From f0ee329c05352d24863851a5250d608dcd595630 Mon Sep 17 00:00:00 2001
From: LeRoyce Pearson <leroycepearson@geemili.xyz>
Date: Fri, 17 Jul 2020 14:55:37 -0600
Subject: [PATCH] Make `canvas_text` example render on expose

Before this change, the `canvas_text` example would become blank after
navigating to another workspace or being put beneath another window.
This change will listen for the SDL window exposed event, and will
render then instead of only at the beginning.
---
 examples/canvas_text/src/main.rs | 37 ++++++++++++++++----------------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/examples/canvas_text/src/main.rs b/examples/canvas_text/src/main.rs
index 5891e0af..39dd1e91 100644
--- a/examples/canvas_text/src/main.rs
+++ b/examples/canvas_text/src/main.rs
@@ -20,7 +20,7 @@ use pathfinder_renderer::gpu::renderer::Renderer;
 use pathfinder_renderer::options::BuildOptions;
 use pathfinder_resources::ResourceLoader;
 use pathfinder_resources::fs::FilesystemResourceLoader;
-use sdl2::event::Event;
+use sdl2::event::{Event, WindowEvent};
 use sdl2::keyboard::Keycode;
 use sdl2::video::GLProfile;
 use std::iter;
@@ -64,28 +64,29 @@ fn main() {
     let font = Handle::from_memory(font_data, 0);
     let font_context = CanvasFontContext::from_fonts(iter::once(font));
 
-    // Make a canvas.
-    let mut canvas = Canvas::new(window_size.to_f32()).get_context_2d(font_context);
-
-    // Draw the text.
-    canvas.set_font("Overpass-Regular");
-    canvas.set_font_size(32.0);
-    canvas.fill_text("Hello Pathfinder!", vec2f(32.0, 48.0));
-    canvas.set_text_align(TextAlign::Right);
-    canvas.stroke_text("Goodbye Pathfinder!", vec2f(608.0, 464.0));
-
-    // Render the canvas to screen.
-    let mut scene = SceneProxy::from_scene(canvas.into_canvas().into_scene(),
-                                           renderer.mode().level,
-                                           RayonExecutor);
-    scene.build_and_render(&mut renderer, BuildOptions::default());
-    window.gl_swap_window();
-
     // Wait for a keypress.
     let mut event_pump = sdl_context.event_pump().unwrap();
     loop {
         match event_pump.wait_event() {
             Event::Quit {..} | Event::KeyDown { keycode: Some(Keycode::Escape), .. } => return,
+            Event::Window { win_event: WindowEvent::Exposed, .. } => {
+                // Make a canvas.
+                let mut canvas = Canvas::new(window_size.to_f32()).get_context_2d(font_context.clone());
+
+                // Draw the text.
+                canvas.set_font("Overpass-Regular");
+                canvas.set_font_size(32.0);
+                canvas.fill_text("Hello Pathfinder!", vec2f(32.0, 48.0));
+                canvas.set_text_align(TextAlign::Right);
+                canvas.stroke_text("Goodbye Pathfinder!", vec2f(608.0, 464.0));
+
+                // Render the canvas to screen.
+                let mut scene = SceneProxy::from_scene(canvas.into_canvas().into_scene(),
+                                                       renderer.mode().level,
+                                                       RayonExecutor);
+                scene.build_and_render(&mut renderer, BuildOptions::default());
+                window.gl_swap_window();
+            },
             _ => {}
         }
     }