Add standalone testbed

imgui/StandaloneImGuiTestbed/Program.cs

@@ -0,0 +1,61 @@
+using Veldrid;
+using Veldrid.Sdl2;
+using Veldrid.StartupUtilities;
+
+namespace StandaloneImGuiTestbed;
+
+class Program
+{
+    static void Main(string[] args)
+    {
+        Sdl2Window window;
+        GraphicsDevice gd;
+
+        ImGuiBackend? backend = null;
+
+        VeldridStartup.CreateWindowAndGraphicsDevice(
+            new WindowCreateInfo(50, 50, 1280, 800, WindowState.Normal, "Dalamud Standalone ImGui Testbed"),
+            new GraphicsDeviceOptions(false, null, true, ResourceBindingModel.Improved, true, true),
+            out window,
+            out gd);
+
+        window.Resized += () =>
+        {
+            gd.MainSwapchain.Resize((uint)window.Width, (uint)window.Height);
+            backend!.WindowResized(window.Width, window.Height);
+        };
+
+        var cl = gd.ResourceFactory.CreateCommandList();
+        backend = new ImGuiBackend(gd, gd.MainSwapchain.Framebuffer.OutputDescription, window.Width, window.Height, new FileInfo("imgui.ini"), 21.0f);
+
+        var testbed = new Testbed();
+
+        while (window.Exists)
+        {
+            Thread.Sleep(50);
+
+            var snapshot = window.PumpEvents();
+
+            if (!window.Exists)
+                break;
+
+            backend.Update(1f / 60f, snapshot);
+
+            testbed.Draw();
+
+            cl.Begin();
+            cl.SetFramebuffer(gd.MainSwapchain.Framebuffer);
+            cl.ClearColorTarget(0, new RgbaFloat(0, 0, 0, 1f));
+            backend.Render(gd, cl);
+            cl.End();
+            gd.SubmitCommands(cl);
+            gd.SwapBuffers(gd.MainSwapchain);
+        }
+
+        // Clean up Veldrid resources
+        gd.WaitForIdle();
+        backend.Dispose();
+        cl.Dispose();
+        gd.Dispose();
+    }
+}