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Dialogue Row Widget

MounteaDialogueRow displays a single line of dialogue - participant name, title, body text, an optional icon - and, unlike the composition-root Dialogue Widget, it actually does something in native C++: it owns a fully working typewriter reveal effect you don't have to build yourself.

1. What This Widget Is For

UMounteaDialogueRow (DisplayName "Mountea Dialogue Row") is a UUserWidget implementing IMounteaDialogueRowInterface and IMounteaDialogueUIBaseInterface. Like every base widget in this section it's implicitly Blueprintable - the intended workflow is a Widget Blueprint subclass, not a C++ subclass. The constructor calls SetIsFocusable(true).

The widget holds one piece of state: DialogueRowData, an FWidgetDialogueRow struct (BlueprintReadOnly, VisibleAnywhere, ExposeOnSpawn). Everything this widget shows on screen comes from that struct.

2. The Data It Displays

FWidgetDialogueRow is a lightweight, BlueprintType copy of the data a dialogue row needs to render - it doesn't hold a reference back into the Graph, just the values:

Field Description Default
DialogueRowParticipantName The speaking participant's display name. "Participant Name"
DialogueRowTitle The row's title text. "This is dialogue row title text."
DialogueRowBody The actual line being spoken - what the typewriter effect reveals. "This is dialogue option title text."
RowDuration How long the row stays on screen / how long the typewriter effect runs. 0.f
UIRowID UI-side row identifier, distinct from the row's RowGuid. 0
RowOptionalIcon An optional UTexture for a speaker portrait or icon. nullptr
RowGuid The row's unique identifier. new FGuid

Three BlueprintNativeEvents manage this data, each with a trivial native default a Blueprint subclass can build on:

  • GetDialogueWidgetRowData / SetNewWidgetDialogueRowData - get/set the whole struct. The setter only actually assigns when the incoming data differs (operator!=), so re-setting identical data is a no-op.
  • ResetWidgetDialogueRow - calls FWidgetDialogueRow::ResetRow(), clearing every field back to empty/default and invalidating RowGuid.
  • InitializeWidgetDialogueRow - an empty native hook (// ... in the .cpp). Override it in your Widget Blueprint to react the moment new row data is set, e.g. to refresh a speaker portrait image.

3. The Built-In Typewriter Effect

This is the part of the widget that isn't just a data holder. StartTypeWriterEffect(SourceText, Duration) drives a genuine native character-by-character reveal using two engine timers:

  1. An update-interval timer, firing once per character (Duration / SourceText.Len() seconds apart). On each tick it grows the visible substring by one character and fires OnTypeWriterEffectUpdated(UpdatedText, Alpha).
  2. A duration timer, firing once when the full Duration elapses, which forces the text to its complete state and fires OnTypeWriterEffectFinished().

Both OnTypeWriterEffectUpdated and OnTypeWriterEffectFinished are BlueprintImplementableEvents - there's no native visual behavior at all, only the timing. Your Widget Blueprint reads UpdatedText and Alpha (0 to 1, elapsed time over total duration) on every update to drive whatever text/opacity animation you want.

Info

StartTypeWriterEffect_Implementation guards against re-entry: if either timer handle is already valid, calling Start again is a no-op rather than a restart. Call StopTypeWriterEffect first if you need to interrupt an in-progress reveal and start over.

Two more moves worth knowing:

  • StopTypeWriterEffect doesn't just cancel the timers - it calls the same completion path as a natural finish (CompleteTypeWriterEffect_Callback), so the full DialogueRowBody text is force-shown and OnTypeWriterEffectFinished still fires. This is the correct way to implement a "skip to end of line" action - it leaves the widget in a consistent finished state instead of a half-revealed one.
  • EnableTypeWriterEffect(bEnable) toggles the bUseTypeWriterEffect flag and broadcasts OnTypeWriterEffectChanged (a BlueprintAssignable multicast delegate) whenever the value actually changes. Nothing in this class reads bUseTypeWriterEffect to conditionally skip the timers - it's a flag your Blueprint checks (via the delegate or the exposed property) to decide whether to call StartTypeWriterEffect at all versus just showing the full text immediately.

4. The Hooks a Blueprint Subclass Fills In

IMounteaDialogueUIBaseInterface's four BlueprintNativeEvents ship the same trivial defaults as on Dialogue Widget: BindEvents/UnbindEvents return true and do nothing else, ProcessStringCommand and ApplyTheme are empty. Override any of them in your Widget Blueprint subclass as needed.

Warning

OnTypeWriterEffectUpdated and OnTypeWriterEffectFinished have no default implementation. If your Widget Blueprint doesn't implement both events, calling StartTypeWriterEffect will run the timers correctly but nothing will visibly update on screen - the timing logic works regardless of whether anything is listening.

5. C++ Reference

#include "WBP/MounteaDialogueRow.h"

class MOUNTEADIALOGUESYSTEM_API UMounteaDialogueRow : public UUserWidget,
    public IMounteaDialogueRowInterface,
    public IMounteaDialogueUIBaseInterface
{
    // StartTypeWriterEffect(SourceText, Duration) / StopTypeWriterEffect() /
    // EnableTypeWriterEffect(bEnable) drive OnTypeWriterEffectUpdated /
    // OnTypeWriterEffectFinished, both BlueprintImplementableEvent.
};

6. Next Steps

Dialogue Option Widget

One answer button - focus handling and selection broadcast