Implement height range (--height ~[VALUE][%])

Close #2953

CHANGELOG.md

@@ -1,6 +1,36 @@
 CHANGELOG
 =========
 
+0.34.0
+------
+- Added support for adaptive `--height`. If the `--height` value is prefixed
+  with `~`, fzf will automatically determine the height in the range according
+  to the input size.
+  ```sh
+  seq 1 | fzf --height ~70% --border --padding 1 --margin 1
+  seq 10 | fzf --height ~70% --border --padding 1 --margin 1
+  seq 100 | fzf --height ~70% --border --padding 1 --margin 1
+  ```
+    - There are a few limitations
+        - Not compatible with percent top/bottom margin/padding
+          ```sh
+          # This is not allowed (top/bottom margin in percent value)
+          fzf --height ~50% --border --margin 5%,10%
+
+          # This is allowed (top/bottom margin in fixed value)
+          fzf --height ~50% --border --margin 2,10%
+          ```
+        - fzf will not start until it can determine the right height for the input
+          ```sh
+          # fzf will open immediately
+          (sleep 2; seq 10) | fzf --height 50%
+
+          # fzf will open after 2 seconds
+          (sleep 2; seq 10) | fzf --height ~50%
+          (sleep 2; seq 1000) | fzf --height ~50%
+          ```
+- Fixed tcell renderer used to render full-screen fzf on Windows
+
 0.33.0
 ------
 - Added `--scheme=[default|path|history]` option to choose scoring scheme

Makefile

@@ -155,6 +155,7 @@ target/$(BINARYLOONG64): $(SOURCES)
 	GOARCH=loong64 $(GO) build $(BUILD_FLAGS) -o $@
 
 bin/fzf: target/$(BINARY) | bin
+	-rm -f bin/fzf
 	cp -f target/$(BINARY) bin/fzf
 
 docker:

man/man1/fzf.1

@@ -177,9 +177,11 @@ actions are affected:
 Label characters for \fBjump\fR and \fBjump-accept\fR
 .SS Layout
 .TP
-.BI "--height=" "HEIGHT[%]"
+.BI "--height=" "[~]HEIGHT[%]"
 Display fzf window below the cursor with the given height instead of using
-the full screen.
+the full screen. When prefixed with \fB~\fR, fzf will automatically determine
+the height in the range according to the input size. Note that adaptive height
+is not compatible with top/bottom margin and padding given in percent size.
 .TP
 .BI "--min-height=" "HEIGHT"
 Minimum height when \fB--height\fR is given in percent (default: 10).

src/core.go

@@ -194,10 +194,17 @@ func Run(opts *Options, version string, revision string) {
 
 	// Terminal I/O
 	terminal := NewTerminal(opts, eventBox)
+	maxFit := 0 // Maximum number of items that can fit on screen
+	padHeight := 0
+	heightUnknown := opts.Height.auto
+	if heightUnknown {
+		maxFit, padHeight = terminal.MaxFitAndPad(opts)
+	}
 	deferred := opts.Select1 || opts.Exit0
 	go terminal.Loop()
-	if !deferred {
-		terminal.startChan <- true
+	if !deferred && !heightUnknown {
+		// Start right away
+		terminal.startChan <- fitpad{-1, -1}
 	}
 
 	// Event coordination
@@ -216,7 +223,19 @@ func Run(opts *Options, version string, revision string) {
 		go reader.restart(command)
 	}
 	eventBox.Watch(EvtReadNew)
+	total := 0
 	query := []rune{}
+	determine := func(final bool) {
+		if heightUnknown {
+			if total >= maxFit || final {
+				heightUnknown = false
+				terminal.startChan <- fitpad{util.Min(total, maxFit), padHeight}
+			}
+		} else if deferred {
+			deferred = false
+			terminal.startChan <- fitpad{-1, -1}
+		}
+	}
 	for {
 		delay := true
 		ticks++
@@ -249,11 +268,15 @@ func Run(opts *Options, version string, revision string) {
 						reading = reading && evt == EvtReadNew
 					}
 					snapshot, count := chunkList.Snapshot()
-					terminal.UpdateCount(count, !reading, value.(*string))
+					total = count
+					terminal.UpdateCount(total, !reading, value.(*string))
 					if opts.Sync {
 						opts.Sync = false
 						terminal.UpdateList(PassMerger(&snapshot, opts.Tac), false)
 					}
+					if heightUnknown && !deferred {
+						determine(!reading)
+					}
 					reset := clearCache()
 					matcher.Reset(snapshot, input(reset), false, !reading, sort, reset)
 
