From 81c75e1b0aedd1df055dc7939a241a32bdb685f0 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Fri, 6 Sep 2024 15:23:40 +0900
Subject: [PATCH] Revert "internal/atlas: refactoring: remove
 ImageTypeVolatile"

This reverts commit def82fd5d30e576134b057c26db84278afa1b66a.

Updates #3083
---
 gameforui.go                 |  4 ++++
 internal/atlas/image.go      |  2 ++
 internal/atlas/image_test.go |  6 +++---
 internal/ui/context.go       |  6 ++++++
 internal/ui/image.go         | 12 +++++++++++-
 5 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/gameforui.go b/gameforui.go
index e496e7843..d86e4fda8 100644
--- a/gameforui.go
+++ b/gameforui.go
@@ -66,6 +66,10 @@ 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 ff6d8d75f..980d24100 100644
--- a/internal/atlas/image.go
+++ b/internal/atlas/image.go
@@ -224,6 +224,8 @@ const (
 	// A screen image is also unmanaged.
 	ImageTypeScreen
 
+	ImageTypeVolatile
+
 	// ImageTypeUnmanaged is an unmanaged image that is not on an atlas.
 	ImageTypeUnmanaged
 )
diff --git a/internal/atlas/image_test.go b/internal/atlas/image_test.go
index 3c5c351ab..1a7d1d300 100644
--- a/internal/atlas/image_test.go
+++ b/internal/atlas/image_test.go
@@ -174,8 +174,8 @@ func TestReputOnSourceBackend(t *testing.T) {
 	}
 	img2.WritePixels(pix, image.Rect(0, 0, size, size))
 
-	// Create an unmanaged image. This should always be on a non-source backend.
-	img3 := atlas.NewImage(size, size, atlas.ImageTypeUnmanaged)
+	// Create a volatile image. This should always be on a non-source backend.
+	img3 := atlas.NewImage(size, size, atlas.ImageTypeVolatile)
 	defer img3.Deallocate()
 	img3.WritePixels(make([]byte, 4*size*size), image.Rect(0, 0, size, size))
 	if got, want := img3.IsOnSourceBackendForTesting(), false; got != want {
@@ -685,7 +685,7 @@ func TestImageIsNotReputOnSourceBackendWithoutUsingAsSource(t *testing.T) {
 }
 
 func TestImageWritePixelsModify(t *testing.T) {
-	for _, typ := range []atlas.ImageType{atlas.ImageTypeRegular, atlas.ImageTypeRegular, atlas.ImageTypeUnmanaged} {
+	for _, typ := range []atlas.ImageType{atlas.ImageTypeRegular, atlas.ImageTypeVolatile, 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 7f94b2d5d..c1af72c37 100644
--- a/internal/ui/context.go
+++ b/internal/ui/context.go
@@ -180,6 +180,12 @@ 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 987d0bcc3..2b56f0e0f 100644
--- a/internal/ui/image.go
+++ b/internal/ui/image.go
@@ -15,6 +15,7 @@
 package ui
 
 import (
+	"fmt"
 	"image"
 	"math"
 
@@ -85,7 +86,16 @@ func (i *Image) DrawTriangles(srcs [graphics.ShaderSrcImageCount]*Image, vertice
 
 	if antialias {
 		if i.bigOffscreenBuffer == nil {
-			i.bigOffscreenBuffer = i.ui.newBigOffscreenImage(i, atlas.ImageTypeUnmanaged)
+			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.drawTriangles(srcs, vertices, indices, blend, dstRegion, srcRegions, shader, uniforms, fillRule, canSkipMipmap)