From d853dbb048e8d2b8593a35c9ddd9be02bc714168 Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <me@as-cii.com>
Date: Wed, 31 Mar 2021 13:30:07 +0200
Subject: [PATCH] Render borders correctly when only a subset of the border is
 visible

---
 gpui/src/platform/mac/shaders/shaders.metal | 14 ++++++++++----
 zed/src/workspace/pane.rs                   |  2 +-
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/gpui/src/platform/mac/shaders/shaders.metal b/gpui/src/platform/mac/shaders/shaders.metal
index e9f8239541..8d136b7621 100644
--- a/gpui/src/platform/mac/shaders/shaders.metal
+++ b/gpui/src/platform/mac/shaders/shaders.metal
@@ -81,11 +81,17 @@ fragment float4 quad_fragment(
     float2 rounded_edge_to_point = abs(center_to_point) - half_size + input.corner_radius;
     float distance = length(max(0., rounded_edge_to_point)) + min(0., max(rounded_edge_to_point.x, rounded_edge_to_point.y)) - input.corner_radius;
 
-    float border_width = 0.;
-    if (edge_to_point.x > edge_to_point.y) {
-        border_width = center_to_point.x <= 0. ? input.border_left : input.border_right;
+    float vertical_border = center_to_point.x <= 0. ? input.border_left : input.border_right;
+    float horizontal_border = center_to_point.y <= 0. ? input.border_top : input.border_bottom;
+    float2 inset_size = half_size - input.corner_radius - float2(vertical_border, horizontal_border);
+    float2 point_to_inset_corner = abs(center_to_point) - inset_size;
+    float border_width;
+    if (point_to_inset_corner.x < 0. && point_to_inset_corner.y < 0.) {
+        border_width = 0.;
+    } else if (point_to_inset_corner.y > point_to_inset_corner.x) {
+        border_width = horizontal_border;
     } else {
-        border_width = center_to_point.y <= 0. ? input.border_top : input.border_bottom;
+        border_width = vertical_border;
     }
 
     float4 color;
diff --git a/zed/src/workspace/pane.rs b/zed/src/workspace/pane.rs
index 22a11be34d..2b248e4505 100644
--- a/zed/src/workspace/pane.rs
+++ b/zed/src/workspace/pane.rs
@@ -173,7 +173,7 @@ impl Pane {
         ctx.emit(Event::Split(direction));
     }
 
-    fn render_tabs<'a>(&self, app: &AppContext) -> ElementBox {
+    fn render_tabs(&self, app: &AppContext) -> ElementBox {
         let settings = smol::block_on(self.settings.read());
         let border_color = ColorU::from_u32(0xdbdbdcff);