Merge pull request #20 from liamg/liamg-fix-output-race-condition

Fix output race condition

Author: liamg

pkg/decorators/decorator.go

@@ -12,8 +12,8 @@ const (
 
 // Decorator is an entity which modifies the terminal output in a desirable way
 type Decorator interface {
-	Draw(rows uint16, cols uint16) // Draw renders the decorator to StdOut
-	GetAnchor() Anchor             // GetAnchor returns the anchor e.g. Top/Bottom
-	GetHeight() (rows uint16)      // GetHeight returns the height of the decorator in terminal character rows
+	Draw(rows uint16, cols uint16, output func(data []byte)) // Draw renders the decorator to StdOut
+	GetAnchor() Anchor                                       // GetAnchor returns the anchor e.g. Top/Bottom
+	GetHeight() (rows uint16)                                // GetHeight returns the height of the decorator in terminal character rows
 	IsVisible() bool
 }

pkg/decorators/statusbar.go

@@ -59,19 +59,22 @@ func (b *StatusBar) SetFg(colour ansi.Colour) {
 }
 
 // Draw renders the decorator to StdOut
-func (b *StatusBar) Draw(rows uint16, cols uint16) {
+func (b *StatusBar) Draw(rows uint16, cols uint16, writeFunc func(data []byte)) {
 
 	var row, col uint16
 	switch b.anchor {
 	case AnchorBottom:
 		row = rows - 1
 	}
-	ansi.SaveCursorPosition()
-	ansi.MoveCursorTo(row+1, col+1)
-	ansi.ClearLine()
+
+	// move cursor to status bar location
+	writeFunc([]byte(fmt.Sprintf("\033[%d;%dH", row+1, col+1)))
+
+	// clear line
+	writeFunc([]byte("\x1b[K"))
 
 	// set colours
-	fmt.Printf("\r\033[%dm\033[%dm", b.bg, b.fg)
+	writeFunc([]byte(fmt.Sprintf("\r\033[%dm\033[%dm", b.bg, b.fg)))
 
 	segments := strings.SplitN(b.format, "|", 3)
 	colSize := int(cols) / len(segments)
@@ -93,15 +96,14 @@ func (b *StatusBar) Draw(rows uint16, cols uint16) {
 			output = padLeft(output, colSize)
 		}
 
-		fmt.Printf("%s", output)
+		writeFunc([]byte(output))
 
 	}
 
 	for i := uint16(0); i < b.padding; i++ {
-		fmt.Printf("\n")
+		writeFunc([]byte{0x0a})
 	}
 
-	ansi.RestoreCursorPosition()
 }
 
 // SetPadding sets a vertical padding on the status bar

pkg/proxy/ansi.go

@@ -17,7 +17,7 @@ func (p *Proxy) proxyANSICommand(input chan byte) (output []byte, original []byt
 	switch b {
 	case 'c': //RIS
 		row, col := p.HandleCoordinates(0, 0)
-		output := []byte(fmt.Sprintf("\033[%d;%dH", row, col))
+		output := []byte(fmt.Sprintf("\033[%d;%dH", row+1, col+1))
 		return output, original, true
 	case '[': // CSI
 		output, original2, redraw, err := p.handleCSI(input)

pkg/proxy/csi.go

@@ -19,6 +19,7 @@ func (p *Proxy) handleCSI(pty chan byte) (output []byte, original []byte, redraw
 		'h': p.csiSetModeHandler,
 		'l': p.csiResetModeHandler,
 		'J': p.csiEraseInDisplayHandler,
+		'r': p.csiSetMarginHandler,
 	}
 
 	var final byte
@@ -136,6 +137,13 @@ func (p *Proxy) csiLinePositionAbsolute(params []string, intermediate string) (o
 	return []byte(fmt.Sprintf("\033[%dd", newRow)), false, nil
 }
 
+// CSI Pt Pb r
+func (p *Proxy) csiSetMarginHandler(params []string, intermediate string) (output []byte, redraw bool, err error) {
+	// pass through command, and inject reset position afterwards
+	row, col := p.HandleCoordinates(0, 0)
+	return []byte(fmt.Sprintf("\033[%d;%dH", row+1, col+1)), true, ErrorCommandNotSupported
+}
+
 // CSI Ps J
 func (p *Proxy) csiEraseInDisplayHandler(params []string, intermediate string) (output []byte, redraw bool, err error) {
 
@@ -151,7 +159,7 @@ func (p *Proxy) csiEraseInDisplayHandler(params []string, intermediate string) (
 	switch n {
 	case "2", "3":
 		row, col := p.HandleCoordinates(0, 0)
-		return []byte(fmt.Sprintf("\033[%d;%dH", row, col)), true, ErrorCommandNotSupported
+		return []byte(fmt.Sprintf("\033[%d;%dH", row+1, col+1)), true, ErrorCommandNotSupported
 	}
 
 	return nil, false, ErrorCommandNotSupported

pkg/proxy/proxy.go

@@ -164,6 +164,7 @@ func (p *Proxy) process() {
 	for {
 		select {
 		case b := <-p.workChan:
+
 			if b == 0x1b {
 				output, original, redraw := p.proxyANSICommand(p.workChan)
 				if original != nil {
@@ -222,12 +223,16 @@ func (p *Proxy) redraw() {
 	if !p.canRender {
 		return
 	}
+	//save cursor pos
+	p.writeOutput([]byte("\x1b[s"))
 	for _, decorator := range p.decorators {
 		if !decorator.IsVisible() {
 			continue
 		}
-		decorator.Draw(p.realRows, p.realCols)
+		decorator.Draw(p.realRows, p.realCols, p.writeOutput)
 	}
+	// restore cursor position
+	p.writeOutput([]byte(fmt.Sprintf("\x1b[u")))
 }
 
 func (p *Proxy) writeOutput(data []byte) {