[SQUASHED] draw-graph-with-branch-drawing-symbols

docs-master/Config.md

@@ -300,6 +300,18 @@ gui:
   # NerdFontsVersion is not empty.
   showFileIcons: true
 
+  # How the commit graph is drawn.
+  # One of: 'auto' (default) | 'classic' | 'detailed'
+  # 'detailed' connects the lines to the commit circles, and shows exactly where
+  # branches fork off and merge. It draws the graph with the git branch drawing
+  # symbols (U+F5D0 to U+F60D), so it needs a terminal that draws these itself:
+  # kitty, Ghostty, WezTerm (nightly builds), Contour, or VS Code's terminal with
+  # GPU acceleration. Other terminals need a font that contains them, such as
+  # https://github.com/rbong/flog-symbols.
+  # 'auto' uses 'detailed' if lazygit recognizes the terminal as one that draws
+  # these symbols (kitty and Ghostty), and 'classic' otherwise.
+  commitGraphStyle: auto
+
   # Length of author name in (non-expanded) commits view. 2 means show initials
   # only.
   commitAuthorShortLength: 2

pkg/config/user_config.go

@@ -179,6 +179,11 @@ type GuiConfig struct {
 	NerdFontsVersion string `yaml:"nerdFontsVersion" jsonschema:"enum=2,enum=3,enum="`
 	// If true (default), file icons are shown in the file views. Only relevant if NerdFontsVersion is not empty.
 	ShowFileIcons bool `yaml:"showFileIcons"`
+	// How the commit graph is drawn.
+	// One of: 'auto' (default) | 'classic' | 'detailed'
+	// 'detailed' connects the lines to the commit circles, and shows exactly where branches fork off and merge. It draws the graph with the git branch drawing symbols (U+F5D0 to U+F60D), so it needs a terminal that draws these itself: kitty, Ghostty, WezTerm (nightly builds), Contour, or VS Code's terminal with GPU acceleration. Other terminals need a font that contains them, such as https://github.com/rbong/flog-symbols.
+	// 'auto' uses 'detailed' if lazygit recognizes the terminal as one that draws these symbols (kitty and Ghostty), and 'classic' otherwise.
+	CommitGraphStyle string `yaml:"commitGraphStyle" jsonschema:"enum=auto,enum=classic,enum=detailed"`
 	// Length of author name in (non-expanded) commits view. 2 means show initials only.
 	CommitAuthorShortLength int `yaml:"commitAuthorShortLength"`
 	// Length of author name in expanded commits view. 2 means show initials only.
@@ -925,6 +930,7 @@ func GetDefaultConfigForPlatform(platform string) *UserConfig {
 			ShowIcons:                           false,
 			NerdFontsVersion:                    "",
 			ShowFileIcons:                       true,
+			CommitGraphStyle:                    "auto",
 			CommitAuthorShortLength:             2,
 			CommitAuthorLongLength:              17,
 			CommitHashLength:                    8,

pkg/config/user_config_validation.go

@@ -30,6 +30,10 @@ func (config *UserConfig) Validate() error {
 		[]string{"mixed", "filesFirst", "foldersFirst"}); err != nil {
 		return err
 	}
+	if err := validateEnum("gui.commitGraphStyle", config.Gui.CommitGraphStyle,
+		[]string{"auto", "classic", "detailed"}); err != nil {
+		return err
+	}
 	if err := validateEnum("git.autoForwardBranches", config.Git.AutoForwardBranches,
 		[]string{"none", "onlyMainBranches", "allBranches"}); err != nil {
 		return err

pkg/gocui/gui.go

@@ -743,6 +743,12 @@ func (g *Gui) DetectedColorScheme() DetectedColorScheme {
 	return g.colorScheme
 }
 
+// Terminal returns the name and version that the terminal reported at
+// startup. Both are empty if it didn't report them.
+func (g *Gui) Terminal() (string, string) {
+	return g.screen.Terminal()
+}
+
 // SetColorSchemeChangeHandler sets a function to call on the UI thread whenever
 // the terminal's colors change after startup.
 func (g *Gui) SetColorSchemeChangeHandler(handler func(DetectedColorScheme) error) {

pkg/gui/context/local_commits_context.go

@@ -12,6 +12,7 @@ import (
 	"github.com/jesseduffield/lazygit/pkg/config"
 	"github.com/jesseduffield/lazygit/pkg/gocui"
 	"github.com/jesseduffield/lazygit/pkg/gui/presentation"
+	"github.com/jesseduffield/lazygit/pkg/gui/presentation/graph"
 	"github.com/jesseduffield/lazygit/pkg/gui/style"
 	"github.com/jesseduffield/lazygit/pkg/gui/types"
 	"github.com/samber/lo"
@@ -132,6 +133,7 @@ func NewLocalCommitsContext(c *ContextCommon) *LocalCommitsContext {
 			startIdx,
 			endIdx,
 			shouldShowGraph(c),
+			commitGraphSymbolSet(c),
 			c.Model().BisectInfo,
 		)
 	}
@@ -408,6 +410,18 @@ func shouldShowGraph(c *ContextCommon) bool {
 	return false
 }
 
