Improve the rendering of the commit graph for terminals that support it

docs-master/Config.md

@@ -301,6 +301,18 @@ 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.
@@ -922,6 +927,7 @@ 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

@@ -733,6 +733,12 @@ 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"
@@ -73,6 +74,7 @@ func NewLocalCommitsContext(c *ContextCommon) *LocalCommitsContext {
 			startIdx,
 			endIdx,
 			shouldShowGraph(c),
+			commitGraphSymbolSet(c),
 			c.Model().BisectInfo,
 		)
 	}
@@ -349,6 +351,18 @@ 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

@@ -75,6 +75,7 @@ func NewSubCommitsContext(
 			startIdx,
 			endIdx,
 			shouldShowGraph(c),
+			commitGraphSymbolSet(c),
 			git_commands.NewNullBisectInfo(),
 		)
 	}

pkg/gui/gui.go

@@ -934,6 +934,8 @@ 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))
+		})
+	}
+}