RenderTargetStack.cs

using Microsoft.Xna.Framework.Graphics;
using System;

namespace Rampastring.XNAUI;

/// <summary>
/// Handles render targets.
/// </summary>
internal static class RenderTargetStack
{
    public static void Initialize(RenderTarget2D finalRenderTarget, GraphicsDevice _graphicsDevice)
    {
        FinalRenderTarget = finalRenderTarget;
        graphicsDevice = _graphicsDevice;

        currentContext = new RenderContext(finalRenderTarget, null);
    }

    internal static void InitDetachedScaledControlRenderTarget(int renderWidth, int renderHeight)
    {
        if (DetachedScaledControlRenderTarget != null)
        {
            DetachedScaledControlRenderTarget.Dispose();
        }

        DetachedScaledControlRenderTarget = new RenderTarget2D(graphicsDevice,
            renderWidth, renderHeight,
            false, SurfaceFormat.Color,
            DepthFormat.None, 0,
            RenderTargetUsage.DiscardContents);
    }

    public static RenderTarget2D FinalRenderTarget { get; internal set; }

    /// <summary>
    /// A render target for controls that
    /// are detached and have scaling applied to them.
    /// </summary>
    public static RenderTarget2D DetachedScaledControlRenderTarget { get; internal set; }

    private static RenderContext currentContext;

    private static GraphicsDevice graphicsDevice;

    public static void PushRenderTarget(RenderTarget2D renderTarget, SpriteBatchSettings newSettings)
    {
        Renderer.EndDraw();
        var context = new RenderContext(renderTarget, currentContext);
        currentContext = context;
        graphicsDevice.SetRenderTarget(renderTarget);
        Renderer.PushSettingsInternal();
        Renderer.CurrentSettings = newSettings;
        Renderer.BeginDraw();
    }

    public static void PopRenderTarget()
    {
        currentContext = currentContext.PreviousContext;

        if (currentContext == null)
        {
            throw new InvalidOperationException("No render context left! This usually " +
                "indicates that a control with an unique render target has " +
                "double-popped their render target.");
        }

        Renderer.EndDraw();
        Renderer.PopSettingsInternal();
        graphicsDevice.SetRenderTarget(currentContext.RenderTarget);
        Renderer.BeginDraw();
    }
}

internal class RenderContext
{
    public RenderContext(RenderTarget2D renderTarget, RenderContext previousContext)
    {
        RenderTarget = renderTarget;
        PreviousContext = previousContext;
    }

    public RenderTarget2D RenderTarget { get; }
    public RenderContext PreviousContext { get; }
}