reduce flicker without worrying about carriage returns

go.mod

@@ -20,7 +20,7 @@ require (
 	github.com/imdario/mergo v0.3.11
 	github.com/integrii/flaggy v1.4.0
 	github.com/jesseduffield/go-git/v5 v5.1.2-0.20201006095850-341962be15a4
-	github.com/jesseduffield/gocui v0.3.1-0.20210405093708-e79dab8f7772
+	github.com/jesseduffield/gocui v0.3.1-0.20210409121040-210802112d8a
 	github.com/jesseduffield/termbox-go v0.0.0-20200823212418-a2289ed6aafe // indirect
 	github.com/jesseduffield/yaml v2.1.0+incompatible
 	github.com/kardianos/osext v0.0.0-20190222173326-2bc1f35cddc0
@@ -40,7 +40,7 @@ require (
 	golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0 // indirect
 	golang.org/x/net v0.0.0-20201002202402-0a1ea396d57c // indirect
 	golang.org/x/sys v0.0.0-20210403161142-5e06dd20ab57 // indirect
-	golang.org/x/term v0.0.0-20210317153231-de623e64d2a6 // indirect
+	golang.org/x/term v0.0.0-20210406210042-72f3dc4e9b72 // indirect
 	golang.org/x/text v0.3.6 // indirect
 )
 

go.sum

@@ -102,6 +102,12 @@ github.com/jesseduffield/gocui v0.3.1-0.20210405041826-439abd8b6e07 h1:BymGR28au
 github.com/jesseduffield/gocui v0.3.1-0.20210405041826-439abd8b6e07/go.mod h1:QWq79xplEoyhQO+dgpk3sojjTVRKjQklyTlzm5nC5Kg=
 github.com/jesseduffield/gocui v0.3.1-0.20210405093708-e79dab8f7772 h1:dg9krj10Udac4IcvlVCOAPktQkfggkgtqRmbDKk7Pzw=
 github.com/jesseduffield/gocui v0.3.1-0.20210405093708-e79dab8f7772/go.mod h1:QWq79xplEoyhQO+dgpk3sojjTVRKjQklyTlzm5nC5Kg=
+github.com/jesseduffield/gocui v0.3.1-0.20210406065811-95ef6e13779b h1:3+4+muhhikpls5FePXSRNFgcdoPx8dTdqaCy3AqLz98=
+github.com/jesseduffield/gocui v0.3.1-0.20210406065811-95ef6e13779b/go.mod h1:QWq79xplEoyhQO+dgpk3sojjTVRKjQklyTlzm5nC5Kg=
+github.com/jesseduffield/gocui v0.3.1-0.20210406065942-1b0c68414064 h1:Oe+QJuUIOd2TU+A3BW5sT1eXqceoBcOOfyoHlGf7F8Y=
+github.com/jesseduffield/gocui v0.3.1-0.20210406065942-1b0c68414064/go.mod h1:QWq79xplEoyhQO+dgpk3sojjTVRKjQklyTlzm5nC5Kg=
+github.com/jesseduffield/gocui v0.3.1-0.20210409121040-210802112d8a h1:ocrSuZxQIgWWt27b+rjiyIIPz6fzfFeoL5Q4cpa2cAo=
+github.com/jesseduffield/gocui v0.3.1-0.20210409121040-210802112d8a/go.mod h1:QWq79xplEoyhQO+dgpk3sojjTVRKjQklyTlzm5nC5Kg=
 github.com/jesseduffield/termbox-go v0.0.0-20200823212418-a2289ed6aafe h1:qsVhCf2RFyyKIUe/+gJblbCpXMUki9rZrHuEctg6M/E=
 github.com/jesseduffield/termbox-go v0.0.0-20200823212418-a2289ed6aafe/go.mod h1:anMibpZtqNxjDbxrcDEAwSdaJ37vyUeM1f/M4uekib4=
 github.com/jesseduffield/yaml v2.1.0+incompatible h1:HWQJ1gIv2zHKbDYNp0Jwjlj24K8aqpFHnMCynY1EpmE=
@@ -226,6 +232,8 @@ golang.org/x/term v0.0.0-20201210144234-2321bbc49cbf h1:MZ2shdL+ZM/XzY3ZGOnh4Nlp
 golang.org/x/term v0.0.0-20201210144234-2321bbc49cbf/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210317153231-de623e64d2a6 h1:EC6+IGYTjPpRfv9a2b/6Puw0W+hLtAhkV1tPsXhutqs=
 golang.org/x/term v0.0.0-20210317153231-de623e64d2a6/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/term v0.0.0-20210406210042-72f3dc4e9b72 h1:VqE9gduFZ4dbR7XoL77lHFp0/DyDUBKSXK7CMFkVcV0=
+golang.org/x/term v0.0.0-20210406210042-72f3dc4e9b72/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=