+func commitGraphSymbolSet(c *ContextCommon) graph.SymbolSet {
+	switch c.UserConfig().Gui.CommitGraphStyle {
+	case "detailed":
+		return graph.BranchDrawingSymbols
+	case "auto":
+		if graph.TerminalDrawsBranchDrawingSymbols(c.GocuiGui().Terminal()) {
+			return graph.BranchDrawingSymbols
+		}
+	}
+	return graph.BoxDrawingSymbols
+}
+
 func searchModelCommits(caseSensitive bool, commits []*models.Commit, columnPositions []int,
 	modelToViewIndex func(int) int, searchStr string,
 ) []gocui.SearchPosition {

pkg/gui/context/sub_commits_context.go

@@ -97,6 +97,7 @@ func NewSubCommitsContext(
 			startIdx,
 			endIdx,
 			shouldShowGraph(c),
+			commitGraphSymbolSet(c),
 			git_commands.NewNullBisectInfo(),
 		)
 	}

pkg/gui/gui.go

@@ -953,6 +953,8 @@ func (gui *Gui) Run(startArgs appTypes.StartArgs) error {
 
 	g.ErrorHandler = gui.PopupHandler.ErrorHandler
 
+	terminalName, terminalVersion := g.Terminal()
+	gui.c.Log.Infof("Terminal: %s %s", terminalName, terminalVersion)
 	gui.c.Log.Infof("Terminal color scheme: %s", g.DetectedColorScheme())
 	g.SetColorSchemeChangeHandler(func(colorScheme gocui.DetectedColorScheme) error {
 		gui.c.Log.Infof("Terminal color scheme changed: %s", colorScheme)

pkg/gui/presentation/commits.go

@@ -59,6 +59,7 @@ func GetCommitListDisplayStrings(
 	startIdx int,
 	endIdx int,
 	showGraph bool,
+	graphSymbolSet graph.SymbolSet,
 	bisectInfo *git_commands.BisectInfo,
 ) [][]string {
 	mutex.Lock()
@@ -107,6 +108,7 @@ func GetCommitListDisplayStrings(
 						graphPipeSets,
 						graphCommits,
 						selectedCommitHashPtr,
+						graphSymbolSet,
 					)
 					allGraphLines = append(allGraphLines, graphLines...)
 				}
@@ -124,6 +126,7 @@ func GetCommitListDisplayStrings(
 						graphPipeSets,
 						graphCommits,
 						selectedCommitHashPtr,
+						graphSymbolSet,
 					)
 					allGraphLines = append(allGraphLines, graphLines...)
 				}
@@ -145,6 +148,7 @@ func GetCommitListDisplayStrings(
 				graphPipeSets,
 				graphCommits,
 				selectedCommitHashPtr,
+				graphSymbolSet,
 			)
 			getGraphLine = func(idx int) string {
 				if idx >= graphOffset {

pkg/gui/presentation/commits_test.go

@@ -611,6 +611,7 @@ func TestGetCommitListDisplayStrings(t *testing.T) {
 					s.startIdx,
 					s.endIdx,
 					s.showGraph,
+					graph.BoxDrawingSymbols,
 					s.bisectInfo,
 				)
 
@@ -635,7 +636,7 @@ func TestGraphColorsFollowTheAuthorColors(t *testing.T) {
 		models.NewCommit(hashPool, models.NewCommitOpts{Hash: "authorcolors2", AuthorName: "Jane Doe"}),
 	}
 	renderGraph := func() string {
-		return strings.Join(graph.RenderAux(loadPipesets(commits), commits, nil), "\n")
+		return strings.Join(graph.RenderAux(loadPipesets(commits), commits, nil, graph.BoxDrawingSymbols), "\n")
 	}
 
 	authors.SetCustomAuthors(map[string]string{"Jane Doe": "red"})

