Allow invisible preview window (--preview-window 0)

Close #820

CHANGELOG.md

@@ -8,6 +8,8 @@ CHANGELOG
 - Added support for composite actions in `--bind`. Multiple actions can be
   chained using `+` separator.
     - e.g. `fzf --bind 'ctrl-y:execute(echo -n {} | pbcopy)+abort'`
+- `--preview-window` with size 0 is allowed. This is used to make fzf execute
+  preview command in the background without displaying the result.
 
 0.16.1
 ------

man/man1/fzf.1

@@ -278,6 +278,9 @@ Determine the layout of the preview window. If the argument ends with
 \fBtoggle-preview\fR action is triggered. Long lines are truncated by default.
 Line wrap can be enabled with \fB:wrap\fR flag.
 
+If size is given as 0, preview window will not be visible, but fzf will still
+execute the command in the background.
+
 .RS
 .B POSITION: (default: right)
     \fBup

src/options.go

@@ -823,7 +823,7 @@ func parsePreviewWindow(opts *previewOpts, input string) {
 	opts.wrap = false
 
 	tokens := strings.Split(input, ":")
-	sizeRegex := regexp.MustCompile("^[1-9][0-9]*%?$")
+	sizeRegex := regexp.MustCompile("^[0-9]+%?$")
 	for _, token := range tokens {
 		switch token {
 		case "hidden":

src/terminal.go

@@ -509,9 +509,11 @@ func (t *Terminal) resizeWindows() {
 			}
 		}
 	}
+
+	previewVisible := t.isPreviewEnabled() && t.preview.size.size > 0
 	minAreaWidth := minWidth
 	minAreaHeight := minHeight
-	if t.isPreviewEnabled() {
+	if previewVisible {
 		switch t.preview.position {
 		case posUp, posDown:
 			minAreaHeight *= 2
@@ -531,7 +533,7 @@ func (t *Terminal) resizeWindows() {
 
 	width := screenWidth - marginInt[1] - marginInt[3]
 	height := screenHeight - marginInt[0] - marginInt[2]
-	if t.isPreviewEnabled() {
+	if previewVisible {
 		createPreviewWindow := func(y int, x int, w int, h int) {
 			t.bwindow = t.tui.NewWindow(y, x, w, h, true)
 			pwidth := w - 4
@@ -889,7 +891,7 @@ func numLinesMax(str string, max int) int {
 }
 
 func (t *Terminal) printPreview() {
-	if !t.isPreviewEnabled() {
+	if !t.hasPreviewWindow() {
 		return
 	}
 	t.pwindow.Erase()
@@ -974,7 +976,7 @@ func (t *Terminal) printAll() {
 
 func (t *Terminal) refresh() {
 	if !t.suppress {
-		if t.isPreviewEnabled() {
+		if t.hasPreviewWindow() {
 			t.tui.RefreshWindows([]tui.Window{t.bwindow, t.pwindow, t.window})
 		} else {
 			t.tui.RefreshWindows([]tui.Window{t.window})
@@ -1107,12 +1109,16 @@ func (t *Terminal) executeCommand(template string, items []*Item) {
 	t.refresh()
 }
 
-func (t *Terminal) hasPreviewWindow() bool {
+func (t *Terminal) hasPreviewer() bool {
 	return t.previewBox != nil
 }
 
 func (t *Terminal) isPreviewEnabled() bool {
-	return t.previewBox != nil && t.previewer.enabled
+	return t.hasPreviewer() && t.previewer.enabled
+}
+
+func (t *Terminal) hasPreviewWindow() bool {
+	return t.pwindow != nil && t.isPreviewEnabled()
 }
 
 func (t *Terminal) currentItem() *Item {
@@ -1174,7 +1180,7 @@ func (t *Terminal) Loop() {
 		}()
 	}
 
-	if t.hasPreviewWindow() {
+	if t.hasPreviewer() {
 		go func() {
 			for {
 				var request *Item
@@ -1358,7 +1364,7 @@ func (t *Terminal) Loop() {
 				t.mutex.Unlock()
 				return false
 			case actTogglePreview:
-				if t.hasPreviewWindow() {
+				if t.hasPreviewer() {
 					t.previewer.enabled = !t.previewer.enabled
 					t.tui.Clear()
 					t.resizeWindows()
@@ -1374,19 +1380,19 @@ func (t *Terminal) Loop() {
 				t.mutex.Unlock()
 				return false
 			case actPreviewUp:
-				if t.isPreviewEnabled() {
+				if t.hasPreviewWindow() {
 					scrollPreview(-1)
 				}
 			case actPreviewDown:
-				if t.isPreviewEnabled() {
+				if t.hasPreviewWindow() {
 					scrollPreview(1)
 				}
 			case actPreviewPageUp:
-				if t.isPreviewEnabled() {
+				if t.hasPreviewWindow() {
 					scrollPreview(-t.pwindow.Height())
 				}
 			case actPreviewPageDown:
-				if t.isPreviewEnabled() {
+				if t.hasPreviewWindow() {
 					scrollPreview(t.pwindow.Height())
 				}
 			case actBeginningOfLine:
@@ -1563,7 +1569,7 @@ func (t *Terminal) Loop() {
 						}
 						t.vmove(me.S)
 						req(reqList)
-					} else if t.isPreviewEnabled() && t.pwindow.Enclose(my, mx) {
+					} else if t.hasPreviewWindow() && t.pwindow.Enclose(my, mx) {
 						scrollPreview(-me.S)
 					}
 				} else if t.window.Enclose(my, mx) {

test/test_go.rb

@@ -1224,6 +1224,19 @@ class TestGoFZF < TestBase
     tmux.send_keys '?'
     tmux.until { |lines| lines[-1] == '> 555' }
   end
+
+  def test_preview_size_0
+    File.unlink tempname rescue nil
+    tmux.send_keys %[seq 100 | #{FZF} --reverse --preview 'echo {} >> #{tempname}; echo ' --preview-window 0], :Enter
+    tmux.until { |lines| lines.item_count == 100 && lines[1] == '  100/100' && lines[2] == '> 1' }
+    tmux.until { |_|  %w[1] == File.readlines(tempname).map(&:chomp) }
+    tmux.send_keys :Down
+    tmux.until { |lines| lines[3] == '> 2' }
+    tmux.until { |_|  %w[1 2] == File.readlines(tempname).map(&:chomp) }
+    tmux.send_keys :Down
+    tmux.until { |lines| lines[4] == '> 3' }
+    tmux.until { |_|  %w[1 2 3] == File.readlines(tempname).map(&:chomp) }
+  end
 end
 
 module TestShell