pkg/gui/tasks_adapter.go

@@ -83,13 +83,23 @@ func (gui *Gui) getManager(view *gocui.View) *tasks.ViewBufferManager {
 			gui.Log,
 			view,
 			func() {
-				view.Clear()
+				// we could clear here, but that actually has the effect of causing a flicker
+				// where the view may contain no content momentarily as the gui refreshes.
+				// Instead, we're rewinding the write pointer so that we will just start
+				// overwriting the existing content from the top down. Once we've reached
+				// the end of the content do display, we call view.FlushStaleCells() to
+				// clear out the remaining content from the previous render.
+				view.Reset()
 			},
 			func() {
 				gui.g.Update(func(*gocui.Gui) error {
 					return nil
 				})
-			})
+			},
+			func() {
+				view.FlushStaleCells()
+			},
+		)
 		gui.viewBufferManagerMap[view.Name()] = manager
 	}
 

pkg/tasks/tasks.go

@@ -33,12 +33,13 @@ type ViewBufferManager struct {
 	readLines    chan int
 
 	// beforeStart is the function that is called before starting a new task
-	beforeStart func()
+	beforeStart     func()
-	refreshView func()
+	refreshView     func()
+	flushStaleCells func()
 }
 
-func NewViewBufferManager(log *logrus.Entry, writer io.Writer, beforeStart func(), refreshView func()) *ViewBufferManager {
+func NewViewBufferManager(log *logrus.Entry, writer io.Writer, beforeStart func(), refreshView func(), flushStaleCells func()) *ViewBufferManager {
-	return &ViewBufferManager{Log: log, writer: writer, beforeStart: beforeStart, refreshView: refreshView, readLines: make(chan int, 1024)}
+	return &ViewBufferManager{Log: log, writer: writer, beforeStart: beforeStart, refreshView: refreshView, flushStaleCells: flushStaleCells, readLines: make(chan int, 1024)}
 }
 
 func (m *ViewBufferManager) ReadLines(n int) {
@@ -75,7 +76,7 @@ func (m *ViewBufferManager) NewCmdTask(r io.Reader, cmd *exec.Cmd, prefix string
 			loaded := false
 
 			go utils.Safe(func() {
-				ticker := time.NewTicker(time.Millisecond * 100)
+				ticker := time.NewTicker(time.Millisecond * 200)
 				defer ticker.Stop()
 				select {
 				case <-ticker.C:
@@ -114,6 +115,9 @@ func (m *ViewBufferManager) NewCmdTask(r io.Reader, cmd *exec.Cmd, prefix string
 						default:
 						}
 						if !ok {
+							// if we're here then there's nothing left to scan from the source
+							// so we're at the EOF and can flush the stale content
+							m.flushStaleCells()
 							m.refreshView()
 							break outer
 						}

vendor/github.com/jesseduffield/gocui/gui.go

@@ -266,11 +266,14 @@ 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.x0 = x0
 		v.y0 = y0
 		v.x1 = x1
 		v.y1 = y1
-		v.tainted = true
 		return v, nil
 	}
 

vendor/github.com/jesseduffield/gocui/view.go

@@ -518,16 +518,20 @@ func (v *View) writeCells(x, y int, cells []cell) {
 // of functions like fmt.Fprintf, fmt.Fprintln, io.Copy, etc. Clear must
 // be called to clear the view's buffer.
 func (v *View) Write(p []byte) (n int, err error) {
-	v.tainted = true
 	v.writeMutex.Lock()
+	defer v.writeMutex.Unlock()
+
+	v.tainted = true
 	v.makeWriteable(v.wx, v.wy)
 	v.writeRunes(bytes.Runes(p))
-	v.writeMutex.Unlock()
 
 	return len(p), nil
 }
 
 func (v *View) WriteRunes(p []rune) {
+	v.writeMutex.Lock()
+	defer v.writeMutex.Unlock()
+
 	v.tainted = true
 
