add scrollbars

8 files changed, 87 insertions, 79 deletions

diff --git a/pkg/gui/context/view_trait.go b/pkg/gui/context/view_trait.go
index 4c0cd9e05..8f2a2e99e 100644
--- a/pkg/gui/context/view_trait.go
+++ b/pkg/gui/context/view_trait.go
@@ -3,7 +3,6 @@ package context
 import (
 	"github.com/jesseduffield/gocui"
 	"github.com/jesseduffield/lazygit/pkg/gui/types"
-	"github.com/jesseduffield/lazygit/pkg/utils"
 )
 
 const HORIZONTAL_SCROLL_FACTOR = 3
@@ -43,20 +42,31 @@ func (self *ViewTrait) SetOriginX(value int) {
 	_ = self.view.SetOriginX(value)
 }
 
-// tells us the bounds of line indexes shown in the view currently
+// tells us the start of line indexes shown in the view currently as well as the capacity of lines shown in the viewport.
 func (self *ViewTrait) ViewPortYBounds() (int, int) {
-	_, min := self.view.Origin()
-	max := self.view.InnerHeight() + 1
-	return min, max
+	_, start := self.view.Origin()
+	length := self.view.InnerHeight() + 1
+	return start, length
 }
 
 func (self *ViewTrait) ScrollLeft() {
-	newOriginX := utils.Max(self.view.OriginX()-self.view.InnerWidth()/HORIZONTAL_SCROLL_FACTOR, 0)
-	_ = self.view.SetOriginX(newOriginX)
+	self.view.ScrollLeft(self.horizontalScrollAmount())
 }
 
 func (self *ViewTrait) ScrollRight() {
-	_ = self.view.SetOriginX(self.view.OriginX() + self.view.InnerWidth()/HORIZONTAL_SCROLL_FACTOR)
+	self.view.ScrollRight(self.horizontalScrollAmount())
+}
+
+func (self *ViewTrait) horizontalScrollAmount() int {
+	return self.view.InnerWidth() / HORIZONTAL_SCROLL_FACTOR
+}
+
+func (self *ViewTrait) ScrollUp() {
+	self.view.ScrollUp(1)
+}
+
+func (self *ViewTrait) ScrollDown() {
+	self.view.ScrollDown(1)
 }
 
 // this returns the amount we'll scroll if we want to scroll by a page.
diff --git a/pkg/gui/context/viewport_list_context_trait.go b/pkg/gui/context/viewport_list_context_trait.go
index ab9b04fb8..b89dea832 100644
--- a/pkg/gui/context/viewport_list_context_trait.go
+++ b/pkg/gui/context/viewport_list_context_trait.go
@@ -15,8 +15,8 @@ type ViewportListContextTrait struct {
 func (self *ViewportListContextTrait) FocusLine() {
 	self.ListContextTrait.FocusLine()
 
-	min, max := self.GetViewTrait().ViewPortYBounds()
-	displayStrings := self.ListContextTrait.getDisplayStrings(min, max)
+	startIdx, length := self.GetViewTrait().ViewPortYBounds()
+	displayStrings := self.ListContextTrait.getDisplayStrings(startIdx, length)
 	content := utils.RenderDisplayStrings(displayStrings)
 	self.GetViewTrait().SetViewPortContent(content)
 }
diff --git a/pkg/gui/controllers/list_controller.go b/pkg/gui/controllers/list_controller.go
index 0f64228bb..7da05710e 100644
--- a/pkg/gui/controllers/list_controller.go
+++ b/pkg/gui/controllers/list_controller.go
@@ -43,14 +43,42 @@ func (self *ListController) HandleNextLine() error {
 }
 
 func (self *ListController) HandleScrollLeft() error {
-	return self.scroll(self.context.GetViewTrait().ScrollLeft)
+	return self.scrollHorizontal(self.context.GetViewTrait().ScrollLeft)
 }
 
 func (self *ListController) HandleScrollRight() error {
-	return self.scroll(self.context.GetViewTrait().ScrollRight)
+	return self.scrollHorizontal(self.context.GetViewTrait().ScrollRight)
 }
 
-func (self *ListController) scroll(scrollFunc func()) error {
+func (self *ListController) HandleScrollUp() error {
+	self.context.GetViewTrait().ScrollUp()
+
+	// we only need to do a line change if our line has been pushed out of the viewport, because
+	// at the moment much logic depends on the selected line always being visible
+	if !self.isSelectedLineInViewPort() {
+		return self.handleLineChange(-1)
+	}
+
+	return nil
+}
+
+func (self *ListController) HandleScrollDown() error {
+	self.context.GetViewTrait().ScrollDown()
+
+	if !self.isSelectedLineInViewPort() {
+		return self.handleLineChange(1)
+	}
+
+	return nil
+}
+
+func (self *ListController) isSelectedLineInViewPort() bool {
+	selectedLineIdx := self.context.GetList().GetSelectedLineIdx()
+	startIdx, length := self.context.GetViewTrait().ViewPortYBounds()
+	return selectedLineIdx >= startIdx && selectedLineIdx < startIdx+length
+}
+
+func (self *ListController) scrollHorizontal(scrollFunc func()) error {
 	scrollFunc()
 
