fix: getting last rendered line counts including alt screen lines (charmbracelet#1254)

semihbkgr · web-flow · commit 2556e01416b7 · 2024-12-04T15:51:28.000-05:00
* get last rendered line counts including alt screen lines

* update the comment
diff --git a/standard_renderer.go b/standard_renderer.go
@@ -258,13 +258,8 @@ func (r *standardRenderer) flush() {
 		}
 	}
 
-	lastLinesRendered := r.linesRendered
-	if r.altScreenActive {
-		lastLinesRendered = r.altLinesRendered
-	}
-
 	// Clearing left over content from last render.
-	if lastLinesRendered > len(newLines) {
+	if r.lastLinesRendered() > len(newLines) {
 		buf.WriteString(ansi.EraseScreenBelow)
 	}
 
@@ -295,6 +290,14 @@ func (r *standardRenderer) flush() {
 	r.buf.Reset()
 }
 
+// lastLinesRendered returns the number of lines rendered lastly.
+func (r *standardRenderer) lastLinesRendered() int {
+	if r.altScreenActive {
+		return r.altLinesRendered
+	}
+	return r.linesRendered
+}
+
 // write writes to the internal buffer. The buffer will be outputted via the
 // ticker which calls flush().
 func (r *standardRenderer) write(s string) {
@@ -507,7 +510,7 @@ func (r *standardRenderer) setWindowTitle(title string) {
 func (r *standardRenderer) setIgnoredLines(from int, to int) {
 	// Lock if we're going to be clearing some lines since we don't want
 	// anything jacking our cursor.
-	if r.linesRendered > 0 {
+	if r.lastLinesRendered() > 0 {
 		r.mtx.Lock()
 		defer r.mtx.Unlock()
 	}
@@ -520,16 +523,17 @@ func (r *standardRenderer) setIgnoredLines(from int, to int) {
 	}
 
 	// Erase ignored lines
-	if r.linesRendered > 0 {
+	lastLinesRendered := r.lastLinesRendered()
+	if lastLinesRendered > 0 {
 		buf := &bytes.Buffer{}
 
-		for i := r.linesRendered - 1; i >= 0; i-- {
+		for i := lastLinesRendered - 1; i >= 0; i-- {
 			if _, exists := r.ignoreLines[i]; exists {
 				buf.WriteString(ansi.EraseEntireLine)
 			}
 			buf.WriteString(ansi.CursorUp1)
 		}
-		buf.WriteString(ansi.SetCursorPosition(0, r.linesRendered)) // put cursor back
+		buf.WriteString(ansi.SetCursorPosition(0, lastLinesRendered)) // put cursor back
 		_, _ = r.out.Write(buf.Bytes())
 	}
 }
@@ -575,7 +579,7 @@ func (r *standardRenderer) insertTop(lines []string, topBoundary, bottomBoundary
 	buf.WriteString(ansi.SetScrollingRegion(0, r.height))
 
 	// Move cursor back to where the main rendering routine expects it to be
-	buf.WriteString(ansi.SetCursorPosition(0, r.linesRendered))
+	buf.WriteString(ansi.SetCursorPosition(0, r.lastLinesRendered()))
 
 	_, _ = r.out.Write(buf.Bytes())
 }
@@ -604,7 +608,7 @@ func (r *standardRenderer) insertBottom(lines []string, topBoundary, bottomBound
 	buf.WriteString(ansi.SetScrollingRegion(0, r.height))
 
 	// Move cursor back to where the main rendering routine expects it to be
-	buf.WriteString(ansi.SetCursorPosition(0, r.linesRendered))
+	buf.WriteString(ansi.SetCursorPosition(0, r.lastLinesRendered()))
 
