Refactor viewport handling in DiceOS for improved scaling and rendering

src/main/java/be/seeseemelk/diceos/DiceOS.java

@@ -6,7 +6,7 @@ import com.badlogic.gdx.ApplicationAdapter;
 import com.badlogic.gdx.graphics.Color;
 import com.badlogic.gdx.graphics.Texture;
 import com.badlogic.gdx.utils.ScreenUtils;
-import com.badlogic.gdx.utils.viewport.FillViewport;
+import com.badlogic.gdx.utils.viewport.ScreenViewport;
 import com.badlogic.gdx.utils.viewport.Viewport;
 import io.avaje.inject.Component;
 import lombok.RequiredArgsConstructor;
@@ -22,14 +22,22 @@ public class DiceOS extends ApplicationAdapter {
     private final List<OnStartup> startupTasks;
     private Texture background;
     private Texture border;
-    private Viewport viewport;
+    private Viewport vmViewport;
+    private Viewport screenViewport;
+    private int stretchFactor = 1;
+    private int offsetX = 0;
+    private int offsetY = 0;
 
     @Override
     public void create() {
         log.info("DiceOS starting...");
         background = new Texture("src/main/resources/background.png");
         border = new Texture("src/main/resources/border.png");
-        viewport = new FillViewport(2, 2);
+
+        screenViewport = new ScreenViewport();
+        vmViewport = new ScreenViewport();
+        vmViewport.update(display.getWidth(), display.getHeight(), true);
+
 
         for (var task : startupTasks) {
             task.onStartup();
@@ -38,11 +46,23 @@ public class DiceOS extends ApplicationAdapter {
         log.info("DiceOS started!");
     }
 
+    @Override
+    public void resize(int width, int height) {
+        screenViewport.update(width, height, true);
+
+        int displayWidth = display.getWidth();
+        int displayHeight = display.getHeight();
+        stretchFactor = Math.min(width / displayWidth, height / displayHeight);
+        offsetX = (width - (displayWidth * stretchFactor)) / 2;
+        offsetY = (height - (displayHeight * stretchFactor)) / 2;
+    }
+
     @Override
     public void render() {
+        ScreenUtils.clear(Color.BLACK);
+        vmViewport.apply();
         display.getScreenBuffer().begin();
-        viewport.apply();
+        display.getBatch().setProjectionMatrix(vmViewport.getCamera().combined);
-        display.getBatch().setProjectionMatrix(viewport.getCamera().combined);
         display.getBatch().begin();
 
         ScreenUtils.clear(Color.GREEN);
@@ -65,9 +85,11 @@ public class DiceOS extends ApplicationAdapter {
         display.getBatch().end();
         display.getScreenBuffer().end();
 
+        screenViewport.apply();
+        display.getBatch().setProjectionMatrix(screenViewport.getCamera().combined);
         display.getBatch().begin();
         display.getBatch().draw(display.getScreenBuffer().getColorBufferTexture(),
-                0, 0);
+                offsetX, offsetY, display.getWidth() * stretchFactor, display.getHeight() * stretchFactor);
         display.getBatch().end();
     }
 }

src/main/java/be/seeseemelk/diceos/system/DisplayService.java

@@ -22,6 +22,7 @@ public class DisplayService implements OnStartup {
     @Override
     public void onStartup() {
         screenBuffer = new FrameBuffer(Pixmap.Format.RGBA8888, getWidth(), getHeight(), false);
+        screenBuffer.getColorBufferTexture().setFilter(Texture.TextureFilter.Nearest, Texture.TextureFilter.Nearest);
         batch = new SpriteBatch();
     }