/*
* 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 <tkInt.h>
#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 = 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;
Tcl_DString buf;
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_DStringInit(&buf);
Tcl_DStringAppend(&buf, s->scrollCmd, -1);
Tcl_DStringAppend(&buf, arg1, -1);
Tcl_DStringAppend(&buf, arg2, -1);
Tcl_Preserve(corePtr);
code = Tcl_EvalEx(interp, Tcl_DStringValue(&buf), -1, TCL_EVAL_GLOBAL);
Tcl_DStringFree(&buf);
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_BackgroundException(interp, code);
}
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(h);
}
