scrollback buffer

buffer/buffer.go

@@ -14,6 +14,7 @@ type Buffer struct {
 	displayChangeHandlers []chan bool
 	savedX                uint16
 	savedY                uint16
+	scrollLinesFromBottom uint
 }
 
 // NewBuffer creates a new terminal buffer
@@ -28,6 +29,49 @@ func NewBuffer(viewCols uint16, viewLines uint16, attr CellAttributes) *Buffer {
 	return b
 }
 
+func (buffer *Buffer) GetScrollOffset() uint {
+	return buffer.scrollLinesFromBottom
+}
+
+func (buffer *Buffer) ScrollDown(lines uint16) {
+
+	if buffer.Height() < int(buffer.ViewHeight()) {
+		return
+	}
+
+	defer buffer.emitDisplayChange()
+	if uint(lines) > buffer.scrollLinesFromBottom {
+		lines = uint16(buffer.scrollLinesFromBottom)
+	}
+	buffer.scrollLinesFromBottom -= uint(lines)
+}
+
+func (buffer *Buffer) ScrollUp(lines uint16) {
+
+	if buffer.Height() < int(buffer.ViewHeight()) {
+		return
+	}
+
+	defer buffer.emitDisplayChange()
+
+	if uint(lines)+buffer.scrollLinesFromBottom >= (uint(buffer.Height()) - uint(buffer.ViewHeight())) {
+		buffer.scrollLinesFromBottom = uint(buffer.Height()) - uint(buffer.ViewHeight())
+	} else {
+		buffer.scrollLinesFromBottom += uint(lines)
+	}
+}
+
+func (buffer *Buffer) ScrollPageDown() {
+	buffer.ScrollDown(buffer.viewHeight)
+}
+func (buffer *Buffer) ScrollPageUp() {
+	buffer.ScrollUp(buffer.viewHeight)
+}
+func (buffer *Buffer) ScrollToEnd() {
+	defer buffer.emitDisplayChange()
+	buffer.scrollLinesFromBottom = 0
+}
+
 func (buffer *Buffer) SaveCursor() {
 	buffer.savedX = buffer.cursorX
 	buffer.savedY = buffer.cursorY
@@ -117,6 +161,10 @@ func (buffer *Buffer) ViewHeight() uint16 {
 
 // Write will write a rune to the terminal at the position of the cursor, and increment the cursor position
 func (buffer *Buffer) Write(runes ...rune) {
+
+	// scroll to bottom on input
+	buffer.scrollLinesFromBottom = 0
+
 	for _, r := range runes {
 		if r == 0x0a {
 			buffer.NewLine()
@@ -249,8 +297,9 @@ func (buffer *Buffer) SetPosition(col uint16, line uint16) {
 func (buffer *Buffer) GetVisibleLines() []Line {
 	lines := []Line{}
 	for i := buffer.Height() - int(buffer.ViewHeight()); i < buffer.Height(); i++ {
-		if i >= 0 && i < len(buffer.lines) {
+		y := i - int(buffer.scrollLinesFromBottom)
-			lines = append(lines, buffer.lines[i])
+		if y >= 0 && y < len(buffer.lines) {
+			lines = append(lines, buffer.lines[y])
 		}
 	}
 	return lines

buffer/buffer_test.go

@@ -422,9 +422,9 @@ func TestBackspaceWithWrap(t *testing.T) {
 	b.Backspace()
 	b.Backspace()
 	b.Backspace()
+	b.EraseLineFromCursor()
 	lines := b.GetVisibleLines()
 	assert.Equal(t, "hello\x00\x00\x00\x00\x00", lines[0].String())
-	assert.Equal(t, "\x00\x00\x00\x00\x00", lines[1].String())
 }
 
 func TestHorizontalResizeView(t *testing.T) {

buffer/line.go

@@ -12,6 +12,10 @@ func newLine() Line {
 	}
 }
 
+func (line *Line) Cells() []Cell {
+	return line.cells
+}
+
 // Cleanse removes null bytes from the end of the row
 func (line *Line) Cleanse() {
 	cut := 0

gui/gui.go

@@ -66,6 +66,15 @@ func (gui *GUI) resize(w *glfw.Window, width int, height int) {
 