 	return self.context.HandleFocus()
@@ -157,7 +185,7 @@ func (self *ListController) GetMouseKeybindings(opts types.KeybindingsOpts) []*g
 			ViewName:  self.context.GetViewName(),
 			ToContext: string(self.context.GetKey()),
 			Key:       gocui.MouseWheelUp,
-			Handler:   func(gocui.ViewMouseBindingOpts) error { return self.HandlePrevLine() },
+			Handler:   func(gocui.ViewMouseBindingOpts) error { return self.HandleScrollUp() },
 		},
 		{
 			ViewName:  self.context.GetViewName(),
@@ -169,7 +197,7 @@ func (self *ListController) GetMouseKeybindings(opts types.KeybindingsOpts) []*g
 			ViewName:  self.context.GetViewName(),
 			ToContext: string(self.context.GetKey()),
 			Key:       gocui.MouseWheelDown,
-			Handler:   func(gocui.ViewMouseBindingOpts) error { return self.HandleNextLine() },
+			Handler:   func(gocui.ViewMouseBindingOpts) error { return self.HandleScrollDown() },
 		},
 	}
 }
diff --git a/pkg/gui/extras_panel.go b/pkg/gui/extras_panel.go
index 462a5118e..6033f8516 100644
--- a/pkg/gui/extras_panel.go
+++ b/pkg/gui/extras_panel.go
@@ -46,15 +46,15 @@ func (gui *Gui) handleFocusCommandLog() error {
 func (gui *Gui) scrollUpExtra() error {
 	gui.Views.Extras.Autoscroll = false
 
-	return gui.scrollUpView(gui.Views.Extras)
+	gui.scrollUpView(gui.Views.Extras)
+
+	return nil
 }
 
 func (gui *Gui) scrollDownExtra() error {
 	gui.Views.Extras.Autoscroll = false
 
-	if err := gui.scrollDownView(gui.Views.Extras); err != nil {
-		return err
-	}
+	gui.scrollDownView(gui.Views.Extras)
 
 	return nil
 }
diff --git a/pkg/gui/global_handlers.go b/pkg/gui/global_handlers.go
index e76c9f1a6..97cf4650d 100644
--- a/pkg/gui/global_handlers.go
+++ b/pkg/gui/global_handlers.go
@@ -2,7 +2,6 @@ package gui
 
 import (
 	"fmt"
-	"math"
 	"strings"
 
 	"github.com/jesseduffield/gocui"
@@ -63,56 +62,17 @@ func (gui *Gui) prevScreenMode() error {
 	return gui.rerenderViewsWithScreenModeDependentContent()
 }
 
-func (gui *Gui) scrollUpView(view *gocui.View) error {
-	ox, oy := view.Origin()
-	newOy := int(math.Max(0, float64(oy-gui.c.UserConfig.Gui.ScrollHeight)))
-	return view.SetOrigin(ox, newOy)
+func (gui *Gui) scrollUpView(view *gocui.View) {
+	view.ScrollUp(gui.c.UserConfig.Gui.ScrollHeight)
 }
 
-func (gui *Gui) scrollDownView(view *gocui.View) error {
-	ox, oy := view.Origin()
-	scrollHeight := gui.linesToScrollDown(view)
-	if scrollHeight > 0 {
-		if err := view.SetOrigin(ox, oy+scrollHeight); err != nil {
-			return err
-		}
-	}
+func (gui *Gui) scrollDownView(view *gocui.View) {
+	scrollHeight := gui.c.UserConfig.Gui.ScrollHeight
+	view.ScrollDown(scrollHeight)
 
 	if manager, ok := gui.viewBufferManagerMap[view.Name()]; ok {
 		manager.ReadLines(scrollHeight)
 	}
-	return nil
-}
-
-func (gui *Gui) linesToScrollDown(view *gocui.View) int {
-	_, oy := view.Origin()
-	y := oy
-	canScrollPastBottom := gui.c.UserConfig.Gui.ScrollPastBottom
-	if !canScrollPastBottom {
-		_, sy := view.Size()
-		y += sy
-	}
-	scrollHeight := gui.c.UserConfig.Gui.ScrollHeight
-	scrollableLines := view.ViewLinesHeight() - y
-	if scrollableLines < 0 {
-		return 0
-	}
-
-	// margin is about how many lines must still appear if you scroll
-	// all the way down. In practice every file ends in a newline so it will really
-	// just show a single line
-	margin := 1
-	if canScrollPastBottom {
-		margin = 2
-	}
-	if scrollableLines-margin < scrollHeight {
-		scrollHeight = scrollableLines - margin
-	}
-	if oy+scrollHeight < 0 {
-		return 0
-	} else {
-		return scrollHeight
-	}
 }
 
 func (gui *Gui) scrollUpMain() error {
@@ -120,7 +80,9 @@ func (gui *Gui) scrollUpMain() error {
 		gui.State.Panels.Merging.UserVerticalScrolling = true
 	}
 
