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diff --git a/vendor/github.com/stefanhaller/tcell/v2/TUTORIAL.md b/vendor/github.com/stefanhaller/tcell/v2/TUTORIAL.md new file mode 100644 index 000000000..2e6f9bc27 --- /dev/null +++ b/vendor/github.com/stefanhaller/tcell/v2/TUTORIAL.md @@ -0,0 +1,313 @@ +# _Tcell_ Tutorial + +_Tcell_ provides a low-level, portable API for building terminal-based programs. +A [terminal emulator](https://en.wikipedia.org/wiki/Terminal_emulator) +(or a real terminal such as a DEC VT-220) is used to interact with such a program. + +_Tcell_'s interface is fairly low-level. +While it provides a reasonably portable way of dealing with all the usual terminal +features, it may be easier to utilize a higher level framework. +A number of such frameworks are listed on the _Tcell_ main [README](README.md). + +This tutorial provides the details of _Tcell_, and is appropriate for developers +wishing to create their own application frameworks or needing more direct access +to the terminal capabilities. + +## Resize events + +Applications receive an event of type `EventResize` when they are first initialized and each time the terminal is resized. +The new size is available as `Size`. + +```go +switch ev := ev.(type) { +case *tcell.EventResize: + w, h := ev.Size() + logMessage(fmt.Sprintf("Resized to %dx%d", w, h)) +} +``` + +## Key events + +When a key is pressed, applications receive an event of type `EventKey`. +This event describes the modifier keys pressed (if any) and the pressed key or rune. + +When a rune key is pressed, an event with its `Key` set to `KeyRune` is dispatched. + +When a non-rune key is pressed, it is available as the `Key` of the event. + +```go +switch ev := ev.(type) { +case *tcell.EventKey: + mod, key, ch := ev.Mod(), ev.Key(), ev.Rune() + logMessage(fmt.Sprintf("EventKey Modifiers: %d Key: %d Rune: %d", mod, key, ch)) +} +``` + +### Key event restrictions + +Terminal-based programs have less visibility into keyboard activity than graphical applications. + +When a key is pressed and held, additional key press events are sent by the terminal emulator. +The rate of these repeated events depends on the emulator's configuration. +Key release events are not available. + +It is not possible to distinguish runes typed while holding shift and runes typed using caps lock. +Capital letters are reported without the Shift modifier. + +## Mouse events + +Applications receive an event of type `EventMouse` when the mouse moves, or a mouse button is pressed or released. +Mouse events are only delivered if +`EnableMouse` has been called. + +The mouse buttons being pressed (if any) are available as `Buttons`, and the position of the mouse is available as `Position`. + +```go +switch ev := ev.(type) { +case *tcell.EventMouse: + mod := ev.Modifiers() + btns := ev.Buttons() + x, y := ev.Position() + logMessage(fmt.Sprintf("EventMouse Modifiers: %d Buttons: %d Position: %d,%d", mod, btns, x, y)) +} +``` + +### Mouse buttons + +Identifier | Alias | Description +-----------|-----------------|----------- +Button1 | ButtonPrimary | Left button +Button2 | ButtonSecondary | Right button +Button3 | ButtonMiddle | Middle button +Button4 | | Side button (thumb/next) +Button5 | | Side button (thumb/prev) +WheelUp | | Scroll wheel up +WheelDown | | Scroll wheel down +WheelLeft | | Horizontal wheel left +WheelRight | | Horizontal wheel right + +## Usage + +To create a _Tcell_ application, first initialize a screen to hold it. + +```go +s, err := tcell.NewScreen() +if err != nil { + log.Fatalf("%+v", err) +} +if err := s.Init(); err != nil { + log.Fatalf("%+v", err) +} + +// Set default text style +defStyle := tcell.StyleDefault.Background(tcell.ColorReset).Foreground(tcell.ColorReset) +s.SetStyle(defStyle) + +// Clear screen +s.Clear() +``` + +Text may be drawn on the screen using `SetContent`. + +```go +s.SetContent(0, 0, 'H', nil, defStyle) +s.SetContent(1, 0, 'i', nil, defStyle) +s.SetContent(2, 0, '!', nil, defStyle) +``` + +To draw text more easily, define a render function. + +```go +func drawText(s tcell.Screen, x1, y1, x2, y2 int, style tcell.Style, text string) { + row := y1 + col := x1 + for _, r := range []rune(text) { + s.SetContent(col, row, r, nil, style) + col++ + if col >= x2 { + row++ + col = x1 + } + if row > y2 { + break + } + } +} +``` + +Lastly, define an event loop to handle user input and update application state. + +```go +quit := func() { + s.Fini() + os.Exit(0) +} +for { + // Update screen + s.Show() + + // Poll event + ev := s.PollEvent() + + // Process event + switch ev := ev.