From 55bcaa8527335c4b5e9b2672f0d85dc621f0b1f1 Mon Sep 17 00:00:00 2001
From: Vladyslav Batyrenko <mvlabat@gmail.com>
Date: Sat, 24 Apr 2021 14:28:49 +0300
Subject: [PATCH] Fix crashes related to invalid scissor or window size (#18)

Co-authored-by: Stephan Buys <hello@stephanbuys.com>
---
 src/egui_node.rs | 27 ++++++++++++++++++++-------
 src/systems.rs   | 19 +++++++++++--------
 2 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/src/egui_node.rs b/src/egui_node.rs
index 960762f33..11d49b342 100644
--- a/src/egui_node.rs
+++ b/src/egui_node.rs
@@ -152,7 +152,7 @@ impl EguiNode {
 struct DrawCommand {
     vertices_count: usize,
     texture_handle: Option<Handle<Texture>>,
-    clipping_zone: egui::Rect,
+    clipping_zone: (u32, u32, u32, u32), // x, y, w, h
 }
 
 impl Node for EguiNode {
@@ -227,7 +227,19 @@ impl Node for EguiNode {
         let mut draw_commands = Vec::new();
         let mut index_offset = 0;
 
+        let scale_factor = window_size.scale_factor * egui_settings.scale_factor as f32;
         for egui::ClippedMesh(rect, triangles) in &egui_paint_jobs {
+            let (x, y, w, h) = (
+                (rect.min.x * scale_factor).round() as u32,
+                (rect.min.y * scale_factor).round() as u32,
+                (rect.width() * scale_factor).round() as u32,
+                (rect.height() * scale_factor).round() as u32,
+            );
+
+            if w < 1 || h < 1 {
+                continue;
+            }
+
             let texture_handle = egui_context
                 .egui_textures
                 .get(&triangles.texture_id)
@@ -254,10 +266,12 @@ impl Node for EguiNode {
             index_buffer.extend_from_slice(indices_with_offset.as_slice().as_bytes());
             index_offset += triangles.vertices.len() as u32;
 
+            let x_viewport_clamp = (x + w).saturating_sub(window_size.physical_width as u32);
+            let y_viewport_clamp = (y + h).saturating_sub(window_size.physical_height as u32);
             draw_commands.push(DrawCommand {
                 vertices_count: triangles.indices.len(),
                 texture_handle,
-                clipping_zone: *rect,
+                clipping_zone: (x, y, w - x_viewport_clamp, h - y_viewport_clamp),
             });
         }
 
@@ -309,12 +323,11 @@ impl Node for EguiNode {
                         None,
                     );
 
-                    let scale_factor = window_size.scale_factor * egui_settings.scale_factor as f32;
                     render_pass.set_scissor_rect(
-                        (draw_command.clipping_zone.min.x * scale_factor) as u32,
-                        (draw_command.clipping_zone.min.y * scale_factor) as u32,
-                        (draw_command.clipping_zone.width() * scale_factor) as u32,
-                        (draw_command.clipping_zone.height() * scale_factor) as u32,
+                        draw_command.clipping_zone.0,
+                        draw_command.clipping_zone.1,
+                        draw_command.clipping_zone.2,
+                        draw_command.clipping_zone.3,
                     );
                     render_pass.draw_indexed(
                         vertex_offset..(vertex_offset + draw_command.vertices_count as u32),
diff --git a/src/systems.rs b/src/systems.rs
index a64d3620a..34819e0be 100644
--- a/src/systems.rs
+++ b/src/systems.rs
@@ -71,17 +71,20 @@ pub fn process_input(
             window.physical_height() as f32,
             window.scale_factor() as f32,
         );
+        let width = window_size.physical_width
+            / window_size.scale_factor
+            / egui_settings.scale_factor as f32;
+        let height = window_size.physical_height
+            / window_size.scale_factor
+            / egui_settings.scale_factor as f32;
+
+        if width < 1.0 || height < 1.0 {
+            continue;
+        }
 
         egui_input.raw_input.screen_rect = Some(egui::Rect::from_min_max(
             egui::pos2(0.0, 0.0),
-            egui::pos2(
-                window_size.physical_width
-                    / window_size.scale_factor
-                    / egui_settings.scale_factor as f32,
-                window_size.physical_height
-                    / window_size.scale_factor
-                    / egui_settings.scale_factor as f32,
-            ),
+            egui::pos2(width, height),
         ));
 
         egui_input.raw_input.pixels_per_point =