feat: improve rendering performance on windows (c-bata#47)

* feat: to ignore the codepoint 0

* feat: hide cursor whole rendering phase

* feat: change EraseDown timing

* feat: add sleep

* feat: to async Read on windows

* style: goimports

* refactor: use defer

* feat: remove ignore flush

* chore: remove ignore output

prompt.go

@@ -237,16 +237,16 @@ func (p *Prompt) Input() string {
 func (p *Prompt) readBuffer(bufCh chan []byte, stopCh chan struct{}) {
 	log.Printf("[INFO] readBuffer start")
 	for {
-		time.Sleep(10 * time.Millisecond)
 		select {
 		case <-stopCh:
 			log.Print("[INFO] stop readBuffer")
 			return
 		default:
-			if b, err := p.in.Read(); err == nil {
+			if b, err := p.in.Read(); err == nil && !(len(b) == 1 && b[0] == 0) {
 				bufCh <- b
 			}
 		}
+		time.Sleep(10 * time.Millisecond)
 	}
 }
 

render.go

@@ -1,6 +1,8 @@
 package prompt
 
-import "runtime"
+import (
+	"runtime"
+)
 
 // Render to render prompt information from state of Buffer.
 type Render struct {
@@ -172,9 +174,7 @@ func (r *Render) Render(buffer *Buffer, completion *CompletionManager) {
 	if r.col == 0 {
 		return
 	}
-
-	// Erasing
-	r.clear(r.previousCursor)
+	r.backward(r.previousCursor, r.previousCursor)
 
 	line := buffer.Text()
 	prefix := r.getCurrentPrefix()
@@ -189,13 +189,20 @@ func (r *Render) Render(buffer *Buffer, completion *CompletionManager) {
 		return
 	}
 
+	defer r.out.Flush()
+
 	// Rendering
+	r.out.HideCursor()
+	defer r.out.ShowCursor()
+
 	r.renderPrefix()
 	r.out.SetColor(r.inputTextColor, r.inputBGColor, false)
 	r.out.WriteStr(line)
 	r.out.SetColor(DefaultColor, DefaultColor, false)
 	r.lineWrap(cursor)
 
+	r.out.EraseDown()
+
 	cursor = r.backward(cursor, len(line)-buffer.CursorPosition)
 
 	r.renderCompletion(buffer, completion)
@@ -209,9 +216,6 @@ func (r *Render) Render(buffer *Buffer, completion *CompletionManager) {
 		cursor += len(suggest.Text)
 		r.lineWrap(cursor)
 	}
-
-	r.out.Flush()
-
 	r.previousCursor = cursor
 }
 

windows_input.go

@@ -4,13 +4,20 @@ package prompt
 
 import (
 	"bytes"
+	"errors"
+	"syscall"
 	"unicode/utf8"
+	"unsafe"
 
 	"github.com/mattn/go-tty"
 )
 
 const maxReadBytes = 1024
 
+var kernel32 = syscall.NewLazyDLL("kernel32.dll")
+
+var procGetNumberOfConsoleInputEvents = kernel32.NewProc("GetNumberOfConsoleInputEvents")
+
 // WindowsParser is a ConsoleParser implementation for Win32 console.
 type WindowsParser struct {
 	tty *tty.TTY
@@ -43,11 +50,21 @@ func (p *WindowsParser) GetKey(b []byte) Key {
 
 // Read returns byte array.
 func (p *WindowsParser) Read() ([]byte, error) {
-	buf := make([]byte, maxReadBytes)
+	var ev uint32
+	r0, _, err := procGetNumberOfConsoleInputEvents.Call(p.tty.Input().Fd(), uintptr(unsafe.Pointer(&ev)))
+	if r0 == 0 {
+		return nil, err
+	}
+	if ev == 0 {
+		return nil, errors.New("EAGAIN")
+	}
+
 	r, err := p.tty.ReadRune()
 	if err != nil {
-		return []byte{}, err
+		return nil, err
 	}
+
+	buf := make([]byte, maxReadBytes)
 	n := utf8.EncodeRune(buf[:], r)
 	for p.tty.Buffered() && n < maxReadBytes {
 		r, err := p.tty.ReadRune()

windows_output.go

@@ -20,8 +20,6 @@ type WindowsWriter struct {
 // WriteRaw to write raw byte array
 func (w *WindowsWriter) WriteRaw(data []byte) {
 	w.buffer = append(w.buffer, data...)
-	// Flush because sometimes the render is broken when a large amount data in buffer.
-	w.Flush()
 	return
 }
 
@@ -257,7 +255,6 @@ func (w *WindowsWriter) SetColor(fg, bg Color, bold bool) {
 	if !ok {
 		b, _ = backgroundANSIColors[DefaultColor]
 	}
-	w.out.Write([]byte{0x1b, 0x5b, 0x33, 0x39, 0x3b, 0x34, 0x39, 0x6d})
 	w.WriteRaw([]byte{0x1b, 0x5b})
 	if !bold {
 		w.WriteRaw([]byte{0x30, 0x3b})