(type) { + case *tcell.EventResize: + s.Sync() + case *tcell.EventKey: + if ev.Key() == tcell.KeyEscape || ev.Key() == tcell.KeyCtrlC { + quit() + } + } +} +``` + +## Demo application + +The following demonstrates how to initialize a screen, draw text/graphics and handle user input. + +```go +package main + +import ( + "fmt" + "log" + + "github.com/stefanhaller/tcell/v2" +) + +func drawText(s tcell.Screen, x1, y1, x2, y2 int, style tcell.Style, text string) { + row := y1 + col := x1 + for _, r := range []rune(text) { + s.SetContent(col, row, r, nil, style) + col++ + if col >= x2 { + row++ + col = x1 + } + if row > y2 { + break + } + } +} + +func drawBox(s tcell.Screen, x1, y1, x2, y2 int, style tcell.Style, text string) { + if y2 < y1 { + y1, y2 = y2, y1 + } + if x2 < x1 { + x1, x2 = x2, x1 + } + + // Fill background + for row := y1; row <= y2; row++ { + for col := x1; col <= x2; col++ { + s.SetContent(col, row, ' ', nil, style) + } + } + + // Draw borders + for col := x1; col <= x2; col++ { + s.SetContent(col, y1, tcell.RuneHLine, nil, style) + s.SetContent(col, y2, tcell.RuneHLine, nil, style) + } + for row := y1 + 1; row < y2; row++ { + s.SetContent(x1, row, tcell.RuneVLine, nil, style) + s.SetContent(x2, row, tcell.RuneVLine, nil, style) + } + + // Only draw corners if necessary + if y1 != y2 && x1 != x2 { + s.SetContent(x1, y1, tcell.RuneULCorner, nil, style) + s.SetContent(x2, y1, tcell.RuneURCorner, nil, style) + s.SetContent(x1, y2, tcell.RuneLLCorner, nil, style) + s.SetContent(x2, y2, tcell.RuneLRCorner, nil, style) + } + + drawText(s, x1+1, y1+1, x2-1, y2-1, style, text) +} + +func main() { + defStyle := tcell.StyleDefault.Background(tcell.ColorReset).Foreground(tcell.ColorReset) + boxStyle := tcell.StyleDefault.Foreground(tcell.ColorWhite).Background(tcell.ColorPurple) + + // Initialize screen + s, err := tcell.NewScreen() + if err != nil { + log.Fatalf("%+v", err) + } + if err := s.Init(); err != nil { + log.Fatalf("%+v", err) + } + s.SetStyle(defStyle) + s.EnableMouse() + s.EnablePaste() + s.Clear() + + // Draw initial boxes + drawBox(s, 1, 1, 42, 7, boxStyle, "Click and drag to draw a box") + drawBox(s, 5, 9, 32, 14, boxStyle, "Press C to reset") + + quit := func() { + // You have to catch panics in a defer, clean up, and + // re-raise them - otherwise your application can + // die without leaving any diagnostic trace. + maybePanic := recover() + s.Fini() + if maybePanic != nil { + panic(maybePanic) + } + } + defer quit() + + // Here's how to get the screen size when you need it. + // xmax, ymax := s.Size() + + // Here's an example of how to inject a keystroke where it will + // be picked up by the next PollEvent call. Note that the + // queue is LIFO, it has a limited length, and PostEvent() can + // return an error. + // s.PostEvent(tcell.NewEventKey(tcell.KeyRune, rune('a'), 0)) + + // Event loop + ox, oy := -1, -1 + for { + // Update screen + s.Show() + + // Poll event + ev := s.PollEvent() + + // Process event + switch ev := ev.(type) { + case *tcell.EventResize: + s.Sync() + case *tcell.EventKey: + if ev.Key() == tcell.KeyEscape || ev.Key() == tcell.KeyCtrlC { + return + } else if ev.Key() == tcell.KeyCtrlL { + s.Sync() + } else if ev.Rune() == 'C' || ev.Rune() == 'c' { + s.Clear() + } + case *tcell.EventMouse: + x, y := ev.Position() + + switch ev.Buttons() { + case tcell.Button1, tcell.Button2: + if ox < 0 { + ox, oy = x, y // record location when click started + } + + case tcell.ButtonNone: + if ox >= 0 { + label := fmt.Sprintf("%d,%d to %d,%d", ox, oy, x, y) + drawBox(s, ox, oy, x, y, boxStyle, label) + ox, oy = -1, -1 + } + } + } + } +} +``` + |