Rewrap patch when view width changes

This makes it so that when the staging view is resized, we keep the same patch
line selected (as opposed to the same view line, which may correspond to a
different patch line after resizing). It doesn't seem like a terribly important
feature for resizing the window, but it is essential when initially entering the
staging view: we select the first line of the first hunk in this case, but we do
that before layout runs. At layout time the view is then split into
unstaged/staged changes, and if this split is horizontal, the view gets narrower
and may be wrapped in a different way. With this commit we ensure that the first
line of the first hunk is still selected after that.

pkg/gui/context/patch_explorer_context.go

@@ -39,12 +39,13 @@ func NewPatchExplorerContext(
 		mutex:                  &deadlock.Mutex{},
 		getIncludedLineIndices: getIncludedLineIndices,
 		SimpleContext: NewSimpleContext(NewBaseContext(NewBaseContextOpts{
-			View:             view,
-			WindowName:       windowName,
-			Key:              key,
-			Kind:             types.MAIN_CONTEXT,
-			Focusable:        true,
-			HighlightOnFocus: true,
+			View:                       view,
+			WindowName:                 windowName,
+			Key:                        key,
+			Kind:                       types.MAIN_CONTEXT,
+			Focusable:                  true,
+			HighlightOnFocus:           true,
+			NeedsRerenderOnWidthChange: types.NEEDS_RERENDER_ON_WIDTH_CHANGE_WHEN_WIDTH_CHANGES,
 		})),
 		SearchTrait: NewSearchTrait(c),
 	}
@@ -58,6 +59,8 @@ func NewPatchExplorerContext(
 		}),
 	)
 
+	ctx.SetHandleRenderFunc(ctx.OnViewWidthChanged)
+
 	return ctx
 }
 
@@ -140,3 +143,11 @@ func (self *PatchExplorerContext) GetMutex() *deadlock.Mutex {
 func (self *PatchExplorerContext) ModelSearchResults(searchStr string, caseSensitive bool) []gocui.SearchPosition {
 	return nil
 }
+
+func (self *PatchExplorerContext) OnViewWidthChanged() {
+	if state := self.GetState(); state != nil {
+		state.OnViewWidthChanged(self.GetView())
+		self.setContent()
+		self.RenderAndFocus()
+	}
+}

pkg/gui/context/simple_context.go

@@ -7,6 +7,7 @@ import (
 
 type SimpleContext struct {
 	*BaseContext
+	handleRenderFunc func()
 }
 
 func NewSimpleContext(baseContext *BaseContext) *SimpleContext {
@@ -54,6 +55,13 @@ func (self *SimpleContext) HandleFocusLost(opts types.OnFocusLostOpts) {
 }
 
 func (self *SimpleContext) HandleRender() {
+	if self.handleRenderFunc != nil {
+		self.handleRenderFunc()
+	}
+}
+
+func (self *SimpleContext) SetHandleRenderFunc(f func()) {
+	self.handleRenderFunc = f
 }
 
 func (self *SimpleContext) HandleRenderToMain() {

pkg/gui/patch_exploring/state.go

@@ -90,6 +90,23 @@ func NewState(diff string, selectedLineIdx int, view *gocui.View, oldState *Stat
 	}
 }
 
+func (s *State) OnViewWidthChanged(view *gocui.View) {
+	if !view.Wrap {
+		return
+	}
+
+	selectedPatchLineIdx := s.patchLineIndices[s.selectedLineIdx]
+	var rangeStartPatchLineIdx int
+	if s.selectMode == RANGE {
+		rangeStartPatchLineIdx = s.patchLineIndices[s.rangeStartLineIdx]
+	}
+	s.viewLineIndices, s.patchLineIndices = wrapPatchLines(s.diff, view)
+	s.selectedLineIdx = s.viewLineIndices[selectedPatchLineIdx]
+	if s.selectMode == RANGE {
+		s.rangeStartLineIdx = s.viewLineIndices[rangeStartPatchLineIdx]
+	}
+}
+
 func (s *State) GetSelectedPatchLineIdx() int {
 	return s.patchLineIndices[s.selectedLineIdx]
 }