Colour pixel-art toolbar icons, 64 px toolbar slots, ViewportCapture: screenshots in sRGB under hdr_2d

src/Tool/ToolBox.cs

@@ -22,6 +22,10 @@ namespace Cthangover.Mods.Interface.Tool
     /// </summary>
     public partial class ToolBox : Control, IToolbarHost, ISaveIconHost
     {
+        /// <summary>Side of a toolbar button and its icon: the icons are 64 px pixel-art sprites (scaled x4), so a
+        /// 64 px slot shows every sprite pixel; at 60 px the nearest filter dropped rows of them.</summary>
+        private const int SlotSize = 64;
+
         private HBoxContainer _buttons;
         private TextureRect _saveIcon;
 
@@ -64,14 +68,14 @@ namespace Cthangover.Mods.Interface.Tool
         {
             var button = new Button
             {
-                CustomMinimumSize = new Vector2(60, 60),
+                CustomMinimumSize = new Vector2(SlotSize, SlotSize),
                 SizeFlagsVertical = SizeFlags.ShrinkCenter,
                 TooltipText = title,
             };
 
             if (icon != null)
             {
-                var iconRect = UiKit.Icon(icon, 60);
+                var iconRect = UiKit.Icon(icon, SlotSize);
                 button.AddChild(iconRect);
                 iconRect.SetAnchorsAndOffsetsPreset(LayoutPreset.FullRect);
             }
@@ -92,7 +96,7 @@ namespace Cthangover.Mods.Interface.Tool
         /// <summary>
         /// Adds one "tools" toolbar button whose popup lists every visible
         /// <see cref="IToolBoxButton"/>. Tools used to get a text button each,
-        /// which did not fit the 60×60 icon row and overlapped its icons; a
+        /// which did not fit the square icon row and overlapped its icons; a
         /// single icon keeps the HUD row uniform no matter how many tools are
         /// installed. Nothing is added when no tool button is visible.
         /// </summary>

src/View/ViewportCapture.cs

@@ -0,0 +1,46 @@
+namespace Cthangover.Mods.Interface.View
+{
+    using System;
+    using System.Runtime.InteropServices;
+    using Godot;
+
+    /// <summary>
+    /// Takes a screenshot of a viewport the way the player sees it.
+    /// </summary>
+    /// <remarks>
+    /// The project renders 2D in HDR (<c>rendering/viewport/hdr_2d</c>): the viewport texture then holds linear
+    /// colour, and Godot converts it to sRGB only when it blits to the window. A plain
+    /// <c>GetTexture().GetImage().SavePng()</c> wrote those linear values, so every screenshot (the site's
+    /// gallery included) came out much darker than the game, shadows most of all. The conversion runs on
+    /// float data before the 8-bit quantisation, so dark gradients do not band.
+    /// </remarks>
+    public static class ViewportCapture
+    {
+        /// <summary>The current frame of <paramref name="viewport"/> as RGBA8 sRGB, or null without a frame.</summary>
+        public static Image Take(Viewport viewport)
+        {
+            var image = viewport.GetTexture()?.GetImage();
+            if (image == null || !viewport.UseHdr2D)
+                return image;
+
+            image.Convert(Image.Format.Rgbaf);
+            var floats = MemoryMarshal.Cast<byte, float>(image.GetData());
+            var bytes = new byte[floats.Length];
+            for (var i = 0; i < floats.Length; i++)
+            {
+                var v = Math.Clamp(floats[i], 0f, 1f);
+                if (i % 4 != 3)
+                    v = v <= 0.0031308f ? v * 12.92f : 1.055f * MathF.Pow(v, 1f / 2.4f) - 0.055f;
+                bytes[i] = (byte)MathF.Round(v * 255f);
+            }
+            return Image.CreateFromData(image.GetWidth(), image.GetHeight(), false, Image.Format.Rgba8, bytes);
+        }
+
+        /// <summary>Saves the current frame of <paramref name="viewport"/> as a PNG; false without a frame.</summary>
+        public static bool SavePng(Viewport viewport, string path)
+        {
+            var image = Take(viewport);
+            return image != null && image.SavePng(path) == Error.Ok;
+        }
+    }
+}