UE5-Modular-Game-Framework/docs/blueprints/06-ui/45_WBP_AccessibilityUI.md

WBP_AccessibilityUI — Widget (Subtitle Display, Accessibility Overlays)

Parent Class: UUserWidget (created via Widget Blueprint) Dependencies: BPC_DialoguePlaybackSystem, BPC_NarrativeStateSystem, SS_SettingsSystem File: WBP_AccessibilityUI

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Purpose

Provides subtitle rendering, speaking-name display, subtitle background styling, and accessibility-focused UI overlays (high-contrast mode, colorblind filters, font scaling). Listens to dialogue events from BPC_DialoguePlaybackSystem and settings changes from SS_SettingsSystem.

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Responsibilities

• Display subtitles at the bottom-center of the screen with speaker name, dialogue text, and optional background
• Support multi-line subtitle display with timed progression
• Display speaker name above the subtitle text (optional per settings)
• React to accessibility settings: font size scaling, background opacity, colorblind mode, high-contrast mode
• Fade subtitles in/out on line start/end
• Queue subtitle lines if multiple fire rapidly
• Handle subtitle grouping: one line at a time per speaker, multi-speaker stacking

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Variables

Name	Type	Description
SubtitleContainer	VerticalBox	Vertical stack for active subtitle lines
SpeakerNameText	TextBlock	Current speaker's display name
SubtitleText	TextBlock	Current subtitle line text
SubtitleBackground	Image or Border	Background behind subtitle text
AnimSubtitleIn	WidgetAnimation	Fade in subtitle
AnimSubtitleOut	WidgetAnimation	Fade out subtitle
ActiveSubtitles	Array of FSubtitleLine	Currently displayed subtitle lines
SubtitleQueue	Array of FSubtitleLine	Queue if multiple lines arrive simultaneously
bSubtitlesEnabled	Bool	From settings
SubtitleFontScale	Float	0.8, 1.0, 1.2, 1.5 from settings
SubtitleBackgroundOpacity	Float	0.0 to 1.0 from settings
bHighContrastMode	Bool	From settings
bIsCurrentlySpeaking	Bool	Prevents flicker between rapid lines

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Structs

FSubtitleLine
{
    FText SpeakerName;      // "Dr. Hartmann"
    FText LineText;         // "The tumor is benign..."
    float Duration;          // seconds, from dialogue data
    float StartTime;         // world time when line started
    bool bIsFinalLine;       // if true, marks end of dialogue sequence
    FColor SpeakerColor;     // optional per-speaker color
}

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Functions / Events

Name	Inputs	Outputs	Description
Construct	—	—	Bind to dialogue dispatchers, load accessibility settings
OnDialogueLineStarted	Data: FSubtitleLine	—	Add subtitle to display, start fade-in timer
OnDialogueLineComplete	Data: FSubtitleLine	—	Start fade-out, remove from active list after animation
OnDialogueSequenceEnded	—	—	Clear all subtitles, fade out
DisplaySubtitle	Line: FSubtitleLine	—	Set speaker name, text, background; play AnimSubtitleIn
HideSubtitle	Line: FSubtitleLine	—	Play AnimSubtitleOut, remove from container
SetSubtitlesEnabled	bEnabled: Bool	—	Show/hide subtitle container
ApplyFontScale	Scale: Float	—	Set subtitle text font size (scalar)
SetBackgroundOpacity	Opacity: Float	—	Set subtitle background render opacity
ApplyHighContrastMode	bEnabled: Bool	—	Toggle high-contrast subtitle background/text colors
OnAccessibilitySettingsChanged	Settings: S_AccessibilitySettings	—	Apply all accessibility settings at once
ClearAllSubtitles	—	—	Remove all active subtitles immediately

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Blueprint Flow — Subtitle Lifecycle

sequenceDiagram
    participant Dialogue as BPC_DialoguePlaybackSystem
    participant Sub as WBP_AccessibilityUI
    participant Timer as Internal Timer

    Dialogue->>Sub: OnDialogueLineStarted LineData
    Sub->>Sub: DisplaySubtitle LineData
    Sub->>Sub: Set SpeakerNameText, SubtitleText
    Sub->>Sub: PlayAnimation FadeIn
    Sub->>Timer: SetTimer by LineData.Duration
    Timer-->>Sub: Timer expired
    Sub->>Sub: PlayAnimation FadeOut
    Sub->>Sub: OnDialogueLineComplete LineData
    Dialogue->>Sub: OnDialogueSequenceEnded
    Sub->>Sub: ClearAllSubtitles

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Accessibility Settings Consumption

flowchart LR
    A[SS_SettingsSystem] -->|Read on Construct| B[Cache settings]
    B --> C[SetSubtitlesEnabled]
    B --> D[ApplyFontScale]
    B --> E[SetBackgroundOpacity]
    B --> F[ApplyHighContrastMode]
    A -->|OnAccessibilitySettingsChanged dispatcher| G[Re-apply all]

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Event Dispatchers

Name	Parameters	Fired When
OnSubtitleStarted	Line: FSubtitleLine	A new subtitle line appears
OnSubtitleEnded	Line: FSubtitleLine	A subtitle line ends
OnAllSubtitlesCleared	—	All subtitles removed

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Communications With

Target System	Method	Why
BPC_DialoguePlaybackSystem	Dispatchers (OnLineStarted, OnLineComplete, OnSequenceEnded)	Receive subtitle data
[SS_SettingsSystem]	Direct reads, dispatcher on settings changed	Apply accessibility preferences
WBP_HUD	Parent reference	Positioning within HUD canvas
[BPC_NarrativeStateSystem]	Query	Speaker display name overrides

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Reuse Notes

The subtitle display widget is purely reactive — it never fetches or filters dialogue data. It can be embedded in any HUD canvas (first-person, third-person, diegetic screen overlay). The FSubtitleLine struct is intentionally compatible with the DA_DialogueSequence line format. If no speaker name is provided, the SpeakerNameText collapses and the subtitle text fills the full width. High-contrast mode inverts colors for readability against any background.