Make vertical channel list scrollable

Seems like I really have too many channels... :)

2 files changed, 33 insertions, 9 deletions

diff --git a/ui/buffers.go b/ui/buffers.go
index c126408..8285fc6 100644
--- a/ui/buffers.go
+++ b/ui/buffers.go
@@ -419,27 +419,35 @@ func (bs *BufferList) idx(netID, title string) int {
 	return -1
 }
 
-func (bs *BufferList) DrawVerticalBufferList(screen tcell.Screen, x0, y0, width, height int) {
+func (bs *BufferList) DrawVerticalBufferList(screen tcell.Screen, x0, y0, width, height int, offset *int) {
+	if y0+len(bs.list)-*offset < height {
+		*offset = y0 + len(bs.list) - height
+		if *offset < 0 {
+			*offset = 0
+		}
+	}
+
 	width--
 	drawVerticalLine(screen, x0+width, y0, height)
 	clearArea(screen, x0, y0, width, height)
 
 	indexPadding := 1 + int(math.Ceil(math.Log10(float64(len(bs.list)))))
-	for i, b := range bs.list {
+	for i, b := range bs.list[*offset:] {
+		bi := *offset + i
 		x := x0
 		y := y0 + i
 		st := tcell.StyleDefault
 		if b.unread {
 			st = st.Bold(true)
-		} else if i == bs.current {
+		} else if bi == bs.current {
 			st = st.Underline(true)
 		}
-		if i == bs.clicked {
+		if bi == bs.clicked {
 			st = st.Reverse(true)
 		}
 		if bs.showBufferNumbers {
 			indexSt := st.Foreground(tcell.ColorGray)
-			indexText := fmt.Sprintf("%d:", i)
+			indexText := fmt.Sprintf("%d:", bi)
 			printString(screen, &x, y, Styled(indexText, indexSt))
 			x = x0 + indexPadding
 		}
@@ -448,7 +456,7 @@ func (bs *BufferList) DrawVerticalBufferList(screen tcell.Screen, x0, y0, width,
 		if b.title == "" {
 			title = b.netName
 		} else {
-			if i == bs.clicked {
+			if bi == bs.clicked {
 				screen.SetContent(x, y, ' ', nil, tcell.StyleDefault.Reverse(true))
 				screen.SetContent(x+1, y, ' ', nil, tcell.StyleDefault.Reverse(true))
 			}
@@ -458,7 +466,7 @@ func (bs *BufferList) DrawVerticalBufferList(screen tcell.Screen, x0, y0, width,
 		title = truncate(title, width-(x-x0), "\u2026")
 		printString(screen, &x, y, Styled(title, st))
 
-		if i == bs.clicked {
+		if bi == bs.clicked {
 			st := tcell.StyleDefault.Reverse(true)
 			for ; x < x0+width; x++ {
 				screen.SetContent(x, y, ' ', nil, st)
diff --git a/ui/ui.go b/ui/ui.go
index 68511ab..cda5a06 100644
--- a/ui/ui.go
+++ b/ui/ui.go
@@ -28,7 +28,8 @@ type UI struct {
 	prompt StyledString
 	status string
 
-	memberOffset int
+	channelOffset int
+	memberOffset  int
 }
 
 func New(config Config) (ui *UI, err error) {
@@ -140,6 +141,21 @@ func (ui *UI) ScrollDownHighlight() bool {
 	return ui.bs.ScrollDownHighlight()
 }
 
+func (ui *UI) ScrollChannelUpBy(n int) {
+	ui.channelOffset -= n
+	if ui.channelOffset < 0 {
+		ui.channelOffset = 0
+	}
+}
+
+func (ui *UI) ScrollChannelDownBy(n int) {
+	ui.channelOffset += n
+}
+
+func (ui *UI) ChannelOffset() int {
+	return ui.channelOffset
+}
+
 func (ui *UI) ScrollMemberUpBy(n int) {
 	ui.memberOffset -= n
 	if ui.memberOffset < 0 {
@@ -315,7 +331,7 @@ func (ui *UI) Draw(members []irc.Member) {
 	if ui.config.ChanColWidth == 0 {
 		ui.bs.DrawHorizontalBufferList(ui.screen, 0, h-1, w-ui.config.MemberColWidth)
 	} else {
-		ui.bs.DrawVerticalBufferList(ui.screen, 0, 0, ui.config.ChanColWidth, h)
+		ui.bs.DrawVerticalBufferList(ui.screen, 0, 0, ui.config.ChanColWidth, h, &ui.channelOffset)
 	}
 	if ui.config.MemberColWidth != 0 {
 		drawVerticalMemberList(ui.screen, w-ui.config.MemberColWidth, 0, ui.config.MemberColWidth, h, members, &ui.memberOffset)