refactor goto-functions to draw frame too

Author: wong-justin

src/main.rs

@@ -488,7 +488,7 @@ impl FrameIterator {
         return view_string;
     }
 
-    fn skip_some_frames(&mut self, num_frames: u32) {
+    fn skip_some_frames(&mut self, num_frames: u32) -> String {
         // When you only want to advance a few frames,
         // without spawning a new ffmpeg process,
         // but also without calling chafa.draw each frame as you would in loop { take_frame() }
@@ -498,16 +498,17 @@ impl FrameIterator {
         for _ in 0..num_frames {
             self.stdout.read_exact(&mut self.pixel_buffer);
         }
+        return self.take_frame();
     }
 
-    fn goto_timestamp(&mut self, timestamp: SecondsFloat) -> Result<(), Box<dyn Error>> {
+    fn goto_timestamp(&mut self, timestamp: SecondsFloat) -> Result<String, Box<dyn Error>> {
         // Start new process at any position in video.
         // This should be faster than reading far ahead in the old process,
         // and this enables "backward seeking" too.
 
         let new_stdout = FrameIterator::_create_decoding_process(&self.video_path, timestamp)?;
         self.stdout = new_stdout;
-        Ok(())
+        Ok(self.take_frame())
     }
 }
 
@@ -705,11 +706,9 @@ fn init() -> Result<Model, String> {
 // --- UPDATE --- //
 
 fn update(m: &mut Model, terminal_event: Event) -> UpdateResult {
-
     m.needs_to_clear = false;
     match terminal_event {
         Event::Key(keyevent) => {
-
             if (keyevent.modifiers == KeyModifiers::CONTROL && keyevent.code == KeyCode::Char('c'))
                 || keyevent.code == KeyCode::Char('q')
             {
@@ -744,7 +743,53 @@ fn update(m: &mut Model, terminal_event: Event) -> UpdateResult {
         return UpdateResult::Continue;
     }
 
-    // --- find the next frame number to render --- //
+    let whole_elapsed_frames = frames_since_prev_instant(m);
+    let is_too_fast = whole_elapsed_frames == 0;
+    match is_too_fast {
+        true => {
+            // slow down by not drawing anything during this tick
+            m.prev_instant = now;
+            return UpdateResult::Continue;
+        },
+        false => {
+            // now we know the next frame number to render
+            m.frame = m.frame_iterator.skip_some_frames(whole_elapsed_frames - 1);
+            m.frame_number += whole_elapsed_frames as u32;
+        }
+    }
+
+    // --- update stats --- //
+
+    let time_to_update_fps =
+        m.frame_iterator.num_frames_rendered % NUM_FRAMES_TO_TRACK_FPS as u32 == 0;
+    if time_to_update_fps {
+        let recent_time_elapsed: SecondsFloat = (now - m.last_fps_check).as_secs_f64();
+        m.recent_fps = Some(NUM_FRAMES_TO_TRACK_FPS as f64 / recent_time_elapsed);
+        m.last_fps_check = now;
+    } else {
+        // Either too early and not enough recent data,
+        // or waiting for next moment to check fps.
+        // No need to constantly update fps every frame.
+    }
+
+    let time_to_log = m.frame_iterator.num_frames_rendered % 100 == 1;
+    if time_to_log {
+        log::info!(
+            "{:?} {:?} {:?} {:?}",
+            now - m.start,
+            m.prev_instant,
+            m.frame_iterator.num_frames_rendered,
+            m.frame_number
+        );
+    }
+
+    m.prev_instant = now;
+    return UpdateResult::Continue;
+}
+
+fn frames_since_prev_instant(m: &mut Model) -> u32 {
+    // find how many frames elapsed since last tick,
+    // and modify leftover time
 
     // example converting elapsed ms to elapsed frames:
     //
@@ -758,6 +803,7 @@ fn update(m: &mut Model, terminal_event: Event) -> UpdateResult {
     // rounding_err = ---------- * --------- = 0.007 seconds
     //                             30 frames
     //
+    let now = std::time::Instant::now();
     let elapsed_secs = (now - m.prev_instant).as_secs_f64();
 
     // how many frames should have passed since last tick; sometimes 0, usually 1 or more
@@ -769,6 +815,7 @@ fn update(m: &mut Model, terminal_event: Event) -> UpdateResult {
     let rounding_err: SecondsFloat =
         elapsed_secs - (whole_elapsed_frames as f64 * m.VIDEO_METADATA.seconds_per_frame);
     m.accumulated_time += rounding_err;
+
     let need_leap_frame = m.accumulated_time > m.VIDEO_METADATA.seconds_per_frame;
     if need_leap_frame {
         whole_elapsed_frames += 1;
@@ -781,57 +828,7 @@ fn update(m: &mut Model, terminal_event: Event) -> UpdateResult {
     //            extra_time,
     //            m.accumulated_time);
 
