Add a partial listbox implementation

internal/ui/list_box.go

@@ -0,0 +1,158 @@
+package ui
+
+import (
+	"fmt"
+	"log"
+
+	"code.ur.gs/lupine/ordoor/internal/menus"
+)
+
+func init() {
+	registerBuilder(menus.TypeLineKbd, ownedByMenu)
+	registerBuilder(menus.TypeLineBriefing, ownedByMenu)
+
+	registerBuilder(menus.TypeThumb, ownedByMenu)
+	registerBuilder(menus.TypeListBoxUp, ownedByMenu)
+	registerBuilder(menus.TypeListBoxDown, ownedByMenu)
+}
+
+// listBox is a TListBox in VCL terms. It has a number of lines of text, one of
+// which may be selected, and a slider with up and down buttons to scroll if the
+// options in the box exceed its viewing capacity.
+//
+// TODO: multi-select functionality? Is it needed?
+type listBox struct {
+	upBtn   *button
+	downBtn *button
+
+	// TODO: can we reuse the slider element for the thumb?
+
+	base  *noninteractive   // The menu itself has a sprite to display
+	lines []*noninteractive // We display to these
+
+	// The list box acts as a window onto these
+	strings []string
+
+	// The start of our window
+	offset int
+}
+
+func registerListBox(d *Driver, menu *menus.Record) ([]*menus.Record, error) {
+	var upBtn *menus.Record
+	var downBtn *menus.Record
+	var slider *menus.Record
+	var items []*menus.Record
+
+	for _, rec := range menu.Children {
+		switch rec.Type {
+		case menus.TypeListBoxUp:
+			if upBtn != nil {
+				return nil, fmt.Errorf("Duplicate up buttons in menu %v", menu.Locator())
+			}
+			upBtn = rec
+		case menus.TypeListBoxDown:
+			if downBtn != nil {
+				return nil, fmt.Errorf("Duplicate down buttons in menu %v", menu.Locator())
+			}
+			downBtn = rec
+		case menus.TypeLineKbd, menus.TypeLineBriefing:
+			items = append(items, rec)
+		case menus.TypeThumb:
+			if slider != nil {
+				return nil, fmt.Errorf("Duplicate thumbs in menu %v", menu.Locator())
+			}
+			slider = rec
+		default:
+			return nil, fmt.Errorf("Unrecognised child in listbox menu: %v", rec.Locator())
+		}
+	}
+
+	if len(items) == 0 || slider == nil || upBtn == nil || downBtn == nil {
+		return nil, fmt.Errorf("Missing items in menu %v", menu.Locator())
+	}
+
+	// Now build the wonderful thing
+	elemUp, err := registerButton(d, upBtn, upBtn.SpriteId[0])
+	if err != nil {
+		return nil, err
+	}
+
+	elemDown, err := registerButton(d, downBtn, downBtn.SpriteId[0])
+	if err != nil {
+		return nil, err
+	}
+
+	element := &listBox{
+		upBtn:   elemUp,
+		downBtn: elemDown,
+	}
+
+	for _, rec := range items {
+		ni, err := registerNoninteractive(d, rec)
+		if err != nil {
+			return nil, err
+		}
+
+		element.lines = append(element.lines, ni)
+	}
+
+	// Internal wiring-up
+	elemUp.onClick(element.up)
+	elemDown.onClick(element.down)
+
+	// FIXME: Test data for now
+	for i := 0; i < 50; i++ {
+		element.strings = append(element.strings, fmt.Sprintf("FOO %v", i))
+	}
+
+	// Register everything
+	// FIXME: we should be able to freeze/unfreeze as a group. The buttons register themselves though...
+
+	return nil, nil
+}
+
+func (l *listBox) SetStrings(to []string) {
+	if len(to) < len(l.strings) {
+		l.offset = 0 // FIXME: unconditional? Trim to max?
+	}
+
+	l.strings = to
+
+	l.refresh()
+}
+
+// TODO: Selected returns the index and value of the selected item
+func (l *listBox) Selected() (int, string) {
+	return 0, ""
+}
+
+func (l *listBox) up() {
+	if l.offset <= 0 {
+		return
+	}
+
+	l.offset -= 1
+	l.refresh()
+}
+
+func (l *listBox) down() {
+	if l.offset > len(l.strings)-len(l.lines) {
+		return
+	}
+
+	l.offset += 1
+	l.refresh()
+}
+
+func (l *listBox) refresh() {
+	for i, ni := range l.lines {
+		// FIXME: noninteractive isn't set up for dynamic text yet. Need to
+		// generate textImg on demand instead of once at start.
+		ni.hoverImpl.text = ""
+		if len(l.strings) > l.offset+i {
+			ni.hoverImpl.text = l.strings[l.offset+i]
+		}
+	}
+
+	log.Printf("Listbox offset: %v", l.offset)
+}