Table of Contents

Class TextOverlayBlock

Namespace
VisioForge.Core.MediaBlocks.VideoProcessing
Assembly
VisioForge.Core.dll

MediaBlock that renders dynamic text overlays onto video streams with full typography control. This block provides comprehensive text rendering capabilities including custom fonts, colors, sizing, positioning, shadows, outlines, and background effects. Supports real-time text updates, multiple text elements, and professional typography features commonly used for titles, subtitles, lower thirds, captions, timestamps, and branding. The text rendering engine supports Unicode, anti-aliasing, and advanced text layout with precise positioning control. Implements the VisioForge.Core.MediaBlocks.MediaBlock. Implements the VisioForge.Core.MediaBlocks.IMediaBlockInternals. Implements the IDisposable.

public class TextOverlayBlock : MediaBlock, IMediaBlock, IDisposable, IMediaBlockInternals

Inheritance

Implements

Inherited Members

Extension Methods

Constructors

TextOverlayBlock(TextOverlaySettings)

Initializes a new instance of the VisioForge.Core.MediaBlocks.VideoProcessing.TextOverlayBlock class with the specified text overlay settings. The settings define all aspects of text rendering including content, typography, positioning, and visual effects.

public TextOverlayBlock(TextOverlaySettings settings)

Parameters

settings TextOverlaySettings

The TextOverlaySettings instance defining text content, font, colors, positioning, and effects.

Properties

Fonts

Gets a collection of available system fonts that can be used for text rendering. This collection includes all fonts installed on the system and accessible to the text rendering engine. Use these font descriptions to configure the Settings.Font property for text appearance.

public ObservableCollection<FontDescriptionX> Fonts { get; }

Property Value

ObservableCollection<FontDescriptionX>

Input

Gets the input.

public override MediaBlockPad Input { get; }

Property Value

MediaBlockPad

Inputs

Gets the inputs.

public override MediaBlockPad[] Inputs { get; }

Property Value

MediaBlockPad[]

Output

Gets the output.

public override MediaBlockPad Output { get; }

Property Value

MediaBlockPad

Outputs

Gets the outputs.

public override MediaBlockPad[] Outputs { get; }

Property Value

MediaBlockPad[]

Settings

Gets or sets the text overlay settings that control text content, appearance, and positioning. These settings include font selection, text content, color, size, alignment, shadows, outlines, background effects, and positioning coordinates. Changes to these settings affect the rendered text.

public TextOverlaySettings Settings { get; set; }

Property Value

TextOverlaySettings

Type

Gets the type.

public override MediaBlockType Type { get; }

Property Value

MediaBlockType

Methods

Build()

Constructs and initializes the text overlay filter and its associated GStreamer elements. This method creates the filter with the specified text settings, establishes input and output pads, and prepares the block for text rendering operations.

public override bool Build()

Returns

bool

true if the filter was successfully built and configured; false if initialization failed.

CleanUp()

Releases all resources and performs cleanup operations for this text overlay block. This method disposes of the GStreamer elements and resets the build state.

public void CleanUp()

Dispose(bool)

Releases unmanaged and - optionally - managed resources.

protected override void Dispose(bool disposing)

Parameters

disposing bool

true to release both managed and unmanaged resources; false to release only unmanaged resources.

GetCore()

Gets the core BaseElement wrapper that provides additional functionality around the GStreamer text overlay filter element.

public BaseElement GetCore()

Returns

BaseElement

The BaseElement wrapper instance that encapsulates the GStreamer text overlay filter.

GetElement()

Gets the underlying GStreamer element that performs the text rendering and overlay processing.

public Element GetElement()

Returns

Element

The GStreamer Element instance representing the text overlay filter.

IsAvailable()

Determines whether the text overlay filter is available on the current system. This checks if the required GStreamer text rendering plugins and font subsystem are installed and accessible. The correct NuGet SDK redistribution package should be included in your project.

public static bool IsAvailable()

Returns

bool

true if the text overlay filter is available and can be used; otherwise, false.

IMediaBlockInternals.SetContext(MediaBlocksPipeline)

Associates this text overlay block with a pipeline and initializes its internal context. This method is called internally when the block is added to a pipeline.

void IMediaBlockInternals.SetContext(MediaBlocksPipeline pipeline)

Parameters

pipeline MediaBlocksPipeline

The MediaBlocksPipeline instance that will manage this block.

See Also