From 3264e707017253cb3c238bca6fa6e43a84e9f20c Mon Sep 17 00:00:00 2001
From: Tim Culverhouse <tim@timculverhouse.com>
Date: Mon, 25 Sep 2023 12:25:45 -0500
Subject: [PATCH] terminal: don't modify pen state when erasing eraseDisplay

Erasing the display should be done with only the background attribute of
the current pen. This is the current behavior but is done by altering
the current pen state. The pen state should remain after erasure. Use a
new pen variable to erase the display to enable retaining the pen state.
Add a test condition.
---
 src/terminal/Terminal.zig | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/src/terminal/Terminal.zig b/src/terminal/Terminal.zig
index 6a32e8ffc..eae35385a 100644
--- a/src/terminal/Terminal.zig
+++ b/src/terminal/Terminal.zig
@@ -214,11 +214,6 @@ pub fn alternateScreen(
 
     if (options.clear_on_enter) {
         self.eraseDisplay(alloc, .complete);
-        // HACK: eraseDisplay needs to work properly here, but alters the state
-        // of our pen in doing so. Either way, we need to set pen state before
-        // erasing, use the semantics of erasing, and end up with the pen state
-        // where it was
-        self.screen.cursor = old.cursor;
     }
 }
 
@@ -1020,7 +1015,7 @@ pub fn eraseDisplay(
     defer tracy.end();
 
     // Erasing clears all attributes / colors _except_ the background
-    self.screen.cursor.pen = if (!self.screen.cursor.pen.attrs.has_bg) .{} else .{
+    const pen: Screen.Cell = if (!self.screen.cursor.pen.attrs.has_bg) .{} else .{
         .bg = self.screen.cursor.pen.bg,
         .attrs = .{ .has_bg = true },
     };
@@ -1031,7 +1026,7 @@ pub fn eraseDisplay(
             while (it.next()) |row| {
                 row.setWrapped(false);
                 row.setDirty(true);
-                row.clear(self.screen.cursor.pen);
+                row.clear(pen);
             }
 
             // Unsets pending wrap state
@@ -1050,7 +1045,7 @@ pub fn eraseDisplay(
                 for (self.screen.cursor.x..self.cols) |x| {
                     if (row.header().flags.grapheme) row.clearGraphemes(x);
                     const cell = row.getCellPtr(x);
-                    cell.* = self.screen.cursor.pen;
+                    cell.* = pen;
                     cell.char = 0;
                 }
             }
@@ -1063,7 +1058,7 @@ pub fn eraseDisplay(
                 for (0..self.cols) |x| {
                     if (row.header().flags.grapheme) row.clearGraphemes(x);
                     const cell = row.getCellPtr(x);
-                    cell.* = self.screen.cursor.pen;
+                    cell.* = pen;
                     cell.char = 0;
                 }
             }
@@ -1077,7 +1072,7 @@ pub fn eraseDisplay(
             var x: usize = 0;
             while (x <= self.screen.cursor.x) : (x += 1) {
                 const cell = self.screen.getCellPtr(.active, self.screen.cursor.y, x);
-                cell.* = self.screen.cursor.pen;
+                cell.* = pen;
                 cell.char = 0;
             }
 
@@ -1087,7 +1082,7 @@ pub fn eraseDisplay(
                 x = 0;
                 while (x < self.cols) : (x += 1) {
                     const cell = self.screen.getCellPtr(.active, y, x);
-                    cell.* = self.screen.cursor.pen;
+                    cell.* = pen;
                     cell.char = 0;
                 }
             }
@@ -1135,6 +1130,9 @@ test "Terminal: eraseDisplay above" {
     try testing.expect(!cell.attrs.bold);
     try testing.expect(cell.attrs.has_bg);
 
+    // Check that our pen hasn't changed
+    try testing.expect(t.screen.cursor.pen.attrs.bold);
+
     // check that another cell got the correct bg
     cell = t.screen.getCell(.active, 0, 1);
     try testing.expect(cell.bg.eql(pink));