-	return gui.scrollUpView(gui.Views.Main)
+	gui.scrollUpView(gui.Views.Main)
+
+	return nil
 }
 
 func (gui *Gui) scrollDownMain() error {
@@ -128,7 +90,9 @@ func (gui *Gui) scrollDownMain() error {
 		gui.State.Panels.Merging.UserVerticalScrolling = true
 	}
 
-	return gui.scrollDownView(gui.Views.Main)
+	gui.scrollDownView(gui.Views.Main)
+
+	return nil
 }
 
 func (gui *Gui) scrollLeftMain() error {
@@ -153,11 +117,15 @@ func (gui *Gui) scrollRight(view *gocui.View) {
 }
 
 func (gui *Gui) scrollUpSecondary() error {
-	return gui.scrollUpView(gui.Views.Secondary)
+	gui.scrollUpView(gui.Views.Secondary)
+
+	return nil
 }
 
 func (gui *Gui) scrollDownSecondary() error {
-	return gui.scrollDownView(gui.Views.Secondary)
+	gui.scrollDownView(gui.Views.Secondary)
+
+	return nil
 }
 
 func (gui *Gui) scrollUpConfirmationPanel() error {
@@ -165,7 +133,9 @@ func (gui *Gui) scrollUpConfirmationPanel() error {
 		return nil
 	}
 
-	return gui.scrollUpView(gui.Views.Confirmation)
+	gui.scrollUpView(gui.Views.Confirmation)
+
+	return nil
 }
 
 func (gui *Gui) scrollDownConfirmationPanel() error {
@@ -173,7 +143,9 @@ func (gui *Gui) scrollDownConfirmationPanel() error {
 		return nil
 	}
 
-	return gui.scrollDownView(gui.Views.Confirmation)
+	gui.scrollDownView(gui.Views.Confirmation)
+
+	return nil
 }
 
 func (gui *Gui) handleRefresh() error {
diff --git a/pkg/gui/gui.go b/pkg/gui/gui.go
index 17ca26f41..23b8ae8ca 100644
--- a/pkg/gui/gui.go
+++ b/pkg/gui/gui.go
@@ -661,11 +661,13 @@ func (gui *Gui) createAllViews() error {
 	gui.Views.Secondary.Wrap = true
 	gui.Views.Secondary.FgColor = theme.GocuiDefaultTextColor
 	gui.Views.Secondary.IgnoreCarriageReturns = true
+	gui.Views.Secondary.CanScrollPastBottom = gui.c.UserConfig.Gui.ScrollPastBottom
 
 	gui.Views.Main.Title = gui.c.Tr.DiffTitle
 	gui.Views.Main.Wrap = true
 	gui.Views.Main.FgColor = theme.GocuiDefaultTextColor
 	gui.Views.Main.IgnoreCarriageReturns = true
+	gui.Views.Main.CanScrollPastBottom = gui.c.UserConfig.Gui.ScrollPastBottom
 
 	gui.Views.Limit.Title = gui.c.Tr.NotEnoughSpace
 	gui.Views.Limit.Wrap = true
diff --git a/pkg/gui/tasks_adapter.go b/pkg/gui/tasks_adapter.go
index d619c58ba..745cc3760 100644
--- a/pkg/gui/tasks_adapter.go
+++ b/pkg/gui/tasks_adapter.go
@@ -98,21 +98,15 @@ func (gui *Gui) getManager(view *gocui.View) *tasks.ViewBufferManager {
 			},
 			func() {
 				// Need to check if the content of the view is well past the origin.
-				// It would be better to use .ViewLinesHeight here (given it considers
-				// wrapping) but when this function is called they haven't been written to yet.
-				linesHeight := view.LinesHeight()
-				_, height := view.Size()
+				linesHeight := view.ViewLinesHeight()
 				_, originY := view.Origin()
 				if linesHeight < originY {
-					newOriginY := linesHeight - height
-					if newOriginY < 0 {
-						newOriginY = 0
-					}
+					newOriginY := linesHeight
+
 					err := view.SetOrigin(0, newOriginY)
 					if err != nil {
 						panic(err)
 					}
-
 				}
 
 				view.FlushStaleCells()
diff --git a/pkg/gui/types/context.go b/pkg/gui/types/context.go
index 6f026fe73..253bb62ef 100644
--- a/pkg/gui/types/context.go
+++ b/pkg/gui/types/context.go
@@ -85,6 +85,8 @@ type IViewTrait interface {
 	ViewPortYBounds() (int, int)
 	ScrollLeft()
 	ScrollRight()
+	ScrollUp()
+	ScrollDown()
 	PageDelta() int
 	SelectedLineIdx() int
 }