Only render visible portion of the screen for commits view

9 files changed, 130 insertions, 62 deletions

diff --git a/pkg/gui/context/base_context.go b/pkg/gui/context/base_context.go
index acece1994..beaa61446 100644
--- a/pkg/gui/context/base_context.go
+++ b/pkg/gui/context/base_context.go
@@ -20,11 +20,12 @@ type BaseContext struct {
 	onFocusFn           onFocusFn
 	onFocusLostFn       onFocusLostFn
 
-	focusable                  bool
-	transient                  bool
-	hasControlledBounds        bool
-	needsRerenderOnWidthChange bool
-	highlightOnFocus           bool
+	focusable                   bool
+	transient                   bool
+	hasControlledBounds         bool
+	needsRerenderOnWidthChange  bool
+	needsRerenderOnHeightChange bool
+	highlightOnFocus            bool
 
 	*ParentContextMgr
 }
@@ -37,15 +38,16 @@ type (
 var _ types.IBaseContext = &BaseContext{}
 
 type NewBaseContextOpts struct {
-	Kind                       types.ContextKind
-	Key                        types.ContextKey
-	View                       *gocui.View
-	WindowName                 string
-	Focusable                  bool
-	Transient                  bool
-	HasUncontrolledBounds      bool // negating for the sake of making false the default
-	HighlightOnFocus           bool
-	NeedsRerenderOnWidthChange bool
+	Kind                        types.ContextKind
+	Key                         types.ContextKey
+	View                        *gocui.View
+	WindowName                  string
+	Focusable                   bool
+	Transient                   bool
+	HasUncontrolledBounds       bool // negating for the sake of making false the default
+	HighlightOnFocus            bool
+	NeedsRerenderOnWidthChange  bool
+	NeedsRerenderOnHeightChange bool
 
 	OnGetOptionsMap func() map[string]string
 }
@@ -56,18 +58,19 @@ func NewBaseContext(opts NewBaseContextOpts) *BaseContext {
 	hasControlledBounds := !opts.HasUncontrolledBounds
 
 	return &BaseContext{
-		kind:                       opts.Kind,
-		key:                        opts.Key,
-		view:                       opts.View,
-		windowName:                 opts.WindowName,
-		onGetOptionsMap:            opts.OnGetOptionsMap,
-		focusable:                  opts.Focusable,
-		transient:                  opts.Transient,
-		hasControlledBounds:        hasControlledBounds,
-		highlightOnFocus:           opts.HighlightOnFocus,
-		needsRerenderOnWidthChange: opts.NeedsRerenderOnWidthChange,
-		ParentContextMgr:           &ParentContextMgr{},
-		viewTrait:                  viewTrait,
+		kind:                        opts.Kind,
+		key:                         opts.Key,
+		view:                        opts.View,
+		windowName:                  opts.WindowName,
+		onGetOptionsMap:             opts.OnGetOptionsMap,
+		focusable:                   opts.Focusable,
+		transient:                   opts.Transient,
+		hasControlledBounds:         hasControlledBounds,
+		highlightOnFocus:            opts.HighlightOnFocus,
+		needsRerenderOnWidthChange:  opts.NeedsRerenderOnWidthChange,
+		needsRerenderOnHeightChange: opts.NeedsRerenderOnHeightChange,
+		ParentContextMgr:            &ParentContextMgr{},
+		viewTrait:                   viewTrait,
 	}
 }
 
@@ -197,6 +200,10 @@ func (self *BaseContext) NeedsRerenderOnWidthChange() bool {
 	return self.needsRerenderOnWidthChange
 }
 
+func (self *BaseContext) NeedsRerenderOnHeightChange() bool {
+	return self.needsRerenderOnHeightChange
+}
+
 func (self *BaseContext) Title() string {
 	return ""
 }
diff --git a/pkg/gui/context/list_context_trait.go b/pkg/gui/context/list_context_trait.go
index 78d524bb2..aca33cbd0 100644
--- a/pkg/gui/context/list_context_trait.go
+++ b/pkg/gui/context/list_context_trait.go
@@ -18,6 +18,9 @@ type ListContextTrait struct {
 	// 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.
 	refreshViewportOnChange bool
+	// If this is true, we only render the visible lines of the list. Useful for lists that can
+	// get very long, because it can save a lot of memory
+	renderOnlyVisibleLines bool
 }
 
 func (self *ListContextTrait) IsListContext() {}
@@ -28,6 +31,8 @@ func (self *ListContextTrait) FocusLine() {
 	// the view could be squashed and won't how to adjust the cursor/origin.
 	// Also, refreshing the viewport needs to happen after the view has been resized.
 	self.c.AfterLayout(func() error {
+		oldOrigin, _ := self.GetViewTrait().ViewPortYBounds()
+
 		self.GetViewTrait().FocusPoint(
 			self.ModelIndexToViewIndex(self.list.GetSelectedLineIdx()))
 
