From 311623d4c14c59db1ebdf87c372baf601226398e Mon Sep 17 00:00:00 2001
From: Harry Jeffery <harry@exec64.co.uk>
Date: Fri, 12 Jul 2019 23:32:44 +0100
Subject: Modernise event loop

---
 src/imv.c    | 10 ++++------
 src/window.c | 46 +++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 49 insertions(+), 7 deletions(-)

(limited to 'src')

diff --git a/src/imv.c b/src/imv.c
index 299dddb..6518f75 100644
--- a/src/imv.c
+++ b/src/imv.c
@@ -1017,10 +1017,10 @@ int imv_run(struct imv *imv)
       double dt = current_time - last_time;
 
       imv->slideshow.elapsed += dt;
-      /* imv->need_redraw = true; /1* need to update display *1/ */
       if (imv->slideshow.elapsed >= imv->slideshow.duration) {
         imv_navigator_select_rel(imv->navigator, 1);
         imv->slideshow.elapsed = 0;
+        imv->need_redraw = true;
       }
     }
 
@@ -1042,9 +1042,7 @@ int imv_run(struct imv *imv)
     double timeout = 1.0; /* seconds */
 
     /* If we need to display the next frame of an animation soon we should
-     * limit our sleep until the next frame is due. If the frame is overdue,
-     * sleep for 1ms at a time to avoid a glfw race between WaitEvents and
-     * PostEmptyEvent.
+     * limit our sleep until the next frame is due.
      */
     if (imv_viewport_is_playing(imv->view) && imv->next_frame.due != 0.0) {
       timeout = imv->next_frame.due - current_time;
@@ -1054,9 +1052,9 @@ int imv_run(struct imv *imv)
     }
 
     if (imv->slideshow.duration > 0) {
-      double timeleft = imv->slideshow.elapsed - imv->slideshow.duration;
+      double timeleft = imv->slideshow.duration - imv->slideshow.elapsed;
       if (timeleft > 0.0 && timeleft < timeout) {
-        timeout = timeleft + 0.005;
+        timeout = timeleft + 0.001;
       }
     }
 
diff --git a/src/window.c b/src/window.c
index 1709468..aed36bd 100644
--- a/src/window.c
+++ b/src/window.c
@@ -1,10 +1,13 @@
 #include "window.h"
 
 #include <assert.h>
+#include <poll.h>
 #include <pthread.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/eventfd.h>
+#include <unistd.h>
 
 #include <wayland-client.h>
 #include <wayland-egl.h>
@@ -28,6 +31,9 @@ struct imv_window {
   EGLSurface           egl_surface;
   struct wl_egl_window *egl_window;
 
+  int display_fd;
+  int event_fd;
+
   int width;
   int height;
   bool fullscreen;
@@ -266,6 +272,8 @@ static void connect_to_wayland(struct imv_window *window)
 {
   window->wl_display = wl_display_connect(NULL);
   assert(window->wl_display);
+  window->display_fd = wl_display_get_fd(window->wl_display);
+  window->event_fd = eventfd(0, 0);
 
   window->wl_registry = wl_display_get_registry(window->wl_display);
   assert(window->wl_registry);
@@ -323,6 +331,7 @@ static void create_window(struct imv_window *window, int width, int height,
 
 static void shutdown_wayland(struct imv_window *window)
 {
+  close(window->event_fd);
   if (window->wl_pointer) {
     wl_pointer_destroy(window->wl_pointer);
   }
@@ -405,6 +414,37 @@ void imv_window_resize(struct imv_window *window, int w, int h)
 
 void imv_window_wait_for_event(struct imv_window *window, double timeout)
 {
+  struct pollfd fds[] = {
+    {.fd = window->display_fd, .events = POLLIN},
+    {.fd = window->event_fd,   .events = POLLIN}
+  };
+  nfds_t nfds = sizeof fds / sizeof *fds;
+
+  while (wl_display_prepare_read(window->wl_display)) {
+    wl_display_dispatch_pending(window->wl_display);
+  }
+
+  wl_display_flush(window->wl_display);
+
+  int rc = poll(fds, nfds, timeout * 1000);
+  if (rc < 0) {
+    wl_display_cancel_read(window->wl_display);
+    return;
+  }
+
+  /* Handle any new wayland events */
+  if (fds[0].revents & POLLIN) {
+    wl_display_read_events(window->wl_display);
+    wl_display_dispatch_pending(window->wl_display);
+  } else {
+    wl_display_cancel_read(window->wl_display);
+  }
+
+  /* Clear the eventfd if hit */
+  if (fds[1].revents & POLLIN) {
+    uint64_t out;
+    read(window->event_fd, &out, sizeof out);
+  }
 }
 
 void imv_window_push_event(struct imv_window *window, struct imv_event *e)
@@ -420,11 +460,15 @@ void imv_window_push_event(struct imv_window *window, struct imv_event *e)
 
   window->events.queue[window->events.len++] = *e;
   pthread_mutex_unlock(&window->events.mutex);
+
+  /* Wake up wait_events */
+  uint64_t in = 1;
+  write(window->event_fd, &in, sizeof in);
 }
 
 void imv_window_pump_events(struct imv_window *window, imv_event_handler handler, void *data)
 {
-  wl_display_dispatch(window->wl_display);
+  wl_display_dispatch_pending(window->wl_display);
 
   pthread_mutex_lock(&window->events.mutex);
   if (handler) {
-- 
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