[Mesa-dev] [PATCH v2] gallium/hud: control visibility at startup and runtime.

[Jimmy Berry]

- env GALLIUM_HUD_VISIBLE: control default visibility
- env GALLIUM_HUD_SIGNAL_TOGGLE: toggle visibility via signal
---
Thanks for the feedback.

I believe all the suggested changes have been implemented.

One note, all the logic except for the toggle was already in hud_create() and
not hud_draw().

On the subject of allowing the user to specify the signo to use. It was
suggested in the original thread that using a fixed signal might end up stealing
signals from the parent application. Seems like the user should except funny
behavior if they set the signal to something like SIGKILL. I am not opposed to a
fixed signo or alternatively providing a default. Something like:

GALLIUM_HUD_TOGGLE_SIGNAL=-1 # (results in SIGUSR1)


 docs/envvars.html                       |  6 ++++++
 src/gallium/auxiliary/hud/hud_context.c | 29 +++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/docs/envvars.html b/docs/envvars.html
index bdfe999..530bbb7 100644
--- a/docs/envvars.html
+++ b/docs/envvars.html
@@ -179,6 +179,12 @@ Mesa EGL supports different sets of environment variables.  See the
 <li>GALLIUM_HUD - draws various information on the screen, like framerate,
     cpu load, driver statistics, performance counters, etc.
     Set GALLIUM_HUD=help and run e.g. glxgears for more info.
+<li>GALLIUM_HUD_VISIBLE - control default visibility, defaults to true.
+<li>GALLIUM_HUD_TOGGLE_SIGNAL - toggle visibility via user specified signal.
+    Especially useful to toggle hud at specific points of application and
+    disable for unencumbered viewing the rest of the time. For example, set
+    GALLIUM_HUD_VISIBLE to false and GALLIUM_HUD_SIGNAL_TOGGLE to 10 (SIGUSR1).
+    Use kill -10 <pid> to toggle the hud as desired.
 <li>GALLIUM_LOG_FILE - specifies a file for logging all errors, warnings, etc.
     rather than stderr.
 <li>GALLIUM_PRINT_OPTIONS - if non-zero, print all the Gallium environment
diff --git a/src/gallium/auxiliary/hud/hud_context.c b/src/gallium/auxiliary/hud/hud_context.c
index ffe30b8..bffbc2f 100644
--- a/src/gallium/auxiliary/hud/hud_context.c
+++ b/src/gallium/auxiliary/hud/hud_context.c
@@ -33,6 +33,7 @@
  * Set GALLIUM_HUD=help for more info.
  */
 
+#include <signal.h>
 #include <stdio.h>
 
 #include "hud/hud_context.h"
@@ -51,6 +52,8 @@
 #include "tgsi/tgsi_text.h"
 #include "tgsi/tgsi_dump.h"
 
+/* controlls the visibility of all hud contexts */
+static boolean huds_visible = TRUE;
 
 struct hud_context {
    struct pipe_context *pipe;
@@ -95,6 +98,11 @@ struct hud_context {
    } text, bg, whitelines;
 };
 
+static void
+signal_visible_handler(int sig, siginfo_t *siginfo, void *context)
+{
+   huds_visible = !huds_visible;
+}
 
 static void
 hud_draw_colored_prims(struct hud_context *hud, unsigned prim,
@@ -441,6 +449,9 @@ hud_draw(struct hud_context *hud, struct pipe_resource *tex)
    struct hud_pane *pane;
    struct hud_graph *gr;
 
+   if (!huds_visible)
+      return;
+
    hud->fb_width = tex->width0;
    hud->fb_height = tex->height0;
    hud->constants.two_div_fb_width = 2.0f / hud->fb_width;
@@ -1125,6 +1136,10 @@ hud_create(struct pipe_context *pipe, struct cso_context *cso)
    struct pipe_sampler_view view_templ;
    unsigned i;
    const char *env = debug_get_option("GALLIUM_HUD", NULL);
+   long signo = debug_get_num_option("GALLIUM_HUD_TOGGLE_SIGNAL", 0);
+   boolean sig_handled = FALSE;
+   struct sigaction action;
+   huds_visible = debug_get_bool_option("GALLIUM_HUD_VISIBLE", TRUE);
 
    if (!env || !*env)
       return NULL;
@@ -1267,6 +1282,20 @@ hud_create(struct pipe_context *pipe, struct cso_context *cso)
 
    LIST_INITHEAD(&hud->pane_list);
 
+   /* setup sig handler once for all hud contexts */
+   if (!sig_handled) {
+      memset(&action, 0, sizeof(action));
+      action.sa_sigaction = &signal_visible_handler;
+      action.sa_flags = SA_SIGINFO;
+
+      if (signo < 1 || signo >= NSIG)
+         fprintf(stderr, "gallium_hud: invalid signal %ld\n", signo);
+      else if (sigaction(signo, &action, NULL) < 0)
+         fprintf(stderr, "gallium_hud: unable to set handler for signal %ld\n", signo);
+
+      sig_handled = TRUE;
+   }
+
    hud_parse_env_var(hud, env);
    return hud;
 }
-- 
2.6.2