respect z_index on all graphics element types (#2765)

CHANGELOG.md

@@ -6,6 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## [Unreleased]
 ### Fixed
 - Use code signing on all Windows executables (`ErsatzTV-Windows.exe`, `ErsatzTV.exe`, `ErsatzTV.Scanner.exe`)
+- Respect `z_index` (draw order) on all graphics element types
 
 ## [26.1.1] - 2026-01-08
 ### Fixed

ErsatzTV.Infrastructure/Streaming/Graphics/GraphicsElement.cs

@@ -7,7 +7,7 @@ namespace ErsatzTV.Infrastructure.Streaming.Graphics;
 
 public abstract class GraphicsElement : IGraphicsElement
 {
-    public int ZIndex { get; protected set; }
+    public abstract int ZIndex { get; }
 
     public bool IsFinished { get; set; }
 

ErsatzTV.Infrastructure/Streaming/Graphics/Image/ImageElement.cs

@@ -11,6 +11,8 @@ public class ImageElement(ImageGraphicsElement imageGraphicsElement, ILogger log
     private Option<Expression> _maybeOpacityExpression;
     private float _opacity;
 
+    public override int ZIndex { get; } = imageGraphicsElement.ZIndex ?? 0;
+
     public override async Task InitializeAsync(GraphicsEngineContext context, CancellationToken cancellationToken)
     {
         try
@@ -26,8 +28,6 @@ public class ImageElement(ImageGraphicsElement imageGraphicsElement, ILogger log
                 _opacity = (imageGraphicsElement.OpacityPercent ?? 100) / 100.0f;
             }
 
-            ZIndex = imageGraphicsElement.ZIndex ?? 0;
-
             foreach (Expression expression in _maybeOpacityExpression)
             {
                 expression.EvaluateFunction += OpacityExpressionHelper.EvaluateFunction;

ErsatzTV.Infrastructure/Streaming/Graphics/Image/WatermarkElement.cs

@@ -29,6 +29,8 @@ public class WatermarkElement : ImageElementBase
 
     public bool IsValid => _imagePath != null && _watermark != null;
 
+    public override int ZIndex { get; }
+
     public override async Task InitializeAsync(GraphicsEngineContext context, CancellationToken cancellationToken)
     {
         try

ErsatzTV.Infrastructure/Streaming/Graphics/Motion/MotionElement.cs

@@ -30,6 +30,8 @@ public class MotionElement(
     private TimeSpan _endTime;
     private MotionElementState _state;
 
+    public override int ZIndex { get; } = motionElement.ZIndex ?? 0;
+
     public void Dispose()
     {
         GC.SuppressFinalize(this);

ErsatzTV.Infrastructure/Streaming/Graphics/Script/ScriptElement.cs

@@ -27,6 +27,8 @@ public class ScriptElement(ScriptGraphicsElement scriptElement, ILogger logger)
     private int _repeatCount;
     private long _totalBytes;
 
+    public override int ZIndex { get; } = scriptElement.ZIndex ?? 0;
+
     public void Dispose()
     {
         logger.LogDebug(

ErsatzTV.Infrastructure/Streaming/Graphics/Subtitle/SubtitleElement.cs

@@ -30,6 +30,8 @@ public class SubtitleElement(
     private SKBitmap _videoFrame;
     private bool _isFinished;
 
+    public override int ZIndex { get; } = subtitleElement.ZIndex ?? 0;
+
     public void Dispose()
     {
         GC.SuppressFinalize(this);

ErsatzTV.Infrastructure/Streaming/Graphics/Text/TextElement.cs

@@ -21,6 +21,8 @@ public partial class TextElement(
     private Option<Expression> _maybeOpacityExpression;
     private float _opacity;
 
+    public override int ZIndex { get; } = textElement.ZIndex ?? 0;
+
     public void Dispose()
     {
         GC.SuppressFinalize(this);
@@ -44,8 +46,6 @@ public partial class TextElement(
                 _opacity = (textElement.OpacityPercent ?? 100) / 100.0f;
             }
 
-            ZIndex = textElement.ZIndex ?? 0;
-
             if (!string.IsNullOrWhiteSpace(textElement.IncludeFontsFrom))
             {
                 if (Directory.Exists(textElement.IncludeFontsFrom))