[display] Overwrite terminal contents

changelog/pending/20221220--cli-display--fix-flickering-in-the-interactive-display.yaml

@@ -0,0 +1,4 @@
+changes:
+- type: fix
+  scope: cli/display
+  description: Fix flickering in the interactive display

pkg/backend/display/internal/terminal/info.go

@@ -10,9 +10,12 @@ import (
 type Info interface {
 	Parse(attr string, params ...interface{}) (string, error)
 
+	ClearEnd(out io.Writer)
 	ClearLine(out io.Writer)
 	CursorUp(out io.Writer, count int)
 	CursorDown(out io.Writer, count int)
+	HideCursor(out io.Writer)
+	ShowCursor(out io.Writer)
 }
 
 /* Satisfied by gotty.TermInfo as well as noTermInfo from below */
@@ -56,6 +59,15 @@ func (i info) ClearLine(out io.Writer) {
 	}
 }
 
+func (i info) ClearEnd(out io.Writer) {
+	// clear line from cursor to end
+	if attr, err := i.Parse("el"); err == nil {
+		fmt.Fprintf(out, "%s", attr)
+	} else {
+		fmt.Fprintf(out, "\x1b[K")
+	}
+}
+
 func (i info) CursorUp(out io.Writer, count int) {
 	if count == 0 { // Should never be the case, but be tolerant
 		return
@@ -77,3 +89,15 @@ func (i info) CursorDown(out io.Writer, count int) {
 		fmt.Fprintf(out, "\x1b[%dB", count)
 	}
 }
+
+func (i info) HideCursor(out io.Writer) {
+	if attr, err := i.Parse("civis"); err == nil {
+		fmt.Fprintf(out, "%s", attr)
+	}
+}
+
+func (i info) ShowCursor(out io.Writer) {
+	if attr, err := i.Parse("cnorm"); err == nil {
+		fmt.Fprintf(out, "%s", attr)
+	}
+}

pkg/backend/display/internal/terminal/mock.go

@@ -52,6 +52,10 @@ func (t *MockTerminal) ClearLine() {
 	t.info.ClearLine(t)
 }
 
+func (t *MockTerminal) ClearEnd() {
+	t.info.ClearEnd(t)
+}
+
 func (t *MockTerminal) CursorUp(count int) {
 	t.info.CursorUp(t, count)
 }
@@ -60,6 +64,14 @@ func (t *MockTerminal) CursorDown(count int) {
 	t.info.CursorDown(t, count)
 }
 
+func (t *MockTerminal) HideCursor() {
+	t.info.HideCursor(t)
+}
+
+func (t *MockTerminal) ShowCursor() {
+	t.info.ShowCursor(t)
+}
+
 func (t *MockTerminal) ReadKey() (string, error) {
 	k, ok := <-t.keys
 	if !ok {

pkg/backend/display/internal/terminal/term.go

@@ -18,8 +18,11 @@ type Terminal interface {
 	Size() (width, height int, err error)
 
 	ClearLine()
+	ClearEnd()
 	CursorUp(count int)
 	CursorDown(count int)
+	HideCursor()
+	ShowCursor()
 
 	ReadKey() (string, error)
 }
@@ -131,6 +134,10 @@ func (t *terminal) ClearLine() {
 	t.info.ClearLine(t.out)
 }
 
+func (t *terminal) ClearEnd() {
+	t.info.ClearEnd(t.out)
+}
+
 func (t *terminal) CursorUp(count int) {
 	t.info.CursorUp(t.out, count)
 }
@@ -139,6 +146,14 @@ func (t *terminal) CursorDown(count int) {
 	t.info.CursorDown(t.out, count)
 }
 
+func (t *terminal) HideCursor() {
+	t.info.HideCursor(t.out)
+}
+
+func (t *terminal) ShowCursor() {
+	t.info.ShowCursor(t.out)
+}
+
 func (t *terminal) ReadKey() (string, error) {
 	if t.in == nil {
 		return "", io.EOF

pkg/backend/display/tree.go

@@ -58,6 +58,7 @@ func newInteractiveRenderer(term terminal.Terminal, opts Options) progressRender
 	if !term.IsRaw() {
 		return newInteractiveMessageRenderer(term, opts)
 	}
+	term.HideCursor()
 
 	r := &treeRenderer{
 		opts:   opts,
@@ -75,6 +76,7 @@ func newInteractiveRenderer(term terminal.Terminal, opts Options) progressRender
 }
 
 func (r *treeRenderer) Close() error {
+	r.term.ShowCursor()
 	return r.term.Close()
 }
 
@@ -110,6 +112,16 @@ func (r *treeRenderer) println(display *ProgressDisplay, text string) {
 	r.print("\n")
 }
 
+func (r *treeRenderer) over(text string) {
+	r.print(text)
+	r.term.ClearEnd()
+}
+
+func (r *treeRenderer) overln(text string) {
+	r.over(text)
+	r.print("\n")
+}
+
 func (r *treeRenderer) render(display *ProgressDisplay) {
 	r.m.Lock()
 	defer r.m.Unlock()
@@ -222,7 +234,7 @@ func (r *treeRenderer) frame(locked, done bool) {
 		}
 
 		treeTableHeight = termHeight - systemMessagesHeight - 1
-		r.maxTreeTableOffset = len(treeTableRows) - treeTableHeight - 1
+		r.maxTreeTableOffset = len(treeTableRows) - treeTableHeight + 1
 
 		treeTableRows = treeTableRows[r.treeTableOffset : r.treeTableOffset+treeTableHeight-1]
 
@@ -239,37 +251,40 @@ func (r *treeRenderer) frame(locked, done bool) {
 		footer := fmt.Sprintf("%smore%s", upArrow, downArrow)
 		padding := termWidth - uniseg.GraphemeClusterCount(footer)
 		treeTableFooter = strings.Repeat(" ", padding) + footer
+
+		if systemMessagesHeight > 0 {
+			treeTableFooter += "\n"
+		}
 	}
 
 	// Re-home the cursor.
-	r.term.ClearLine()
+	r.print("\r")
 	for ; r.rewind > 0; r.rewind-- {
 		r.term.CursorUp(1)
-		r.term.ClearLine()
 	}
 	r.rewind = totalHeight - 1
 
 	// Render the tree table.
-	r.println(nil, r.clampLine(treeTableHeader, termWidth))
+	r.overln(r.clampLine(treeTableHeader, termWidth))
 	for _, row := range treeTableRows {
-		r.println(nil, r.clampLine(row, termWidth))
+		r.overln(r.clampLine(row, termWidth))
 	}
 	if treeTableFooter != "" {
-		r.print(treeTableFooter)
+		r.over(treeTableFooter)
 	}
 
 	// Render the system messages.
 	if systemMessagesHeight > 0 {
-		r.println(nil, "")
-		r.println(nil, colors.Yellow+"System Messages"+colors.Reset)
+		r.overln("")
+		r.overln(colors.Yellow + "System Messages" + colors.Reset)
 
 		for _, line := range systemMessages {
-			r.println(nil, "  "+line)
+			r.overln("  " + line)
 		}
 	}
 
 	if done && totalHeight > 0 {
-		r.println(nil, "")
+		r.overln("")
 	}
 }