From 80dc5c0635b4a4c9f874feca0c5ca7946476ba50 Mon Sep 17 00:00:00 2001
From: Ben Olden-Cooligan <ben.cyanfish@gmail.com>
Date: Tue, 6 Feb 2024 20:22:36 -0800
Subject: [PATCH] Match thumbnail placeholders to background

---
 NAPS2.Images/Bitwise/FillColorImageOp.cs | 54 ++++++++++++++++++++++++
 NAPS2.Lib/EtoForms/EtoExtensions.cs      |  6 +++
 NAPS2.Lib/Images/UiThumbnailProvider.cs  |  5 ++-
 3 files changed, 64 insertions(+), 1 deletion(-)
 create mode 100644 NAPS2.Images/Bitwise/FillColorImageOp.cs

diff --git a/NAPS2.Images/Bitwise/FillColorImageOp.cs b/NAPS2.Images/Bitwise/FillColorImageOp.cs
new file mode 100644
index 000000000..04ae67c41
--- /dev/null
+++ b/NAPS2.Images/Bitwise/FillColorImageOp.cs
@@ -0,0 +1,54 @@
+namespace NAPS2.Images.Bitwise;
+
+public class FillColorImageOp : UnaryBitwiseImageOp
+{
+    private readonly byte _r, _g, _b, _a;
+
+    public FillColorImageOp(byte r, byte g, byte b, byte a)
+    {
+        _r = r;
+        _g = g;
+        _b = b;
+        _a = a;
+    }
+
+    protected override void PerformCore(BitwiseImageData data, int partStart, int partEnd)
+    {
+        if (data.bytesPerPixel is 1 or 3 or 4)
+        {
+            PerformRgba(data, partStart, partEnd);
+        }
+        else
+        {
+            throw new InvalidOperationException("Unsupported pixel format");
+        }
+    }
+
+    private unsafe void PerformRgba(BitwiseImageData data, int partStart, int partEnd)
+    {
+        bool gray = data.bytesPerPixel == 1;
+        byte luma = (byte) ((_r * R_MULT + _g * G_MULT + _b * B_MULT) / 1000);
+        for (int i = partStart; i < partEnd; i++)
+        {
+            var row = data.ptr + data.stride * i;
+            for (int j = 0; j < data.w; j++)
+            {
+                var pixel = row + j * data.bytesPerPixel;
+                if (gray)
+                {
+                    *pixel = luma;
+                }
+                else
+                {
+                    *(pixel + data.rOff) = _r;
+                    *(pixel + data.gOff) = _g;
+                    *(pixel + data.bOff) = _b;
+                }
+                if (data.hasAlpha)
+                {
+                    *(pixel + data.aOff) = _a;
+                }
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/NAPS2.Lib/EtoForms/EtoExtensions.cs b/NAPS2.Lib/EtoForms/EtoExtensions.cs
index 70537777e..7b5cbb90b 100644
--- a/NAPS2.Lib/EtoForms/EtoExtensions.cs
+++ b/NAPS2.Lib/EtoForms/EtoExtensions.cs
@@ -1,5 +1,6 @@
 using Eto.Drawing;
 using Eto.Forms;
+using NAPS2.Images.Bitwise;
 
 namespace NAPS2.EtoForms;
 
@@ -40,4 +41,9 @@ public static class EtoExtensions
     {
         return checkBox.Checked == true;
     }
+
+    public static void Fill(this IMemoryImage image, Color color)
+    {
+        new FillColorImageOp((byte) color.Rb, (byte) color.Gb, (byte) color.Bb, (byte) color.Ab).Perform(image);
+    }
 }
\ No newline at end of file
diff --git a/NAPS2.Lib/Images/UiThumbnailProvider.cs b/NAPS2.Lib/Images/UiThumbnailProvider.cs
index 73726747f..bbdb7d3be 100644
--- a/NAPS2.Lib/Images/UiThumbnailProvider.cs
+++ b/NAPS2.Lib/Images/UiThumbnailProvider.cs
@@ -9,11 +9,13 @@ namespace NAPS2.Images;
 public class UiThumbnailProvider
 {
     private readonly ImageContext _imageContext;
+    private readonly ColorScheme _colorScheme;
     private IMemoryImage? _placeholder;
 
-    public UiThumbnailProvider(ImageContext imageContext)
+    public UiThumbnailProvider(ImageContext imageContext, ColorScheme colorScheme)
     {
         _imageContext = imageContext;
+        _colorScheme = colorScheme;
     }
 
     public IMemoryImage GetThumbnail(UiImage img, int thumbnailSize)
@@ -43,6 +45,7 @@ public class UiThumbnailProvider
             }
             _placeholder?.Dispose();
             _placeholder = _imageContext.Create(thumbnailSize, thumbnailSize, ImagePixelFormat.RGB24);
+            _placeholder.Fill(_colorScheme.BackgroundColor);
             _placeholder = EtoPlatform.Current.DrawHourglass(_imageContext, _placeholder);
             return _placeholder;
         }