Rerender fewer views when their width changes

In d5b4f7b and 58a83b0 we introduced a combined mechanism for rerendering
views when either their width changes (needed for the branches view which
truncates long branch names), or the screen mode (needed for those views that
display more information in half or full screen mode, e.g. the commits view).

This was a bad idea, because it unnecessarily rerenders too many views when just
their width changes, which causes a noticable lag. This is a problem, for
example, when selecting a file in the files panel that has only unstaged
changes, and then going to one that has both staged and unstaged changes; this
splits the main view, causing the side panels to become a bit narrower, and
rerendering all those views took almost 500ms on my machine. Another similar
example is entering or leaving staging mode.

Fix this by being more specific about which views need rerendering under what
conditions; this improves the time it takes to rerender in the above scenarios
from 450-500s down to about 20ms.

This reintroduces the code that was removed in 58a83b0, but in a slightly
different way.

pkg/gui/context/base_context.go

@@ -23,7 +23,7 @@ type BaseContext struct {
  focusable bool
  transient bool
  hasControlledBounds bool
- needsRerenderOnWidthChange bool
+ needsRerenderOnWidthChange types.NeedsRerenderOnWidthChangeLevel
  needsRerenderOnHeightChange bool
  highlightOnFocus bool
 
@@ -46,7 +46,7 @@ type NewBaseContextOpts struct {
  Transient bool
  HasUncontrolledBounds bool // negating for the sake of making false the default
  HighlightOnFocus bool
- NeedsRerenderOnWidthChange bool
+ NeedsRerenderOnWidthChange types.NeedsRerenderOnWidthChangeLevel
  NeedsRerenderOnHeightChange bool
 
  OnGetOptionsMap func() map[string]string
@@ -201,7 +201,7 @@ func (self *BaseContext) HasControlledBounds() bool {
  return self.hasControlledBounds
 }
 
-func (self *BaseContext) NeedsRerenderOnWidthChange() bool {
+func (self *BaseContext) NeedsRerenderOnWidthChange() types.NeedsRerenderOnWidthChangeLevel {
  return self.needsRerenderOnWidthChange
 }
 

pkg/gui/context/branches_context.go

@@ -46,7 +46,7 @@ func NewBranchesContext(c *ContextCommon) *BranchesContext {
  Key: LOCAL_BRANCHES_CONTEXT_KEY,
  Kind: types.SIDE_CONTEXT,
  Focusable: true,
- NeedsRerenderOnWidthChange: true,
+ NeedsRerenderOnWidthChange: types.NEEDS_RERENDER_ON_WIDTH_CHANGE_WHEN_WIDTH_CHANGES,
  })),
  ListRenderer: ListRenderer{
  list: viewModel,

pkg/gui/context/local_commits_context.go

@@ -77,7 +77,7 @@ func NewLocalCommitsContext(c *ContextCommon) *LocalCommitsContext {
  Key: LOCAL_COMMITS_CONTEXT_KEY,
  Kind: types.SIDE_CONTEXT,
  Focusable: true,
- NeedsRerenderOnWidthChange: true,
+ NeedsRerenderOnWidthChange: types.NEEDS_RERENDER_ON_WIDTH_CHANGE_WHEN_SCREEN_MODE_CHANGES,
  NeedsRerenderOnHeightChange: true,
  })),
  ListRenderer: ListRenderer{

pkg/gui/context/reflog_commits_context.go

@@ -48,7 +48,7 @@ func NewReflogCommitsContext(c *ContextCommon) *ReflogCommitsContext {
  Key: REFLOG_COMMITS_CONTEXT_KEY,
  Kind: types.SIDE_CONTEXT,
  Focusable: true,
- NeedsRerenderOnWidthChange: true,
+ NeedsRerenderOnWidthChange: types.NEEDS_RERENDER_ON_WIDTH_CHANGE_WHEN_SCREEN_MODE_CHANGES,
  })),
  ListRenderer: ListRenderer{
  list: viewModel,

