clear screen conditionally

cursor.go

@@ -19,11 +19,17 @@ func NewGridCursor() *GridCursor {
 func (gc *GridCursor) Len() int             { return len(gc.containers) }
 func (gc *GridCursor) Selected() *Container { return gc.containers[gc.Idx()] }
 
-func (gc *GridCursor) RefreshContainers() {
+// Refresh containers from source
+func (gc *GridCursor) RefreshContainers() (lenChanged bool) {
+	oldLen := gc.Len()
 	gc.containers = gc.cSource.All().Filter()
+	if oldLen != gc.Len() {
+		lenChanged = true
+	}
 	if gc.selectedID == "" {
 		gc.Reset()
 	}
+	return lenChanged
 }
 
 // Set an initial cursor position, if possible

grid.go

@@ -10,7 +10,7 @@ func maxRows() int {
 	return ui.TermHeight() - 2 - cGrid.Y
 }
 
-func RedrawRows() {
+func RedrawRows(clr bool) {
 	// reinit body rows
 	cGrid.Clear()
 
@@ -39,7 +39,10 @@ func RedrawRows() {
 		cursor.Reset()
 	}
 
-	ui.Clear()
+	if clr {
+		ui.Clear()
+		log.Debugf("screen cleared")
+	}
 	if config.GetSwitchVal("enableHeader") {
 		header.Render()
 	}
@@ -73,6 +76,11 @@ func ExpandView(c *Container) {
 	c.SetUpdater(c.Widgets)
 }
 
+func RefreshDisplay() {
+	needsClear := cursor.RefreshContainers()
+	RedrawRows(needsClear)
+}
+
 func Display() bool {
 	var menu func()
 	var expand bool
@@ -83,7 +91,7 @@ func Display() bool {
 	// initial draw
 	header.Align()
 	cursor.RefreshContainers()
-	RedrawRows()
+	RedrawRows(true)
 
 	ui.Handle("/sys/kbd/<up>", func(ui.Event) {
 		cursor.Up()
@@ -98,8 +106,7 @@ func Display() bool {
 
 	ui.Handle("/sys/kbd/a", func(ui.Event) {
 		config.Toggle("allContainers")
-		cursor.RefreshContainers()
-		RedrawRows()
+		RefreshDisplay()
 	})
 	ui.Handle("/sys/kbd/D", func(ui.Event) {
 		dumpContainer(cursor.Selected())
@@ -114,7 +121,7 @@ func Display() bool {
 	})
 	ui.Handle("/sys/kbd/H", func(ui.Event) {
 		config.Toggle("enableHeader")
-		RedrawRows()
+		RedrawRows(true)
 	})
 	ui.Handle("/sys/kbd/q", func(ui.Event) {
 		ui.StopLoop()
@@ -128,15 +135,14 @@ func Display() bool {
 	})
 
 	ui.Handle("/timer/1s", func(e ui.Event) {
-		cursor.RefreshContainers()
-		RedrawRows()
+		RefreshDisplay()
 	})
 
 	ui.Handle("/sys/wnd/resize", func(e ui.Event) {
 		header.Align()
 		cGrid.SetWidth(ui.TermWidth())
 		log.Infof("resize: width=%v max-rows=%v", cGrid.Width, maxRows())
-		RedrawRows()
+		RedrawRows(true)
 	})
 
 	ui.Loop()

menus.go

@@ -46,8 +46,7 @@ func FilterMenu() {
 	go func() {
 		for s := range stream {
 			config.Update("filterStr", s)
-			cursor.RefreshContainers()
-			RedrawRows()
+			RefreshDisplay()
 			ui.Render(i)
 		}
 	}()