@@ -295,8 +318,7 @@ func Run(opts *Options, version string, revision string) {
 						if deferred {
 							count := val.Length()
 							if opts.Select1 && count > 1 || opts.Exit0 && !opts.Select1 && count > 0 {
-								deferred = false
-								terminal.startChan <- true
+								determine(val.final)
 							} else if val.final {
 								if opts.Exit0 && count == 0 || opts.Select1 && count == 1 {
 									if opts.PrintQuery {
@@ -313,8 +335,7 @@ func Run(opts *Options, version string, revision string) {
 									}
 									os.Exit(exitNoMatch)
 								}
-								deferred = false
-								terminal.startChan <- true
+								determine(val.final)
 							}
 						}
 						terminal.UpdateList(val, clearSelection())

src/options.go

@@ -53,8 +53,10 @@ const usage = `usage: fzf [options]
     --jump-labels=CHARS   Label characters for jump and jump-accept
 
   Layout
-    --height=HEIGHT[%]    Display fzf window below the cursor with the given
-                          height instead of using fullscreen
+    --height=[~]HEIGHT[%] Display fzf window below the cursor with the given
+                          height instead of using fullscreen.
+                          If prefixed with '~', fzf will determine the height
+                          according to the input size.
     --min-height=HEIGHT   Minimum height when --height is given in percent
                           (default: 10)
     --layout=LAYOUT       Choose layout: [default|reverse|reverse-list]
@@ -131,6 +133,12 @@ const (
 	byEnd
 )
 
+type heightSpec struct {
+	size    float64
+	percent bool
+	auto    bool
+}
+
 type sizeSpec struct {
 	size    float64
 	percent bool
@@ -180,6 +188,10 @@ type previewOpts struct {
 	alternative *previewOpts
 }
 
+func (a previewOpts) aboveOrBelow() bool {
+	return a.size.size > 0 && (a.position == posUp || a.position == posDown)
+}
+
 func (a previewOpts) sameLayout(b previewOpts) bool {
 	return a.size == b.size && a.position == b.position && a.border == b.border && a.hidden == b.hidden && a.threshold == b.threshold &&
 		(a.alternative != nil && b.alternative != nil && a.alternative.sameLayout(*b.alternative) ||
@@ -211,7 +223,7 @@ type Options struct {
 	Theme       *tui.ColorTheme
 	Black       bool
 	Bold        bool
-	Height      sizeSpec
+	Height      heightSpec
 	MinHeight   int
 	Layout      layoutType
 	Cycle       bool
@@ -1076,11 +1088,6 @@ func parseKeymap(keymap map[tui.Event][]*action, str string) {
 					}
 					if t == actUnbind || t == actRebind {
 						parseKeyChords(actionArg, spec[0:offset]+" target required")
-					} else if t == actChangePreviewWindow {
-						opts := previewOpts{}
-						for _, arg := range strings.Split(actionArg, "|") {
-							parsePreviewWindow(&opts, arg)
-						}
 					}
 				}
 			}
@@ -1160,9 +1167,17 @@ func parseSize(str string, maxPercent float64, label string) sizeSpec {
 	return sizeSpec{val, percent}
 }
 