@@ -41,6 +46,11 @@ func (self *ListContextTrait) FocusLine() {
 
 		if self.refreshViewportOnChange {
 			self.refreshViewport()
+		} else if self.renderOnlyVisibleLines {
+			newOrigin, _ := self.GetViewTrait().ViewPortYBounds()
+			if oldOrigin != newOrigin {
+				return self.HandleRender()
+			}
 		}
 		return nil
 	})
@@ -83,8 +93,21 @@ func (self *ListContextTrait) HandleFocusLost(opts types.OnFocusLostOpts) error
 // OnFocus assumes that the content of the context has already been rendered to the view. OnRender is the function which actually renders the content to the view
 func (self *ListContextTrait) HandleRender() error {
 	self.list.ClampSelection()
-	content := self.renderLines(-1, -1)
-	self.GetViewTrait().SetContent(content)
+	if self.renderOnlyVisibleLines {
+		// Rendering only the visible area can save a lot of cell memory for
+		// those views that support it.
+		totalLength := self.list.Len()
+		if self.getNonModelItems != nil {
+			totalLength += len(self.getNonModelItems())
+		}
+		self.GetViewTrait().SetContentLineCount(totalLength)
+		startIdx, length := self.GetViewTrait().ViewPortYBounds()
+		content := self.renderLines(startIdx, startIdx+length)
+		self.GetViewTrait().SetViewPortContentAndClearEverythingElse(content)
+	} else {
+		content := self.renderLines(-1, -1)
+		self.GetViewTrait().SetContent(content)
+	}
 	self.c.Render()
 	self.setFooter()
 
diff --git a/pkg/gui/context/local_commits_context.go b/pkg/gui/context/local_commits_context.go
index c02fa3fe6..ab42cfb70 100644
--- a/pkg/gui/context/local_commits_context.go
+++ b/pkg/gui/context/local_commits_context.go
@@ -72,12 +72,13 @@ func NewLocalCommitsContext(c *ContextCommon) *LocalCommitsContext {
 		SearchTrait:           NewSearchTrait(c),
 		ListContextTrait: &ListContextTrait{
 			Context: NewSimpleContext(NewBaseContext(NewBaseContextOpts{
-				View:                       c.Views().Commits,
-				WindowName:                 "commits",
-				Key:                        LOCAL_COMMITS_CONTEXT_KEY,
-				Kind:                       types.SIDE_CONTEXT,
-				Focusable:                  true,
-				NeedsRerenderOnWidthChange: true,
+				View:                        c.Views().Commits,
+				WindowName:                  "commits",
+				Key:                         LOCAL_COMMITS_CONTEXT_KEY,
+				Kind:                        types.SIDE_CONTEXT,
+				Focusable:                   true,
+				NeedsRerenderOnWidthChange:  true,
+				NeedsRerenderOnHeightChange: true,
 			})),
 			ListRenderer: ListRenderer{
 				list:              viewModel,
@@ -85,6 +86,7 @@ func NewLocalCommitsContext(c *ContextCommon) *LocalCommitsContext {
 			},
 			c:                       c,
 			refreshViewportOnChange: true,
+			renderOnlyVisibleLines:  true,
 		},
 	}
 