pkg/gui/presentation/graph/branch_drawing.go

@@ -0,0 +1,132 @@
+package graph
+
+import (
+	"slices"
+	"strconv"
+	"strings"
+)
+
+// The branch drawing symbols are characters in the Unicode Private Use Area
+// (U+F5D0 to U+F60D) for drawing git graphs, introduced by kitty in
+// https://github.com/kovidgoyal/kitty/pull/7681. Unlike the box drawing
+// characters, they can show how the lines in a cell connect. For example, there
+// is a symbol for a cell in which a line from above bends to the left and a
+// line from the left bends down.
+
+const branchDrawingHorizontal = "\uf5d0"
+
+// The lines in a cell that isn't a commit
+type lineCourses struct {
+	up, down   verticalLine
+	horizontal bool
+}
+
+var branchDrawingConnections = map[lineCourses]string{
+	{}:                 " ",
+	{horizontal: true}: branchDrawingHorizontal,
+	// A horizontal line passing behind a vertical one only shows in the
+	// neighbouring cells
+	{up: straightLine, down: straightLine}:                   "\uf5d1", // │
+	{up: straightLine, down: straightLine, horizontal: true}: "\uf5d1", // │
+	{up: lineToLeft}:                                       "\uf5d9", // ╯
+	{up: lineToRight}:                                      "\uf5d8", // ╰
+	{down: lineToLeft}:                                     "\uf5d7", // ╮
+	{down: lineToRight}:                                    "\uf5d6", // ╭
+	{up: lineToLeft, horizontal: true}:                     "\uf5e3", // ╯ on ─
+	{up: lineToRight, horizontal: true}:                    "\uf5e4", // ╰ on ─
+	{down: lineToLeft, horizontal: true}:                   "\uf5e0", // ╮ on ─
+	{down: lineToRight, horizontal: true}:                  "\uf5e1", // ╭ on ─
+	{up: lineToLeft, down: lineToLeft}:                     "\uf5df", // ╯ and ╮
+	{up: lineToRight, down: lineToRight}:                   "\uf5dc", // ╰ and ╭
+	{up: lineToLeft, down: lineToLeft, horizontal: true}:   "\uf5e8", // ╯ and ╮ on ─
+	{up: lineToRight, down: lineToRight, horizontal: true}: "\uf5e9", // ╰ and ╭ on ─
+	{up: lineToLeft, down: lineToRight, horizontal: true}:  "\uf5ec", // ╯ and ╭ on ─
+	{up: lineToRight, down: lineToLeft, horizontal: true}:  "\uf5ed", // ╰ and ╮ on ─
+}
+
+// The edges of a commit's cell that its lines touch
+type commitEdges struct {
+	up, down, left, right bool
+}
+
+// Commits are drawn as hollow circles, merge commits as filled ones. Both
+// connect to the lines at the given edges.
+var branchDrawingCommitSymbols = map[commitEdges]struct{ commit, merge string }{
+	{}:                                    {"\uf5ef", "\uf5ee"},
+	{right: true}:                         {"\uf5f1", "\uf5f0"},
+	{left: true}:                          {"\uf5f3", "\uf5f2"},
+	{left: true, right: true}:             {"\uf5f5", "\uf5f4"},
+	{down: true}:                          {"\uf5f7", "\uf5f6"},
+	{up: true}:                            {"\uf5f9", "\uf5f8"},
+	{up: true, down: true}:                {"\uf5fb", "\uf5fa"},
+	{down: true, right: true}:             {"\uf5fd", "\uf5fc"},
+	{down: true, left: true}:              {"\uf5ff", "\uf5fe"},
+	{up: true, right: true}:               {"\uf601", "\uf600"},
+	{up: true, left: true}:                {"\uf603", "\uf602"},
+	{up: true, down: true, right: true}:   {"\uf605", "\uf604"},
+	{up: true, down: true, left: true}:    {"\uf607", "\uf606"},
+	{down: true, left: true, right: true}: {"\uf609", "\uf608"},
+	{up: true, left: true, right: true}:   {"\uf60b", "\uf60a"},
+	{up: true, down: true, left: true, right: true}: {"\uf60d", "\uf60c"},
+}
+
+func (cell *Cell) branchDrawingChars() (string, string) {
+	second := " "
+	if cell.right {
+		second = branchDrawingHorizontal
+	}
+
+	switch cell.cellType {
+	case COMMIT, MERGE:
+		symbols := branchDrawingCommitSymbols[commitEdges{
+			up:    cell.up != noLine,
+			down:  cell.down != noLine,
+			left:  cell.left,
+			right: cell.right,
+		}]
+		if cell.cellType == MERGE {
+			return symbols.merge, second
+		}
+		return symbols.commit, second
+	default:
+		if cell.horizontalOnTop {
+			return branchDrawingHorizontal, second
+		}
+		if first, ok := branchDrawingConnections[lineCourses{cell.up, cell.down, cell.horizontal}]; ok {
+			return first, second
+		}
+		// There is no symbol for lines that the layout of the graph never
+		// produces, such as a lone half of a line
+		first, _ := getBoxDrawingChars(cell.up != noLine, cell.down != noLine, cell.left, cell.right)
+		return first, second
+	}
+}
+
+// The terminals that draw the branch drawing symbols themselves, with the
+// first version that draws all of them
+var terminalsWithBranchDrawingSymbols = map[string][]int{
+	"kitty":   {0, 36, 2},
+	"ghostty": {1, 0, 0},
+}
+
+// TerminalDrawsBranchDrawingSymbols says whether a terminal is known to draw
+// the branch drawing symbols itself, given the name and version it reports
+func TerminalDrawsBranchDrawingSymbols(name, version string) bool {
+	minVersion, ok := terminalsWithBranchDrawingSymbols[strings.ToLower(name)]
+	return ok && slices.Compare(versionNumbers(version), minVersion) >= 0
+}
+
+// The numbers at the start of the dot-separated parts of a version, e.g.
+// [1 3 0] for "1.3.0-dev+abc"
+func versionNumbers(version string) []int {
+	var numbers []int
+	for part := range strings.SplitSeq(version, ".") {
+		digits := part[:len(part)-len(strings.TrimLeft(part, "0123456789"))]
+		number, err := strconv.Atoi(digits)
+		if err != nil {
+			break
+		}
+		numbers = append(numbers, number)
+	}
+	return numbers
+}

pkg/gui/presentation/graph/branch_drawing_test.go

@@ -0,0 +1,33 @@
+package graph
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTerminalDrawsBranchDrawingSymbols(t *testing.T) {
+	tests := []struct {
+		name     string
+		version  string
+		expected bool
+	}{
+		{name: "kitty", version: "0.36.1", expected: false},
+		{name: "kitty", version: "0.36.2", expected: true},
+		{name: "kitty", version: "0.44.0", expected: true},
+		{name: "ghostty", version: "0.9.0", expected: false},
+		{name: "ghostty", version: "1.0.0", expected: true},
+		{name: "ghostty", version: "1.3.0-main+0123abcd", expected: true},
+		{name: "WezTerm", version: "20250601-102030-89abcdef", expected: false},
+		{name: "tmux", version: "3.5a", expected: false},
+		{name: "iTerm2", version: "3.6.4", expected: false},
+		{name: "kitty", version: "", expected: false},
+		{name: "", version: "", expected: false},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name+" "+test.version, func(t *testing.T) {
+			assert.Equal(t, test.expected, TerminalDrawsBranchDrawingSymbols(test.name, test.version))
+		})
+	}
+}

pkg/gui/presentation/graph/cell.go

@@ -13,6 +13,14 @@ const (
 	CommitSymbol = '○'
 )
 
+// The characters that the commit graph is drawn with
+type SymbolSet uint8
+
+const (
+	BoxDrawingSymbols SymbolSet = iota
+	BranchDrawingSymbols
+)
+
 type cellType int
 
 const (
@@ -21,25 +29,40 @@ const (
 	MERGE
 )
 
+// How a line that touches the top or bottom edge of a cell runs within it
+type verticalLine uint8
+
+const (
+	noLine verticalLine = iota
+	// On to the opposite edge, or into the commit symbol
+	straightLine
+	// Bends towards the left edge
+	lineToLeft
+	// Bends towards the right edge
+	lineToRight
+)
+
 type Cell struct {
-	up, down, left, right bool
-	cellType              cellType
-	rightStyle            *style.TextStyle
-	style                 *style.TextStyle
+	// The lines that touch the top and bottom edges
+	up, down verticalLine
+	// Whether lines touch the left and right edges
+	left, right bool
+	// Whether a line passes through from the left edge to the right edge
+	horizontal bool
+	// Whether that line is drawn over the vertical line that it crosses
+	horizontalOnTop bool
+	cellType        cellType
+	rightStyle      *style.TextStyle
+	style           *style.TextStyle
 }
 
