1 files changed, 144 insertions, 0 deletions
diff --git a/generic/ttk/ttkTrace.c b/generic/ttk/ttkTrace.c
new file mode 100644
index 0000000..0128a1d
--- /dev/null
+++ b/generic/ttk/ttkTrace.c
@@ -0,0 +1,144 @@
+/*
+ * 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 "ttkTheme.h"
+#include "ttkWidget.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*/