WTF-427 Add KeyboardWidget and switch Todo widget to using it

wtf/keyboard_widget.go

@@ -0,0 +1,58 @@
+package wtf
+
+import (
+	"github.com/gdamore/tcell"
+)
+
+// KeyboardWidget manages keyboard control for a widget
+type KeyboardWidget struct {
+	charMap map[string]func()
+	keyMap  map[tcell.Key]func()
+}
+
+// NewKeyboardWidget creates and returns a new instance of KeyboardWidget
+func NewKeyboardWidget() KeyboardWidget {
+	return KeyboardWidget{
+		charMap: make(map[string]func()),
+		keyMap:  make(map[tcell.Key]func()),
+	}
+}
+
+// SetKeyboardChar sets a character/function combination that responds to key presses
+// Example:
+//
+//    widget.SetKeyboardChar("d", widget.deleteSelectedItem)
+//
+func (widget *KeyboardWidget) SetKeyboardChar(char string, fn func()) {
+	widget.charMap[char] = fn
+}
+
+// SetKeyboardKey sets a tcell.Key/function combination that responds to key presses
+// Example:
+//
+//    widget.SetKeyboardKey(tcell.KeyCtrlD, widget.deleteSelectedItem)
+//
+func (widget *KeyboardWidget) SetKeyboardKey(key tcell.Key, fn func()) {
+	widget.keyMap[key] = fn
+}
+
+// InputCapture is the function passed to tview's SetInputCapture() function
+// This is done during the main widget's creation process using the following code:
+//
+//    widget.View.SetInputCapture(widget.InputCapture)
+//
+func (widget *KeyboardWidget) InputCapture(event *tcell.EventKey) *tcell.EventKey {
+	fn := widget.charMap[string(event.Rune())]
+	if fn != nil {
+		fn()
+		return nil
+	}
+
+	fn = widget.keyMap[event.Key()]
+	if fn != nil {
+		fn()
+		return nil
+	}
+
+	return event
+}