From def82fd5d30e576134b057c26db84278afa1b66a Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sun, 30 Jun 2024 18:40:13 +0900
Subject: [PATCH] internal/atlas: refactoring: remove ImageTypeVolatile

ImageTypeVolatile was meaningful when Ebitengine had `restorable`
package, but now this doesn't make sense.
---
 gameforui.go                 |  4 ----
 internal/atlas/image.go      |  1 -
 internal/atlas/image_test.go |  6 +++---
 internal/ui/context.go       |  6 ------
 internal/ui/image.go         | 12 +-----------
 5 files changed, 4 insertions(+), 25 deletions(-)

diff --git a/gameforui.go b/gameforui.go
index d86e4fda8..e496e7843 100644
--- a/gameforui.go
+++ b/gameforui.go
@@ -66,10 +66,6 @@ func (g *gameForUI) NewOffscreenImage(width, height int) *ui.Image {
 	// An image on an atlas is surrounded by a transparent edge,
 	// and the shader program unexpectedly picks the pixel on the edges.
 	imageType := atlas.ImageTypeUnmanaged
-	if ui.Get().IsScreenClearedEveryFrame() {
-		// A volatile image is also always isolated.
-		imageType = atlas.ImageTypeVolatile
-	}
 	g.offscreen = newImage(image.Rect(0, 0, width, height), imageType)
 	return g.offscreen.image
 }
diff --git a/internal/atlas/image.go b/internal/atlas/image.go
index c1bf42268..d52681f99 100644
--- a/internal/atlas/image.go
+++ b/internal/atlas/image.go
@@ -225,7 +225,6 @@ type ImageType int
 const (
 	ImageTypeRegular ImageType = iota
 	ImageTypeScreen
-	ImageTypeVolatile
 	ImageTypeUnmanaged
 )
 
diff --git a/internal/atlas/image_test.go b/internal/atlas/image_test.go
index 3bc0d796f..ab17d5cd0 100644
--- a/internal/atlas/image_test.go
+++ b/internal/atlas/image_test.go
@@ -177,8 +177,8 @@ func TestReputOnSourceBackend(t *testing.T) {
 	}
 	img2.WritePixels(pix, image.Rect(0, 0, size, size))
 
-	// Create a volatile image. This should always be on a non-source backend.
-	img3 := atlas.NewImage(size, size, atlas.ImageTypeVolatile)
+	// Create an unmanaged image. This should always be on a non-source backend.
+	img3 := atlas.NewImage(size, size, atlas.ImageTypeUnmanaged)
 	defer img3.Deallocate()
 	img3.WritePixels(make([]byte, 4*size*size), image.Rect(0, 0, size, size))
 	if got, want := img3.IsOnSourceBackendForTesting(), false; got != want {
@@ -688,7 +688,7 @@ func TestImageIsNotReputOnSourceBackendWithoutUsingAsSource(t *testing.T) {
 }
 
 func TestImageWritePixelsModify(t *testing.T) {
-	for _, typ := range []atlas.ImageType{atlas.ImageTypeRegular, atlas.ImageTypeVolatile, atlas.ImageTypeUnmanaged} {
+	for _, typ := range []atlas.ImageType{atlas.ImageTypeRegular, atlas.ImageTypeRegular, atlas.ImageTypeUnmanaged} {
 		const size = 16
 		img := atlas.NewImage(size, size, typ)
 		defer img.Deallocate()
diff --git a/internal/ui/context.go b/internal/ui/context.go
index 48274c171..9af591f6f 100644
--- a/internal/ui/context.go
+++ b/internal/ui/context.go
@@ -178,12 +178,6 @@ func (c *context) newOffscreenImage(w, h int) *Image {
 }
 
 func (c *context) drawGame(graphicsDriver graphicsdriver.Graphics, ui *UserInterface, forceDraw bool) error {
-	if (c.offscreen.imageType == atlas.ImageTypeVolatile) != ui.IsScreenClearedEveryFrame() {
-		w, h := c.offscreen.width, c.offscreen.height
-		c.offscreen.Deallocate()
-		c.offscreen = c.newOffscreenImage(w, h)
-	}
-
 	// isOffscreenModified is updated when an offscreen's modifyCallback.
 	c.isOffscreenModified = false
 
diff --git a/internal/ui/image.go b/internal/ui/image.go
index d0a63ec37..c49d854cd 100644
--- a/internal/ui/image.go
+++ b/internal/ui/image.go
@@ -15,7 +15,6 @@
 package ui
 
 import (
-	"fmt"
 	"image"
 	"math"
 
@@ -86,16 +85,7 @@ func (i *Image) DrawTriangles(srcs [graphics.ShaderSrcImageCount]*Image, vertice
 
 	if antialias {
 		if i.bigOffscreenBuffer == nil {
-			var imageType atlas.ImageType
-			switch i.imageType {
-			case atlas.ImageTypeRegular, atlas.ImageTypeUnmanaged:
-				imageType = atlas.ImageTypeUnmanaged
-			case atlas.ImageTypeScreen, atlas.ImageTypeVolatile:
-				imageType = atlas.ImageTypeVolatile
-			default:
-				panic(fmt.Sprintf("ui: unexpected image type: %d", imageType))
-			}
-			i.bigOffscreenBuffer = i.ui.newBigOffscreenImage(i, imageType)
+			i.bigOffscreenBuffer = i.ui.newBigOffscreenImage(i, atlas.ImageTypeUnmanaged)
 		}
 
 		i.bigOffscreenBuffer.drawTriangles(srcs, vertices, indices, blend, dstRegion, srcRegions, shader, uniforms, fillRule, canSkipMipmap)