-func (cell *Cell) render(writer io.StringWriter) {
-	up, down, left, right := cell.up, cell.down, cell.left, cell.right
-
-	first, second := getBoxDrawingChars(up, down, left, right)
-	var adjustedFirst string
-	switch cell.cellType {
-	case CONNECTION:
-		adjustedFirst = first
-	case COMMIT:
-		adjustedFirst = string(CommitSymbol)
-	case MERGE:
-		adjustedFirst = string(MergeSymbol)
+func (cell *Cell) render(writer io.StringWriter, symbolSet SymbolSet) {
+	var first, second string
+	switch symbolSet {
+	case BoxDrawingSymbols:
+		first, second = cell.boxDrawingChars()
+	case BranchDrawingSymbols:
+		first, second = cell.branchDrawingChars()
 	}
 
 	var rightStyle *style.TextStyle
@@ -59,10 +82,22 @@ func (cell *Cell) render(writer io.StringWriter) {
 		styledSecondChar = cachedSprint(*rightStyle, second)
 	}
 
-	_, _ = writer.WriteString(cachedSprint(*cell.style, adjustedFirst))
+	_, _ = writer.WriteString(cachedSprint(*cell.style, first))
 	_, _ = writer.WriteString(styledSecondChar)
 }
 
+func (cell *Cell) boxDrawingChars() (string, string) {
+	first, second := getBoxDrawingChars(cell.up != noLine, cell.down != noLine, cell.left, cell.right)
+	switch cell.cellType {
+	case COMMIT:
+		return string(CommitSymbol), second
+	case MERGE:
+		return string(MergeSymbol), second
+	default:
+		return first, second
+	}
+}
+
 type rgbCacheKey struct {
 	*color.RGBStyle
 	str string
@@ -98,34 +133,35 @@ func cachedSprint(style style.TextStyle, str string) string {
 }
 
 func (cell *Cell) reset() {
-	cell.up = false
-	cell.down = false
+	cell.up = noLine
+	cell.down = noLine
 	cell.left = false
 	cell.right = false
+	cell.horizontal = false
+	cell.horizontalOnTop = false
 }
 
-func (cell *Cell) setUp(style *style.TextStyle) *Cell {
-	cell.up = true
+func (cell *Cell) setUp(style *style.TextStyle, line verticalLine) *Cell {
+	cell.up = line
 	cell.style = style
 	return cell
 }
 
-func (cell *Cell) setDown(style *style.TextStyle) *Cell {
-	cell.down = true
+func (cell *Cell) setDown(style *style.TextStyle, line verticalLine) *Cell {
+	cell.down = line
 	cell.style = style
 	return cell
 }
 
 func (cell *Cell) setLeft(style *style.TextStyle) *Cell {
 	cell.left = true
-	if !cell.up && !cell.down {
+	if cell.up == noLine && cell.down == noLine {
 		// vertical trumps left
 		cell.style = style
 	}
 	return cell
 }
 
-//nolint:unparam
 func (cell *Cell) setRight(style *style.TextStyle, override bool) *Cell {
 	cell.right = true
 	if cell.rightStyle == nil || override {
@@ -134,6 +170,11 @@ func (cell *Cell) setRight(style *style.TextStyle, override bool) *Cell {
 	return cell
 }
 
+func (cell *Cell) setHorizontal(style *style.TextStyle, overrideRightStyle bool) *Cell {
+	cell.horizontal = true
+	return cell.setLeft(style).setRight(style, overrideRightStyle)
+}
+
 func (cell *Cell) setStyle(style *style.TextStyle) *Cell {
 	cell.style = style
 	return cell

pkg/gui/presentation/graph/graph.go

@@ -45,13 +45,13 @@ func (self Pipe) right() int16 {
 	return max(self.fromPos, self.toPos)
 }
 
-func RenderCommitGraph(commits []*models.Commit, selectedCommitHashPtr *string, getStyle func(c *models.Commit) *style.TextStyle) []string {
+func RenderCommitGraph(commits []*models.Commit, selectedCommitHashPtr *string, getStyle func(c *models.Commit) *style.TextStyle, symbolSet SymbolSet) []string {
 	pipeSets := GetPipeSets(commits, getStyle)
 	if len(pipeSets) == 0 {
 		return nil
 	}
 
-	lines := RenderAux(pipeSets, commits, selectedCommitHashPtr)
+	lines := RenderAux(pipeSets, commits, selectedCommitHashPtr, symbolSet)
 
 	return lines
 }
@@ -69,7 +69,7 @@ func GetPipeSets(commits []*models.Commit, getStyle func(c *models.Commit) *styl
 	})
 }
 
-func RenderAux(pipeSets [][]Pipe, commits []*models.Commit, selectedCommitHashPtr *string) []string {
+func RenderAux(pipeSets [][]Pipe, commits []*models.Commit, selectedCommitHashPtr *string, symbolSet SymbolSet) []string {
 	maxProcs := runtime.GOMAXPROCS(0)
 
 	// splitting up the rendering of the graph into multiple goroutines allows us to render the graph in parallel
@@ -93,7 +93,7 @@ func RenderAux(pipeSets [][]Pipe, commits []*models.Commit, selectedCommitHashPt
 				if k > 0 {
 					prevCommit = commits[k-1]
 				}
-				line := renderPipeSet(pipeSet, selectedCommitHashPtr, prevCommit)
+				line := renderPipeSet(pipeSet, selectedCommitHashPtr, prevCommit, symbolSet)
 				innerLines = append(innerLines, line)
 			}
 			chunks[i] = innerLines
@@ -276,6 +276,7 @@ func renderPipeSet(
 	pipes []Pipe,
 	selectedCommitHashPtr *string,
 	prevCommit *models.Commit,
+	symbolSet SymbolSet,
 ) string {
 	maxPos := int16(0)
 	commitPos := int16(0)
@@ -304,17 +305,17 @@ func renderPipeSet(
 
 		if left != right {
 			for i := left + 1; i < right; i++ {
-				cells[i].setLeft(style).setRight(style, overrideRightStyle)
+				cells[i].setHorizontal(style, overrideRightStyle)
 			}
 			cells[left].setRight(style, overrideRightStyle)
 			cells[right].setLeft(style)
 		}
 
 		if pipe.kind == STARTS || pipe.kind == CONTINUES {
-			cells[pipe.toPos].setDown(style)
+			cells[pipe.toPos].setDown(style, lineTowards(pipe.toPos, pipe.fromPos))
 		}
 		if pipe.kind == TERMINATES || pipe.kind == CONTINUES {
-			cells[pipe.fromPos].setUp(style)
+			cells[pipe.fromPos].setUp(style, lineTowards(pipe.fromPos, pipe.toPos))
 		}
 	}
 
