1 /*
2 * Copyright 2004, Joe English
3 *
4 * Support routines for scrollable widgets.
5 *
6 * (This is sort of half-baked; needs some work)
7 *
8 * Scrollable interface:
9 *
10 * + 'first' is controlled by [xy]view widget command
11 * and other scrolling commands like 'see';
12 * + 'total' depends on widget contents;
13 * + 'last' depends on first, total, and widget size.
14 *
15 * Choreography (typical usage):
16 *
17 * 1. User adjusts scrollbar, scrollbar widget calls its -command
18 * 2. Scrollbar -command invokes the scrollee [xy]view widget method
19 * 3. TtkScrollviewCommand calls TtkScrollTo(), which updates
20 * 'first' and schedules a redisplay.
21 * 4. Once the scrollee knows 'total' and 'last' (typically in
22 * the LayoutProc), call TtkScrolled(h,first,last,total) to
23 * synchronize the scrollbar.
24 * 5. The scrollee -[xy]scrollcommand is called (in an idle callback)
25 * 6. Which calls the scrollbar 'set' method and redisplays the scrollbar.
26 *
27 * If the scrollee has internal scrolling (e.g., a 'see' method),
28 * it should TtkScrollTo() directly (step 2).
29 *
30 * If the widget value changes, it should call TtkScrolled() (step 4).
31 * (This usually happens automatically when the widget is redisplayed).
32 *
33 * If the scrollee's -[xy]scrollcommand changes, it should call
34 * TtkScrollbarUpdateRequired, which will invoke step (5) (@@@ Fix this)
35 */
36
37 #include <tkInt.h>
38 #include "ttkTheme.h"
39 #include "ttkWidget.h"
40
41 /* Private data:
42 */
43 #define SCROLL_UPDATE_PENDING (0x1)
44 #define SCROLL_UPDATE_REQUIRED (0x2)
45
46 struct ScrollHandleRec
47 {
48 unsigned flags;
49 WidgetCore *corePtr;
50 Scrollable *scrollPtr;
51 };
52
53 /* TtkCreateScrollHandle --
54 * Initialize scroll handle.
55 */
TtkCreateScrollHandle(WidgetCore * corePtr,Scrollable * scrollPtr)56 ScrollHandle TtkCreateScrollHandle(WidgetCore *corePtr, Scrollable *scrollPtr)
57 {
58 ScrollHandle h = (ScrollHandle)ckalloc(sizeof(*h));
59
60 h->flags = 0;
61 h->corePtr = corePtr;
62 h->scrollPtr = scrollPtr;
63
64 scrollPtr->first = 0;
65 scrollPtr->last = 1;
66 scrollPtr->total = 1;
67 return h;
68 }
69
70 /* UpdateScrollbar --
71 * Call the -scrollcommand callback to sync the scrollbar.
72 * Returns: Whatever the -scrollcommand does.
73 */
UpdateScrollbar(Tcl_Interp * interp,ScrollHandle h)74 static int UpdateScrollbar(Tcl_Interp *interp, ScrollHandle h)
75 {
76 Scrollable *s = h->scrollPtr;
77 WidgetCore *corePtr = h->corePtr;
78 char arg1[TCL_DOUBLE_SPACE + 2];
79 char arg2[TCL_DOUBLE_SPACE + 2];
80 int code;
81 Tcl_DString buf;
82
83 h->flags &= ~SCROLL_UPDATE_REQUIRED;
84
85 if (s->scrollCmd == NULL) {
86 return TCL_OK;
87 }
88
89 arg1[0] = arg2[0] = ' ';
90 Tcl_PrintDouble(interp, (double)s->first / s->total, arg1+1);
91 Tcl_PrintDouble(interp, (double)s->last / s->total, arg2+1);
92 Tcl_DStringInit(&buf);
93 Tcl_DStringAppend(&buf, s->scrollCmd, -1);
94 Tcl_DStringAppend(&buf, arg1, -1);
95 Tcl_DStringAppend(&buf, arg2, -1);
96
97 Tcl_Preserve(corePtr);
98 code = Tcl_EvalEx(interp, Tcl_DStringValue(&buf), -1, TCL_EVAL_GLOBAL);
99 Tcl_DStringFree(&buf);
100 if (WidgetDestroyed(corePtr)) {
101 Tcl_Release(corePtr);
102 return TCL_ERROR;
103 }
104 Tcl_Release(corePtr);
105
106 if (code != TCL_OK && !Tcl_InterpDeleted(interp)) {
107 /* Disable the -scrollcommand, add to stack trace:
108 */
109 ckfree(s->scrollCmd);
110 s->scrollCmd = 0;
111
112 Tcl_AddErrorInfo(interp, /* @@@ "horizontal" / "vertical" */
113 "\n (scrolling command executed by ");
114 Tcl_AddErrorInfo(interp, Tk_PathName(h->corePtr->tkwin));
115 Tcl_AddErrorInfo(interp, ")");
116 }
117 return code;
118 }
119
120 /* UpdateScrollbarBG --
121 * Idle handler to update the scrollbar.