 }
 
+func (gui *GUI) glfwScrollCallback(w *glfw.Window, xoff float64, yoff float64) {
+	//fmt.Printf("Scroll x=%f y=%f\n", xoff, yoff)
+	if yoff > 0 {
+		gui.terminal.ScrollUp(1)
+	} else {
+		gui.terminal.ScrollDown(1)
+	}
+}
+
 func (gui *GUI) getTermSize() (int, int) {
 	if gui.renderer == nil {
 		return 0, 0
@@ -113,6 +122,7 @@ func (gui *GUI) Render() error {
 	gui.window.SetFramebufferSizeCallback(gui.resize)
 	gui.window.SetKeyCallback(gui.key)
 	gui.window.SetCharCallback(gui.char)
+	gui.window.SetScrollCallback(gui.glfwScrollCallback)
 	gui.window.SetRefreshCallback(func(w *glfw.Window) {
 		select {
 		case changeChan <- true:
@@ -187,17 +197,18 @@ func (gui *GUI) Render() error {
 		if gui.config.Rendering.AlwaysRepaint || frames > 0 {
 
 			gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
-			cols, rows := gui.getTermSize()
 
-			for row := 0; row < rows; row++ {
+			lines := gui.terminal.GetVisibleLines()
-				for col := 0; col < cols; col++ {
+			for y := 0; y < len(lines); y++ {
-					gui.renderer.DrawCell(gui.terminal.GetCell(col, row), col, row)
+				for x, cell := range lines[y].Cells() {
+					gui.renderer.DrawCell(cell, x, y)
 				}
 			}
 
 			if gui.terminal.Modes().ShowCursor {
 				cx := int(gui.terminal.GetLogicalCursorX())
 				cy := int(gui.terminal.GetLogicalCursorY())
+				cy = int(cy) + int(gui.terminal.GetScrollOffset())
 				gui.renderer.DrawCursor(cx, cy, gui.config.ColourScheme.Cursor)
 			}
 

gui/renderer.go

@@ -12,7 +12,7 @@ import (
 
 type Renderer interface {
 	SetArea(areaX int, areaY int, areaWidth int, areaHeight int)
-	DrawCell(cell *buffer.Cell, col int, row int)
+	DrawCell(cell buffer.Cell, col int, row int)
 	DrawCursor(col int, row int, colour config.Colour)
 	GetTermSize() (int, int)
 }
@@ -218,9 +218,9 @@ func (r *OpenGLRenderer) DrawCursor(col int, row int, colour config.Colour) {
 	//gl.PolygonMode(gl.FRONT_AND_BACK, gl.FILL)
 }
 
-func (r *OpenGLRenderer) DrawCell(cell *buffer.Cell, col int, row int) {
+func (r *OpenGLRenderer) DrawCell(cell buffer.Cell, col int, row int) {
 
-	if cell == nil || cell.Attr().Hidden || (cell.Rune() == 0x00) {
+	if cell.Attr().Hidden || (cell.Rune() == 0x00) {
 		return
 	}
 

terminal/terminal.go

@@ -66,6 +66,32 @@ func New(pty *os.File, logger *zap.SugaredLogger, config config.Config) *Termina
 	}
 }
 
+func (terminal *Terminal) GetScrollOffset() uint {
+	return terminal.buffer.GetScrollOffset()
+}
+
+func (terminal *Terminal) ScrollDown(lines uint16) {
+	terminal.buffer.ScrollDown(lines)
+}
+
+func (terminal *Terminal) ScrollUp(lines uint16) {
+	terminal.buffer.ScrollUp(lines)
+}
+
+func (terminal *Terminal) ScrollPageDown() {
+	terminal.buffer.ScrollPageDown()
+}
+func (terminal *Terminal) ScrollPageUp() {
+	terminal.buffer.ScrollPageUp()
+}
+func (terminal *Terminal) ScrollToEnd() {
+	terminal.buffer.ScrollToEnd()
+}
+
+func (terminal *Terminal) GetVisibleLines() []buffer.Line {
+	return terminal.buffer.GetVisibleLines()
+}
+
 func (terminal *Terminal) GetCell(col int, row int) *buffer.Cell {
 	return terminal.buffer.GetCell(col, row)
 }