Add auto-skip support to protected fields

example1/example1.go

@@ -26,13 +26,13 @@ var screen1 = go3270.Screen{
 	{Row: 2, Col: 0, Content: "Welcome to the go3270 example application. Please enter your name."},
 	{Row: 4, Col: 0, Content: "First Name  . . ."},
 	{Row: 4, Col: 19, Name: "fname", Write: true, Highlighting: go3270.Underscore},
-	{Row: 4, Col: 40}, // field "stop" character
+	{Row: 4, Col: 40, Autoskip: true}, // field "stop" character
 	{Row: 5, Col: 0, Content: "Last Name . . . ."},
 	{Row: 5, Col: 19, Name: "lname", Write: true, Highlighting: go3270.Underscore},
-	{Row: 5, Col: 40}, // field "stop" character,
+	{Row: 5, Col: 40, Autoskip: true}, // field "stop" character
 	{Row: 6, Col: 0, Content: "Password  . . . ."},
 	{Row: 6, Col: 19, Name: "password", Write: true, Hidden: true},
-	{Row: 6, Col: 40}, // field "stop" character,
+	{Row: 6, Col: 40}, // field "stop" character
 	{Row: 8, Col: 0, Content: "Press"},
 	{Row: 8, Col: 6, Intense: true, Content: "enter"},
 	{Row: 8, Col: 12, Content: "to submit your name."},

example2/example2.go

@@ -26,13 +26,13 @@ var screen1 = go3270.Screen{
 	{Row: 2, Col: 0, Content: "Welcome to the go3270 example application. Please enter your name."},
 	{Row: 4, Col: 0, Content: "First Name  . . ."},
 	{Row: 4, Col: 19, Name: "fname", Write: true, Highlighting: go3270.Underscore},
-	{Row: 4, Col: 40}, // field "stop" character
+	{Row: 4, Col: 40, Autoskip: true}, // field "stop" character
 	{Row: 5, Col: 0, Content: "Last Name . . . ."},
 	{Row: 5, Col: 19, Name: "lname", Write: true, Highlighting: go3270.Underscore},
-	{Row: 5, Col: 40}, // field "stop" character,
+	{Row: 5, Col: 40, Autoskip: true}, // field "stop" character,
 	{Row: 6, Col: 0, Content: "Password  . . . ."},
 	{Row: 6, Col: 19, Name: "password", Write: true, Hidden: true},
-	{Row: 6, Col: 40}, // field "stop" character,
+	{Row: 6, Col: 40, Autoskip: true}, // field "stop" character,
 	{Row: 7, Col: 0, Content: "Change me  . . ."},
 	{Row: 7, Col: 19, Name: "changeme", Content: "change me", Write: true, Highlighting: go3270.Underscore},
 	{Row: 7, Col: 40}, // field "stop" character

screen.go

@@ -28,6 +28,11 @@ type Field struct {
 	// Write allows the user to edit the value of the field.
 	Write bool
 
+	// Autoskip causes protected (Write = false) fields to automatically be
+	// skipped and the cursor should move to the next field upon encountering
+	// this field. Autoskip is ignored on fields with Write = true.
+	Autoskip bool
+
 	// Intense indicates this field should be displayed with high intensity.
 	Intense bool
 
@@ -188,7 +193,7 @@ func buildField(f Field) []byte {
 	if f.Color == DefaultColor && f.Highlighting == DefaultHighlight {
 		// this is a traditional field, issue a normal sf command
 		buf.WriteByte(0x1d) // sf - "start field"
-		buf.WriteByte(sfAttribute(f.Write, f.Intense, f.Hidden))
+		buf.WriteByte(sfAttribute(f.Write, f.Intense, f.Hidden, f.Autoskip))
 		return buf.Bytes()
 	}
 
@@ -205,7 +210,7 @@ func buildField(f Field) []byte {
 
 	// Write the basic field attribute
 	buf.WriteByte(0xc0)
-	buf.WriteByte(sfAttribute(f.Write, f.Intense, f.Hidden))
+	buf.WriteByte(sfAttribute(f.Write, f.Intense, f.Hidden, f.Autoskip))
 
 	// Write the highlighting attribute
 	if f.Highlighting != DefaultHighlight {
@@ -223,10 +228,13 @@ func buildField(f Field) []byte {
 }
 
 // sfAttribute builds the attribute byte for the "start field" 3270 command
-func sfAttribute(write, intense, hidden bool) byte {
+func sfAttribute(write, intense, hidden, skip bool) byte {
 	var attribute byte
 	if !write {
 		attribute |= 1 << 5 // set "bit 2"
+		if skip {
+			attribute |= 1 << 4 // set "bit 3"
+		}
 	} else {
 		// The MDT bit -- we always want writable field values returned,
 		// even if unchanged