Fix and/or break scroll bar

This commit is contained in:
Tulir Asokan 2018-03-26 14:31:44 +03:00
parent ef326eae82
commit 6095638fbb
2 changed files with 57 additions and 31 deletions

View File

@ -232,11 +232,16 @@ func (view *MainView) MouseEventHandler(roomView *widget.RoomView, event *tcell.
go view.LoadHistory(roomView.Room.ID, false)
} else {
msgView.AddScrollOffset(WheelScrollOffsetDiff)
view.parent.Render()
}
case tcell.WheelDown:
msgView.AddScrollOffset(-WheelScrollOffsetDiff)
view.parent.Render()
default:
debug.Print("Mouse event received:", event.Buttons(), event.Modifiers(), x, y)
return event
}
return event

View File

@ -214,20 +214,16 @@ func (view *MessageView) AddScrollOffset(diff int) {
_, _, _, height := view.GetInnerRect()
totalHeight := len(view.textBuffer)
if diff >= 0 && view.ScrollOffset >= totalHeight-height {
// If the user is at the top and presses page up again, add a bit of blank space.
if view.ScrollOffset+diff >= totalHeight-height+PaddingAtTop {
view.ScrollOffset = totalHeight - height + PaddingAtTop
} else {
view.ScrollOffset += diff
}
return
if diff >= 0 && view.ScrollOffset+diff >= totalHeight-height+PaddingAtTop {
view.ScrollOffset = totalHeight - height + PaddingAtTop
} else {
view.ScrollOffset += diff
}
view.ScrollOffset += diff
if view.ScrollOffset > totalHeight-height {
view.ScrollOffset = totalHeight - height
} else if view.ScrollOffset < 0 {
if view.ScrollOffset > totalHeight-height+PaddingAtTop {
view.ScrollOffset = totalHeight - height + PaddingAtTop
}
if view.ScrollOffset < 0 {
view.ScrollOffset = 0
}
}
@ -253,6 +249,30 @@ const (
SenderMessageGap = 3
)
func getScrollbarStyle(scrollbarHere, isTop, isBottom bool) (char rune, style tcell.Style) {
char = '│'
style = tcell.StyleDefault
if scrollbarHere {
style = style.Foreground(tcell.ColorGreen)
}
if isTop {
if scrollbarHere {
char = '╥'
} else {
char = '┬'
}
} else if isBottom {
if scrollbarHere {
char = '╨'
} else {
char = '┴'
}
} else if scrollbarHere {
char = '║'
}
return
}
func (view *MessageView) Draw(screen tcell.Screen) {
view.Box.Draw(screen)
@ -260,7 +280,7 @@ func (view *MessageView) Draw(screen tcell.Screen) {
view.recalculateBuffers()
if len(view.textBuffer) == 0 {
writeLine(screen, tview.AlignLeft,"It's quite empty in here.", x, y+height, width, tcell.ColorDefault)
writeLine(screen, tview.AlignLeft, "It's quite empty in here.", x, y+height, width, tcell.ColorDefault)
return
}
@ -282,37 +302,38 @@ func (view *MessageView) Draw(screen tcell.Screen) {
return
}
totalHeight := float64(len(view.textBuffer))
// The height of the scrollbar: ceil(height / (totalHeight / height))
scrollBarHeight := int(math.Ceil(float64(height) / (totalHeight / float64(height))))
// The position of the scrollbar from the bottom: height - ceil(scrollOffset) / totalHeight * height
scrollBarPos := height - int(math.Ceil(float64(view.ScrollOffset)/totalHeight*float64(height)))
var scrollBarHeight, scrollBarPos int
// Black magic (aka math) used to figure out where the scroll bar should be put.
{
viewportHeight := float64(height)
contentHeight := float64(len(view.textBuffer))
scrollBarHeight = int(math.Ceil(viewportHeight / (contentHeight / viewportHeight)))
scrollBarPos = height - int(math.Round(float64(view.ScrollOffset)/contentHeight*viewportHeight))
}
var prevMeta types.MessageMeta
firstLine := true
skippedLines := 0
for line := 0; line < height; line++ {
index := indexOffset + line
if index < 0 {
skippedLines++
continue
} else if index >= len(view.textBuffer) {
break
}
borderChar := '│'
borderStyle := tcell.StyleDefault
if firstLine && view.ScrollOffset+height >= len(view.textBuffer) {
// At top of loaded message history
borderChar = '┬'
} else if line == height-1 && view.ScrollOffset == 0 {
// At bottom of message history
borderChar = '┴'
} else if line >= scrollBarPos && line < scrollBarPos+scrollBarHeight {
// Scroll bar
borderChar = '║'
borderStyle = borderStyle.Foreground(tcell.ColorGreen)
}
showScrollbar := line-skippedLines >= scrollBarPos-scrollBarHeight && line-skippedLines < scrollBarPos
isTop := firstLine && view.ScrollOffset+height >= len(view.textBuffer)
isBottom := line == height-1 && view.ScrollOffset == 0
borderChar, borderStyle := getScrollbarStyle(showScrollbar, isTop, isBottom)
firstLine = false
screen.SetContent(separatorX, y+line, borderChar, nil, borderStyle)
text, meta := view.textBuffer[index], view.metaBuffer[index]