@@ -343,14 +344,31 @@ func renderPipeSet(
 	}
 
 	for _, pipe := range nonSelectedPipes {
-		if pipe.kind != STARTS && !(pipe.kind == TERMINATES && pipe.fromPos == commitPos && pipe.toPos == commitPos) {
-			renderPipe(&pipe, pipe.style, false)
+		if pipe.kind == STARTS {
+			continue
 		}
+		if pipe.kind == TERMINATES && pipe.fromPos == commitPos && pipe.toPos == commitPos {
+			// Record this line without drawing it, so that the commit symbol
+			// keeps the style of the commit itself. The branch drawing commit
+			// symbols connect to it. The pipe from above the first commit
+			// doesn't come from a commit, so it has no line.
+			if !equalHashes(pipe.fromHash, &StartCommitHash) {
+				cells[commitPos].up = straightLine
+			}
+			continue
+		}
+		renderPipe(&pipe, pipe.style, false)
 	}
 
-	for _, pipe := range selectedPipes {
-		for i := pipe.left(); i <= pipe.right(); i++ {
-			cells[i].reset()
+	// Box drawing characters can't show every combination of lines in a cell,
+	// so the cells that the selected commit's lines run through show only
+	// those lines. The branch drawing symbols can, so they keep the other
+	// lines too.
+	if symbolSet == BoxDrawingSymbols {
+		for _, pipe := range selectedPipes {
+			for i := pipe.left(); i <= pipe.right(); i++ {
+				cells[i].reset()
+			}
 		}
 	}
 	for _, pipe := range selectedPipes {
@@ -360,6 +378,22 @@ func renderPipeSet(
 		}
 	}
 
+	// Where a line of the selected commit crosses the vertical line of another
+	// commit, draw it over that line, so that it reads as one line. The
+	// vertical line visibly continues above and below. A vertical line in a
+	// cell that doesn't have the highlight style belongs to another commit.
+	if symbolSet == BranchDrawingSymbols {
+		for _, pipe := range selectedPipes {
+			for i := pipe.left() + 1; i < pipe.right(); i++ {
+				cell := cells[i]
+				if cell.up == straightLine && cell.down == straightLine && cell.style != &highlightStyle {
+					cell.horizontalOnTop = true
+					cell.style = &highlightStyle
+				}
+			}
+		}
+	}
+
 	cType := COMMIT
 	if isMerge {
 		cType = MERGE
@@ -371,11 +405,24 @@ func renderPipeSet(
 	writer := &strings.Builder{}
 	writer.Grow(len(cells) * 2)
 	for _, cell := range cells {
-		cell.render(writer)
+		cell.render(writer, symbolSet)
 	}
 	return writer.String()
 }
 
+// The course of a line through the top or bottom edge of the cell at pos,
+// given the column of the pipe's other end
+func lineTowards(pos, otherPos int16) verticalLine {
+	switch {
+	case otherPos < pos:
+		return lineToLeft
+	case otherPos > pos:
+		return lineToRight
+	default:
+		return straightLine
+	}
+}
+
 func equalHashes(a, b *string) bool {
 	// if our selectedCommitHashPtr is nil, there is no selected commit
 	if a == nil || b == nil {

pkg/gui/presentation/graph/graph_test.go

@@ -224,7 +224,7 @@ func TestRenderCommitGraph(t *testing.T) {
 			getStyle := func(c *models.Commit) *style.TextStyle { return &style.FgDefault }
 			commits := lo.Map(test.commitOpts,
 				func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(hashPool, opts) })
-			lines := RenderCommitGraph(commits, hashPool.Add("blah"), getStyle)
+			lines := RenderCommitGraph(commits, hashPool.Add("blah"), getStyle, BoxDrawingSymbols)
 
 			trimmedExpectedOutput := ""
 			for line := range strings.SplitSeq(strings.TrimPrefix(test.expectedOutput, "\n"), "\n") {
@@ -247,6 +247,325 @@ func TestRenderCommitGraph(t *testing.T) {
 	}
 }
 
