Implement change-preview and change-preview-window actions

The new actions are named with 'change-' prefix to differentiate from
the pre-existing, one-off 'preview(...)' action.

Fix #2360
Fix #2505
Fix #2666

Related #2435
Related #2376
  - Can set up multiple bindings with different change-preview-window actions
  - Not possible to "rotate" through the options with a single binding
  - Enlarge or shrink not possible

CHANGELOG.md

@@ -1,6 +1,13 @@
 CHANGELOG
 =========
 
+0.29.0
+------
+- Added `change-preview(...)` action to change the `--preview` command
+    - cf. `preview(...)` is a one-off action that doesn't change the default
+      preview command
+- Added `change-preview-window(...)` action
+
 0.28.0
 ------
 - Added `--header-first` option to print header before the prompt line

man/man1/fzf.1

@@ -21,7 +21,7 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 ..
-.TH fzf 1 "Nov 2021" "fzf 0.28.0" "fzf - a command-line fuzzy finder"
+.TH fzf 1 "Dec 2021" "fzf 0.29.0" "fzf - a command-line fuzzy finder"
 
 .SH NAME
 fzf - a command-line fuzzy finder
@@ -820,6 +820,8 @@ A key or an event can be bound to one or more of the following actions.
     \fBbackward-word\fR              \fIalt-b   shift-left\fR
     \fBbeginning-of-line\fR          \fIctrl-a  home\fR
     \fBcancel\fR                     (clear query string if not empty, abort fzf otherwise)
+    \fBchange-preview(...)\fR        (change \fB--preview\fR option)
+    \fBchange-preview-window(...)\fR (change \fB--preview-window\fR option)
     \fBchange-prompt(...)\fR         (change prompt to the given string)
     \fBclear-screen\fR               \fIctrl-l\fR
     \fBclear-selection\fR            (clear multi-selection)

src/options.go

@@ -176,6 +176,14 @@ type previewOpts struct {
 	headerLines int
 }
 
+func (a previewOpts) sameLayout(b previewOpts) bool {
+	return a.size == b.size && a.position == b.position && a.border == b.border && a.hidden == b.hidden
+}
+
+func (a previewOpts) sameContentLayout(b previewOpts) bool {
+	return a.wrap == b.wrap && a.headerLines == b.headerLines
+}
+
 // Options stores the values of command-line options
 type Options struct {
 	Fuzzy       bool
@@ -787,7 +795,7 @@ func init() {
 	// Backreferences are not supported.
 	// "~!@#$%^&*;/|".each_char.map { |c| Regexp.escape(c) }.map { |c| "#{c}[^#{c}]*#{c}" }.join('|')
 	executeRegexp = regexp.MustCompile(
-		`(?si)[:+](execute(?:-multi|-silent)?|reload|preview|change-prompt|unbind):.+|[:+](execute(?:-multi|-silent)?|reload|preview|change-prompt|unbind)(\([^)]*\)|\[[^\]]*\]|~[^~]*~|![^!]*!|@[^@]*@|\#[^\#]*\#|\$[^\$]*\$|%[^%]*%|\^[^\^]*\^|&[^&]*&|\*[^\*]*\*|;[^;]*;|/[^/]*/|\|[^\|]*\|)`)
+		`(?si)[:+](execute(?:-multi|-silent)?|reload|preview|change-prompt|change-preview-window|change-preview|unbind):.+|[:+](execute(?:-multi|-silent)?|reload|preview|change-prompt|change-preview-window|change-preview|unbind)(\([^)]*\)|\[[^\]]*\]|~[^~]*~|![^!]*!|@[^@]*@|\#[^\#]*\#|\$[^\$]*\$|%[^%]*%|\^[^\^]*\^|&[^&]*&|\*[^\*]*\*|;[^;]*;|/[^/]*/|\|[^\|]*\|)`)
 }
 
