Merge pull request #100 from Mohit-Agarwa1/patch-1

Adding scroll feature
@Mohit-Agarwa1 thank you for developing this very useful feature.

README.md

@@ -37,6 +37,8 @@ For demonstration purposes Mop comes preconfigured with a number of stock ticker
     g       Group stocks by advancing/declining issues.
     f       Set a filtering expression.
     F       Unset a filtering expression.
+    PgDn    Scroll Down, down arrow key also works.
+    PgUp    Scroll up, up arrow key also works.
     ?       Display help screen.
     esc     Quit mop.
 

cmd/mop/main.go

@@ -33,6 +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.
+   Scroll  Scroll up/down.
+   PgUp/PgDn; Up/Down arrow; j/k;J/K also all scroll up/down
    q       Quit mop.
   esc      Ditto.
 
@@ -46,12 +48,19 @@ 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, 128)
+
 	timestampQueue := time.NewTicker(1 * time.Second)
 	quotesQueue := time.NewTicker(5 * time.Second)
 	marketQueue := time.NewTicker(12 * time.Second)
 	showingHelp := false
 	paused := false
+	upDownJump := profile.UpDownJump
+	redrawQuotesFlag := false
+	redrawMarketFlag := false
 
 	go func() {
 		for {
@@ -61,7 +70,8 @@ func mainLoop(screen *mop.Screen, profile *mop.Profile) {
 
 	market := mop.NewMarket()
 	quotes := mop.NewQuotes(market, profile)
-	screen.Draw(market, quotes)
+	screen.Draw(market)
+	screen.Draw(quotes)
 
 loop:
 	for {
@@ -92,6 +102,26 @@ loop:
 					} else if event.Ch == '?' || event.Ch == 'h' || event.Ch == 'H' {
 						showingHelp = true
 						screen.Clear().Draw(help)
+					} else if event.Key == termbox.KeyPgdn ||
+						event.Ch == 'J' {
+						screen.IncreaseOffset(upDownJump)
+						redrawQuotesFlag = true
+					} else if event.Key == termbox.KeyPgup ||
+						event.Ch == 'K' {
+						screen.DecreaseOffset(upDownJump)
+						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)
+						redrawQuotesFlag = true
+					} else if event.Key == termbox.KeyHome {
+						screen.ScrollTop()
+						redrawQuotesFlag = true
+					} else if event.Key == termbox.KeyEnd {
+						screen.ScrollBottom()
+						redrawQuotesFlag = true
 					}
 				} else if lineEditor != nil {
 					if done := lineEditor.Handle(event); done {
@@ -108,10 +138,26 @@ loop:
 			case termbox.EventResize:
 				screen.Resize()
 				if !showingHelp {
-					screen.Draw(market, quotes)
+					//screen.Draw(market)
+					//redrawQuotesFlag = true
+					//screen.Draw(market)
+					redrawQuotesFlag = true
+					redrawMarketFlag = true
+					//screen.DrawOldQuotes(quotes)
 				} else {
 					screen.Draw(help)
 				}
+			case termbox.EventMouse:
+				if lineEditor == nil && columnEditor == nil && !showingHelp {
+					switch event.Key {
+					case termbox.MouseWheelUp:
+						screen.DecreaseOffset(5)
+						redrawQuotesFlag = true
+					case termbox.MouseWheelDown:
+						screen.IncreaseOffset(5)
+						redrawQuotesFlag = true
+					}
+				}
 			}
 
 		case <-timestampQueue.C:
@@ -120,8 +166,9 @@ loop:
 			}
 
 		case <-quotesQueue.C:
-			if !showingHelp && !paused {
-				screen.Draw(quotes)
+			if !showingHelp && !paused && len(keyboardQueue) == 0 {
+				go quotes.Fetch()
+				redrawQuotesFlag = true
 			}
 
 		case <-marketQueue.C:
@@ -129,6 +176,15 @@ loop:
 				screen.Draw(market)
 			}
 		}
+
+		if redrawQuotesFlag && len(keyboardQueue) == 0 {
+			screen.DrawOldQuotes(quotes)
+			redrawQuotesFlag = false
+		}
+		if redrawMarketFlag && len(keyboardQueue) == 0 {
+			screen.Draw(market)
+			redrawMarketFlag = false
+		}
 	}
 }
 

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

@@ -22,6 +22,9 @@ type Screen struct {
 	layout     *Layout    // Pointer to layout (gets created by screen).
 	markup     *Markup    // Pointer to markup processor (gets created by screen).
 	pausedAt   *time.Time // Timestamp of the pause request or nil if none.
+	offset     int        // Offset for scolling
+	headerLine int        // Line number of header for scroll feature
+	max        int        // highest offset
 }
 