+// Box drawing look-alikes for the branch drawing symbols, so that the expected
+// output in tests is readable. The box drawing characters of the graph never
+// use ┤ and ┼; here they stand for the symbols that have two bends. Commit
+// symbols are shown as ○ and ◎, whichever lines they connect to.
+var branchDrawingLookAlikes = func() map[rune]rune {
+	lookAlikes := map[rune]rune{
+		'\uf5d0': '─',
+		'\uf5d1': '│',
+		'\uf5d6': '╭',
+		'\uf5d7': '╮',
+		'\uf5d8': '╰',
+		'\uf5d9': '╯',
+		'\uf5e0': '┬', // ╮ on ─
+		'\uf5e3': '┴', // ╯ on ─
+		'\uf5df': '┤', // ╯ and ╮
+		'\uf5e8': '┼', // ╯ and ╮ on ─
+	}
+	for _, symbols := range branchDrawingCommitSymbols {
+		lookAlikes[[]rune(symbols.commit)[0]] = CommitSymbol
+		lookAlikes[[]rune(symbols.merge)[0]] = MergeSymbol
+	}
+	return lookAlikes
+}()
+
+func TestRenderCommitGraphWithBranchDrawingSymbols(t *testing.T) {
+	tests := []struct {
+		name           string
+		commitOpts     []models.NewCommitOpts
+		selectedHash   string
+		expectedOutput string
+	}{
+		{
+			name: "branch forked off a merge commit",
+			commitOpts: []models.NewCommitOpts{
+				{Hash: "1", Parents: []string{"2", "3"}},
+				{Hash: "3", Parents: []string{"5"}},
+				{Hash: "2", Parents: []string{"5", "4"}},
+				{Hash: "4", Parents: []string{"5"}},
+				{Hash: "5", Parents: []string{"6", "7"}},
+				{Hash: "7", Parents: []string{"6"}},
+				{Hash: "6", Parents: []string{"8"}},
+			},
+			expectedOutput: `
+			1 ◎─╮
+			3 │ ○
+			2 ◎─│─╮
+			4 │ │ ○
+			5 ◎─┼─╯
+			7 │ ○
+			6 ○─╯`,
+		},
+		{
+			name: "branch forked off a merge commit, with the merge commit selected",
+			commitOpts: []models.NewCommitOpts{
+				{Hash: "1", Parents: []string{"2", "3"}},
+				{Hash: "3", Parents: []string{"5"}},
+				{Hash: "2", Parents: []string{"5", "4"}},
+				{Hash: "4", Parents: []string{"5"}},
+				{Hash: "5", Parents: []string{"6", "7"}},
+				{Hash: "7", Parents: []string{"6"}},
+				{Hash: "6", Parents: []string{"8"}},
+			},
+			selectedHash: "5",
+			expectedOutput: `
+			1 ◎─╮
+			3 │ ○
+			2 ◎─│─╮
+			4 │ │ ○
+			5 ◎─┼─╯
+			7 │ ○
+			6 ○─╯`,
+		},
+		{
+			name: "branch forked off a merge commit, with the merge commit above it selected",
+			commitOpts: []models.NewCommitOpts{
+				{Hash: "1", Parents: []string{"2", "3"}},
+				{Hash: "3", Parents: []string{"5"}},
+				{Hash: "2", Parents: []string{"5", "4"}},
+				{Hash: "4", Parents: []string{"5"}},
+				{Hash: "5", Parents: []string{"6", "7"}},
+				{Hash: "7", Parents: []string{"6"}},
+				{Hash: "6", Parents: []string{"8"}},
+			},
+			selectedHash: "2",
+			expectedOutput: `
+			1 ◎─╮
+			3 │ ○
+			2 ◎───╮
+			4 │ │ ○
+			5 ◎─┼─╯
+			7 │ ○
+			6 ○─╯`,
+		},
+		{
+			name: "branch forked off a merge commit, with no line passing through",
+			commitOpts: []models.NewCommitOpts{
+				{Hash: "1", Parents: []string{"2", "3"}},
+				{Hash: "3", Parents: []string{"2"}},
+				{Hash: "2", Parents: []string{"4", "5"}},
+				{Hash: "4", Parents: []string{"6", "7"}},
+				{Hash: "6", Parents: []string{"8"}},
+			},
+			expectedOutput: `
+			1 ◎─╮
+			3 │ ○
+			2 ◎─┤
+			4 ◎─│─╮
+			6 ○ │ │`,
+		},
+		{
+			name: "several lines ending in a commit",
+			commitOpts: []models.NewCommitOpts{
+				{Hash: "1", Parents: []string{"2"}},
+				{Hash: "2", Parents: []string{"3", "4"}},
+				{Hash: "3", Parents: []string{"5", "4"}},
+				{Hash: "5", Parents: []string{"7", "8"}},
+				{Hash: "7", Parents: []string{"4", "A"}},
+				{Hash: "4", Parents: []string{"B"}},
+				{Hash: "B", Parents: []string{"C"}},
+			},
+			expectedOutput: `
+			1 ○
+			2 ◎─╮
+			3 ◎─│─╮
+			5 ◎─│─│─╮
+			7 ◎─│─│─│─╮
+			4 ○─┴─╯ │ │
+			B ○ ╭───╯ │`,
+		},
+	}
+
+	oldColorLevel := color.ForceSetColorLevel(terminfo.ColorLevelMillions)
+	defer color.ForceSetColorLevel(oldColorLevel)
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			hashPool := &utils.StringPool{}
+
+			getStyle := func(c *models.Commit) *style.TextStyle { return &style.FgDefault }
+			commits := lo.Map(test.commitOpts,
+				func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(hashPool, opts) })
+			lines := RenderCommitGraph(commits, hashPool.Add(test.selectedHash), getStyle, BranchDrawingSymbols)
+
+			trimmedExpectedOutput := ""
+			for line := range strings.SplitSeq(strings.TrimPrefix(test.expectedOutput, "\n"), "\n") {
+				trimmedExpectedOutput += strings.TrimSpace(line) + "\n"
+			}
+
+			output := ""
+			for i, line := range lines {
+				lookAlikes := strings.Map(func(r rune) rune {
+					return lo.ValueOr(branchDrawingLookAlikes, r, r)
+				}, utils.Decolorise(line))
+				output += strings.TrimSpace(test.commitOpts[i].Hash+" "+lookAlikes) + "\n"
+			}
+
+			assert.Equal(t, trimmedExpectedOutput, output)
+		})
+	}
+}
+
+func TestRenderPipeSetWithBranchDrawingSymbols(t *testing.T) {
+	cyan := style.FgCyan
+	red := style.FgRed
+	green := style.FgGreen
+	yellow := style.FgYellow
+	magenta := style.FgMagenta
+	nothing := style.Nothing
+
+	hashPool := &utils.StringPool{}
+	pool := func(s string) *string { return hashPool.Add(s) }
+
+	tests := []struct {
+		name           string
+		pipes          []Pipe
+		prevCommit     *models.Commit
+		expectedStr    string
+		expectedStyles []style.TextStyle
+	}{
+		{
+			name: "commit with lines above and below",
+			pipes: []Pipe{
+				{fromPos: 0, toPos: 0, fromHash: pool("a"), toHash: pool("b"), kind: TERMINATES, style: &cyan},
+				{fromPos: 0, toPos: 0, fromHash: pool("b"), toHash: pool("c"), kind: STARTS, style: &green},
+			},
+			prevCommit:     models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a"}),
+			expectedStr:    "\uf5fb", // ○ with lines up and down
+			expectedStyles: []style.TextStyle{green},
+		},
+		{
+			name: "first commit",
+			pipes: []Pipe{
+				{fromPos: 0, toPos: 0, fromHash: &StartCommitHash, toHash: pool("b"), kind: TERMINATES, style: &cyan},
+				{fromPos: 0, toPos: 0, fromHash: pool("b"), toHash: pool("c"), kind: STARTS, style: &green},
+			},
+			expectedStr:    "\uf5f7", // ○ with a line down
+			expectedStyles: []style.TextStyle{green},
+		},
+		{
+			name: "selected commit",
+			pipes: []Pipe{
+				{fromPos: 0, toPos: 0, fromHash: pool("a"), toHash: pool("selected"), kind: TERMINATES, style: &cyan},
+				{fromPos: 0, toPos: 0, fromHash: pool("selected"), toHash: pool("c"), kind: STARTS, style: &green},
+			},
+			prevCommit:     models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a"}),
+			expectedStr:    "\uf5fb", // ○ with lines up and down
+			expectedStyles: []style.TextStyle{highlightStyle},
+		},
+		{
+			name: "commit whose previous commit is selected and is a merge commit",
+			pipes: []Pipe{
+				{fromPos: 0, toPos: 0, fromHash: pool("selected"), toHash: pool("a2"), kind: TERMINATES, style: &red},
+				{fromPos: 0, toPos: 0, fromHash: pool("a2"), toHash: pool("a3"), kind: STARTS, style: &green},
