Use boolean field to control whether viewport is refreshed on line focus

Go really doesn't like us doing anything inheritance-y: it does not support open recursion meaning
it's really hard to re-use code. As such, here we're falling back to conditional logic.

This fixes an issue where our ListContextTrait was calling FocusLine which was intended to be
overridden by ViewportListContextTrait, but the subclassed function wasn't being called. I'm
not actually sure how this went wrong given that it was working fine in the past, but at any rate,
the new code is easy to follow.

pkg/gui/context/list_context_trait.go

@@ -13,8 +13,15 @@ type ListContextTrait struct {
 	c                 *ContextCommon
 	list              types.IList
 	getDisplayStrings func(startIdx int, length int) [][]string
-	// alignment for each column. If nil, the default is left alignment
+	// Alignment for each column. If nil, the default is left alignment
 	columnAlignments []utils.Alignment
+	// Some contexts, like the commit context, will highlight the path from the selected commit
+	// to its parents, because it's ambiguous otherwise. For these, we need to refresh the viewport
+	// so that we show the highlighted path.
+	// TODO: now that we allow scrolling, we should be smarter about what gets refreshed:
+	// we should find out exactly which lines are now part of the path and refresh those.
+	// We should also keep track of the previous path and refresh those lines too.
+	refreshViewportOnLineFocus bool
 }
 
 func (self *ListContextTrait) IsListContext() {}
@@ -24,9 +31,19 @@ func (self *ListContextTrait) GetList() types.IList {
 }
 
 func (self *ListContextTrait) FocusLine() {
-	// we need a way of knowing whether we've rendered to the view yet.
 	self.GetViewTrait().FocusPoint(self.list.GetSelectedLineIdx())
 	self.setFooter()
+
+	if self.refreshViewportOnLineFocus {
+		self.refreshViewport()
+	}
+}
+
+func (self *ListContextTrait) refreshViewport() {
+	startIdx, length := self.GetViewTrait().ViewPortYBounds()
+	displayStrings := self.getDisplayStrings(startIdx, length)
+	content := utils.RenderDisplayStrings(displayStrings, nil)
+	self.GetViewTrait().SetViewPortContent(content)
 }
 
 func (self *ListContextTrait) setFooter() {

pkg/gui/context/local_commits_context.go

@@ -11,7 +11,7 @@ import (
 
 type LocalCommitsContext struct {
 	*LocalCommitsViewModel
-	*ViewportListContextTrait
+	*ListContextTrait
 }
 
 var (
@@ -56,19 +56,18 @@ func NewLocalCommitsContext(c *ContextCommon) *LocalCommitsContext {
 
 	return &LocalCommitsContext{
 		LocalCommitsViewModel: viewModel,
-		ViewportListContextTrait: &ViewportListContextTrait{
-			ListContextTrait: &ListContextTrait{
-				Context: NewSimpleContext(NewBaseContext(NewBaseContextOpts{
-					View:       c.Views().Commits,
-					WindowName: "commits",
-					Key:        LOCAL_COMMITS_CONTEXT_KEY,
-					Kind:       types.SIDE_CONTEXT,
-					Focusable:  true,
-				})),
-				list:              viewModel,
-				getDisplayStrings: getDisplayStrings,
-				c:                 c,
-			},
+		ListContextTrait: &ListContextTrait{
+			Context: NewSimpleContext(NewBaseContext(NewBaseContextOpts{
+				View:       c.Views().Commits,
+				WindowName: "commits",
+				Key:        LOCAL_COMMITS_CONTEXT_KEY,
+				Kind:       types.SIDE_CONTEXT,
+				Focusable:  true,
+			})),
+			list:                       viewModel,
+			getDisplayStrings:          getDisplayStrings,
+			c:                          c,
+			refreshViewportOnLineFocus: true,
 		},
 	}
 }

pkg/gui/context/sub_commits_context.go

@@ -12,7 +12,7 @@ import (
 
 type SubCommitsContext struct {
 	*SubCommitsViewModel
-	*ViewportListContextTrait
+	*ListContextTrait
 	*DynamicTitleBuilder
 }
 
@@ -60,20 +60,19 @@ func NewSubCommitsContext(
 	return &SubCommitsContext{
 		SubCommitsViewModel: viewModel,
 		DynamicTitleBuilder: NewDynamicTitleBuilder(c.Tr.SubCommitsDynamicTitle),
-		ViewportListContextTrait: &ViewportListContextTrait{
-			ListContextTrait: &ListContextTrait{
-				Context: NewSimpleContext(NewBaseContext(NewBaseContextOpts{
-					View:       c.Views().SubCommits,
-					WindowName: "branches",
-					Key:        SUB_COMMITS_CONTEXT_KEY,
-					Kind:       types.SIDE_CONTEXT,
-					Focusable:  true,
-					Transient:  true,
-				})),
-				list:              viewModel,
-				getDisplayStrings: getDisplayStrings,
-				c:                 c,
-			},
+		ListContextTrait: &ListContextTrait{
+			Context: NewSimpleContext(NewBaseContext(NewBaseContextOpts{
+				View:       c.Views().SubCommits,
+				WindowName: "branches",
+				Key:        SUB_COMMITS_CONTEXT_KEY,
+				Kind:       types.SIDE_CONTEXT,
+				Focusable:  true,
+				Transient:  true,
+			})),
+			list:                       viewModel,
+			getDisplayStrings:          getDisplayStrings,
+			c:                          c,
+			refreshViewportOnLineFocus: true,
 		},
 	}
 }

pkg/gui/context/viewport_list_context_trait.go

@@ -1,22 +0,0 @@
-package context
-
-import (
-	"github.com/jesseduffield/lazygit/pkg/utils"
-)
-
-// This embeds a list context trait and adds logic to re-render the viewport
-// whenever a line is focused. We use this in the commits panel because different
-// sections of the log graph need to be highlighted depending on the currently selected line
-
-type ViewportListContextTrait struct {
-	*ListContextTrait
-}
-
-func (self *ViewportListContextTrait) FocusLine() {
-	self.ListContextTrait.FocusLine()
-
-	startIdx, length := self.GetViewTrait().ViewPortYBounds()
-	displayStrings := self.ListContextTrait.getDisplayStrings(startIdx, length)
-	content := utils.RenderDisplayStrings(displayStrings, nil)
-	self.GetViewTrait().SetViewPortContent(content)
-}