prevent issues from re-rendering views

edit.go

@@ -430,7 +430,7 @@ func (v *View) mergeLines(y int) error {
 	v.writeMutex.Lock()
 	defer v.writeMutex.Unlock()
 
-	v.tainted = true
+	v.clearViewLines()
 
 	_, y, err := v.realPosition(0, y)
 	if err != nil {

gui.go

@@ -272,7 +272,7 @@ func (g *Gui) SetView(name string, x0, y0, x1, y1 int, overlaps byte) (*View, er
 
 	if v, err := g.View(name); err == nil {
 		if v.x0 != x0 || v.x1 != x1 || v.y0 != y0 || v.y1 != y1 {
-			v.tainted = true
+			v.clearViewLines()
 		}
 
 		v.x0 = x0
@@ -660,11 +660,7 @@ func (g *Gui) handleEvent(ev *GocuiEvent) error {
 }
 
 func (g *Gui) onResize() {
-	for _, v := range g.views {
-		// wonder if we should be calling this in other contexts e.g. whenever the view's dimensions change in general
-		v.FlushStaleCells()
-	}
-	// Not sure if we actually need this
+	// not sure if we actually need this
 	// g.screen.Sync()
 }
 
@@ -677,7 +673,7 @@ func (g *Gui) flush() error {
 	// if GUI's size has changed, we need to redraw all views
 	if maxX != g.maxX || maxY != g.maxY {
 		for _, v := range g.views {
-			v.tainted = true
+			v.clearViewLines()
 		}
 	}
 	g.maxX, g.maxY = maxX, maxY

view.go

@@ -48,7 +48,12 @@ type View struct {
 	// tained is true if the viewLines must be updated
 	tainted bool
 
-	// internal representation of the view's buffer
+	// internal representation of the view's buffer. We will keep viewLines around
+	// from a previous render until we explicitly set them to nil, allowing us to
+	// render the same content twice without flicker. Wherever we want to render
+	// something without any chance of old content appearing (e.g. when actually
+	// rendering new content or if the view is resized) we should set tainted to
+	// true and viewLines to nil
 	viewLines []viewLine
 
 	// writeMutex protects locks the write process
@@ -155,6 +160,14 @@ type View struct {
 	KeybindOnEdit bool
 }
 
+// call this in the event of a view resize, or if you want to render new content
+// without the chance of old content still appearing, or if you want to remove
+// a line from the existing content
+func (v *View) clearViewLines() {
+	v.tainted = true
+	v.viewLines = nil
+}
+
 type searcher struct {
 	searchString       string
 	searchPositions    []cellPos
@@ -651,9 +664,8 @@ func (v *View) Clear() {
 	defer v.writeMutex.Unlock()
 
 	v.rewind()
-	v.tainted = true
 	v.lines = nil
-	v.viewLines = nil
+	v.clearViewLines()
 	v.clearRunes()
 }
 
@@ -683,8 +695,7 @@ func (v *View) FlushStaleCells() {
 	v.writeMutex.Lock()
 	defer v.writeMutex.Unlock()
 
-	v.tainted = true
-	v.viewLines = nil
+	v.clearViewLines()
 }
 
 func (v *View) rewind() {