toolbar block icons centred in their 16px box (test for all icons), tutorials say where the objects tab is

src/main/java/com/eliasmueller/llamamod/editor/tools/geometry/GeoIcons.java

@@ -19,8 +19,8 @@ final class GeoIcons {
     private static final Color RED = new Color(0xD93F3F);
 
     static void register() {
-        Icons.register("prim-box", (g, fg) -> block(g, 2, 5, 12, 8, TOP, SIDE));
-        Icons.register("prim-platform", (g, fg) -> block(g, 1, 4, 14, 4, TOP, SIDE));
+        Icons.register("prim-box", (g, fg) -> block(g, 2, 1, 12, 8, TOP, SIDE));
+        Icons.register("prim-platform", (g, fg) -> block(g, 1, 2.5, 14, 4, TOP, SIDE));
         Icons.register("prim-floor", (g, fg) -> {
             Path2D p = poly(1, 10, 8, 6.5, 15, 10, 8, 13.5);
             g.setColor(TOP);
@@ -47,7 +47,7 @@ final class GeoIcons {
             g.setColor(fg);
             g.draw(p);
         });
-        Icons.register("prim-pillar", (g, fg) -> block(g, 5, 2, 6, 12, STONE, STONE.darker()));
+        Icons.register("prim-pillar", (g, fg) -> block(g, 5, 0.5, 6, 12, STONE, STONE.darker()));
         Icons.register("prim-cylinder", (g, fg) -> {
             g.setColor(STONE.darker());
             g.fill(new java.awt.geom.Rectangle2D.Double(2, 6, 12, 5));
@@ -122,7 +122,7 @@ final class GeoIcons {
         Icons.register("prim-invbox", (g, fg) -> {
             g.setStroke(
                     new BasicStroke(1.2f, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND, 1, new float[] {2, 1.5f}, 0));
-            outlineBlock(g, 2, 5, 12, 8, new Color(255, 60, 60, 60), RED);
+            outlineBlock(g, 2, 1, 12, 8, new Color(255, 60, 60, 60), RED);
         });
         Icons.register("geo-collision", (g, fg) -> {
             Path2D p = poly(1, 10, 8, 6.5, 15, 10, 8, 13.5);
@@ -221,6 +221,7 @@ final class GeoIcons {
     }
 
     /** Isometric block: x, y of the top-left, width w, side height h. */
+    /** An isometric block filling y .. y + w / 2 + h; keep that within the 16 × 16 icon box. */
     private static void block(Graphics2D g, double x, double y, double w, double h, Color top, Color side) {
         Color fg = g.getColor();
         double d = w / 4;

src/main/java/com/eliasmueller/llamamod/editor/ui/Icons.java

@@ -40,6 +40,11 @@ public final class Icons {
 
     private Icons() {}
 
+    /** Names of all registered icons (sorted). */
+    public static java.util.List<String> names() {
+        return PAINTERS.keySet().stream().sorted().toList();
+    }
+
     public static void register(String name, Painter p) {
         PAINTERS.put(name, p);
         CACHE.keySet().removeIf(k -> k.startsWith(name + "@"));

src/test/java/com/eliasmueller/llamamod/editor/tools/geometry/IconBoundsTest.java

@@ -0,0 +1,40 @@
+package com.eliasmueller.llamamod.editor.tools.geometry;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.eliasmueller.llamamod.editor.ui.Icons;
+import java.awt.Graphics2D;
+import java.awt.image.BufferedImage;
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+/** Every vector icon stays inside its 16 × 16 box, so toolbar icons line up. */
+class IconBoundsTest {
+    @Test
+    void iconsStayInsideTheirBox() {
+        GeoIcons.register();
+        List<String> outside = new ArrayList<>();
+        for (String name : Icons.names()) {
+            BufferedImage img = new BufferedImage(32, 32, BufferedImage.TYPE_INT_ARGB);
+            Graphics2D g = img.createGraphics();
+            Icons.get(name, 16).paintIcon(null, g, 8, 8);
+            g.dispose();
+            int minY = 32, maxY = -1, minX = 32, maxX = -1;
+            for (int y = 0; y < 32; y++) {
+                for (int x = 0; x < 32; x++) {
+                    if ((img.getRGB(x, y) >>> 24) > 40) {
+                        minY = Math.min(minY, y);
+                        maxY = Math.max(maxY, y);
+                        minX = Math.min(minX, x);
+                        maxX = Math.max(maxX, x);
+                    }
+                }
+            }
+            if (maxY >= 0 && (minY < 7 || maxY > 24 || minX < 7 || maxX > 24)) {
+                outside.add(name + " x " + (minX - 8) + ".." + (maxX - 8) + " y " + (minY - 8) + ".." + (maxY - 8));
+            }
+        }
+        assertTrue(outside.isEmpty(), "icons drawn outside their 16x16 box: " + outside);
+    }
+}