Update Studio previews

- Merge the eight additional commits from PR #1254.
- Preserve closure guards while refreshing object and hidden 3D views.
- Stop hidden crossfade timers and verify frame retention.

core/src/test/java/art/arcane/iris/studio/map/FrameCrossfadeTest.java

@@ -0,0 +1,119 @@
+package art.arcane.iris.studio.map;
+
+import org.junit.After;
+import org.junit.Test;
+
+import javax.swing.SwingUtilities;
+import javax.swing.Timer;
+import java.lang.reflect.Field;
+import java.util.concurrent.TimeUnit;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+
+public final class FrameCrossfadeTest {
+    private final FrameCrossfade crossfade = new FrameCrossfade(() -> {
+    });
+
+    @After
+    public void stopRepaintTimer() throws Exception {
+        SwingUtilities.invokeAndWait(crossfade::clear);
+    }
+
+    @Test
+    public void heldFrameStaysFullyVisibleUntilTheNextFrameArrives() {
+        NoiseRenderCoordinator.Result frame = frame();
+
+        crossfade.hold(frame);
+
+        assertSame(frame, crossfade.outgoing());
+        assertEquals(1F, crossfade.outgoingOpacity(), 0F);
+    }
+
+    @Test
+    public void heldFrameFadesOnceTheNextFrameArrives() throws Exception {
+        SwingUtilities.invokeAndWait(() -> {
+            crossfade.hold(frame());
+            crossfade.reveal();
+        });
+        Thread.sleep(20L);
+
+        SwingUtilities.invokeAndWait(() -> assertTrue(crossfade.outgoing() == null || crossfade.outgoingOpacity() < 1F));
+    }
+
+    @Test
+    public void fadingStopsAndReleasesTheFrameWithoutPainting() throws Exception {
+        Timer timer = (Timer) field("repaintTimer");
+        SwingUtilities.invokeAndWait(() -> {
+            crossfade.hold(frame());
+            crossfade.reveal();
+            assertTrue(timer.isRunning());
+        });
+
+        long deadline = System.nanoTime() + TimeUnit.SECONDS.toNanos(2L);
+        while (timer.isRunning() && System.nanoTime() < deadline) {
+            Thread.sleep(10L);
+        }
+        SwingUtilities.invokeAndWait(() -> { });
+
+        assertFalse("Hidden views must stop scheduling fade repaints", timer.isRunning());
+        assertNull(field("outgoing"));
+    }
+
+    @Test
+    public void holdingDuringFadeStopsRepaintsUntilAnotherFrameArrives() throws Exception {
+        Timer timer = (Timer) field("repaintTimer");
+        NoiseRenderCoordinator.Result frame = frame();
+        SwingUtilities.invokeAndWait(() -> {
+            crossfade.hold(frame);
+            crossfade.reveal();
+            crossfade.hold(null);
+
+            assertFalse("A held frame must not keep the fade timer running", timer.isRunning());
+            assertSame(frame, crossfade.outgoing());
+            assertEquals(1F, crossfade.outgoingOpacity(), 0F);
+
+            crossfade.reveal();
+            assertTrue(timer.isRunning());
+        });
+    }
+
+    @Test
+    public void switchingAgainBeforeAnythingDrewKeepsTheFrameHeld() {
+        NoiseRenderCoordinator.Result frame = frame();
+        crossfade.hold(frame);
+
+        crossfade.hold(null);
+
+        assertSame(frame, crossfade.outgoing());
+    }
+
+    @Test
+    public void frameWithoutAHeldFrameHasNothingToFade() {
+        crossfade.reveal();
+
+        assertNull(crossfade.outgoing());
+    }
+
+    @Test
+    public void clearDropsTheHeldFrame() {
+        crossfade.hold(frame());
+
+        crossfade.clear();
+
+        assertNull(crossfade.outgoing());
+    }
+
+    private static NoiseRenderCoordinator.Result frame() {
+        return new NoiseRenderCoordinator.Result(null, null, 1D, 1L, 0D, 1D, 0.5D, 0L, 0L, 0L);
+    }
+
+    private Object field(String name) throws Exception {
+        Field field = FrameCrossfade.class.getDeclaredField(name);
+        field.setAccessible(true);
+        return field.get(crossfade);
+    }
+}

