Show same fg/bg text when inversed

If a cell has a matching foreground and background and is inversed
through the escape or selection, it will now fall back to the default
background on top of the default foreground.

This makes it possible to show invisible text like this by selecting it.

Hidden text is unaffected by this change.

This fixes #2315.

CHANGELOG.md

@@ -9,7 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Added ToggleFullscreen action
-- On macOS, there's a ToggleSimpleFullscreen action which allows switching to 
+- On macOS, there's a ToggleSimpleFullscreen action which allows switching to
     fullscreen without occupying another space
 - A new window option `startup_mode` which controls how the window is created
 
@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - On Windows, Alacritty will now use the native DirectWrite font API
 - The `start_maximized` window option is now `startup_mode: Maximized`
+- Cells with identical foreground and background will now show their text upon selection/inversion
 
 ### Fixed
 

src/term/mod.rs

@@ -281,17 +281,19 @@ impl RenderableCell {
         let mut bg_rgb = Self::compute_bg_rgb(colors, cell.bg);
 
         let selection_background = config.colors().selection.background;
-        let bg_alpha = if let (true, Some(col)) = (selected, selection_background) {
+        if let (true, Some(col)) = (selected, selection_background) {
             // Override selection background with config colors
             bg_rgb = col;
-            1.0
         } else if selected ^ cell.inverse() {
-            // Invert cell fg and bg colors
-            mem::swap(&mut fg_rgb, &mut bg_rgb);
-            Self::compute_bg_alpha(cell.fg)
-        } else {
-            Self::compute_bg_alpha(cell.bg)
-        };
+            if fg_rgb == bg_rgb && !cell.flags.contains(Flags::HIDDEN) {
+                // Reveal inversed text when fg/bg is the same
+                fg_rgb = colors[NamedColor::Background];
+                bg_rgb = colors[NamedColor::Foreground];
+            } else {
+                // Invert cell fg and bg colors
+                mem::swap(&mut fg_rgb, &mut bg_rgb);
+            }
+        }
 
         // Override selection text with config colors
         if let (true, Some(col)) = (selected, config.colors().selection.text) {
@@ -304,7 +306,7 @@ impl RenderableCell {
             inner: RenderableCellContent::Chars(cell.chars()),
             fg: fg_rgb,
             bg: bg_rgb,
-            bg_alpha,
+            bg_alpha: Self::compute_bg_alpha(colors, bg_rgb),
             flags: cell.flags,
         }
     }
@@ -347,10 +349,11 @@ impl RenderableCell {
     }
 
     #[inline]
-    fn compute_bg_alpha(bg: Color) -> f32 {
-        match bg {
-            Color::Named(NamedColor::Background) => 0.0,
-            _ => 1.0,
+    fn compute_bg_alpha(colors: &color::List, bg: Rgb) -> f32 {
+        if colors[NamedColor::Background] == bg {
+            0.
+        } else {
+            1.
         }
     }