Revision: 75629
http://sourceforge.net/p/brlcad/code/75629
Author: starseeker
Date: 2020-04-29 15:00:45 +0000 (Wed, 29 Apr 2020)
Log Message:
-----------
fix a few comments
Modified Paths:
--------------
brlcad/trunk/src/libdm/tests/tcl_img.cpp
Modified: brlcad/trunk/src/libdm/tests/tcl_img.cpp
===================================================================
--- brlcad/trunk/src/libdm/tests/tcl_img.cpp 2020-04-29 14:44:15 UTC (rev
75628)
+++ brlcad/trunk/src/libdm/tests/tcl_img.cpp 2020-04-29 15:00:45 UTC (rev
75629)
@@ -56,7 +56,14 @@
// Main thread id - used to send a rendering event back to
// the parent thread.
Tcl_ThreadId parent_id;
- // DO NOT USE in thread - present here to pass through event back to parent
+
+ // Tcl interp can only be used by the thread that created it, and the
+ // Tk_Photo calls require an interpreter. Thus we keep track of which
+ // interpreter is the parent interp in the primary data container, as this
+ // interp (and ONLY this interp) is requried to do Tk_Photo processing when
+ // triggered from thread events sent back to the parent. Those callbacks
+ // don't by default encode knowledge about the parent's Tcl_Interp, so we
+ // store it where we know we can access it.
Tcl_Interp *parent_interp;
// Manager thread id
@@ -73,27 +80,30 @@
int bwidth;
int bheight;
- // Used for image generation
+ // Used for image generation - these are presisted across renders so the
+ // image contents will vary as expected.
std::default_random_engine *gen;
std::uniform_int_distribution<int> *colors;
std::uniform_int_distribution<int> *vals;
- // This gets interesting - a Tcl interp can only be used by the
- // thread that created it, so the thread operates on its own
- // buffer which is exposted to the parent's Tk_Photo image update
- // via an event.
+ // The rendering memory used to actually generate the image contents.
long buff_size;
unsigned char *pixelPtr;
};
+// Event container passed to routines triggered by events.
struct DmRenderEvent {
Tcl_Event event; /* Must be first */
struct img_data *idata;
};
+// Even for events where we don't intend to actually run a proc,
+// we need to tell Tcl it successfully processed them. For that
+// we define a no-op callback proc.
static int
noop_proc(Tcl_Event *UNUSED(evPtr), int UNUSED(mask))
{
+ // Return one to signify a successful completion of the process execution
return 1;
}
@@ -124,7 +134,7 @@
// Tk_PhotoPutBlock appears to be making a copy of the data, so we should
// be able to point to our thread's rendered data to feed it in for
- // copying.
+ // copying without worrying that Tk might alter it.
dm_data.pixelPtr = idata->pixelPtr;
Tk_PhotoPutBlock(interp, dm_img, &dm_data, 0, 0, dm_data.width,
dm_data.height, TK_PHOTO_COMPOSITE_SET);
@@ -143,7 +153,7 @@
if (argc == 3) {
// Unpack the current width and height. If these don't match what
idata has
- // or thinks its working on, set the flag indicating we need a render.
+ // or thinks its working on, update the image size.
// (Note: checking errno, although it may not truly be necessary if we
// trust Tk to always give us valid coordinates...)
char *p_end;
@@ -337,6 +347,7 @@
Tcl_ThreadAlert(idata->manager_id);
Tcl_MutexUnlock(&threadMutex);
+ // Render complete, we're done with this thread
Tcl_ExitThread(TCL_OK);
TCL_THREAD_CREATE_RETURN;
}
@@ -344,7 +355,7 @@
static Tcl_ThreadCreateType
Dm_Update_Manager(ClientData clientData)
{
- // This thread needs to process events - give it its own interp
+ // This thread needs to process events - give it its own interp so it can
do so.
Tcl_Interp *interp = Tcl_CreateInterp();
Tcl_Init(interp);
@@ -360,7 +371,8 @@
idata->colors = &colors;
idata->vals = &vals;
- // Until we're shutting down, check for and process events
+ // Until we're shutting down, check for and process events - this thread
will persist
+ // for the life of the application.
while (!idata->render_shutdown) {
// Events can come from either the parent (requesting a rendering,
announcing a shutdown)
@@ -551,9 +563,13 @@
while (1) {
Tcl_DoOneEvent(0);
if (!Tk_GetNumMainWindows()) {
- // If we've closed the window, we're done
+
+ // If we've closed the window, we're done - start spreading the word
Tcl_MutexLock(&dilock);
idata->render_shutdown = 1;
+
+ // After setting the shutdown flag, send an event to wake up the
update manager thread.
+ // It will see the change in status and proceed to shut itself down.
struct DmRenderEvent *threadEventPtr = (struct DmRenderEvent
*)ckalloc(sizeof(DmRenderEvent));
threadEventPtr->idata = idata;
threadEventPtr->event.proc = noop_proc;
@@ -560,13 +576,17 @@
Tcl_ThreadQueueEvent(idata->manager_id, (Tcl_Event *)
threadEventPtr, TCL_QUEUE_TAIL);
Tcl_ThreadAlert(idata->manager_id);
Tcl_MutexUnlock(&dilock);
+
+ // Wait for the thread cleanup to complete
int tret;
Tcl_JoinThread(threadID, &tret);
if (tret != TCL_OK) {
- std::cerr << "Failure to shut down display thread\n";
+ std::cerr << "Failed to shut down display management thread\n";
} else {
- std::cout << "Successful display thread shutdown\n";
+ std::cout << "Successful display management thread shutdown\n";
}
+
+ // Clean up memory and exit
BU_PUT(idata, struct img_data);
exit(0);
}
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