 	// Fill with empty cells, if writing outside current view buffer
@@ -640,8 +644,53 @@ func (v *View) Read(p []byte) (n int, err error) {
 	return offset, io.EOF
 }
 
+// Clear empties the view's internal buffer.
+// And resets reading and writing offsets.
+func (v *View) Clear() {
+	v.writeMutex.Lock()
+	defer v.writeMutex.Unlock()
+
+	v.rewind()
+	v.tainted = true
+	v.lines = nil
+	v.viewLines = nil
+	v.clearRunes()
+}
+
 // Rewind sets read and write pos to (0, 0).
 func (v *View) Rewind() {
+	v.writeMutex.Lock()
+	defer v.writeMutex.Unlock()
+
+	v.rewind()
+}
+
+// similar to Rewind but clears lines. Also similar to Clear but doesn't reset
+// viewLines
+func (v *View) Reset() {
+	v.writeMutex.Lock()
+	defer v.writeMutex.Unlock()
+
+	v.rewind()
+	v.lines = nil
+}
+
+// This is for when we've done a restart for the sake of avoiding a flicker and
+// we've reached the end of the new content to display: we need to clear the remaining
+// content from the previous round. We do this by setting v.viewLines to nil so that
+// we just render the new content from v.lines directly
+func (v *View) FlushStaleCells() {
+	v.writeMutex.Lock()
+	defer v.writeMutex.Unlock()
+
+	v.rewind()
+	v.tainted = true
+	v.viewLines = nil
+}
+
+func (v *View) rewind() {
+	v.ei.reset()
+
 	if err := v.SetReadPos(0, 0); err != nil {
 		// SetReadPos returns error only if x and y are negative
 		// we are passing 0, 0, thus no error should occur.
@@ -718,7 +767,7 @@ func (v *View) draw() error {
 		v.ox = 0
 	}
 	if v.tainted {
-		v.viewLines = nil
+		lineIdx := 0
 		lines := v.lines
 		if v.HasLoader {
 			lines = v.loaderLines()
@@ -732,7 +781,13 @@ func (v *View) draw() error {
 			ls := lineWrap(line, wrap)
 			for j := range ls {
 				vline := viewLine{linesX: j, linesY: i, line: ls[j]}
-				v.viewLines = append(v.viewLines, vline)
+
+				if lineIdx > len(v.viewLines)-1 {
+					v.viewLines = append(v.viewLines, vline)
+				} else {
+					v.viewLines[lineIdx] = vline
+				}
+				lineIdx++
 			}
 		}
 		if !v.HasLoader {
@@ -828,19 +883,6 @@ func (v *View) realPosition(vx, vy int) (x, y int, err error) {
 	return x, y, nil
 }
 
-// Clear empties the view's internal buffer.
-// And resets reading and writing offsets.
-func (v *View) Clear() {
-	v.writeMutex.Lock()
-	v.Rewind()
-	v.tainted = true
-	v.ei.reset()
-	v.lines = nil
-	v.viewLines = nil
-	v.clearRunes()
-	v.writeMutex.Unlock()
-}
-
 // clearRunes erases all the cells in the view.
 func (v *View) clearRunes() {
 	maxX, maxY := v.Size()

