Merge pull request #906 from Artemis-RGB/feature/small-led-render-scale

Keep small LEDs addressable at reduced render scales and reduce texture readback allocations

src/Artemis.Core/RGB.NET/SKTexture.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using Artemis.Core.SkiaSharp;
 using HPPH;
-using HPPH.SkiaSharp;
 using RGB.NET.Core;
 using RGB.NET.Presets.Extensions;
 using SkiaSharp;
@@ -25,33 +24,85 @@ public sealed class SKTexture : ITexture, IDisposable
         Surface = graphicsContext == null
             ? SKSurface.Create(ImageInfo)
             : SKSurface.Create(graphicsContext.GraphicsContext, true, ImageInfo);
+        _readback = new SKBitmap(new SKImageInfo(width, height, SKColorType.Bgra8888, SKAlphaType.Unpremul));
 
         foreach (ArtemisDevice artemisDevice in devices)
         {
             foreach (ArtemisLed artemisLed in artemisDevice.Leds)
-            {
-                _ledRects[artemisLed.RgbLed] = SKRectI.Create(
-                    (int)(artemisLed.AbsoluteRectangle.Left * RenderScale),
-                    (int)(artemisLed.AbsoluteRectangle.Top * RenderScale),
-                    (int)(artemisLed.AbsoluteRectangle.Width * RenderScale),
-                    (int)(artemisLed.AbsoluteRectangle.Height * RenderScale)
-                );
-            }
+                _ledRects[artemisLed.RgbLed] = CreateSampleRect(artemisLed.RgbLed.AbsoluteBoundary, scale, width, height);
         }
     }
 
     #endregion
 
+    private static SKRectI CreateSampleRect(Rectangle boundary, float scale, int width, int height)
+    {
+        (int left, int right) = ScaleSpan(boundary.Location.X, boundary.Size.Width, scale, width);
+        (int top, int bottom) = ScaleSpan(boundary.Location.Y, boundary.Size.Height, scale, height);
+        return new SKRectI(left, top, right, bottom);
+    }
+
+    private static (int Start, int End) ScaleSpan(float location, float size, float scale, int max)
+    {
+        float start = location * scale;
+        float end = (location + size) * scale;
+        if (end <= 0 || start >= max)
+            return (0, 0);
+
+        // Always sample at least one pixel
+        int startPixel = Math.Clamp(start.RoundToInt(), 0, max - 1);
+        int endPixel = Math.Clamp(end.RoundToInt(), startPixel + 1, max);
+        return (startPixel, endPixel);
+    }
+
     internal Color GetColorAtRenderTarget(in RenderTarget renderTarget)
     {
-        if (_image == null) return Color.Transparent;
+        if (!_hasPixels) return Color.Transparent;
 
         SKRectI skRectI = _ledRects[renderTarget.Led];
 
         if (skRectI.Width <= 0 || skRectI.Height <= 0)
             return Color.Transparent;
 
-        return _image[skRectI.Left, skRectI.Top, skRectI.Width, skRectI.Height].Average().ToColor();
+        return AveragePixels(_readback, skRectI);
+    }
+
+    internal static unsafe Color AveragePixels(SKBitmap bitmap, SKRectI rectangle)
+    {
+        int left = Math.Max(0, rectangle.Left);
+        int top = Math.Max(0, rectangle.Top);
+        int right = Math.Min(bitmap.Width, rectangle.Right);
+        int bottom = Math.Min(bitmap.Height, rectangle.Bottom);
+        if (left >= right || top >= bottom)
+            return Color.Transparent;
+
+        byte* pixels = (byte*)bitmap.GetPixels().ToPointer();
+        if (pixels == null)
+            return Color.Transparent;
+
+        long blue = 0;
+        long green = 0;
+        long red = 0;
+        long alpha = 0;
+        int rowBytes = bitmap.RowBytes;
+        for (int y = top; y < bottom; y++)
+        {
+            byte* pixel = pixels + y * rowBytes + left * 4;
+            for (int x = left; x < right; x++, pixel += 4)
+            {
+                blue += pixel[0];
+                green += pixel[1];
+                red += pixel[2];
+                alpha += pixel[3];
+            }
+        }
+
+        float count = (right - left) * (bottom - top);
+        return new ColorBGRA(
+            (byte)MathF.Round(blue / count),
+            (byte)MathF.Round(green / count),
+            (byte)MathF.Round(red / count),
+            (byte)MathF.Round(alpha / count)).ToColor();
     }
 
     /// <inheritdoc />
@@ -63,6 +114,8 @@ public sealed class SKTexture : ITexture, IDisposable
     /// <inheritdoc />
     public void Dispose()
     {
+        _hasPixels = false;
+        _readback.Dispose();
         Surface.Dispose();
         GC.SuppressFinalize(this);
     }
@@ -79,15 +132,15 @@ public sealed class SKTexture : ITexture, IDisposable
 
     internal void CopyPixelData()
     {
-        using SKImage skImage = Surface.Snapshot();
-        _image = skImage.ToImage();
+        _hasPixels = Surface.ReadPixels(_readback.Info, _readback.GetPixels(), _readback.RowBytes, 0, 0);
     }
 
     #endregion
 
     #region Properties & Fields
 
-    private IImage? _image;
+    private readonly SKBitmap _readback;
+    private bool _hasPixels;
     private readonly Dictionary<Led, SKRectI> _ledRects = [];
 
     /// <inheritdoc />

src/Artemis.Core/Services/RenderService.cs

@@ -47,6 +47,7 @@ internal class RenderService : IRenderService, IRenderer, IDisposable
         _preferredGraphicsContext.SettingChanged += PreferredGraphicsContextOnSettingChanged;
 
         Utilities.ShutdownRequested += UtilitiesOnShutdownRequested;
+        ApplyRenderScaleMultiplier();
         _surfaceManager = new SurfaceManager(this, GraphicsContext, _targetFrameRateSetting.Value, (float) _renderScaleSetting.Value);
     }
 
@@ -189,9 +190,14 @@ internal class RenderService : IRenderService, IRenderer, IDisposable
         _surfaceManager.UpdateTargetFrameRate(_targetFrameRateSetting.Value);
     }
 
-    private void RenderScaleSettingOnSettingChanged(object? sender, EventArgs e)
+    private void ApplyRenderScaleMultiplier()
     {
         RenderScale.SetRenderScaleMultiplier((int) (1 / _renderScaleSetting.Value));
+    }
+
+    private void RenderScaleSettingOnSettingChanged(object? sender, EventArgs e)
+    {
+        ApplyRenderScaleMultiplier();
         _surfaceManager.UpdateRenderScale((float) _renderScaleSetting.Value);
     }