-    // TODO:
-    // cap fps if we're rendering too quickly.
-    // i think we should choose to save CPU by capping at decent framerate
-    // than to be faithful to high fps and use extra CPU
-    // aka
-    // if < 15 ms elapsed, that means we're getting +60 fps
-    // so probably better skip rendering at this moment and save some CPU cycles
-    // and still get smooth 30fps,
-    // than overuse CPU to get more than is necessary
-    // aka
-    // let is_too_fast = immediate_fps > min(m.VIDEO_METADATA.fps, 30fps) || elapsed_frames == 0
-
-    let is_too_fast = whole_elapsed_frames == 0;
-    if is_too_fast {
-        // slow down by not drawing anything during this tick
-        m.prev_instant = now;
-        return UpdateResult::Continue;
-    }
-
-    // now we know the next frame number to render
-    m.frame_iterator.skip_some_frames(whole_elapsed_frames - 1);
-    m.frame = m.frame_iterator.take_frame();
-    m.frame_number += whole_elapsed_frames as u32;
-
-    // --- update stats --- //
-
-    let time_to_update_fps =
-        m.frame_iterator.num_frames_rendered % NUM_FRAMES_TO_TRACK_FPS as u32 == 0;
-    if time_to_update_fps {
-        let recent_time_elapsed: SecondsFloat = (now - m.last_fps_check).as_secs_f64();
-        m.recent_fps = Some(NUM_FRAMES_TO_TRACK_FPS as f64 / recent_time_elapsed);
-        m.last_fps_check = now;
-    } else {
-        // Either too early and not enough recent data,
-        // or waiting for next moment to check fps.
-        // No need to constantly update fps every frame.
-    }
-
-    let time_to_log = m.frame_iterator.num_frames_rendered % 100 == 1;
-    if time_to_log {
-        log::info!(
-            "{:?} {:?} {:?} {:?}",
-            now - m.start,
-            m.prev_instant,
-            m.frame_iterator.num_frames_rendered,
-            m.frame_number
-        );
-    }
-
-    m.prev_instant = now;
-    return UpdateResult::Continue;
+    return whole_elapsed_frames;
 }
 
 fn toggle_paused(m: &mut Model) {
@@ -847,12 +844,14 @@ fn toggle_controls_visibility(m: &mut Model) {
     m.needs_to_clear = true; // controls will still show at bottom unless cleared/drawn over
 }
 
+// note: any function that modifies playerhead position aka m.frame_number in Segment mode
+// must check if segment number has changed
+
 fn seek_backwards_15s(m: &mut Model) {
     let frames_to_backtrack = (m.VIDEO_METADATA.fps * 15.0) as u32;
     m.frame_number = std::cmp::max(m.frame_number as i32 - frames_to_backtrack as i32, 0) as u32;
     let timestamp = m.frame_number as SecondsFloat / m.VIDEO_METADATA.fps;
-    m.frame_iterator.goto_timestamp(timestamp).unwrap();
-    m.frame = m.frame_iterator.take_frame();
+    m.frame = m.frame_iterator.goto_timestamp(timestamp).unwrap();
 
     // TODO: update current segment
     // let old_position = m.hovering.position;
@@ -864,8 +863,7 @@ fn seek_forwards_15s(m: &mut Model) {
     let frames_to_skip = (m.VIDEO_METADATA.fps * 15.0) as u32;
     m.frame_number += frames_to_skip;
     let timestamp = m.frame_number as SecondsFloat / m.VIDEO_METADATA.fps;
-    m.frame_iterator.goto_timestamp(timestamp).unwrap();
-    m.frame = m.frame_iterator.take_frame();
+    m.frame = m.frame_iterator.goto_timestamp(timestamp).unwrap();
 
     // TODO: update current segment
     // let upcoming_markers =
@@ -889,8 +887,7 @@ fn goto_prev_marker(m: &mut Model) {
             };
             let timestamp: SecondsFloat = m.markers[new_position as usize];
             m.frame_number = (timestamp * m.VIDEO_METADATA.fps) as u32;
-            m.frame_iterator.goto_timestamp(timestamp).unwrap();
-            m.frame = m.frame_iterator.take_frame();
+            m.frame = m.frame_iterator.goto_timestamp(timestamp).unwrap();
             m.paused = true;
         }
     }
@@ -917,16 +914,14 @@ fn goto_next_marker(m: &mut Model) {
             };
             let timestamp: SecondsFloat = m.markers[new_position];
             m.frame_number = (timestamp * m.VIDEO_METADATA.fps) as u32;
-            m.frame_iterator.goto_timestamp(timestamp).unwrap();
-            m.frame = m.frame_iterator.take_frame();
+            m.frame = m.frame_iterator.goto_timestamp(timestamp).unwrap();
             m.paused = true;
         }
     };
 }
 
 fn create_marker(m: &mut Model) {
     // create new marker at current timestamp
-    //
     match m.hovering.mode {
         HoverMode::Markers => (),
         HoverMode::Segments => {
@@ -939,7 +934,6 @@ fn create_marker(m: &mut Model) {
 
 fn delete_marker(m: &mut Model) {
     // delete current marker and enter segments mode
-    //
     match m.hovering.mode {
         HoverMode::Segments => (),
         HoverMode::Markers => {
@@ -953,18 +947,12 @@ fn advance_one_frame(m: &mut Model) {
     match m.paused {
         false => (),
         true => {
-            m.frame = m.frame_iterator.take_frame();
+            m.frame = m.frame_iterator.skip_some_frames(1);
             m.frame_number += 1;
         }
     }
 }
 
-
-
-
-
-
-
 // --- VIEW --- //
 
 fn format_secs_to_mm_ss(seconds: SecondsFloat) -> String {