+				{fromPos: 1, toPos: 1, fromHash: pool("selected"), toHash: pool("b3"), kind: CONTINUES, style: &red},
+			},
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "selected"}),
+			expectedStr: "\uf5fb \uf5d1", // ○ with lines up and down, │
+			expectedStyles: []style.TextStyle{
+				highlightStyle, nothing, highlightStyle,
+			},
+		},
+		{
+			name: "merge commit that a branch forks off",
+			pipes: []Pipe{
+				{fromPos: 0, toPos: 0, fromHash: pool("a1"), toHash: pool("a2"), kind: TERMINATES, style: &red},
+				{fromPos: 1, toPos: 0, fromHash: pool("b1"), toHash: pool("a2"), kind: TERMINATES, style: &magenta},
+				{fromPos: 2, toPos: 0, fromHash: pool("c1"), toHash: pool("a2"), kind: TERMINATES, style: &cyan},
+				{fromPos: 0, toPos: 0, fromHash: pool("a2"), toHash: pool("a3"), kind: STARTS, style: &green},
+				{fromPos: 0, toPos: 1, fromHash: pool("a2"), toHash: pool("b3"), kind: STARTS, style: &green},
+			},
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a1"}),
+			expectedStr: "\uf604\uf5d0\uf5e8\uf5d0\uf5d9", // ◎ with lines up, down and right, ─, ╯ and ╮ on ─, ─, ╯
+			expectedStyles: []style.TextStyle{
+				green, green, magenta, cyan, cyan,
+			},
+		},
+		{
+			name: "merge commit that a branch forks off, with the branch's first commit selected",
+			pipes: []Pipe{
+				{fromPos: 0, toPos: 0, fromHash: pool("a1"), toHash: pool("a2"), kind: TERMINATES, style: &red},
+				{fromPos: 1, toPos: 0, fromHash: pool("selected"), toHash: pool("a2"), kind: TERMINATES, style: &magenta},
+				{fromPos: 2, toPos: 0, fromHash: pool("c1"), toHash: pool("a2"), kind: TERMINATES, style: &cyan},
+				{fromPos: 0, toPos: 0, fromHash: pool("a2"), toHash: pool("a3"), kind: STARTS, style: &green},
+				{fromPos: 0, toPos: 1, fromHash: pool("a2"), toHash: pool("b3"), kind: STARTS, style: &green},
+			},
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a1"}),
+			expectedStr: "\uf604\uf5d0\uf5e8\uf5d0\uf5d9", // ◎ with lines up, down and right, ─, ╯ and ╮ on ─, ─, ╯
+			expectedStyles: []style.TextStyle{
+				highlightStyle, highlightStyle, highlightStyle, cyan, cyan,
+			},
+		},
+		{
+			name: "line of the selected commit crossing another line",
+			pipes: []Pipe{
+				{fromPos: 0, toPos: 0, fromHash: pool("a1"), toHash: pool("selected"), kind: TERMINATES, style: &red},
+				{fromPos: 0, toPos: 0, fromHash: pool("selected"), toHash: pool("a3"), kind: STARTS, style: &yellow},
+				{fromPos: 1, toPos: 1, fromHash: pool("b1"), toHash: pool("b2"), kind: CONTINUES, style: &magenta},
+				{fromPos: 3, toPos: 0, fromHash: pool("e1"), toHash: pool("selected"), kind: TERMINATES, style: &green},
+				{fromPos: 0, toPos: 2, fromHash: pool("selected"), toHash: pool("c3"), kind: STARTS, style: &yellow},
+			},
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a1"}),
+			expectedStr: "\uf604\uf5d0\uf5d0\uf5d0\uf5e0\uf5d0\uf5d9", // ◎ with lines up, down and right, ─, ─, ─, ╮ on ─, ─, ╯
+			expectedStyles: []style.TextStyle{
+				highlightStyle, highlightStyle, highlightStyle, highlightStyle, highlightStyle, green, green,
+			},
+		},
+		{
+			name: "line of the selected commit passing through a cell in which other lines bend",
+			pipes: []Pipe{
+				{fromPos: 0, toPos: 0, fromHash: pool("a1"), toHash: pool("a2"), kind: TERMINATES, style: &red},
+				{fromPos: 1, toPos: 0, fromHash: pool("b1"), toHash: pool("a2"), kind: TERMINATES, style: &magenta},
+				{fromPos: 2, toPos: 0, fromHash: pool("selected"), toHash: pool("a2"), kind: TERMINATES, style: &cyan},
+				{fromPos: 0, toPos: 0, fromHash: pool("a2"), toHash: pool("a3"), kind: STARTS, style: &green},
+				{fromPos: 0, toPos: 1, fromHash: pool("a2"), toHash: pool("b3"), kind: STARTS, style: &green},
+			},
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a1"}),
+			expectedStr: "\uf604\uf5d0\uf5e8\uf5d0\uf5d9", // ◎ with lines up, down and right, ─, ╯ and ╮ on ─, ─, ╯
+			expectedStyles: []style.TextStyle{
+				highlightStyle, highlightStyle, magenta, highlightStyle, highlightStyle,
+			},
+		},
+	}
+
+	oldColorLevel := color.ForceSetColorLevel(terminfo.ColorLevelMillions)
+	defer color.ForceSetColorLevel(oldColorLevel)
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			actualStr := renderPipeSet(test.pipes, pool("selected"), test.prevCommit, BranchDrawingSymbols)
+			if len([]rune(test.expectedStr)) != len(test.expectedStyles) {
+				t.Fatalf("Error in test setup: you have %d characters in the expected output but have specified %d styles", len([]rune(test.expectedStr)), len(test.expectedStyles))
+			}
+			expectedStr := ""
+			for i, char := range []rune(test.expectedStr) {
+				expectedStr += test.expectedStyles[i].Sprint(string(char))
+			}
+			expectedStr += " "
+
+			assert.Equal(t, expectedStr, actualStr)
+		})
+	}
+}
+
+func TestBranchDrawingSymbolsCoverAllCells(t *testing.T) {
+	hashPool := &utils.StringPool{}
+	commits := generateCommits(hashPool, 1000)
+	getStyle := func(commit *models.Commit) *style.TextStyle { return &style.FgDefault }
+	isBoxDrawingChar := func(r rune) bool { return r >= '\u2500' && r <= '\u257f' }
+
+	for _, selectedHash := range []string{"none", commits[10].Hash(), commits[500].Hash()} {
+		lines := RenderCommitGraph(commits, hashPool.Add(selectedHash), getStyle, BranchDrawingSymbols)
+		for i, line := range lines {
+			line = utils.Decolorise(line)
+			assert.False(t, strings.ContainsFunc(line, isBoxDrawingChar),
+				"row %d falls back to box drawing characters: %q", i, line)
+		}
+	}
+}
+
 func TestRenderPipeSet(t *testing.T) {
 	cyan := style.FgCyan
 	red := style.FgRed
@@ -462,7 +781,7 @@ func TestRenderPipeSet(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			actualStr := renderPipeSet(test.pipes, pool("selected"), test.prevCommit)
+			actualStr := renderPipeSet(test.pipes, pool("selected"), test.prevCommit, BoxDrawingSymbols)
 			t.Log("actual cells:")
 			t.Log(actualStr)
 			expectedStr := ""
@@ -540,8 +859,8 @@ func TestGetNextPipes(t *testing.T) {
 		getStyle := func(c *models.Commit) *style.TextStyle { return &style.FgDefault }
 		pipes := getNextPipes(test.prevPipes, test.commit, getStyle)
 		// rendering cells so that it's easier to see what went wrong
-		actualStr := renderPipeSet(pipes, pool("selected"), nil)
-		expectedStr := renderPipeSet(test.expected, pool("selected"), nil)
+		actualStr := renderPipeSet(pipes, pool("selected"), nil, BoxDrawingSymbols)
+		expectedStr := renderPipeSet(test.expected, pool("selected"), nil, BoxDrawingSymbols)
 		t.Log("expected cells:")
 		t.Log(expectedStr)
 		t.Log("actual cells:")
@@ -562,7 +881,7 @@ func BenchmarkRenderCommitGraph(b *testing.B) {
 	}
 	b.ResetTimer()
 	for b.Loop() {
-		RenderCommitGraph(commits, hashPool.Add("selected"), getStyle)
+		RenderCommitGraph(commits, hashPool.Add("selected"), getStyle, BoxDrawingSymbols)
 	}
 }
 

