Consume less energy when screen is standing still

For static editors too much energy is being consumed in order to draw the screen pixels each frame.

This commit changes how often screen pixels are replaced in graphics card memory.

ebitengine/game.go

@@ -5,6 +5,8 @@ package ebitengine
 
 import (
 	_ "embed"
+	"fmt"
+	"slices"
 	"sync/atomic"
 	"time"
 
@@ -19,6 +21,7 @@ type game struct {
 	screenDataRGBA     []byte // reused RGBA pixels
 	screenChanged      bool
 	shouldSkipNextDraw bool
+	lastScreenDrawn    []byte
 }
 
 func (e *game) Update() error {
@@ -56,9 +59,18 @@ func (e *game) Update() error {
 		if elapsed.Seconds() > 1/float64(tps) {
 			e.shouldSkipNextDraw = true
 		}
-	}
 
-	e.screenChanged = true
+		scrPix := pi.Scr().Pix()
+		if !slices.Equal(e.lastScreenDrawn, scrPix) { // TODO And palette + clipping region not changed
+			e.screenChanged = true
+			if len(e.lastScreenDrawn) != len(scrPix) {
+				e.lastScreenDrawn = make([]byte, len(scrPix))
+			}
+			copy(e.lastScreenDrawn, scrPix)
+		} else {
+			fmt.Println("skipping")
+		}
+	}
 
 	return nil
 }