122 */
UpdateScrollbarBG(ClientData clientData)123 static void UpdateScrollbarBG(ClientData clientData)
124 {
125 ScrollHandle h = (ScrollHandle)clientData;
126 Tcl_Interp *interp = h->corePtr->interp;
127 int code;
128
129 h->flags &= ~SCROLL_UPDATE_PENDING;
130 Tcl_Preserve((ClientData) interp);
131 code = UpdateScrollbar(interp, h);
132 if (code == TCL_ERROR && !Tcl_InterpDeleted(interp)) {
133 Tcl_BackgroundError(interp);
134 }
135 Tcl_Release((ClientData) interp);
136 }
137
138 /* TtkScrolled --
139 * Update scroll info, schedule scrollbar update.
140 */
TtkScrolled(ScrollHandle h,int first,int last,int total)141 void TtkScrolled(ScrollHandle h, int first, int last, int total)
142 {
143 Scrollable *s = h->scrollPtr;
144
145 /* Sanity-check inputs:
146 */
147 if (total <= 0) {
148 first = 0;
149 last = 1;
150 total = 1;
151 }
152
153 if (last > total) {
154 first -= (last - total);
155 if (first < 0) first = 0;
156 last = total;
157 }
158
159 if (s->first != first || s->last != last || s->total != total
160 || (h->flags & SCROLL_UPDATE_REQUIRED))
161 {
162 s->first = first;
163 s->last = last;
164 s->total = total;
165
166 if (!(h->flags & SCROLL_UPDATE_PENDING)) {
167 Tcl_DoWhenIdle(UpdateScrollbarBG, (ClientData)h);
168 h->flags |= SCROLL_UPDATE_PENDING;
169 }
170 }
171 }
172
173 /* TtkScrollbarUpdateRequired --
174 * Force a scrollbar update at the next call to TtkScrolled(),
175 * even if scroll parameters haven't changed (e.g., if
176 * -yscrollcommand has changed).
177 */
178
TtkScrollbarUpdateRequired(ScrollHandle h)179 void TtkScrollbarUpdateRequired(ScrollHandle h)
180 {
181 h->flags |= SCROLL_UPDATE_REQUIRED;
182 }
183
184 /* TtkScrollviewCommand --
185 * Widget [xy]view command implementation.
186 *
187 * $w [xy]view -- return current view region
188 * $w [xy]view $index -- set topmost item
189 * $w [xy]view moveto $fraction
190 * $w [xy]view scroll $number $what -- scrollbar interface
191 */
TtkScrollviewCommand(Tcl_Interp * interp,int objc,Tcl_Obj * const objv[],ScrollHandle h)192 int TtkScrollviewCommand(
193 Tcl_Interp *interp, int objc, Tcl_Obj *const objv[], ScrollHandle h)
194 {
195 Scrollable *s = h->scrollPtr;
196 int newFirst = s->first;
197
198 if (objc == 2) {
199 Tcl_Obj *result[2];
200 result[0] = Tcl_NewDoubleObj((double)s->first / s->total);
201 result[1] = Tcl_NewDoubleObj((double)s->last / s->total);
202 Tcl_SetObjResult(interp, Tcl_NewListObj(2, result));
203 return TCL_OK;
204 } else if (objc == 3) {
205 if (Tcl_GetIntFromObj(interp, objv[2], &newFirst) != TCL_OK) {
206 return TCL_ERROR;
207 }
208 } else {
209 double fraction;
210 int count;
211
212 switch (Tk_GetScrollInfoObj(interp, objc, objv, &fraction, &count)) {
213 case TK_SCROLL_ERROR:
214 return TCL_ERROR;
215 case TK_SCROLL_MOVETO:
216 newFirst = (int) ((fraction * s->total) + 0.5);
217 break;
218 case TK_SCROLL_UNITS:
219 newFirst = s->first + count;
220 break;
221 case TK_SCROLL_PAGES: {
222 int perPage = s->last - s->first; /* @@@ */
223 newFirst = s->first + count * perPage;
224 break;
225 }
226 }
227 }
228
229 TtkScrollTo(h, newFirst);
230
231 return TCL_OK;
232 }
233
TtkScrollTo(ScrollHandle h,int newFirst)234 void TtkScrollTo(ScrollHandle h, int newFirst)
235 {
236 Scrollable *s = h->scrollPtr;
237
238 if (newFirst >= s->total)
239 newFirst = s->total - 1;
240 if (newFirst > s->first && s->last >= s->total) /* don't scroll past end */
241 newFirst = s->first;
242 if (newFirst < 0)
243 newFirst = 0;
244
245 if (newFirst != s->first) {
246 s->first = newFirst;
247 TtkRedisplayWidget(h->corePtr);
248 }
249 }
250
TtkFreeScrollHandle(ScrollHandle h)251 void TtkFreeScrollHandle(ScrollHandle h)
252 {
253 if (h->flags & SCROLL_UPDATE_PENDING) {
254 Tcl_CancelIdleCall(UpdateScrollbarBG, (ClientData)h);
255 }
256 ckfree((ClientData)h);
257 }
258
259