pkg/gui/context/sub_commits_context.go

@@ -121,7 +121,7 @@ func NewSubCommitsContext(
  Kind: types.SIDE_CONTEXT,
  Focusable: true,
  Transient: true,
- NeedsRerenderOnWidthChange: true,
+ NeedsRerenderOnWidthChange: types.NEEDS_RERENDER_ON_WIDTH_CHANGE_WHEN_SCREEN_MODE_CHANGES,
  NeedsRerenderOnHeightChange: true,
  })),
  ListRenderer: ListRenderer{

pkg/gui/controllers/screen_mode_actions.go

@@ -1,6 +1,7 @@
 package controllers
 
 import (
+ "github.com/jesseduffield/gocui"
  "github.com/jesseduffield/lazygit/pkg/gui/types"
 )
 
@@ -16,7 +17,7 @@ func (self *ScreenModeActions) Next() error {
  ),
  )
 
- return nil
+ return self.rerenderViewsWithScreenModeDependentContent()
 }
 
 func (self *ScreenModeActions) Prev() error {
@@ -27,9 +28,33 @@ func (self *ScreenModeActions) Prev() error {
  ),
  )
 
+ return self.rerenderViewsWithScreenModeDependentContent()
+}
+
+// these views need to be re-rendered when the screen mode changes. The commits view,
+// for example, will show authorship information in half and full screen mode.
+func (self *ScreenModeActions) rerenderViewsWithScreenModeDependentContent() error {
+ for _, context := range self.c.Context().AllList() {
+ if context.NeedsRerenderOnWidthChange() == types.NEEDS_RERENDER_ON_WIDTH_CHANGE_WHEN_SCREEN_MODE_CHANGES {
+ if err := self.rerenderView(context.GetView()); err != nil {
+ return err
+ }
+ }
+ }
+
  return nil
 }
 
+func (self *ScreenModeActions) rerenderView(view *gocui.View) error {
+ context, ok := self.c.Helpers().View.ContextForView(view.Name())
+ if !ok {
+ self.c.Log.Errorf("no context found for view %s", view.Name())
+ return nil
+ }
+
+ return context.HandleRender()
+}
+
 func nextIntInCycle(sl []types.WindowMaximisation, current types.WindowMaximisation) types.WindowMaximisation {
  for i, val := range sl {
  if val == current {

pkg/gui/layout.go

@@ -73,7 +73,7 @@ func (gui *Gui) layout(g *gocui.Gui) error {
  }
 
  mustRerender := false
- if context.NeedsRerenderOnWidthChange() {
+ if context.NeedsRerenderOnWidthChange() == types.NEEDS_RERENDER_ON_WIDTH_CHANGE_WHEN_WIDTH_CHANGES {
  // view.Width() returns the width -1 for some reason
  oldWidth := view.Width() + 1
  newWidth := dimensionsObj.X1 - dimensionsObj.X0 + 2*frameOffset

pkg/gui/types/context.go

@@ -39,6 +39,18 @@ type ParentContexter interface {
  GetParentContext() (Context, bool)
 }
 
+type NeedsRerenderOnWidthChangeLevel int
+
+const (
+ // view doesn't render differently when its width changes
+ NEEDS_RERENDER_ON_WIDTH_CHANGE_NONE NeedsRerenderOnWidthChangeLevel = iota
+ // view renders differently when its width changes. An example is a view
+ // that truncates long lines to the view width, e.g. the branches view
+ NEEDS_RERENDER_ON_WIDTH_CHANGE_WHEN_WIDTH_CHANGES
+ // view renders differently only when the screen mode changes
+ NEEDS_RERENDER_ON_WIDTH_CHANGE_WHEN_SCREEN_MODE_CHANGES
+)
+
 type IBaseContext interface {
  HasKeybindings
  ParentContexter
@@ -60,8 +72,8 @@ type IBaseContext interface {
  // determined independently.
  HasControlledBounds() bool
 
- // true if the view needs to be rerendered when its width changes
- NeedsRerenderOnWidthChange() bool
+ // to what extent the view needs to be rerendered when its width changes
+ NeedsRerenderOnWidthChange() NeedsRerenderOnWidthChangeLevel
 
  // true if the view needs to be rerendered when its height changes
  NeedsRerenderOnHeightChange() bool