Explain empty object views

Icon, where to add them, path chip.

core/src/main/java/com/volmit/iris/core/gui/EmptyState.java

@@ -0,0 +1,102 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.gui;
+
+import javax.swing.Icon;
+import java.awt.Color;
+import java.awt.Component;
+import java.awt.Font;
+import java.awt.FontMetrics;
+import java.awt.Graphics2D;
+import java.awt.RenderingHints;
+import java.awt.geom.RoundRectangle2D;
+
+/**
+ * What an empty view says, drawn in the middle of it the way IntelliJ fills an empty tool window: a large icon, what
+ * is missing, and where to add it.
+ *
+ * @param location the pack folder or file the hint points to, drawn as code
+ */
+record EmptyState(Icon icon, String title, String hint, String location, String footer) {
+    private static final int ICON_GAP = 18;
+    private static final int TITLE_GAP = 8;
+    private static final int LOCATION_GAP = 10;
+    private static final int FOOTER_GAP = 14;
+    private static final int CHIP_PADDING_X = 8;
+    private static final int CHIP_PADDING_Y = 4;
+    private static final int CHIP_ARC = 8;
+
+    /**
+     * Draws the empty state centred on the given point.
+     */
+    void paint(Graphics2D graphics, Component owner, int centerX, int centerY) {
+        Graphics2D canvas = (Graphics2D) graphics.create();
+        try {
+            canvas.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
+            canvas.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+            int top = centerY - height(canvas) / 2;
+            icon.paintIcon(owner, canvas, centerX - icon.getIconWidth() / 2, top);
+            top += icon.getIconHeight() + StudioTheme.scale(ICON_GAP);
+            top = drawCentered(canvas, title, StudioTheme.titleFont(), StudioTheme.TEXT, centerX, top);
+            top = drawCentered(canvas, hint, StudioTheme.font(), StudioTheme.SECONDARY_TEXT, centerX,
+                    top + StudioTheme.scale(TITLE_GAP));
+            top = drawLocationChip(canvas, centerX, top + StudioTheme.scale(LOCATION_GAP));
+            drawCentered(canvas, footer, StudioTheme.smallFont(), StudioTheme.MUTED_TEXT, centerX, top + StudioTheme.scale(FOOTER_GAP));
+        } finally {
+            canvas.dispose();
+        }
+    }
+
+    private int height(Graphics2D canvas) {
+        return icon.getIconHeight() + StudioTheme.scale(ICON_GAP)
+                + canvas.getFontMetrics(StudioTheme.titleFont()).getHeight()
+                + StudioTheme.scale(TITLE_GAP) + canvas.getFontMetrics(StudioTheme.font()).getHeight()
+                + StudioTheme.scale(LOCATION_GAP) + chipHeight(canvas)
+                + StudioTheme.scale(FOOTER_GAP) + canvas.getFontMetrics(StudioTheme.smallFont()).getHeight();
+    }
+
+    private int chipHeight(Graphics2D canvas) {
+        return canvas.getFontMetrics(StudioTheme.monospacedFont()).getHeight() + StudioTheme.scale(CHIP_PADDING_Y) * 2;
+    }
+
+    private int drawLocationChip(Graphics2D canvas, int centerX, int top) {
+        canvas.setFont(StudioTheme.monospacedFont());
+        FontMetrics metrics = canvas.getFontMetrics();
+        int width = metrics.stringWidth(location) + StudioTheme.scale(CHIP_PADDING_X) * 2;
+        int height = chipHeight(canvas);
+        int left = centerX - width / 2;
+        RoundRectangle2D chip = new RoundRectangle2D.Double(left + 0.5D, top + 0.5D, width - 1D, height - 1D,
+                StudioTheme.scale(CHIP_ARC), StudioTheme.scale(CHIP_ARC));
+        canvas.setColor(StudioTheme.PANEL_BACKGROUND);
+        canvas.fill(chip);
+        canvas.setColor(StudioTheme.CONTROL_BORDER);
+        canvas.draw(chip);
+        canvas.setColor(StudioTheme.TEXT);
+        canvas.drawString(location, left + StudioTheme.scale(CHIP_PADDING_X), top + StudioTheme.scale(CHIP_PADDING_Y) + metrics.getAscent());
+        return top + height;
+    }
+
+    private static int drawCentered(Graphics2D canvas, String text, Font font, Color color, int centerX, int top) {
+        canvas.setFont(font);
+        canvas.setColor(color);
+        FontMetrics metrics = canvas.getFontMetrics();
+        canvas.drawString(text, centerX - metrics.stringWidth(text) / 2, top + metrics.getAscent());
+        return top + metrics.getHeight();
+    }
+}

core/src/main/java/com/volmit/iris/core/gui/MapViewIcon.java

@@ -37,11 +37,18 @@ final class MapViewIcon {
     }
 
     static Icon of(MapView view) {
-        return LOADED.computeIfAbsent(view, MapViewIcon::load);
+        return LOADED.computeIfAbsent(view, shown -> load(shown, SIZE));
     }
 