 func parseKeymap(keymap map[tui.Event][]action, str string) {
@@ -799,6 +807,10 @@ func parseKeymap(keymap map[tui.Event][]action, str string) {
 		prefix := symbol + "execute"
 		if strings.HasPrefix(src[1:], "reload") {
 			prefix = symbol + "reload"
+		} else if strings.HasPrefix(src[1:], "change-preview-window") {
+			prefix = symbol + "change-preview-window"
+		} else if strings.HasPrefix(src[1:], "change-preview") {
+			prefix = symbol + "change-preview"
 		} else if strings.HasPrefix(src[1:], "preview") {
 			prefix = symbol + "preview"
 		} else if strings.HasPrefix(src[1:], "unbind") {
@@ -1002,6 +1014,10 @@ func parseKeymap(keymap map[tui.Event][]action, str string) {
 						offset = len("reload")
 					case actPreview:
 						offset = len("preview")
+					case actChangePreviewWindow:
+						offset = len("change-preview-window")
+					case actChangePreview:
+						offset = len("change-preview")
 					case actChangePrompt:
 						offset = len("change-prompt")
 					case actUnbind:
@@ -1028,6 +1044,9 @@ func parseKeymap(keymap map[tui.Event][]action, str string) {
 					}
 					if t == actUnbind {
 						parseKeyChords(actionArg, "unbind target required")
+					} else if t == actChangePreviewWindow {
+						opts := previewOpts{}
+						parsePreviewWindow(&opts, actionArg)
 					}
 				}
 			}
@@ -1053,6 +1072,10 @@ func isExecuteAction(str string) actionType {
 		return actUnbind
 	case "preview":
 		return actPreview
+	case "change-preview-window":
+		return actChangePreviewWindow
+	case "change-preview":
+		return actChangePreview
 	case "change-prompt":
 		return actChangePrompt
 	case "execute":
@@ -1633,11 +1656,29 @@ func postProcessOptions(opts *Options) {
 	// Extend the default key map
 	keymap := defaultKeymap()
 	for key, actions := range opts.Keymap {
+		lastChangePreviewWindow := action{t: actIgnore}
 		for _, act := range actions {
-			if act.t == actToggleSort {
+			switch act.t {
+			case actToggleSort:
+				// To display "+S"/"-S" on info line
 				opts.ToggleSort = true
+			case actChangePreviewWindow:
+				lastChangePreviewWindow = act
 			}
 		}
+		// Re-organize actions so that we only keep the last change-preview-window
+		// and it comes first in the list.
+		//  *  change-preview-window(up,+10)+preview(sleep 3; cat {})+change-preview-window(up,+20)
+		//  -> change-preview-window(up,+20)+preview(sleep 3; cat {})
+		if lastChangePreviewWindow.t == actChangePreviewWindow {
+			reordered := []action{lastChangePreviewWindow}
+			for _, act := range actions {
+				if act.t != actChangePreviewWindow {
+					reordered = append(reordered, act)
+				}
+			}
+			actions = reordered
+		}
 		keymap[key] = actions
 	}
 	opts.Keymap = keymap

src/terminal.go

@@ -170,6 +170,7 @@ type Terminal struct {
 	selected           map[int32]selectedItem
 	version            int64
 	reqBox             *util.EventBox
+	initialPreviewOpts previewOpts
 	previewOpts        previewOpts
 	previewer          previewer
 	previewed          previewed
@@ -286,6 +287,8 @@ const (
 	actTogglePreview
 	actTogglePreviewWrap
 	actPreview
+	actChangePreview
+	actChangePreviewWindow
 	actPreviewTop
 	actPreviewBottom
 	actPreviewUp
@@ -326,6 +329,7 @@ type searchRequest struct {
 type previewRequest struct {
 	template     string
 	pwindow      tui.Window
+	scrollOffset int
 	list         []*Item
 }
 
@@ -416,7 +420,7 @@ func trimQuery(query string) []rune {
 func hasPreviewAction(opts *Options) bool {
 	for _, actions := range opts.Keymap {
 		for _, action := range actions {
-			if action.t == actPreview {
+			if action.t == actPreview || action.t == actChangePreview {
 				return true
 			}
 		}
@@ -547,6 +551,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 		merger:             EmptyMerger,
 		selected:           make(map[int32]selectedItem),
 		reqBox:             util.NewEventBox(),
+		initialPreviewOpts: opts.Preview,
 		previewOpts:        opts.Preview,
 		previewer:          previewer{0, []string{}, 0, showPreviewWindow, false, true, false, ""},
 		previewed:          previewed{0, 0, 0, false},
@@ -1642,9 +1647,14 @@ func (t *Terminal) replacePlaceholder(template string, forcePlus bool, input str
 		template, t.ansi, t.delimiter, t.printsep, forcePlus, input, list)
 }
 
