Add `--preview-window noborder` option to disable preview border

Close #1699

4 files changed, 16 insertions, 4 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0a1a8a6d..b8eb3f5e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -43,6 +43,8 @@ CHANGELOG
     - `--info=default`
     - `--info=inline` (same as old `--inline-info`)
     - `--info=hidden`
+- Preview window border can be disabled by adding `noborder` to
+  `--preview-window`.
 - When you transform the input with `--with-nth`, the trailing white spaces
   are removed.
 - `ctrl-\`, `ctrl-]`, `ctrl-^`, and `ctrl-/` can now be used with `--bind`
diff --git a/man/man1/fzf.1 b/man/man1/fzf.1
index f90a0571..877330cd 100644
--- a/man/man1/fzf.1
+++ b/man/man1/fzf.1
@@ -361,8 +361,8 @@ Preview window will be updated even when there is no match for the current
 query if any of the placeholder expressions evaluates to a non-empty string.
 .RE
 .TP
-.BI "--preview-window=" "[POSITION][:SIZE[%]][:wrap][:hidden]"
-Determine the layout of the preview window. If the argument ends with
+.BI "--preview-window=" "[POSITION][:SIZE[%]][:noborder][:wrap][:hidden]"
+Determines the layout of the preview window. If the argument contains
 \fB:hidden\fR, the preview window will be hidden by default until
 \fBtoggle-preview\fR action is triggered. Long lines are truncated by default.
 Line wrap can be enabled with \fB:wrap\fR flag.
diff --git a/src/options.go b/src/options.go
index fe0d06d3..26c67e8e 100644
--- a/src/options.go
+++ b/src/options.go
@@ -156,6 +156,7 @@ type previewOpts struct {
 	size     sizeSpec
 	hidden   bool
 	wrap     bool
+	border   bool
 }
 
 // Options stores the values of command-line options
@@ -248,7 +249,7 @@ func defaultOptions() *Options {
 		ToggleSort:  false,
 		Expect:      make(map[int]string),
 		Keymap:      make(map[int][]action),
-		Preview:     previewOpts{"", posRight, sizeSpec{50, true}, false, false},
+		Preview:     previewOpts{"", posRight, sizeSpec{50, true}, false, false, true},
 		PrintQuery:  false,
 		ReadZero:    false,
 		Printer:     func(str string) { fmt.Println(str) },
@@ -937,6 +938,7 @@ func parsePreviewWindow(opts *previewOpts, input string) {
 	sizeRegex := regexp.MustCompile("^[0-9]+%?$")
 	for _, token := range tokens {
 		switch token {
+		case "":
 		case "hidden":
 			opts.hidden = true
 		case "wrap":
@@ -949,6 +951,10 @@ func parsePreviewWindow(opts *previewOpts, input string) {
 			opts.position = posLeft
 		case "right":
 			opts.position = posRight
+		case "border":
+			opts.border = true
+		case "noborder":
+			opts.border = false
 		default:
 			if sizeRegex.MatchString(token) {
 				opts.size = parseSize(token, 99, "window size")
diff --git a/src/terminal.go b/src/terminal.go
index 0b812ccc..13b932e5 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -624,7 +624,11 @@ func (t *Terminal) resizeWindows() {
 	noBorder := tui.MakeBorderStyle(tui.BorderNone, t.unicode)
 	if previewVisible {
 		createPreviewWindow := func(y int, x int, w int, h int) {
-			t.pborder = t.tui.NewWindow(y, x, w, h, tui.MakeBorderStyle(tui.BorderAround, t.unicode))
+			previewBorder := noBorder
+			if t.preview.border {
+				previewBorder = tui.MakeBorderStyle(tui.BorderAround, t.unicode)
+			}
+			t.pborder = t.tui.NewWindow(y, x, w, h, previewBorder)
 			pwidth := w - 4
 			// ncurses auto-wraps the line when the cursor reaches the right-end of
 			// the window. To prevent unintended line-wraps, we use the width one