Revert "internal/restorable: remove ImageType"

This reverts commit 21ef462.

Updates #3083

internal/atlas/image.go

@@ -119,8 +119,7 @@ func (b *backend) tryAlloc(width, height int) (*packing.Node, bool) {
 		return nil, false
 	}
 
-	w, h := b.page.Size()
-	b.restorable = b.restorable.Extend(w, h)
+	b.restorable = b.restorable.Extend(b.page.Size())
 
 	return n, true
 }
@@ -672,7 +671,7 @@ func (i *Image) allocate(forbiddenBackends []*backend, asSource bool) {
 		}
 		// A screen image doesn't have a padding.
 		i.backend = &backend{
-			restorable: restorable.NewImage(i.width, i.height, true),
+			restorable: restorable.NewImage(i.width, i.height, restorable.ImageTypeScreen),
 		}
 		theBackends = append(theBackends, i.backend)
 		return
@@ -687,7 +686,7 @@ func (i *Image) allocate(forbiddenBackends []*backend, asSource bool) {
 		}
 
 		i.backend = &backend{
-			restorable: restorable.NewImage(wp, hp, false),
+			restorable: restorable.NewImage(wp, hp, restorable.ImageTypeRegular),
 			source:     asSource && i.imageType == ImageTypeRegular,
 		}
 		theBackends = append(theBackends, i.backend)
@@ -733,7 +732,7 @@ loop:
 	}
 
 	b := &backend{
-		restorable: restorable.NewImage(width, height, false),
+		restorable: restorable.NewImage(width, height, restorable.ImageTypeRegular),
 		page:       packing.NewPage(width, height, maxSize),
 		source:     asSource,
 	}

internal/restorable/image.go

@@ -23,6 +23,16 @@ import (
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver"
 )
 
+type ImageType int
+
+const (
+	// ImageTypeRegular indicates the image is a regular image.
+	ImageTypeRegular ImageType = iota
+
+	// ImageTypeScreen indicates the image is used as an actual screen.
+	ImageTypeScreen
+)
+
 // Image represents an image.
 type Image struct {
 	// Image is the underlying image.
@@ -32,18 +42,21 @@ type Image struct {
 
 	width  int
 	height int
+
+	imageType ImageType
 }
 
 // NewImage creates an emtpy image with the given size.
 //
 // The returned image is cleared.
 //
 // Note that Dispose is not called automatically.
-func NewImage(width, height int, screen bool) *Image {
+func NewImage(width, height int, imageType ImageType) *Image {
 	i := &Image{
-		Image:  graphicscommand.NewImage(width, height, screen),
-		width:  width,
-		height: height,
+		Image:     graphicscommand.NewImage(width, height, imageType == ImageTypeScreen),
+		width:     width,
+		height:    height,
+		imageType: imageType,
 	}
 
 	// This needs to use 'InternalSize' to render the whole region, or edges are unexpectedly cleared on some
@@ -61,8 +74,7 @@ func (i *Image) Extend(width, height int) *Image {
 		return i
 	}
 
-	// Assume that the screen image is never extended.
-	newImg := NewImage(width, height, false)
+	newImg := NewImage(width, height, i.imageType)
 
 	// Use DrawTriangles instead of WritePixels because the image i might be stale and not have its pixels
 	// information.