diff --git a/pkg/gui/context/remote_branches_context.go b/pkg/gui/context/remote_branches_context.go
index 884d3debb..fff80e076 100644
--- a/pkg/gui/context/remote_branches_context.go
+++ b/pkg/gui/context/remote_branches_context.go
@@ -37,13 +37,14 @@ func NewRemoteBranchesContext(
 		DynamicTitleBuilder:   NewDynamicTitleBuilder(c.Tr.RemoteBranchesDynamicTitle),
 		ListContextTrait: &ListContextTrait{
 			Context: NewSimpleContext(NewBaseContext(NewBaseContextOpts{
-				View:                       c.Views().RemoteBranches,
-				WindowName:                 "branches",
-				Key:                        REMOTE_BRANCHES_CONTEXT_KEY,
-				Kind:                       types.SIDE_CONTEXT,
-				Focusable:                  true,
-				Transient:                  true,
-				NeedsRerenderOnWidthChange: true,
+				View:                        c.Views().RemoteBranches,
+				WindowName:                  "branches",
+				Key:                         REMOTE_BRANCHES_CONTEXT_KEY,
+				Kind:                        types.SIDE_CONTEXT,
+				Focusable:                   true,
+				Transient:                   true,
+				NeedsRerenderOnWidthChange:  true,
+				NeedsRerenderOnHeightChange: true,
 			})),
 			ListRenderer: ListRenderer{
 				list:              viewModel,
diff --git a/pkg/gui/context/sub_commits_context.go b/pkg/gui/context/sub_commits_context.go
index 842b364b3..ab0d2784a 100644
--- a/pkg/gui/context/sub_commits_context.go
+++ b/pkg/gui/context/sub_commits_context.go
@@ -115,13 +115,14 @@ func NewSubCommitsContext(
 		DynamicTitleBuilder: NewDynamicTitleBuilder(c.Tr.SubCommitsDynamicTitle),
 		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,
-				NeedsRerenderOnWidthChange: true,
+				View:                        c.Views().SubCommits,
+				WindowName:                  "branches",
+				Key:                         SUB_COMMITS_CONTEXT_KEY,
+				Kind:                        types.SIDE_CONTEXT,
+				Focusable:                   true,
+				Transient:                   true,
+				NeedsRerenderOnWidthChange:  true,
+				NeedsRerenderOnHeightChange: true,
 			})),
 			ListRenderer: ListRenderer{
 				list:              viewModel,
@@ -130,6 +131,7 @@ func NewSubCommitsContext(
 			},
 			c:                       c,
 			refreshViewportOnChange: true,
+			renderOnlyVisibleLines:  true,
 		},
 	}
 
diff --git a/pkg/gui/context/view_trait.go b/pkg/gui/context/view_trait.go
index 1179a8b14..191419897 100644
--- a/pkg/gui/context/view_trait.go
+++ b/pkg/gui/context/view_trait.go
@@ -34,6 +34,15 @@ func (self *ViewTrait) SetViewPortContent(content string) {
 	self.view.OverwriteLines(y, content)
 }
 
+func (self *ViewTrait) SetViewPortContentAndClearEverythingElse(content string) {
+	_, y := self.view.Origin()
+	self.view.OverwriteLinesAndClearEverythingElse(y, content)
+}
+
+func (self *ViewTrait) SetContentLineCount(lineCount int) {
+	self.view.SetContentLineCount(lineCount)
+}
+
 func (self *ViewTrait) SetContent(content string) {
 	self.view.SetContent(content)
 }
diff --git a/pkg/gui/layout.go b/pkg/gui/layout.go
index 01c397628..4e2b49477 100644
--- a/pkg/gui/layout.go
+++ b/pkg/gui/layout.go
@@ -72,14 +72,26 @@ func (gui *Gui) layout(g *gocui.Gui) error {
 			frameOffset = 0
 		}
 
+		mustRerender := false
 		if context.NeedsRerenderOnWidthChange() {
 			// view.Width() returns the width -1 for some reason
 			oldWidth := view.Width() + 1
 			newWidth := dimensionsObj.X1 - dimensionsObj.X0 + 2*frameOffset
 			if oldWidth != newWidth {
-				contextsToRerender = append(contextsToRerender, context)
+				mustRerender = true
 			}
 		}
+		if context.NeedsRerenderOnHeightChange() {
+			// view.Height() returns the height -1 for some reason
+			oldHeight := view.Height() + 1
+			newHeight := dimensionsObj.Y1 - dimensionsObj.Y0 + 2*frameOffset
+			if oldHeight != newHeight {
+				mustRerender = true
+			}
+		}
+		if mustRerender {
+			contextsToRerender = append(contextsToRerender, context)
+		}
 
 		_, err = g.SetView(
 			viewName,
diff --git a/pkg/gui/types/context.go b/pkg/gui/types/context.go
index b0e312c97..29b53b9eb 100644
--- a/pkg/gui/types/context.go
+++ b/pkg/gui/types/context.go
@@ -63,6 +63,9 @@ type IBaseContext interface {
 	// true if the view needs to be rerendered when its width changes
 	NeedsRerenderOnWidthChange() bool
 