-func parseHeight(str string) sizeSpec {
+func parseHeight(str string) heightSpec {
+	heightSpec := heightSpec{}
+	if strings.HasPrefix(str, "~") {
+		heightSpec.auto = true
+		str = str[1:]
+	}
+
 	size := parseSize(str, 100, "height")
-	return size
+	heightSpec.size = size.size
+	heightSpec.percent = size.percent
+	return heightSpec
 }
 
 func parseLayout(str string) layoutType {
@@ -1525,11 +1540,11 @@ func parseOptions(opts *Options, allArgs []string) {
 			parsePreviewWindow(&opts.Preview,
 				nextString(allArgs, &i, "preview window layout required: [up|down|left|right][,SIZE[%]][,border-BORDER_OPT][,wrap][,cycle][,hidden][,+SCROLL[OFFSETS][/DENOM]][,~HEADER_LINES][,default]"))
 		case "--height":
-			opts.Height = parseHeight(nextString(allArgs, &i, "height required: HEIGHT[%]"))
+			opts.Height = parseHeight(nextString(allArgs, &i, "height required: [~]HEIGHT[%]"))
 		case "--min-height":
 			opts.MinHeight = nextInt(allArgs, &i, "height required: HEIGHT")
 		case "--no-height":
-			opts.Height = sizeSpec{}
+			opts.Height = heightSpec{}
 		case "--no-margin":
 			opts.Margin = defaultMargin()
 		case "--no-padding":
@@ -1709,6 +1724,7 @@ func postProcessOptions(opts *Options) {
 	}
 
 	// Extend the default key map
+	previewEnabled := len(opts.Preview.command) > 0 || hasPreviewAction(opts)
 	keymap := defaultKeymap()
 	for key, actions := range opts.Keymap {
 		var lastChangePreviewWindow *action
@@ -1719,8 +1735,18 @@ func postProcessOptions(opts *Options) {
 				opts.ToggleSort = true
 			case actChangePreviewWindow:
 				lastChangePreviewWindow = act
+				if !previewEnabled {
+					// Doesn't matter
+					continue
+				}
+				opts := previewOpts{}
+				for _, arg := range strings.Split(act.a, "|") {
+					// Make sure that each expression is valid
+					parsePreviewWindow(&opts, arg)
+				}
 			}
 		}
+
 		// 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)
@@ -1738,6 +1764,19 @@ func postProcessOptions(opts *Options) {
 	}
 	opts.Keymap = keymap
 
+	if opts.Height.auto {
+		for _, s := range []sizeSpec{opts.Margin[0], opts.Margin[2]} {
+			if s.percent {
+				errorExit("adaptive height is not compatible with top/bottom percent margin")
+			}
+		}
+		for _, s := range []sizeSpec{opts.Padding[0], opts.Padding[2]} {
+			if s.percent {
+				errorExit("adaptive height is not compatible with top/bottom percent padding")
+			}
+		}
+	}
+
 	// If we're not using extended search mode, --nth option becomes irrelevant
 	// if it contains the whole range
 	if !opts.Extended || len(opts.Nth) == 1 {

src/terminal.go

@@ -100,6 +100,11 @@ type itemLine struct {
 	result   Result
 }
 
+type fitpad struct {
+	fit int
+	pad int
+}
+
 var emptyLine = itemLine{}
 
 // Terminal represents terminal input/output
@@ -183,7 +188,7 @@ type Terminal struct {
 	prevLines          []itemLine
 	suppress           bool
 	sigstop            bool
-	startChan          chan bool
+	startChan          chan fitpad
 	killChan           chan int
 	slab               *util.Slab
 	theme              *tui.ColorTheme
@@ -439,6 +444,13 @@ func makeSpinner(unicode bool) []string {
 	return []string{`-`, `\`, `|`, `/`, `-`, `\`, `|`, `/`}
 }
 
