Improved scrolling.

* Added scrolling with scroll wheel on mouse.
 * Added scrolling with vim style j/k keys.
 * Changed scrolling so that it is more smooth and the whole screen is
   not redrawn each time
 * Changed channel keyboardQueue to a buffered queue, so there are not
   too many scroll requests, and the draw commands can be done once the
   queue is empty.
 * Added UpDownJump in profile, so user can set how much PgUp/PgDown jumps

 * Have not tested with a _huge_ number of stocks in ticker, probably
   worth doing

cmd/mop/main.go

@@ -33,8 +33,8 @@ NO WARRANTIES OF ANY KIND WHATSOEVER. SEE THE LICENSE FILE FOR DETAILS.
    g       Group stocks by advancing/declining issues.
    o       Change column sort order.
    p       Pause market data and stock updates.
-   PgDn    Scroll Down, down arrow key also works.
+   Scroll  Scroll up/down.
-   PgUp    Scroll up, up arrow key also works.
+   PgUp/PgDn; Up/Down arrow; j/k;J/K also all scroll up/down
    q       Quit mop.
   esc      Ditto.
 
@@ -48,13 +48,18 @@ func mainLoop(screen *mop.Screen, profile *mop.Profile) {
 	var lineEditor *mop.LineEditor
 	var columnEditor *mop.ColumnEditor
 
-	keyboardQueue := make(chan termbox.Event)
+	termbox.SetInputMode(termbox.InputMouse)
+
+	// use buffered channel for keyboard event queue
+	keyboardQueue := make(chan termbox.Event, 16)
+
 	timestampQueue := time.NewTicker(1 * time.Second)
 	quotesQueue := time.NewTicker(5 * time.Second)
 	marketQueue := time.NewTicker(12 * time.Second)
 	showingHelp := false
 	paused := false
-	pgUpDownLines := 10
+	upDownJump := profile.UpDownJump
+	redrawQuotesFlag := false
 
 	go func() {
 		for {
@@ -96,13 +101,19 @@ loop:
 						showingHelp = true
 						screen.Clear().Draw(help)
 					} else if event.Key == termbox.KeyPgdn ||
-						event.Key == termbox.KeyArrowDown {
+						event.Ch == 'J' {
-						screen.IncreaseOffset(pgUpDownLines, len(profile.Tickers))
+						screen.IncreaseOffset(upDownJump, len(profile.Tickers))
-						screen.Clear().Draw(market, quotes)
+						redrawQuotesFlag = true
 					} else if event.Key == termbox.KeyPgup ||
-						event.Key == termbox.KeyArrowUp {
+						event.Ch == 'K' {
-						screen.DecreaseOffset(pgUpDownLines)
+						screen.DecreaseOffset(upDownJump)
-						screen.Clear().Draw(market, quotes)
+						redrawQuotesFlag = true
+					} else if event.Key == termbox.KeyArrowUp || event.Ch == 'k' {
+						screen.DecreaseOffset(1)
+						redrawQuotesFlag = true
+					} else if event.Key == termbox.KeyArrowDown || event.Ch == 'j' {
+						screen.IncreaseOffset(1, len(profile.Tickers))
+						redrawQuotesFlag = true
 					}
 				} else if lineEditor != nil {
 					if done := lineEditor.Handle(event); done {
@@ -123,6 +134,17 @@ loop:
 				} else {
 					screen.Draw(help)
 				}
+			case termbox.EventMouse:
+				if lineEditor == nil && columnEditor == nil && !showingHelp {
+					switch event.Key {
+					case termbox.MouseWheelUp:
+						screen.DecreaseOffset(1)
+						redrawQuotesFlag = true
+					case termbox.MouseWheelDown:
+						screen.IncreaseOffset(1, len(profile.Tickers))
+						redrawQuotesFlag = true
+					}
+				}
 			}
 
 		case <-timestampQueue.C:
@@ -140,6 +162,10 @@ loop:
 				screen.Draw(market)
 			}
 		}
+
+		if redrawQuotesFlag && len(keyboardQueue) == 0 {
+			screen.Draw(quotes)
+		}
 	}
 }
 

profile.go

@@ -31,6 +31,7 @@ type Profile struct {
 	Ascending     bool     // True when sort order is ascending.
 	Grouped       bool     // True when stocks are grouped by advancing/declining.
 	Filter        string   // Filter in human form
+	UpDownJump    int      // Number of lines to go up/down when scrolling.
 	Colors        struct { // User defined colors
 		Gain    string
 		Loss    string
@@ -93,6 +94,10 @@ func NewProfile(filename string) (*Profile, error) {
 	}
 	profile.selectedColumn = -1
 
+	if profile.UpDownJump < 1 {
+		profile.UpDownJump = 10
+	}
+
 	return profile, err
 }
 
@@ -105,6 +110,7 @@ func (profile *Profile) InitDefaultProfile() {
 	profile.SortColumn = 0   // Stock quotes are sorted by ticker name.
 	profile.Ascending = true // A to Z.
 	profile.Filter = ""
+	profile.UpDownJump = 10
 	profile.Colors.Gain = defaultGainColor
 	profile.Colors.Loss = defaultLossColor
 	profile.Colors.Tag = defaultTagColor

screen.go

@@ -92,7 +92,7 @@ func (screen *Screen) ClearLine(x int, y int) *Screen {
 // Increase the offset for scrolling feature by n
 // Takes number of tickers as max, so not scrolling down forever
 func (screen *Screen) IncreaseOffset(n int, max int) {
-	if screen.offset+n < max {
+	if screen.offset+n+1 < max {
 		screen.offset += n
 	}
 }
@@ -205,7 +205,7 @@ func (screen *Screen) draw(str string, offset bool) {
 	// cycle.  In that case, padding with blank lines would overwrite the
 	// stocks list.)
 	if drewHeading {
-		for i := len(allLines) - 1; i < screen.height; i++ {
+		for i := len(allLines) - 1 - screen.offset; i < screen.height; i++ {
 			screen.DrawLine(0, i, blankLine)
 		}
 	}