+	// true if the view needs to be rerendered when its height changes
+	NeedsRerenderOnHeightChange() bool
+
 	// returns the desired title for the view upon activation. If there is no desired title (returns empty string), then
 	// no title will be set
 	Title() string
@@ -172,6 +175,8 @@ type IViewTrait interface {
 	SetRangeSelectStart(yIdx int)
 	CancelRangeSelect()
 	SetViewPortContent(content string)
+	SetViewPortContentAndClearEverythingElse(content string)
+	SetContentLineCount(lineCount int)
 	SetContent(content string)
 	SetFooter(value string)
 	SetOriginX(value int)
diff --git a/pkg/integration/components/view_driver.go b/pkg/integration/components/view_driver.go
index b6f917603..3abd63a9e 100644
--- a/pkg/integration/components/view_driver.go
+++ b/pkg/integration/components/view_driver.go
@@ -431,6 +431,11 @@ func (self *ViewDriver) SelectPreviousItem() *ViewDriver {
 	return self.PressFast(self.t.keys.Universal.PrevItem)
 }
 
+// i.e. pressing '<'
+func (self *ViewDriver) GotoTop() *ViewDriver {
+	return self.PressFast(self.t.keys.Universal.GotoTop)
+}
+
 // i.e. pressing space
 func (self *ViewDriver) PressPrimaryAction() *ViewDriver {
 	return self.Press(self.t.keys.Universal.Select)
@@ -457,21 +462,15 @@ func (self *ViewDriver) PressEscape() *ViewDriver {
 // - the user is not in a list item
 // - no list item is found containing the given text
 // - multiple list items are found containing the given text in the initial page of items
-//
-// NOTE: this currently assumes that BufferLines returns all the lines that can be accessed.
-// If this changes in future, we'll need to update this code to first attempt to find the item
-// in the current page and failing that, jump to the top of the view and iterate through all of it,
-// looking for the item.
 func (self *ViewDriver) NavigateToLine(matcher *TextMatcher) *ViewDriver {
 	self.IsFocused()
 
 	view := self.getView()
 	lines := view.BufferLines()
 
-	var matchIndex int
+	matchIndex := -1
 
 	self.t.assertWithRetries(func() (bool, string) {
-		matchIndex = -1
 		var matches []string
 		// first we look for a duplicate on the current screen. We won't bother looking beyond that though.
 		for i, line := range lines {
@@ -483,13 +482,19 @@ func (self *ViewDriver) NavigateToLine(matcher *TextMatcher) *ViewDriver {
 		}
 		if len(matches) > 1 {
 			return false, fmt.Sprintf("Found %d matches for `%s`, expected only a single match. Matching lines:\n%s", len(matches), matcher.name(), strings.Join(matches, "\n"))
-		} else if len(matches) == 0 {
-			return false, fmt.Sprintf("Could not find item matching: %s. Lines:\n%s", matcher.name(), strings.Join(lines, "\n"))
-		} else {
-			return true, ""
 		}
+		return true, ""
 	})
 
+	// If no match was found, it could be that this is a view that renders only
+	// the visible lines. In that case, we jump to the top and then press
+	// down-arrow until we found the match. We simply return the first match we
+	// find, so we have no way to assert that there are no duplicates.
+	if matchIndex == -1 {
+		self.GotoTop()
+		matchIndex = len(lines)
+	}
+
 	selectedLineIdx := self.getSelectedLineIdx()
 	if selectedLineIdx == matchIndex {
 		return self.SelectedLine(matcher)
@@ -514,12 +519,14 @@ func (self *ViewDriver) NavigateToLine(matcher *TextMatcher) *ViewDriver {
 	for i := 0; i < maxNumKeyPresses; i++ {
 		keyPress()
 		idx := self.getSelectedLineIdx()
-		if ok, _ := matcher.test(lines[idx]); ok {
+		// It is important to use view.BufferLines() here and not lines, because it
+		// could change with every keypress.
+		if ok, _ := matcher.test(view.BufferLines()[idx]); ok {
 			return self
 		}
 	}
 
-	self.t.fail(fmt.Sprintf("Could not navigate to item matching: %s. Lines:\n%s", matcher.name(), strings.Join(lines, "\n")))
+	self.t.fail(fmt.Sprintf("Could not navigate to item matching: %s. Lines:\n%s", matcher.name(), strings.Join(view.BufferLines(), "\n")))
 	return self
 }