Make the menu buttons work

internal/assetstore/object.go

@@ -2,6 +2,7 @@ package assetstore
 
 import (
 	"fmt"
+	"image"
 	"log"
 	"path/filepath"
 	"strings"
@@ -23,12 +24,13 @@ type Object struct {
 type Sprite struct {
 	obj *Object
 
-	ID      string
-	XOffset int
+	XOffset int // TODO: replace these everywhere with Rect
 	YOffset int
 	Width   int
 	Height  int
 
+	ID    string
+	Rect  image.Rectangle
 	Image *ebiten.Image
 }
 
@@ -106,13 +108,21 @@ func (o *Object) Sprite(idx int) (*Sprite, error) {
 		return nil, err
 	}
 
+	rect := image.Rect(
+		int(raw.XOffset),
+		int(raw.YOffset),
+		int(raw.XOffset+raw.Width),
+		int(raw.YOffset+raw.Height),
+	)
+
 	sprite := &Sprite{
 		ID:      fmt.Sprintf("%v:%v", o.raw.Name, idx),
 		obj:     o,
-		Width:   int(raw.Width),
-		Height:  int(raw.Width),
-		XOffset: int(raw.XOffset),
-		YOffset: int(raw.YOffset),
+		Width:   rect.Dx(),
+		Height:  rect.Dy(),
+		XOffset: rect.Min.X,
+		YOffset: rect.Min.Y,
+		Rect:    rect,
 		Image:   img,
 	}