text type animation

bin/text-inspect.rs

@@ -1,6 +1,6 @@
 use std::time::Duration;
 
-use bevy::{diagnostic::FrameTimeDiagnosticsPlugin, prelude::*};
+use bevy::prelude::*;
 
 const LOREM: [&str; 5] = [
     "Ullam nostrum aut amet adipisci consequuntur quisquam nemo consequatur. Vel eum et ullam ullam aperiam earum voluptas consequuntur. Blanditiis earum voluptatem voluptas animi dolorum fuga aliquam ea.\n",
@@ -23,7 +23,7 @@ fn main() {
         .add_startup_system(load_fonts)
         .add_startup_system(init_ui)
         .add_system(manage_buttons)
-        .add_system(update)
+        .add_system(update_font)
         .add_system(mouse_cursor)
         .add_system(play)
         .run();
@@ -166,24 +166,16 @@ fn manage_buttons(
     }
 }
 
-fn update(
+fn update_font(
     mut texts: Query<&mut Text, (With<Marker>, With<PreviewText>)>,
     interaction: Query<(&Interaction, &FontButton), Changed<Interaction>>,
 ) {
     for (i, f) in interaction.iter() {
         match (i, f) {
             (Interaction::Clicked, FontButton(font)) => {
-                let mut text = texts.single_mut();
-                *text = Text::from_sections(LOREM.iter().flat_map(|&l| {
-                    l.chars().map(|c| TextSection {
-                        value: c.into(),
-                        style: TextStyle {
-                            font: font.clone(),
-                            font_size: 16.0,
-                            ..default()
-                        },
-                    })
-                }));
+                texts.single_mut().sections.iter_mut().for_each(|section| {
+                    section.style.font = font.clone();
+                });
             }
             _ => (),
         }
@@ -209,24 +201,79 @@ fn play(
     interactions: Query<&Interaction, (Changed<Interaction>, With<FontButton>)>,
     time: Res<Time>,
     mut duration: Local<Duration>,
+    mut desired: Local<Vec<String>>,
 ) {
     for interaction in interactions.iter() {
         match interaction {
-            Interaction::Clicked => *duration = Duration::from_secs(30),
+            Interaction::Clicked => {
+                if *duration == Duration::ZERO {
+                    // Get end result desired strings
+                    *desired = texts
+                        .single_mut()
+                        .sections
+                        .iter()
+                        .map(|section| section.value.clone())
+                        .collect();
+                    // Clear current text
+                    texts
+                        .single_mut()
+                        .sections
+                        .iter_mut()
+                        .for_each(|section| section.value = String::new());
+                }
+                *duration = Duration::from_secs(30);
+            }
             _ => (),
         }
     }
+
+    // PERF: Why does this slow down immediatly?
     if *duration > Duration::ZERO {
+        *duration = duration.saturating_sub(time.delta());
+
+        info!("Delta: {:?}", time.delta());
+
+        let percentage = 1.0 - (duration.as_secs_f32() / 30.0);
+
         let mut text = texts.single_mut();
-        let total_sections = text.sections.len();
 
-        *duration = duration.saturating_sub(time.delta());
+        let len_total = desired.iter().fold(0, |acc, curr| acc + curr.len());
+        let mut len_total = ((len_total as f32 * percentage) as usize).min(len_total as usize);
+
+        for (section, desired) in text.sections.iter_mut().zip(desired.iter()) {
+            // This section is empty, initialize with capacity
+            if len_total == 0 {
+                break;
 
-        for (idx, section) in text.sections.iter_mut().enumerate() {
-            let ratio = ((idx + 1) as f32) / (total_sections as f32);
-            let cursor = 1.0 - ((*duration).as_secs_f32() / 30.0);
-            let alpha = if cursor > ratio { 1.0 } else { 0.0 };
-            section.style.color.set_a(alpha);
+            // Total amount of remaining text is greater than this section
+            // Set this text block to the full section
+            } else if len_total >= desired.len() {
+                info!("len_total >= desired.len()");
+                len_total -= desired.len();
+                if section.value.len() != desired.len() {
+                    info!("value != desired");
+                    section.value = desired.clone();
+                }
+
+            // Total remaining text is less than this section
+            // Set to a sub-string of text
+            } else if len_total < desired.len() {
+                info!("len total < desired len");
+                // Difference between current value and desired length
+                let diff = desired
+                    .split_at(section.value.len())
+                    .1
+                    .split_at(len_total - section.value.len())
+                    .0
+                    .into();
+                info!("adding value {}", diff);
+                section.value.push_str(diff);
+                len_total = 0;
+
+            // Undefined behavior
+            } else {
+                info!("Unexpected text animation situation");
+            }
         }
     }
 }