 	_, _ = r.out.Write(buf.Bytes())
 }

Original file line number	Diff line number	Diff line change
`@@ -258,13 +258,8 @@ func (r *standardRenderer) flush() {`
`258`	`258`	`}`
`259`	`259`	`}`
`260`	`260`
`261`		`- lastLinesRendered := r.linesRendered`
`262`		`- if r.altScreenActive {`
`263`		`- lastLinesRendered = r.altLinesRendered`
`264`		`- }`
`265`		`-`
`266`	`261`	`// Clearing left over content from last render.`
`267`		`- if lastLinesRendered > len(newLines) {`
	`262`	`+ if r.lastLinesRendered() > len(newLines) {`
`268`	`263`	`buf.WriteString(ansi.EraseScreenBelow)`
`269`	`264`	`}`
`270`	`265`
`@@ -295,6 +290,14 @@ func (r *standardRenderer) flush() {`
`295`	`290`	`r.buf.Reset()`
`296`	`291`	`}`
`297`	`292`
	`293`	`+// lastLinesRendered returns the number of lines rendered lastly.`
	`294`	`+func (r *standardRenderer) lastLinesRendered() int {`
	`295`	`+ if r.altScreenActive {`
	`296`	`+ return r.altLinesRendered`
	`297`	`+ }`
	`298`	`+ return r.linesRendered`
	`299`	`+}`
	`300`	`+`
`298`	`301`	`// write writes to the internal buffer. The buffer will be outputted via the`
`299`	`302`	`// ticker which calls flush().`
`300`	`303`	`func (r *standardRenderer) write(s string) {`
`@@ -507,7 +510,7 @@ func (r *standardRenderer) setWindowTitle(title string) {`
`507`	`510`	`func (r *standardRenderer) setIgnoredLines(from int, to int) {`
`508`	`511`	`// Lock if we're going to be clearing some lines since we don't want`
`509`	`512`	`// anything jacking our cursor.`
`510`		`- if r.linesRendered > 0 {`
	`513`	`+ if r.lastLinesRendered() > 0 {`
`511`	`514`	`r.mtx.Lock()`
`512`	`515`	`defer r.mtx.Unlock()`
`513`	`516`	`}`
`@@ -520,16 +523,17 @@ func (r *standardRenderer) setIgnoredLines(from int, to int) {`
`520`	`523`	`}`
`521`	`524`
`522`	`525`	`// Erase ignored lines`
`523`		`- if r.linesRendered > 0 {`
	`526`	`+ lastLinesRendered := r.lastLinesRendered()`
	`527`	`+ if lastLinesRendered > 0 {`
`524`	`528`	`buf := &bytes.Buffer{}`
`525`	`529`
`526`		`- for i := r.linesRendered - 1; i >= 0; i-- {`
	`530`	`+ for i := lastLinesRendered - 1; i >= 0; i-- {`
`527`	`531`	`if _, exists := r.ignoreLines[i]; exists {`
`528`	`532`	`buf.WriteString(ansi.EraseEntireLine)`
`529`	`533`	`}`
`530`	`534`	`buf.WriteString(ansi.CursorUp1)`
`531`	`535`	`}`
`532`		`- buf.WriteString(ansi.SetCursorPosition(0, r.linesRendered)) // put cursor back`
	`536`	`+ buf.WriteString(ansi.SetCursorPosition(0, lastLinesRendered)) // put cursor back`
`533`	`537`	`_, _ = r.out.Write(buf.Bytes())`
`534`	`538`	`}`
`535`	`539`	`}`
`@@ -575,7 +579,7 @@ func (r *standardRenderer) insertTop(lines []string, topBoundary, bottomBoundary`
`575`	`579`	`buf.WriteString(ansi.SetScrollingRegion(0, r.height))`
`576`	`580`
`577`	`581`	`// Move cursor back to where the main rendering routine expects it to be`
`578`		`- buf.WriteString(ansi.SetCursorPosition(0, r.linesRendered))`
	`582`	`+ buf.WriteString(ansi.SetCursorPosition(0, r.lastLinesRendered()))`
`579`	`583`
`580`	`584`	`_, _ = r.out.Write(buf.Bytes())`
`581`	`585`	`}`
`@@ -604,7 +608,7 @@ func (r *standardRenderer) insertBottom(lines []string, topBoundary, bottomBound`
`604`	`608`	`buf.WriteString(ansi.SetScrollingRegion(0, r.height))`
`605`	`609`
`606`	`610`	`// Move cursor back to where the main rendering routine expects it to be`
`607`		`- buf.WriteString(ansi.SetCursorPosition(0, r.linesRendered))`
	`611`	`+ buf.WriteString(ansi.SetCursorPosition(0, r.lastLinesRendered()))`
`608`	`612`
`609`	`613`	`_, _ = r.out.Write(buf.Bytes())`
`610`	`614`	`}`