schema-master/config.json

@@ -1221,6 +1221,16 @@
           "description": "If true (default), file icons are shown in the file views. Only relevant if NerdFontsVersion is not empty.",
           "default": true
         },
+        "commitGraphStyle": {
+          "type": "string",
+          "enum": [
+            "auto",
+            "classic",
+            "detailed"
+          ],
+          "description": "How the commit graph is drawn.\nOne of: 'auto' (default) | 'classic' | 'detailed'\n'detailed' connects the lines to the commit circles, and shows exactly where branches fork off and merge. It draws the graph with the git branch drawing symbols (U+F5D0 to U+F60D), so it needs a terminal that draws these itself: kitty, Ghostty, WezTerm (nightly builds), Contour, or VS Code's terminal with GPU acceleration. Other terminals need a font that contains them, such as https://github.com/rbong/flog-symbols.\n'auto' uses 'detailed' if lazygit recognizes the terminal as one that draws these symbols (kitty and Ghostty), and 'classic' otherwise.",
+          "default": "auto"
+        },
         "commitAuthorShortLength": {
           "type": "integer",
           "description": "Length of author name in (non-expanded) commits view. 2 means show initials only.",

test/default_test_config/config.yml

@@ -12,6 +12,9 @@ gui:
     - black
   # Not important in tests but it creates clutter in demos
   showRandomTip: false
+  # The expected output of the tests draws the commit graph with box drawing
+  # characters, whichever terminal a test runs in
+  commitGraphStyle: classic
   animateExplosion: false # takes too long
 git:
   # We don't want to run any periodic background git commands because it'll introduce race conditions and flakiness.