-func (t *Terminal) evaluateScrollOffset(list []*Item, height int) int {
+func (t *Terminal) evaluateScrollOffset() int {
+	if t.pwindow == nil {
+		return 0
+	}
+
+	// We only need the current item to calculate the scroll offset
 	offsetExpr := offsetTrimCharsRegex.ReplaceAllString(
-		t.replacePlaceholder(t.previewOpts.scroll, false, "", list), "")
+		t.replacePlaceholder(t.previewOpts.scroll, false, "", []*Item{t.currentItem(), nil}), "")
 
 	atoi := func(s string) int {
 		n, e := strconv.Atoi(s)
@@ -1655,20 +1665,21 @@ func (t *Terminal) evaluateScrollOffset(list []*Item, height int) int {
 	}
 
 	base := -1
+	height := util.Max(0, t.pwindow.Height()-t.previewOpts.headerLines)
 	for _, component := range offsetComponentRegex.FindAllString(offsetExpr, -1) {
 		if strings.HasPrefix(component, "-/") {
 			component = component[1:]
 		}
 		if component[0] == '/' {
 			denom := atoi(component[1:])
-			if denom == 0 {
+			if denom != 0 {
-				return base
+				base -= height / denom
 			}
-			return base - height/denom
+			break
 		}
 		base += atoi(component)
 	}
-	return base
+	return util.Max(0, base)
 }
 
 func replacePlaceholder(template string, stripAnsi bool, delimiter Delimiter, printsep string, forcePlus bool, query string, allItems []*Item) string {
@@ -1972,12 +1983,14 @@ func (t *Terminal) Loop() {
 				var items []*Item
 				var commandTemplate string
 				var pwindow tui.Window
+				initialOffset := 0
 				t.previewBox.Wait(func(events *util.Events) {
 					for req, value := range *events {
 						switch req {
 						case reqPreviewEnqueue:
 							request := value.(previewRequest)
 							commandTemplate = request.template
+							initialOffset = request.scrollOffset
 							items = request.list
 							pwindow = request.pwindow
 						}
@@ -1989,11 +2002,9 @@ func (t *Terminal) Loop() {
 				if items[0] != nil {
 					_, query := t.Input()
 					command := t.replacePlaceholder(commandTemplate, false, string(query), items)
-					initialOffset := 0
 					cmd := util.ExecCommand(command, true)
 					if pwindow != nil {
 						height := pwindow.Height()
-						initialOffset = util.Max(0, t.evaluateScrollOffset(items, util.Max(0, height-t.previewOpts.headerLines)))
 						env := os.Environ()
 						lines := fmt.Sprintf("LINES=%d", height)
 						columns := fmt.Sprintf("COLUMNS=%d", pwindow.Width())
@@ -2128,7 +2139,7 @@ func (t *Terminal) Loop() {
 		if len(command) > 0 && t.isPreviewEnabled() {
 			_, list := t.buildPlusList(command, false)
 			t.cancelPreview()
-			t.previewBox.Set(reqPreviewEnqueue, previewRequest{command, t.pwindow, list})
+			t.previewBox.Set(reqPreviewEnqueue, previewRequest{command, t.pwindow, t.evaluateScrollOffset(), list})
 		}
 	}
 
