Added masking to InputField, password field to form. Resolves #7, resolves #8.

demos/form/main.go

@@ -12,6 +12,7 @@ func main() {
 		AddInputField("First name", "", 20, nil, nil).
 		AddInputField("Last name", "", 20, nil, nil).
 		AddCheckbox("Age 18+", false, nil).
+		AddPasswordField("Password", "", 10, '*', nil).
 		AddButton("Save", nil).
 		AddButton("Quit", func() {
 			app.Stop()

form.go

@@ -138,7 +138,27 @@ func (f *Form) AddInputField(label, value string, fieldLength int, accept func(t
 		SetLabel(label).
 		SetText(value).
 		SetFieldLength(fieldLength).
-		SetAcceptanceFunc(accept))
+		SetAcceptanceFunc(accept).
+		SetChangedFunc(changed))
+	return f
+}
+
+// AddPasswordField adds a password field to the form. This is similar to an
+// input field except that the user's input not shown. Instead, a "mask"
+// character is displayed. The password field has a label, an optional initial
+// value, a field length (a value of 0 extends it as far as possible), and an
+// (optional) callback function which is invoked when the input field's text has
+// changed.
+func (f *Form) AddPasswordField(label, value string, fieldLength int, mask rune, changed func(text string)) *Form {
+	if mask == 0 {
+		mask = '*'
+	}
+	f.items = append(f.items, NewInputField().
+		SetLabel(label).
+		SetText(value).
+		SetFieldLength(fieldLength).
+		SetMaskCharacter(mask).
+		SetChangedFunc(changed))
 	return f
 }
 

inputfield.go

@@ -3,6 +3,8 @@ package tview
 import (
 	"math"
 	"regexp"
+	"strings"
+	"unicode/utf8"
 
 	"github.com/gdamore/tcell"
 	runewidth "github.com/mattn/go-runewidth"
@@ -11,6 +13,9 @@ import (
 // InputField is a one-line box (three lines if there is a title) where the
 // user can enter text.
 //
+// Use SetMaskCharacter() to hide input from onlookers (e.g. for password
+// input).
+//
 // See https://github.com/rivo/tview/wiki/InputField for an example.
 type InputField struct {
 	*Box
@@ -34,6 +39,10 @@ type InputField struct {
 	// possible.
 	fieldLength int
 
+	// A character to mask entered text (useful for password fields). A value of 0
+	// disables masking.
+	maskCharacter rune
+
 	// An optional function which may reject the last character that was entered.
 	accept func(text string, ch rune) bool
 
@@ -116,6 +125,13 @@ func (i *InputField) SetFieldLength(length int) *InputField {
 	return i
 }
 
+// SetMaskCharacter sets a character that masks user input on a screen. A value
+// of 0 disables masking.
+func (i *InputField) SetMaskCharacter(mask rune) *InputField {
+	i.maskCharacter = mask
+	return i
+}
+
 // SetAcceptanceFunc sets a handler which may reject the last character that was
 // entered (by returning false).
 //
@@ -180,11 +196,15 @@ func (i *InputField) Draw(screen tcell.Screen) {
 	}
 
 	// Draw entered text.
+	text := i.text
+	if i.maskCharacter > 0 {
+		text = strings.Repeat(string(i.maskCharacter), utf8.RuneCountInString(i.text))
+	}
 	fieldLength-- // We need one cell for the cursor.
 	if fieldLength < runewidth.StringWidth(i.text) {
-		Print(screen, i.text, x, y, fieldLength, AlignRight, i.fieldTextColor)
+		Print(screen, text, x, y, fieldLength, AlignRight, i.fieldTextColor)
 	} else {
-		Print(screen, i.text, x, y, fieldLength, AlignLeft, i.fieldTextColor)
+		Print(screen, text, x, y, fieldLength, AlignLeft, i.fieldTextColor)
 	}
 
 	// Set cursor.