From c575dec15b9219cffdb4188b445590fe15190eb9 Mon Sep 17 00:00:00 2001
From: Joonas Javanainen <joonas.javanainen@gmail.com>
Date: Tue, 7 Jul 2020 23:07:56 +0300
Subject: [PATCH] Change update_delta_time to accept a Duration

Fixes #333
---
 imgui-examples/examples/support/mod.rs     | 6 +++++-
 imgui-gfx-examples/examples/support/mod.rs | 4 +++-
 src/io.rs                                  | 7 ++-----
 3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/imgui-examples/examples/support/mod.rs b/imgui-examples/examples/support/mod.rs
index 344980a..ca36a72 100644
--- a/imgui-examples/examples/support/mod.rs
+++ b/imgui-examples/examples/support/mod.rs
@@ -95,7 +95,11 @@ impl System {
         let mut last_frame = Instant::now();
 
         event_loop.run(move |event, _, control_flow| match event {
-            Event::NewEvents(_) => last_frame = imgui.io_mut().update_delta_time(last_frame),
+            Event::NewEvents(_) => {
+                let now = Instant::now();
+                imgui.io_mut().update_delta_time(now - last_frame);
+                last_frame = now;
+            }
             Event::MainEventsCleared => {
                 let gl_window = display.gl_window();
                 platform
diff --git a/imgui-gfx-examples/examples/support/mod.rs b/imgui-gfx-examples/examples/support/mod.rs
index f58a905..409c452 100644
--- a/imgui-gfx-examples/examples/support/mod.rs
+++ b/imgui-gfx-examples/examples/support/mod.rs
@@ -94,7 +94,9 @@ impl System {
             platform
                 .prepare_frame(io, render_sys.window())
                 .expect("Failed to start frame");
-            last_frame = io.update_delta_time(last_frame);
+            let now = Instant::now();
+            io.update_delta_time(now - last_frame);
+            last_frame = now;
             let mut ui = imgui.frame();
             run_ui(&mut run, &mut ui);
 
diff --git a/src/io.rs b/src/io.rs
index 1ba90cb..0d7a242 100644
--- a/src/io.rs
+++ b/src/io.rs
@@ -2,7 +2,7 @@ use bitflags::bitflags;
 use std::f32;
 use std::ops::{Index, IndexMut};
 use std::os::raw::{c_char, c_int, c_void};
-use std::time::Instant;
+use std::time::Duration;
 
 use crate::fonts::atlas::FontAtlas;
 use crate::fonts::font::Font;
@@ -327,9 +327,7 @@ impl Io {
             sys::ImGuiIO_ClearInputCharacters(self.raw_mut());
         }
     }
-    pub fn update_delta_time(&mut self, previous: Instant) -> Instant {
-        let now = Instant::now();
-        let delta = now - previous;
+    pub fn update_delta_time(&mut self, delta: Duration) {
         let delta_s = delta.as_secs() as f32 + delta.subsec_nanos() as f32 / 1_000_000_000.0;
         if delta_s > 0.0 {
             self.delta_time = delta_s;
@@ -337,7 +335,6 @@ impl Io {
             self.delta_time = f32::MIN_POSITIVE;
         }
         self.delta_time = delta_s;
-        now
     }
 }