+func evaluateHeight(opts *Options, termHeight int) int {
+	if opts.Height.percent {
+		return util.Max(int(opts.Height.size*float64(termHeight)/100.0), opts.MinHeight)
+	}
+	return int(opts.Height.size)
+}
+
 // NewTerminal returns new Terminal object
 func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 	input := trimQuery(opts.Query)
@@ -465,7 +477,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 		strongAttr = tui.AttrRegular
 	}
 	var renderer tui.Renderer
-	fullscreen := opts.Height.size == 0 || opts.Height.percent && opts.Height.size == 100
+	fullscreen := !opts.Height.auto && (opts.Height.size == 0 || opts.Height.percent && opts.Height.size == 100)
 	if fullscreen {
 		if tui.HasFullscreenRenderer() {
 			renderer = tui.NewFullscreenRenderer(opts.Theme, opts.Black, opts.Mouse)
@@ -475,24 +487,16 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 		}
 	} else {
 		maxHeightFunc := func(termHeight int) int {
-			var maxHeight int
-			if opts.Height.percent {
-				maxHeight = util.Max(int(opts.Height.size*float64(termHeight)/100.0), opts.MinHeight)
-			} else {
-				maxHeight = int(opts.Height.size)
-			}
-
+			// Minimum height required to render fzf excluding margin and padding
 			effectiveMinHeight := minHeight
-			if previewBox != nil && (opts.Preview.position == posUp || opts.Preview.position == posDown) {
-				effectiveMinHeight *= 2
+			if previewBox != nil && opts.Preview.aboveOrBelow() {
+				effectiveMinHeight += 1 + borderLines(opts.Preview.border)
 			}
 			if opts.InfoStyle != infoDefault {
 				effectiveMinHeight--
 			}
-			if opts.BorderShape != tui.BorderNone {
-				effectiveMinHeight += 2
-			}
-			return util.Min(termHeight, util.Max(maxHeight, effectiveMinHeight))
+			effectiveMinHeight += borderLines(opts.BorderShape)
+			return util.Min(termHeight, util.Max(evaluateHeight(opts, termHeight), effectiveMinHeight))
 		}
 		renderer = tui.NewLightRenderer(opts.Theme, opts.Black, opts.Mouse, opts.Tabstop, opts.ClearOnExit, false, maxHeightFunc)
 	}
@@ -572,7 +576,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 		sigstop:            false,
 		slab:               util.MakeSlab(slab16Size, slab32Size),
 		theme:              opts.Theme,
-		startChan:          make(chan bool, 1),
+		startChan:          make(chan fitpad, 1),
 		killChan:           make(chan int),
 		tui:                renderer,
 		initFunc:           func() { renderer.Init() },
@@ -587,6 +591,32 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 	return &t
 }
 
+func borderLines(shape tui.BorderShape) int {
+	switch shape {
+	case tui.BorderHorizontal, tui.BorderRounded, tui.BorderSharp:
+		return 2
+	case tui.BorderTop, tui.BorderBottom:
+		return 1
+	}
+	return 0
+}
+
+// Extra number of lines needed to display fzf
+func (t *Terminal) extraLines() int {
+	extra := len(t.header0) + t.headerLines + 1
+	if !t.noInfoLine() {
+		extra++
+	}
+	return extra
+}
+
+func (t *Terminal) MaxFitAndPad(opts *Options) (int, int) {
+	_, screenHeight, marginInt, paddingInt := t.adjustMarginAndPadding()
+	padHeight := marginInt[0] + marginInt[2] + paddingInt[0] + paddingInt[2]
+	fit := screenHeight - padHeight - t.extraLines()
+	return fit, padHeight
+}
+
 func (t *Terminal) parsePrompt(prompt string) (func(), int) {
 	var state *ansiState
 	trimmed, colors, _ := extractColor(prompt, state, nil)
@@ -725,22 +755,23 @@ func (t *Terminal) displayWidth(runes []rune) int {
 
 const (
 	minWidth  = 4
-	minHeight = 4
+	minHeight = 3
 )
 
 func calculateSize(base int, size sizeSpec, occupied int, minSize int, pad int) int {
 	max := base - occupied
+	if max < minSize {
+		max = minSize
+	}
 	if size.percent {
 		return util.Constrain(int(float64(base)*0.01*size.size), minSize, max)
 	}
 	return util.Constrain(int(size.size)+pad, minSize, max)
 }
 