 // Initializes Termbox, creates screen along with layout and markup, and
@@ -34,6 +37,7 @@ func NewScreen(profile *Profile) *Screen {
 	screen := &Screen{}
 	screen.layout = NewLayout()
 	screen.markup = NewMarkup(profile)
+	screen.offset = 0
 
 	return screen.Resize()
 }
@@ -86,6 +90,45 @@ func (screen *Screen) ClearLine(x int, y int) *Screen {
 	return 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) {
+	if screen.offset+n <= screen.max {
+		screen.offset += n
+	} else if screen.max > screen.height {
+		screen.offset = screen.max
+	}
+}
+
+// Decrease the offset for scrolling feature by n
+func (screen *Screen) DecreaseOffset(n int) {
+	if screen.offset > n {
+		screen.offset -= n
+	} else {
+		screen.offset = 0
+	}
+}
+
+func (screen *Screen) ScrollTop() {
+	screen.offset = 0
+}
+
+func (screen *Screen) ScrollBottom() {
+	if screen.max > screen.height {
+		screen.offset = screen.max
+	}
+}
+
+func (screen *Screen) DrawOldQuotes(quotes *Quotes) {
+	screen.draw(screen.layout.Quotes(quotes), true)
+	termbox.Flush()
+}
+
+func (screen *Screen) DrawOldMarket(market *Market) {
+	screen.draw(screen.layout.Market(market), false)
+	termbox.Flush()
+}
+
 // Draw accepts variable number of arguments and knows how to display the
 // market data, stock quotes, current time, and an arbitrary string.
 func (screen *Screen) Draw(objects ...interface{}) *Screen {
@@ -97,24 +140,34 @@ func (screen *Screen) Draw(objects ...interface{}) *Screen {
 		switch ptr.(type) {
 		case *Market:
 			object := ptr.(*Market)
-			screen.draw(screen.layout.Market(object.Fetch()))
+			screen.draw(screen.layout.Market(object.Fetch()), false)
 		case *Quotes:
 			object := ptr.(*Quotes)
-			screen.draw(screen.layout.Quotes(object.Fetch()))
+			screen.draw(screen.layout.Quotes(object.Fetch()), true)
 		case time.Time:
 			timestamp := ptr.(time.Time).Format(`3:04:05pm ` + zonename)
 			screen.DrawLine(0, 0, `<right><time>`+timestamp+`</></right>`)
 		default:
-			screen.draw(ptr.(string))
+			screen.draw(ptr.(string), false)
 		}
 	}
 
+	termbox.Flush()
+
 	return screen
 }
 
 // DrawLine takes the incoming string, tokenizes it to extract markup
 // elements, and displays it all starting at (x,y) location.
+
+// DrawLineFlush gives the option to flush screen after drawing
+
+// wrapper for DrawLineFlush
 func (screen *Screen) DrawLine(x int, y int, str string) {
+	screen.DrawLineFlush(x, y, str, true)
+}
+
+func (screen *Screen) DrawLineFlush(x int, y int, str string, flush bool) {
 	start, column := 0, 0
 
 	for _, token := range screen.markup.Tokenize(str) {
@@ -134,31 +187,57 @@ func (screen *Screen) DrawLine(x int, y int, str string) {
 			termbox.SetCell(start, y, char, screen.markup.Foreground, screen.markup.Background)
 		}
 	}
+	if flush {
 		termbox.Flush()
 	}
+}
 
 // Underlying workhorse function that takes multiline string, splits it into
 // lines, and displays them row by row.
-func (screen *Screen) draw(str string) {
+func (screen *Screen) draw(str string, offset bool) {
 	if !screen.cleared {
 		screen.Clear()
 	}
 	var allLines []string
 	drewHeading := false
 
+	screen.width, screen.height = termbox.Size()
+
 	tempFormat := "%" + strconv.Itoa(screen.width) + "s"
 	blankLine := fmt.Sprintf(tempFormat, "")
 	allLines = strings.Split(str, "\n")
 
+	if offset {
+		screen.max = len(allLines) - screen.height + screen.headerLine
+	}
+
 	// Write the lines being updated.
 	for row := 0; row < len(allLines); row++ {
-		screen.DrawLine(0, row, allLines[row])
+		if offset {
 			// Did we draw the underlined heading row?  This is a crude
 			// check, but--see comments below...
+			// --- Heading row only appears for quotes, so offset is true
+			if !drewHeading {
 				if strings.Contains(allLines[row], "Ticker") &&
 					strings.Contains(allLines[row], "Last") &&
 					strings.Contains(allLines[row], "Change") {
 					drewHeading = true
+					screen.headerLine = row
+					screen.DrawLine(0, row, allLines[row])
+					// move on to the point to offset to
+					row += screen.offset
+				}
+			} else {
+				// only write the necessary lines
+				if row <= len(allLines) &&
+					row > screen.headerLine {
+					screen.DrawLineFlush(0, row-screen.offset, allLines[row], false)
+				} else if row > len(allLines) + 1 {
+					row = len(allLines)
+				}
+			}
+		} else {
+			screen.DrawLineFlush(0, row, allLines[row], false)
 		}
 	}
 	// If the quotes lines in this cycle are shorter than in the previous
@@ -174,8 +253,10 @@ func (screen *Screen) draw(str string) {
 	// 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++ {
+			if i > screen.headerLine {
 				screen.DrawLine(0, i, blankLine)
 			}
 		}
 	}
+}