@@ -2253,13 +2264,16 @@ func (t *Terminal) Loop() {
 				}
 			}
 		}
-		togglePreview := func(enabled bool) {
+		togglePreview := func(enabled bool) bool {
 			if t.previewer.enabled != enabled {
 				t.previewer.enabled = enabled
+				// We need to immediately update t.pwindow so we don't use reqRedraw
 				t.tui.Clear()
 				t.resizeWindows()
 				req(reqPrompt, reqList, reqInfo, reqHeader)
+				return true
 			}
+			return false
 		}
 		toggle := func() bool {
 			current := t.currentItem()
@@ -2327,7 +2341,7 @@ func (t *Terminal) Loop() {
 						if valid {
 							t.cancelPreview()
 							t.previewBox.Set(reqPreviewEnqueue,
-								previewRequest{t.previewOpts.command, t.pwindow, list})
+								previewRequest{t.previewOpts.command, t.pwindow, t.evaluateScrollOffset(), list})
 						}
 					}
 				}
@@ -2707,6 +2721,39 @@ func (t *Terminal) Loop() {
 				for key := range keys {
 					delete(t.keymap, key)
 				}
+			case actChangePreview:
+				if t.previewOpts.command != a.a {
+					togglePreview(len(a.a) > 0)
+					t.previewOpts.command = a.a
+					refreshPreview(t.previewOpts.command)
+				}
+			case actChangePreviewWindow:
+				currentPreviewOpts := t.previewOpts
+
+				// Reset preview options and apply the additional options
+				t.previewOpts = t.initialPreviewOpts
+				parsePreviewWindow(&t.previewOpts, a.a)
+
+				if t.previewOpts.hidden {
+					togglePreview(false)
+				} else {
+					// Full redraw
+					if !currentPreviewOpts.sameLayout(t.previewOpts) {
+						if togglePreview(true) {
+							refreshPreview(t.previewOpts.command)
+						} else {
+							req(reqRedraw)
+						}
+					} else if !currentPreviewOpts.sameContentLayout(t.previewOpts) {
+						t.previewed.version = 0
+						req(reqPreviewRefresh)
+					}
+
+					// Adjust scroll offset
+					if t.hasPreviewWindow() && currentPreviewOpts.scroll != t.previewOpts.scroll {
+						scrollPreviewTo(t.evaluateScrollOffset())
+					}
+				}
 			}
 			return true
 		}

test/test_go.rb

@@ -2142,6 +2142,55 @@ class TestGoFZF < TestBase
       assert_equal expected.chomp, lines.take(6).join("\n")
     end
   end
+
+  def test_change_preview_window
+    tmux.send_keys "seq 1000 | #{FZF} --preview 'echo [[{}]]' --preview-window border-none --bind '" \
+      'a:change-preview(echo __{}__),' \
+      'b:change-preview-window(down)+change-preview(echo =={}==)+change-preview-window(up),' \
+      'c:change-preview(),d:change-preview-window(hidden),' \
+      "e:preview(printf ::%${FZF_PREVIEW_COLUMNS}s{})+change-preview-window(up),f:change-preview-window(up,wrap)'", :Enter
+    tmux.until { |lines| assert_equal 1000, lines.item_count }
+    tmux.until { |lines| assert_includes lines[0], '[[1]]' }
+
+    # change-preview action permanently changes the preview command set by --preview
+    tmux.send_keys 'a'
+    tmux.until { |lines| assert_includes lines[0], '__1__' }
+    tmux.send_keys :Up
+    tmux.until { |lines| assert_includes lines[0], '__2__' }
+
+    # When multiple change-preview-window actions are bound to a single key,
+    # the last one wins and the updated options are immediately applied to the new preview
+    tmux.send_keys 'b'
+    tmux.until { |lines| assert_equal '==2==', lines[0] }
+    tmux.send_keys :Up
+    tmux.until { |lines| assert_equal '==3==', lines[0] }
+
+    # change-preview with an empty preview command closes the preview window
+    tmux.send_keys 'c'
+    tmux.until { |lines| refute_includes lines[0], '==' }
+
+    # change-preview again to re-open the preview window
+    tmux.send_keys 'a'
+    tmux.until { |lines| assert_equal '__3__', lines[0] }
+
+    # Hide the preview window with hidden flag
+    tmux.send_keys 'd'
+    tmux.until { |lines| refute_includes lines[0], '__3__' }
+
+    # One-off preview
+    tmux.send_keys 'e'
+    tmux.until do |lines|
+      assert_equal '::', lines[0]
+      refute_includes lines[1], '3'
+    end
+
+    # Wrapped
+    tmux.send_keys 'f'
+    tmux.until do |lines|
+      assert_equal '::', lines[0]
+      assert_equal '  3', lines[1]
+    end
+  end
 end
 
 module TestShell