Add 'alt-bg' color for striped lines (#4370)

Test cases:

1. 'jump' should show alternating background colors even when 'alt-bg' is
not defined as before.

  go run main.go --bind load:jump

Two differences:
  * The alternating lines will not be in bold (was a bug)
  * The marker column will not be rendered with alternating background color

2. Use alternating background color when 'alt-bg' is set

  go run main.go --color bg:238,alt-bg:237
  go run main.go --color bg:238,alt-bg:237 --highlight-line

3. 'selected-bg' should take precedence

  go run main.go --color bg:238,alt-bg:237,selected-bg:232 \
                 --highlight-line --multi --bind 'load:select+up+select+up'

4. Should work with text with ANSI colors

  declare -f | perl -0777 -pe 's/^}\n/}\0/gm' |
    bat --plain --language bash --color always |
    go run main.go --read0 --ansi --reverse --multi \
                   --color bg:237,alt-bg:238,current-bg:236 --highlight-line

---

Close #4354
Fix #4372

1 files changed, 3 insertions, 11 deletions

diff --git a/src/result.go b/src/result.go
index 28d42e7d..3e4a81c0 100644
--- a/src/result.go
+++ b/src/result.go
@@ -119,7 +119,7 @@ func minRank() Result {
 	return Result{item: &minItem, points: [4]uint16{math.MaxUint16, 0, 0, 0}}
 }
 
-func (result *Result) colorOffsets(matchOffsets []Offset, nthOffsets []Offset, theme *tui.ColorTheme, colBase tui.ColorPair, colMatch tui.ColorPair, attrNth tui.Attr, current bool) []colorOffset {
+func (result *Result) colorOffsets(matchOffsets []Offset, nthOffsets []Offset, theme *tui.ColorTheme, colBase tui.ColorPair, colMatch tui.ColorPair, attrNth tui.Attr) []colorOffset {
 	itemColors := result.item.Colors()
 
 	// No ANSI codes
@@ -182,18 +182,10 @@ func (result *Result) colorOffsets(matchOffsets []Offset, nthOffsets []Offset, t
 		fg := ansi.color.fg
 		bg := ansi.color.bg
 		if fg == -1 {
-			if current {
-				fg = theme.Current.Color
-			} else {
-				fg = theme.Fg.Color
-			}
+			fg = colBase.Fg()
 		}
 		if bg == -1 {
-			if current {
-				bg = theme.DarkBg.Color
-			} else {
-				bg = theme.Bg.Color
-			}
+			bg = colBase.Bg()
 		}
 		return tui.NewColorPair(fg, bg, ansi.color.attr).MergeAttr(base)
 	}