refactor contexts code

pkg/gui/context/view_trait.go

@@ -0,0 +1,80 @@
+package context
+
+import (
+	"github.com/jesseduffield/gocui"
+	"github.com/jesseduffield/lazygit/pkg/utils"
+)
+
+const HORIZONTAL_SCROLL_FACTOR = 3
+
+type ViewTrait struct {
+	getView func() *gocui.View
+}
+
+func NewViewTrait(getView func() *gocui.View) *ViewTrait {
+	return &ViewTrait{getView: getView}
+}
+
+func (self *ViewTrait) FocusPoint(yIdx int) {
+	view := self.getView()
+	view.FocusPoint(view.OriginX(), yIdx)
+}
+
+func (self *ViewTrait) SetViewPortContent(content string) {
+	view := self.getView()
+
+	_, y := view.Origin()
+	view.OverwriteLines(y, content)
+}
+
+func (self *ViewTrait) SetContent(content string) {
+	self.getView().SetContent(content)
+}
+
+func (self *ViewTrait) SetFooter(value string) {
+	self.getView().Footer = value
+}
+
+func (self *ViewTrait) SetOriginX(value int) {
+	self.getView().SetOriginX(value)
+}
+
+// tells us the bounds of line indexes shown in the view currently
+func (self *ViewTrait) ViewPortYBounds() (int, int) {
+	view := self.getView()
+
+	_, min := view.Origin()
+	max := view.InnerHeight() + 1
+	return min, max
+}
+
+func (self *ViewTrait) ScrollLeft() {
+	view := self.getView()
+
+	newOriginX := utils.Max(view.OriginX()-view.InnerWidth()/HORIZONTAL_SCROLL_FACTOR, 0)
+	_ = view.SetOriginX(newOriginX)
+}
+
+func (self *ViewTrait) ScrollRight() {
+	view := self.getView()
+
+	_ = view.SetOriginX(view.OriginX() + view.InnerWidth()/HORIZONTAL_SCROLL_FACTOR)
+}
+
+// this returns the amount we'll scroll if we want to scroll by a page.
+func (self *ViewTrait) PageDelta() int {
+	view := self.getView()
+
+	_, height := view.Size()
+
+	delta := height - 1
+	if delta == 0 {
+		return 1
+	}
+
+	return delta
+}
+
+func (self *ViewTrait) SelectedLineIdx() int {
+	return self.getView().SelectedLineIdx()
+}