26.2 Collapsible Categories

🗂️ Collapsible Categories

Parameter	Specification
System Component	CollapsibleCategoryRuleEntry (Inner Class)
Enclosing Mixin	AbstractGameRulesScreenRuleListMixin
Target Class	net.minecraft.client.gui.screens.worldselection.AbstractGameRulesScreen.RuleList
Indicator Icons	Expanded: ▼ | Collapsed: ▶
Count Badge Format	(N rules) in ChatFormatting.GRAY
Hover Highlight Color	0x22FFFFFF (25% Alpha White Box)
Separator Line Color	0x44AAAAAA (Subtle Bottom Divider)
Text Color	Hovered: 0xFFFFFFAA | Normal: 0xFFFFFFFF
Interaction Sound	net.minecraft.sounds.SoundEvents.UI_BUTTON_CLICK (Volume: 1.0F)
Narration Type	NarratedElementType.TITLE (NarrationPriority.HOVERED)

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📖 Overview

In vanilla Minecraft, the Game Rules screen renders category headers as static, non-interactive text labels (CategoryRuleEntry), with all child rules listed sequentially in a single scrolling pane. When mods add dozens of custom GameRules, the screen becomes excessively long and difficult to navigate.

Collapsible Categories replaces static headers with interactive CollapsibleCategoryRuleEntry widgets that can be expanded or collapsed at will.

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🎨 Visual Layout & Hierarchy

When rendered inside the RuleList, each category header features dynamic visual indicators and status badges:

┌─────────────────────────────────────────────────────────────────────────────┐
│ [ Expand All ]                                             [ Collapse All ] │ ◄── GlobalActionsRuleEntry (Index 0)
├─────────────────────────────────────────────────────────────────────────────┤
│ ▼ ⚔️ Mobs (14 rules)                                                        │ ◄── CollapsibleCategoryRuleEntry (Expanded)
│ ─────────────────────────────────────────────────────────────────────────── │
│   mobGriefing                                                     [ ON ]    │ ◄── Child RuleEntry
│   doMobSpawning                                                   [ ON ]    │ ◄── Child RuleEntry
│   doMobLoot                                                       [ ON ]    │ ◄── Child RuleEntry
├─────────────────────────────────────────────────────────────────────────────┤
│ ▶ 👤 Player (8 rules)                                                       │ ◄── CollapsibleCategoryRuleEntry (Collapsed)
│ ─────────────────────────────────────────────────────────────────────────── │
│ ▼ 🌧️ Updates (6 rules)                                                      │ ◄── CollapsibleCategoryRuleEntry (Expanded)
│ ─────────────────────────────────────────────────────────────────────────── │
│   doFireTick                                                      [ ON ]    │ ◄── Child RuleEntry
│   randomTickSpeed                                                 [ 3  ]    │ ◄── Child RuleEntry
└─────────────────────────────────────────────────────────────────────────────┘

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⚙️ Technical Mechanics

1. Child Rule Counting Algorithm

When updateVisibleEntries() iterates through allEntries, it determines the exact number of child rules belonging to a category before the next category begins:

int childCount = 0;
for (int j = i + 1; j < this.collapsible_game_rules$allEntries.size(); j++) {
    if (this.collapsible_game_rules$allEntries.get(j) instanceof AbstractGameRulesScreen.CategoryRuleEntry) {
        break;
    }
    childCount++;
}

2. Category Rendering Pipeline (extractContent)

The rendering process is executed via Minecraft's modern GuiGraphicsExtractor interface:

1. Hover Box: If the cursor hovers over the category entry, a semi-transparent box (0x22FFFFFF) is drawn across [getX() - 2, getY()] to [getX() + getWidth() + 2, getY() + 24].
2. Directional Arrow & Text: The prefix (▼ if expanded, ▶ if collapsed) is prepended to the category label, followed by the gray child count badge ( (N rules)).
3. Centered Alignment: The combined component is drawn centered horizontally at getContentXMiddle() with vertical offset getContentY() + 5.
4. Bottom Divider: A subtle dividing line (0x44AAAAAA) is drawn at getY() + 23 across the entry width to demarcate category boundaries.

3. Mouse Interaction Handling

The category header captures mouse clicks in mouseClicked(MouseButtonEvent event, boolean doubleClick):

• Left Click (event.button() == 0) or Right Click (event.button() == 1):
  1. Invokes the category's toggleAction.run().
  2. Updates GameRuleStateConfig with the new boolean state.
  3. Plays the vanilla UI click sound: SimpleSoundInstance.forUI(SoundEvents.UI_BUTTON_CLICK, 1.0F).
  4. Triggers updateVisibleEntries() to dynamically add or remove child rule entries from the active list.
  5. Recalculates list dimensions via updateSizeAndPosition(...).

4. Accessibility & Screen Narration

CollapsibleCategoryRuleEntry implements NarratableEntry:

• Priority: NarrationPriority.HOVERED
• Narration Output: Pushes the category label as NarratedElementType.TITLE to ensure screen readers narrate the active category name when focused or hovered.

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🔗 Related Documentation

• Master Wiki Portal
• MC 26.2 Version Portal
• Global Actions & Bulk Toggles
• Keyboard Navigation & Accessibility
• Architecture & Mixin Subsystem