vendor/golang.org/x/term/term_solaris.go

@@ -1,111 +0,0 @@
-// Copyright 2019 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package term
-
-import (
-	"io"
-	"syscall"
-
-	"golang.org/x/sys/unix"
-)
-
-// State contains the state of a terminal.
-type state struct {
-	termios unix.Termios
-}
-
-func isTerminal(fd int) bool {
-	_, err := unix.IoctlGetTermio(fd, unix.TCGETA)
-	return err == nil
-}
-
-func readPassword(fd int) ([]byte, error) {
-	// see also: http://src.illumos.org/source/xref/illumos-gate/usr/src/lib/libast/common/uwin/getpass.c
-	val, err := unix.IoctlGetTermios(fd, unix.TCGETS)
-	if err != nil {
-		return nil, err
-	}
-	oldState := *val
-
-	newState := oldState
-	newState.Lflag &^= syscall.ECHO
-	newState.Lflag |= syscall.ICANON | syscall.ISIG
-	newState.Iflag |= syscall.ICRNL
-	err = unix.IoctlSetTermios(fd, unix.TCSETS, &newState)
-	if err != nil {
-		return nil, err
-	}
-
-	defer unix.IoctlSetTermios(fd, unix.TCSETS, &oldState)
-
-	var buf [16]byte
-	var ret []byte
-	for {
-		n, err := syscall.Read(fd, buf[:])
-		if err != nil {
-			return nil, err
-		}
-		if n == 0 {
-			if len(ret) == 0 {
-				return nil, io.EOF
-			}
-			break
-		}
-		if buf[n-1] == '\n' {
-			n--
-		}
-		ret = append(ret, buf[:n]...)
-		if n < len(buf) {
-			break
-		}
-	}
-
-	return ret, nil
-}
-
-func makeRaw(fd int) (*State, error) {
-	// see http://cr.illumos.org/~webrev/andy_js/1060/
-	termios, err := unix.IoctlGetTermios(fd, unix.TCGETS)
-	if err != nil {
-		return nil, err
-	}
-
-	oldState := State{state{termios: *termios}}
-
-	termios.Iflag &^= unix.IGNBRK | unix.BRKINT | unix.PARMRK | unix.ISTRIP | unix.INLCR | unix.IGNCR | unix.ICRNL | unix.IXON
-	termios.Oflag &^= unix.OPOST
-	termios.Lflag &^= unix.ECHO | unix.ECHONL | unix.ICANON | unix.ISIG | unix.IEXTEN
-	termios.Cflag &^= unix.CSIZE | unix.PARENB
-	termios.Cflag |= unix.CS8
-	termios.Cc[unix.VMIN] = 1
-	termios.Cc[unix.VTIME] = 0
-
-	if err := unix.IoctlSetTermios(fd, unix.TCSETS, termios); err != nil {
-		return nil, err
-	}
-
-	return &oldState, nil
-}
-
-func restore(fd int, oldState *State) error {
-	return unix.IoctlSetTermios(fd, unix.TCSETS, &oldState.termios)
-}
-
-func getState(fd int) (*State, error) {
-	termios, err := unix.IoctlGetTermios(fd, unix.TCGETS)
-	if err != nil {
-		return nil, err
-	}
-
-	return &State{state{termios: *termios}}, nil
-}
-
-func getSize(fd int) (width, height int, err error) {
-	ws, err := unix.IoctlGetWinsize(fd, unix.TIOCGWINSZ)
-	if err != nil {
-		return 0, 0, err
-	}
-	return int(ws.Col), int(ws.Row), nil
-}

vendor/golang.org/x/term/term_unix.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || zos
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
-// +build aix darwin dragonfly freebsd linux netbsd openbsd zos
+// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris zos
 
 package term
 

vendor/golang.org/x/term/term_unix_solaris.go

@@ -0,0 +1,10 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package term
+
+import "golang.org/x/sys/unix"
+
+const ioctlReadTermios = unix.TCGETS
+const ioctlWriteTermios = unix.TCSETS

vendor/modules.txt

@@ -149,7 +149,7 @@ github.com/jesseduffield/go-git/v5/utils/merkletrie/filesystem
 github.com/jesseduffield/go-git/v5/utils/merkletrie/index
 github.com/jesseduffield/go-git/v5/utils/merkletrie/internal/frame
 github.com/jesseduffield/go-git/v5/utils/merkletrie/noder
-# github.com/jesseduffield/gocui v0.3.1-0.20210405093708-e79dab8f7772
+# github.com/jesseduffield/gocui v0.3.1-0.20210409121040-210802112d8a
 ## explicit
 github.com/jesseduffield/gocui
 # github.com/jesseduffield/termbox-go v0.0.0-20200823212418-a2289ed6aafe
@@ -242,7 +242,7 @@ golang.org/x/sys/internal/unsafeheader
 golang.org/x/sys/plan9
 golang.org/x/sys/unix
 golang.org/x/sys/windows
-# golang.org/x/term v0.0.0-20210317153231-de623e64d2a6
+# golang.org/x/term v0.0.0-20210406210042-72f3dc4e9b72
 ## explicit
 golang.org/x/term
 # golang.org/x/text v0.3.6