-func (t *Terminal) resizeWindows() {
+func (t *Terminal) adjustMarginAndPadding() (int, int, [4]int, [4]int) {
 	screenWidth := t.tui.MaxX()
 	screenHeight := t.tui.MaxY()
-	t.prevLines = make([]itemLine, screenHeight)
-
 	marginInt := [4]int{}  // TRBL
 	paddingInt := [4]int{} // TRBL
 	sizeSpecToInt := func(index int, spec sizeSpec) int {
@@ -789,31 +820,48 @@ func (t *Terminal) resizeWindows() {
 	}
 
 	adjust := func(idx1 int, idx2 int, max int, min int) {
-		if max >= min {
-			margin := marginInt[idx1] + marginInt[idx2] + paddingInt[idx1] + paddingInt[idx2]
-			if max-margin < min {
-				desired := max - min
-				paddingInt[idx1] = desired * paddingInt[idx1] / margin
-				paddingInt[idx2] = desired * paddingInt[idx2] / margin
-				marginInt[idx1] = util.Max(extraMargin[idx1], desired*marginInt[idx1]/margin)
-				marginInt[idx2] = util.Max(extraMargin[idx2], desired*marginInt[idx2]/margin)
-			}
+		if min > max {
+			min = max
+		}
+		margin := marginInt[idx1] + marginInt[idx2] + paddingInt[idx1] + paddingInt[idx2]
+		if max-margin < min {
+			desired := max - min
+			paddingInt[idx1] = desired * paddingInt[idx1] / margin
+			paddingInt[idx2] = desired * paddingInt[idx2] / margin
+			marginInt[idx1] = util.Max(extraMargin[idx1], desired*marginInt[idx1]/margin)
+			marginInt[idx2] = util.Max(extraMargin[idx2], desired*marginInt[idx2]/margin)
 		}
 	}
 
-	previewVisible := t.isPreviewEnabled() && t.previewOpts.size.size > 0
 	minAreaWidth := minWidth
 	minAreaHeight := minHeight
-	if previewVisible {
+	if t.noInfoLine() {
+		minAreaHeight -= 1
+	}
+	if t.isPreviewVisible() {
+		minPreviewHeight := 1 + borderLines(t.previewOpts.border)
+		minPreviewWidth := 5
 		switch t.previewOpts.position {
 		case posUp, posDown:
-			minAreaHeight *= 2
+			minAreaHeight += minPreviewHeight
+			minAreaWidth = util.Max(minPreviewWidth, minAreaWidth)
 		case posLeft, posRight:
-			minAreaWidth *= 2
+			minAreaWidth += minPreviewWidth
+			minAreaHeight = util.Max(minPreviewHeight, minAreaHeight)
 		}
 	}
 	adjust(1, 3, screenWidth, minAreaWidth)
 	adjust(0, 2, screenHeight, minAreaHeight)
+
+	return screenWidth, screenHeight, marginInt, paddingInt
+}
+
+func (t *Terminal) resizeWindows() {
+	screenWidth, screenHeight, marginInt, paddingInt := t.adjustMarginAndPadding()
+	width := screenWidth - marginInt[1] - marginInt[3]
+	height := screenHeight - marginInt[0] - marginInt[2]
+
+	t.prevLines = make([]itemLine, screenHeight)
 	if t.border != nil {
 		t.border.Close()
 	}
@@ -832,8 +880,6 @@ func (t *Terminal) resizeWindows() {
 	// Reset preview version so that full redraw occurs
 	t.previewed.version = 0
 
-	width := screenWidth - marginInt[1] - marginInt[3]
-	height := screenHeight - marginInt[0] - marginInt[2]
 	switch t.borderShape {
 	case tui.BorderHorizontal:
 		t.border = t.tui.NewWindow(
@@ -865,16 +911,16 @@ func (t *Terminal) resizeWindows() {
 			false, tui.MakeBorderStyle(t.borderShape, t.unicode))
 	}
 
-	// Add padding
+	// Add padding to margin
 	for idx, val := range paddingInt {
 		marginInt[idx] += val
 	}
-	width = screenWidth - marginInt[1] - marginInt[3]
-	height = screenHeight - marginInt[0] - marginInt[2]
+	width -= paddingInt[1] + paddingInt[3]
+	height -= paddingInt[0] + paddingInt[2]
 
