl_InterpDeleted(interp)) { /* Disable the -scrollcommand, add to stack trace: */ ckfree(s->scrollCmd); s->scrollCmd = 0; Tcl_AddErrorInfo(interp, /* @@@ "horizontal" / "vertical" */ "\n (scrolling command executed by "); Tcl_AddErrorInfo(interp, Tk_PathName(h->corePtr->tkwin)); Tcl_AddErrorInfo(interp, ")"); } return code; } /* UpdateScrollbarBG -- * Idle handler to update the scrollbar. */ static void UpdateScrollbarBG(ClientData clientData) { ScrollHandle h = (ScrollHandle)clientData; Tcl_Interp *interp = h->corePtr->interp; int code; h->flags &= ~SCROLL_UPDATE_PENDING; Tcl_Preserve((ClientData) interp); code = UpdateScrollbar(interp, h); if (code == TCL_ERROR && !Tcl_InterpDeleted(interp)) { Tcl_BackgroundError(interp); } Tcl_Release((ClientData) interp); } /* TtkScrolled -- * Update scroll info, schedule scrollbar update. */ void TtkScrolled(ScrollHandle h, int first, int last, int total) { Scrollable *s = h->scrollPtr; /* Sanity-check inputs: */ if (total <= 0) { first = 0; last = 1; total = 1; } if (last > total) { first -= (last - total); if (first < 0) first = 0; last = total; } if (s->first != first || s->last != last || s->total != total || (h->flags & SCROLL_UPDATE_REQUIRED)) { s->first = first; s->last = last; s->total = total; if (!(h->flags & SCROLL_UPDATE_PENDING)) { Tcl_DoWhenIdle(UpdateScrollbarBG, (ClientData)h); h->flags |= SCROLL_UPDATE_PENDING; } } } /* TtkScrollbarUpdateRequired -- * Force a scrollbar update at the next call to TtkScrolled(), * even if scroll parameters haven't changed (e.g., if * -yscrollcommand has changed). */ void TtkScrollbarUpdateRequired(ScrollHandle h) { h->flags |= SCROLL_UPDATE_REQUIRED; } /* TtkScrollviewCommand -- * Widget [xy]view command implementation. * * $w [xy]view -- return current view region * $w [xy]view $index -- set topmost item * $w [xy]view moveto $fraction * $w [xy]view scroll $number $what -- scrollbar interface */ int TtkScrollviewCommand( Tcl_Interp *interp, int objc, Tcl_Obj *const objv[], ScrollHandle h) { Scrollable *s = h->scrollPtr; int newFirst = s->first; if (objc == 2) { Tcl_Obj *result[2]; result[0] = Tcl_NewDoubleObj((double)s->first / s->total); result[1] = Tcl_NewDoubleObj((double)s->last / s->total); Tcl_SetObjResult(interp, Tcl_NewListObj(2, result)); return TCL_OK; } else if (objc == 3) { if (Tcl_GetIntFromObj(interp, objv[2], &newFirst) != TCL_OK) { return TCL_ERROR; } } else { double fraction; int count; switch (Tk_GetScrollInfoObj(interp, objc, objv, &fraction, &count)) { case TK_SCROLL_ERROR: return TCL_ERROR; case TK_SCROLL_MOVETO: newFirst = (int) ((fraction * s->total) + 0.5); break; case TK_SCROLL_UNITS: newFirst = s->first + count; break; case TK_SCROLL_PAGES: { int perPage = s->last - s->first; /* @@@ */ newFirst = s->first + count * perPage; break; } } } TtkScrollTo(h, newFirst); return TCL_OK; } void TtkScrollTo(ScrollHandle h, int newFirst) { Scrollable *s = h->scrollPtr; if (newFirst >= s->total) newFirst = s->total - 1; if (newFirst > s->first && s->last >= s->total) /* don't scroll past end */ newFirst = s->first; if (newFirst < 0) newFirst = 0; if (newFirst != s->first) { s->first = newFirst; TtkRedisplayWidget(h->corePtr); } } void TtkFreeScrollHandle(ScrollHandle h) { if (h->flags & SCROLL_UPDATE_PENDING) { Tcl_CancelIdleCall(UpdateScrollbarBG, (ClientData)h); } ckfree((ClientData)h); }