1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
|
/* trace.c,v 1.4 2005/09/12 03:11:01 jenglish Exp
*
* Copyright 2003, Joe English
*
* Simplified interface to Tcl_TraceVariable.
*
* PROBLEM: Can't distinguish "variable does not exist" (which is OK)
* from other errors (which are not).
*/
#include <tk.h>
#include "tkTheme.h"
#include "widget.h"
struct TtkTraceHandle_
{
Tcl_Interp *interp; /* Containing interpreter */
Tcl_Obj *varnameObj; /* Name of variable being traced */
Ttk_TraceProc callback; /* Callback procedure */
void *clientData; /* Data to pass to callback */
};
/*
* Tcl_VarTraceProc for trace handles.
*/
static char *
VarTraceProc(
ClientData clientData, /* Widget record pointer */
Tcl_Interp *interp, /* Interpreter containing variable. */
CONST char *name1, /* (unused) */
CONST char *name2, /* (unused) */
int flags) /* Information about what happened. */
{
Ttk_TraceHandle *tracePtr = clientData;
const char *name, *value;
Tcl_Obj *valuePtr;
if (flags & TCL_INTERP_DESTROYED) {
return NULL;
}
name = Tcl_GetString(tracePtr->varnameObj);
/*
* If the variable is being unset, then re-establish the trace:
*/
if (flags & TCL_TRACE_DESTROYED) {
Tcl_TraceVar(interp, name,
TCL_GLOBAL_ONLY|TCL_TRACE_WRITES|TCL_TRACE_UNSETS,
VarTraceProc, clientData);
tracePtr->callback(tracePtr->clientData, NULL);
return NULL;
}
/*
* Call the callback:
*/
valuePtr = Tcl_GetVar2Ex(interp, name, NULL, TCL_GLOBAL_ONLY);
value = valuePtr ? Tcl_GetString(valuePtr) : NULL;
tracePtr->callback(tracePtr->clientData, value);
return NULL;
}
/* Ttk_TraceVariable(interp, varNameObj, callback, clientdata) --
* Attach a write trace to the specified variable,
* which will pass the variable's value to 'callback'
* whenever the variable is set.
*
* When the variable is unset, passes NULL to the callback
* and reattaches the trace.
*/
Ttk_TraceHandle *Ttk_TraceVariable(
Tcl_Interp *interp,
Tcl_Obj *varnameObj,
Ttk_TraceProc callback,
void *clientData)
{
Ttk_TraceHandle *h = (Ttk_TraceHandle*)ckalloc(sizeof(*h));
int status;
h->interp = interp;
h->varnameObj = Tcl_DuplicateObj(varnameObj);
Tcl_IncrRefCount(h->varnameObj);
h->clientData = clientData;
h->callback = callback;
status = Tcl_TraceVar(interp, Tcl_GetString(varnameObj),
TCL_GLOBAL_ONLY|TCL_TRACE_WRITES|TCL_TRACE_UNSETS,
VarTraceProc, (ClientData)h);
if (status != TCL_OK) {
Tcl_DecrRefCount(h->varnameObj);
ckfree((ClientData)h);
return NULL;
}
return h;
}
/*
* Ttk_UntraceVariable --
* Remove previously-registered trace and free the handle.
*/
void Ttk_UntraceVariable(Ttk_TraceHandle *h)
{
if (h) {
Tcl_UntraceVar(h->interp, Tcl_GetString(h->varnameObj),
TCL_GLOBAL_ONLY|TCL_TRACE_WRITES|TCL_TRACE_UNSETS,
VarTraceProc, (ClientData)h);
Tcl_DecrRefCount(h->varnameObj);
ckfree((ClientData)h);
}
}
/*
* Ttk_FireTrace --
* Executes a trace handle as if the variable has been written.
*
* Note: may reenter the interpreter.
*/
int Ttk_FireTrace(Ttk_TraceHandle *tracePtr)
{
Tcl_Interp *interp = tracePtr->interp;
void *clientData = tracePtr->clientData;
const char *name = Tcl_GetString(tracePtr->varnameObj);
Ttk_TraceProc callback = tracePtr->callback;
Tcl_Obj *valuePtr;
const char *value;
/* Read the variable.
* Note that this can reenter the interpreter, and anything can happen --
* including the current trace handle being freed!
*/
valuePtr = Tcl_GetVar2Ex(interp, name, NULL, TCL_GLOBAL_ONLY);
value = valuePtr ? Tcl_GetString(valuePtr) : NULL;
/* Call callback.
*/
callback(clientData, value);
return TCL_OK;
}
/*EOF*/
|