 	// Set up preview window
 	noBorder := tui.MakeBorderStyle(tui.BorderNone, t.unicode)
-	if previewVisible {
+	if t.isPreviewVisible() {
 		var resizePreviewWindows func(previewOpts previewOpts)
 		resizePreviewWindows = func(previewOpts previewOpts) {
 			hasThreshold := previewOpts.threshold > 0 && previewOpts.alternative != nil
@@ -1863,6 +1909,10 @@ func (t *Terminal) isPreviewEnabled() bool {
 	return t.hasPreviewer() && t.previewer.enabled
 }
 
+func (t *Terminal) isPreviewVisible() bool {
+	return t.isPreviewEnabled() && t.previewOpts.size.size > 0
+}
+
 func (t *Terminal) hasPreviewWindow() bool {
 	return t.pwindow != nil && t.isPreviewEnabled()
 }
@@ -1962,7 +2012,28 @@ func (t *Terminal) cancelPreview() {
 // Loop is called to start Terminal I/O
 func (t *Terminal) Loop() {
 	// prof := profile.Start(profile.ProfilePath("/tmp/"))
-	<-t.startChan
+	fitpad := <-t.startChan
+	fit := fitpad.fit
+	if fit >= 0 {
+		pad := fitpad.pad
+		t.tui.Resize(func(termHeight int) int {
+			contentHeight := fit + t.extraLines()
+			if t.hasPreviewer() {
+				if t.previewOpts.aboveOrBelow() {
+					if t.previewOpts.size.percent {
+						newContentHeight := int(float64(contentHeight) * 100. / (100. - t.previewOpts.size.size))
+						contentHeight = util.Max(contentHeight+1+borderLines(t.previewOpts.border), newContentHeight)
+					} else {
+						contentHeight += int(t.previewOpts.size.size) + borderLines(t.previewOpts.border)
+					}
+				} else {
+					// Minimum height if preview window can appear
+					contentHeight = util.Max(contentHeight, 1+borderLines(t.previewOpts.border))
+				}
+			}
+			return util.Min(termHeight, contentHeight+pad)
+		})
+	}
 	{ // Late initialization
 		intChan := make(chan os.Signal, 1)
 		signal.Notify(intChan, os.Interrupt, syscall.SIGTERM)

src/tui/dummy.go

@@ -27,12 +27,13 @@ const (
 	StrikeThrough = Attr(1 << 7)
 )
 
-func (r *FullscreenRenderer) Init()             {}
-func (r *FullscreenRenderer) Pause(bool)        {}
-func (r *FullscreenRenderer) Resume(bool, bool) {}
-func (r *FullscreenRenderer) Clear()            {}
-func (r *FullscreenRenderer) Refresh()          {}
-func (r *FullscreenRenderer) Close()            {}
+func (r *FullscreenRenderer) Init()                              {}
+func (r *FullscreenRenderer) Resize(maxHeightFunc func(int) int) {}
+func (r *FullscreenRenderer) Pause(bool)                         {}
+func (r *FullscreenRenderer) Resume(bool, bool)                  {}
+func (r *FullscreenRenderer) Clear()                             {}
+func (r *FullscreenRenderer) Refresh()                           {}
+func (r *FullscreenRenderer) Close()                             {}
 
 func (r *FullscreenRenderer) GetChar() Event { return Event{} }
 func (r *FullscreenRenderer) MaxX() int      { return 0 }

src/tui/light.go

@@ -189,6 +189,10 @@ func (r *LightRenderer) Init() {
 	}
 }
 
+func (r *LightRenderer) Resize(maxHeightFunc func(int) int) {
+	r.maxHeightFunc = maxHeightFunc
+}
+
 func (r *LightRenderer) makeSpace() {
 	r.stderr("\n")
 	r.csi("G")
@@ -676,6 +680,9 @@ func (r *LightRenderer) MaxX() int {
 }
 
 func (r *LightRenderer) MaxY() int {
+	if r.height == 0 {
+		r.updateTerminalSize()
+	}
 	return r.height
 }
 

src/tui/tcell.go

@@ -99,6 +99,8 @@ const (
 	AttrClear     = Attr(1 << 8)
 )
 