-    private static Icon load(MapView view) {
+    /**
+     * The view's icon drawn larger, for an empty view.
+     */
+    static Icon large(MapView view, int size) {
+        return load(view, size);
+    }
+
+    private static Icon load(MapView view, int size) {
         String fileName = view.name().toLowerCase(Locale.ROOT).replace('_', '-') + ".svg";
-        return new FlatSVGIcon(ICON_FOLDER + fileName, SIZE, SIZE, MapViewIcon.class.getClassLoader());
+        return new FlatSVGIcon(ICON_FOLDER + fileName, size, size, MapViewIcon.class.getClassLoader());
     }
 }

core/src/main/java/com/volmit/iris/core/gui/ObjectExplorer.java

@@ -190,7 +190,7 @@ final class ObjectExplorer {
         browser.showObjects(keys);
         String key = shownKey != null && keys.contains(shownKey) ? shownKey : browser.firstObject();
         if (key == null) {
-            viewport.showMessage("This pack has no " + source.noun() + "s");
+            viewport.showEmptyState(source.emptyState());
             overview.clear();
             layerCut.showHeight(1);
             if (comparingVariants) {

core/src/main/java/com/volmit/iris/core/gui/ObjectSource.java

@@ -31,6 +31,9 @@ interface ObjectSource {
     /** What one entry is called, such as "object", for the browser's texts. */
     String noun();
 
+    /** What the view shows when the pack has no entries. */
+    EmptyState emptyState();
+
     /** The key of every entry, where a slash separates folders. */
     List<String> keys(IrisData data);
 

core/src/main/java/com/volmit/iris/core/gui/ObjectViewport.java

@@ -64,6 +64,7 @@ final class ObjectViewport extends JComponent {
     private ObjectCamera camera = ObjectCamera.START;
     private BufferedImage frame;
     private String message = "Choose an object";
+    private EmptyState emptyState;
     private boolean rendering;
     private boolean renderAgain;
     private Point dragPoint;
@@ -98,6 +99,7 @@ final class ObjectViewport extends JComponent {
         mesh = nextMesh;
         camera = ObjectCamera.START;
         message = nextMesh.isEmpty() ? "No visible blocks" : null;
+        emptyState = null;
         if (nextMesh.isEmpty()) {
             frame = null;
             finishLoading();
@@ -116,6 +118,7 @@ final class ObjectViewport extends JComponent {
         }
         loadingText = text;
         message = null;
+        emptyState = null;
         loadingTicker.start();
     }
 
@@ -130,6 +133,7 @@ final class ObjectViewport extends JComponent {
     void replaceMesh(ObjectMesh nextMesh) {
         mesh = nextMesh;
         message = nextMesh.isEmpty() ? "No visible blocks" : null;
+        emptyState = null;
         requestFrame();
         repaint();
     }
@@ -147,6 +151,16 @@ final class ObjectViewport extends JComponent {
     void showMessage(String text) {
         mesh = null;
         message = text;
+        emptyState = null;
+        frame = null;
+        finishLoading();
+        repaint();
+    }
+
+    void showEmptyState(EmptyState state) {
+        mesh = null;
+        message = null;
+        emptyState = state;
         frame = null;
         finishLoading();
         repaint();
@@ -223,6 +237,9 @@ final class ObjectViewport extends JComponent {
         if (message != null) {
             drawMessage((Graphics2D) graphics);
         }
+        if (emptyState != null) {
+            emptyState.paint((Graphics2D) graphics, this, coveredLeftWidth + (getWidth() - coveredLeftWidth) / 2, getHeight() / 2);
+        }
     }
 
     private void drawLoading(Graphics2D graphics) {

core/src/main/java/com/volmit/iris/core/gui/PackObjectSource.java

@@ -27,11 +27,19 @@ import java.util.List;
  * The pack's object files, by their load keys.
  */
 final class PackObjectSource implements ObjectSource {
+    private static final int EMPTY_ICON_SIZE = 40;
+
     @Override
     public String noun() {
         return "object";
     }
 
+    @Override
+    public EmptyState emptyState() {
+        return new EmptyState(MapViewIcon.large(MapView.OBJECTS, EMPTY_ICON_SIZE), "No objects yet",
+                "Put the pack's .iob objects in", "objects/", "They appear here once the pack reloads.");
+    }
+
     @Override
     public List<String> keys(IrisData data) {
         return Arrays.asList(data.getObjectLoader().getPossibleKeys());

core/src/main/java/com/volmit/iris/core/gui/ProceduralObjectSource.java

@@ -39,6 +39,8 @@ final class ProceduralObjectSource implements ObjectSource {
             "fungi", "Fungi",
             "ruins", "Ruins");
 
+    private static final int EMPTY_ICON_SIZE = 40;
+
     private Map<String, ResolvedProceduralPlacement> definitionsByKey = Map.of();
 
     @Override
@@ -46,6 +48,13 @@ final class ProceduralObjectSource implements ObjectSource {
         return "procedural object";
     }
 
+    @Override
+    public EmptyState emptyState() {
+        return new EmptyState(MapViewIcon.large(MapView.PROCEDURAL, EMPTY_ICON_SIZE), "No procedural objects yet",
+                "Declare them in a biome or region, or save a settings file per object, like",
+                "snippet/" + ProceduralObjectCatalog.TREE_FOLDER + "/oak.json", "They appear here once the pack reloads.");
+    }
+
     // The type folder gets its label; the rest of the path stays as the pack has it.
     @Override
     public List<String> keys(IrisData data) {