core/src/test/java/art/arcane/iris/studio/map/ModelFrontViewTest.java

@@ -0,0 +1,103 @@
+package art.arcane.iris.studio.map;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonParser;
+import org.junit.Test;
+
+import java.awt.image.BufferedImage;
+import java.util.Map;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+public final class ModelFrontViewTest {
+    private static final String SEA_PICKLE = """
+            [
+              { "from": [6, 0, 6], "to": [10, 6, 10], "faces": {
+                  "up":    { "uv": [4, 1, 8, 5], "texture": "#all" },
+                  "south": { "uv": [0, 5, 4, 11], "texture": "#all" } } },
+              { "from": [6, 5.95, 6], "to": [10, 5.95, 10], "faces": {
+                  "up": { "uv": [8, 1, 12, 5], "texture": "#all" } } },
+              { "from": [7.5, 5.2, 8], "to": [8.5, 8.7, 8],
+                "rotation": { "origin": [8, 8, 8], "axis": "y", "angle": 45, "rescale": true },
+                "faces": { "south": { "uv": [3, 0, 1, 5], "texture": "#all" } } }
+            ]
+            """;
+    private static final String PRESSURE_PLATE = """
+            [
+              { "from": [1, 0, 1], "to": [15, 1, 15], "faces": {
+                  "up":    { "uv": [1, 1, 15, 15], "texture": "#all" },
+                  "south": { "uv": [1, 15, 15, 16], "texture": "#all" } } }
+            ]
+            """;
+    private static final Map<String, String> TEXTURES = Map.of("all", "block/test");
+    private static final int SIZE = 16;
+
+    private final BufferedImage texture = everyTexelItsOwnColour();
+
+    @Test
+    public void bodyShowsItsOwnPartOfTheTexture() throws Exception {
+        ModelFrontView front = draw(SEA_PICKLE);
+
+        assertEquals(litAsFront(0, 5), front.image().getRGB(6, 7));
+        assertEquals(litAsFront(3, 10), front.image().getRGB(9, 12));
+    }
+
+    @Test
+    public void topShowsAboveTheFrontOverThePlaneJustUnderIt() throws Exception {
+        ModelFrontView front = draw(SEA_PICKLE);
+
+        assertEquals(texture.getRGB(5, 2), front.image().getRGB(7, 5));
+    }
+
+    @Test
+    public void crossedPlaneIsMirroredWhereItsUvRunsBackwards() throws Exception {
+        ModelFrontView front = draw(SEA_PICKLE);
+
+        assertEquals(litAsFront(1, 1), front.image().getRGB(8, 4));
+    }
+
+    @Test
+    public void spotsNoBoxCoversStayClear() throws Exception {
+        ModelFrontView front = draw(SEA_PICKLE);
+
+        assertEquals(0, front.image().getRGB(2, 12) >>> 24);
+        assertEquals(0, front.image().getRGB(7, 2) >>> 24);
+    }
+
+    @Test
+    public void smallShapeLeavesMostOfItsSpotOpen() {
+        assertFalse(ModelFrontView.fillsMostOfItsSpotFromAbove(elements(SEA_PICKLE)));
+    }
+
+    @Test
+    public void flatShapeFillsMostOfItsSpot() {
+        assertTrue(ModelFrontView.fillsMostOfItsSpotFromAbove(elements(PRESSURE_PLATE)));
+    }
+
+    private int litAsFront(int textureX, int textureY) {
+        return 0xFF000000 | BlockPreviewColors.shade(texture.getRGB(textureX, textureY), CubeFace.SOUTH.shade());
+    }
+
+    private ModelFrontView draw(String elements) throws Exception {
+        ModelFrontView front = ModelFrontView.draw(elements(elements), TEXTURES, name -> texture);
+        assertNotNull(front);
+        return front;
+    }
+
+    private static JsonArray elements(String json) {
+        return JsonParser.parseString(json).getAsJsonArray();
+    }
+
+    private static BufferedImage everyTexelItsOwnColour() {
+        BufferedImage image = new BufferedImage(SIZE, SIZE, BufferedImage.TYPE_INT_ARGB);
+        for (int y = 0; y < SIZE; y++) {
+            for (int x = 0; x < SIZE; x++) {
+                image.setRGB(x, y, 0xFF000000 | x << 16 | y << 8 | 0x40);
+            }
+        }
+        return image;
+    }
+}