+func (r *FullscreenRenderer) Resize(maxHeightFunc func(int) int) {}
+
 func (r *FullscreenRenderer) defaultTheme() *ColorTheme {
 	if _screen.Colors() >= 256 {
 		return Dark256

src/tui/tui.go

@@ -358,6 +358,7 @@ func MakeTransparentBorder() BorderStyle {
 
 type Renderer interface {
 	Init()
+	Resize(maxHeightFunc func(int) int)
 	Pause(clear bool)
 	Resume(clear bool, sigcont bool)
 	Clear()

test/test_go.rb

@@ -2245,6 +2245,93 @@ class TestGoFZF < TestBase
     tmux.until { |lines| assert_equal 1, lines.match_count }
     tmux.until { |lines| assert_match(/^> SNIPSNIP.*SNIPSNIP$/, lines[-3]) }
   end
+
+  def assert_block(expected, lines)
+    cols = expected.lines.map(&:chomp).map(&:length).max
+    actual = lines.reverse.take(expected.lines.length).reverse.map { _1[0, cols].rstrip + "\n" }.join
+    assert_equal expected, actual
+  end
+
+  def test_height_range_fit
+    tmux.send_keys 'seq 3 | fzf --height ~100% --info=inline --border', :Enter
+    expected = <<~OUTPUT
+      ╭──────────
+      │   3
+      │   2
+      │ > 1
+      │ >   < 3/3
+      ╰──────────
+    OUTPUT
+    tmux.until { assert_block(expected, _1) }
+  end
+
+  def test_height_range_fit_preview_above
+    tmux.send_keys 'seq 3 | fzf --height ~100% --info=inline --border --preview "seq {}" --preview-window up,60%', :Enter
+    expected = <<~OUTPUT
+      ╭──────────
+      │ ╭────────
+      │ │ 1
+      │ │
+      │ │
+      │ │
+      │ ╰────────
+      │   3
+      │   2
+      │ > 1
+      │ >   < 3/3
+      ╰──────────
+    OUTPUT
+    tmux.until { assert_block(expected, _1) }
+  end
+
+  def test_height_range_fit_preview_above_alternative
+    tmux.send_keys 'seq 3 | fzf --height ~100% --border=sharp --preview "seq {}" --preview-window up,40%,border-bottom --padding 1 --exit-0 --header hello --header-lines=2', :Enter
+    expected = <<~OUTPUT
+      ┌─────────
+      │
+      │  1
+      │  2
+      │  3
+      │  ───────
+      │  > 3
+      │    2
+      │    1
+      │    hello
+      │    1/1
+      │  >
+      │
+      └─────────
+    OUTPUT
+    tmux.until { assert_block(expected, _1) }
+  end
+
+  def test_height_range_fit_preview_left
+    tmux.send_keys "seq 3 | fzf --height ~100% --border=vertical --preview 'seq {}' --preview-window left,5,border-right --padding 1 --exit-0 --header $'hello\\nworld' --header-lines=2", :Enter
+    expected = <<~OUTPUT
+      │
+      │  1       │> 3
+      │  2       │  2
+      │  3       │  1
+      │          │  hello
+      │          │  world
+      │          │  1/1
+      │          │>
+      │
+    OUTPUT
+    tmux.until { assert_block(expected, _1) }
+  end
+
+  def test_height_range_overflow
+    tmux.send_keys 'seq 100 | fzf --height ~5 --info=inline --border', :Enter
+    expected = <<~OUTPUT
+      ╭──────────────
+      │   2
+      │ > 1
+      │ >   < 100/100
+      ╰──────────────
+    OUTPUT
+    tmux.until { assert_block(expected, _1) }
+  end
 end
 
 module TestShell