[GUI] Improve memory usage of image previews

- also a bit increased performance of alpha mask resizing for previews

AssetStudioGUI/AssetStudioGUIForm.cs

@@ -797,7 +797,7 @@ namespace AssetStudioGUI
             var image = m_Texture2D.ConvertToImage(true);
             if (image != null)
             {
-                var bitmap = new DirectBitmap(image.ConvertToBytes(), m_Texture2D.m_Width, m_Texture2D.m_Height);
+                var bitmap = new DirectBitmap(image);
                 image.Dispose();
                 assetItem.InfoText = $"Width: {m_Texture2D.m_Width}\nHeight: {m_Texture2D.m_Height}\nFormat: {m_Texture2D.m_TextureFormat}";
                 switch (m_Texture2D.m_TextureSettings.m_FilterMode)
@@ -1215,10 +1215,10 @@ namespace AssetStudioGUI
 
         private void PreviewSprite(AssetItem assetItem, Sprite m_Sprite)
         {
-            var image = m_Sprite.GetImage(spriteMaskVisibleMode);
+            var image = m_Sprite.GetImage(spriteMaskMode: spriteMaskVisibleMode);
             if (image != null)
             {
-                var bitmap = new DirectBitmap(image.ConvertToBytes(), image.Width, image.Height);
+                var bitmap = new DirectBitmap(image);
                 image.Dispose();
                 assetItem.InfoText = $"Width: {bitmap.Width}\nHeight: {bitmap.Height}\n";
                 PreviewTexture(bitmap);

AssetStudioGUI/DirectBitmap.cs

@@ -1,4 +1,7 @@
-using System;
+using AssetStudio;
+using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.PixelFormats;
+using System;
 using System.Drawing;
 using System.Drawing.Imaging;
 using System.Runtime.InteropServices;
@@ -7,13 +10,16 @@ namespace AssetStudioGUI
 {
     public sealed class DirectBitmap : IDisposable
     {
-        public DirectBitmap(byte[] buff, int width, int height)
+        public DirectBitmap(Image<Bgra32> image)
         {
-            Width = width;
+            Width = image.Width;
-            Height = height;
+            Height = image.Height;
+            var buff = BigArrayPool<byte>.Shared.Rent(Width * Height * 4);
+            image.CopyPixelDataTo(buff);
             Bits = buff;
             m_handle = GCHandle.Alloc(Bits, GCHandleType.Pinned);
             m_bitmap = new Bitmap(Width, Height, Stride, PixelFormat.Format32bppArgb, m_handle.AddrOfPinnedObject());
+            BigArrayPool<byte>.Shared.Return(buff);
         }
 
         private void Dispose(bool disposing)

AssetStudioGUI/Exporter.cs

@@ -231,10 +231,10 @@ namespace AssetStudioGUI
         public static bool ExportSprite(AssetItem item, string exportPath)
         {
             var type = Properties.Settings.Default.convertType;
-            var alphaMask = Properties.Settings.Default.exportSpriteWithMask ? SpriteMaskMode.On : SpriteMaskMode.Off;
+            var spriteMaskMode = Properties.Settings.Default.exportSpriteWithMask ? SpriteMaskMode.Export : SpriteMaskMode.Off;
             if (!TryExportFile(exportPath, item, "." + type.ToString().ToLower(), out var exportFullPath))
                 return false;
-            var image = ((Sprite)item.Asset).GetImage(alphaMask);
+            var image = ((Sprite)item.Asset).GetImage(spriteMaskMode: spriteMaskMode);
             if (image != null)
             {
                 using (image)

AssetStudioUtility/ImageExtensions.cs

@@ -2,10 +2,7 @@
 using SixLabors.ImageSharp.Formats.Bmp;
 using SixLabors.ImageSharp.Formats.Tga;
 using SixLabors.ImageSharp.Formats.Webp;
-using SixLabors.ImageSharp.PixelFormats;
-using System;
 using System.IO;
-using System.Runtime.InteropServices;
 
 namespace AssetStudio
 {
@@ -51,16 +48,5 @@ namespace AssetStudio
             image.WriteToStream(stream, imageFormat);
             return stream;
         }
-
-        public static byte[] ConvertToBytes<TPixel>(this Image<TPixel> image) where TPixel : unmanaged, IPixel<TPixel>
-        {
-            using (image)
-            {
-                Span<byte> imageSpan = new byte[image.Width * image.Height * 4];
-                image.CopyPixelDataTo(imageSpan);
-
-                return MemoryMarshal.AsBytes(imageSpan).ToArray();
-            }
-        }
     }
 }

AssetStudioUtility/SpriteHelper.cs

@@ -15,12 +15,13 @@ namespace AssetStudio
     {
         Off,
         On,
-        MaskOnly
+        MaskOnly,
+        Export
     }
 
     public static class SpriteHelper
     {
-        public static Image<Bgra32> GetImage(this Sprite m_Sprite, SpriteMaskMode spriteMaskVisibleMode = SpriteMaskMode.On)
+        public static Image<Bgra32> GetImage(this Sprite m_Sprite, SpriteMaskMode spriteMaskMode = SpriteMaskMode.On)
         {
             if (m_Sprite.m_SpriteAtlas != null && m_Sprite.m_SpriteAtlas.TryGet(out var m_SpriteAtlas))
             {
@@ -31,20 +32,19 @@ namespace AssetStudio
             }
             else
             {
-                if (m_Sprite.m_RD.texture.TryGet(out var m_Texture2D) && m_Sprite.m_RD.alphaTexture.TryGet(out var m_AlphaTexture2D) && spriteMaskVisibleMode != SpriteMaskMode.Off)
+                if (m_Sprite.m_RD.texture.TryGet(out var m_Texture2D) && m_Sprite.m_RD.alphaTexture.TryGet(out var m_AlphaTexture2D) && spriteMaskMode != SpriteMaskMode.Off)
                 {
                     var tex = CutImage(m_Sprite, m_Texture2D, m_Sprite.m_RD.textureRect, m_Sprite.m_RD.textureRectOffset, m_Sprite.m_RD.downscaleMultiplier, m_Sprite.m_RD.settingsRaw);
                     var alphaTex = CutImage(m_Sprite, m_AlphaTexture2D, m_Sprite.m_RD.textureRect, m_Sprite.m_RD.textureRectOffset, m_Sprite.m_RD.downscaleMultiplier, m_Sprite.m_RD.settingsRaw);
 
-                    if (tex.Width != alphaTex.Width || tex.Height != alphaTex.Height)
+                    switch (spriteMaskMode)
-                    {
-                        alphaTex.Mutate(x => x.Resize(tex.Width, tex.Height));
-                    }
-
-                    switch (spriteMaskVisibleMode)
                     {
                         case SpriteMaskMode.On:
-                            return ApplyRGBMask(tex, alphaTex);
+                            tex.ApplyRGBMask(alphaTex, isPreview: true);
+                            return tex;
+                        case SpriteMaskMode.Export:
+                            tex.ApplyRGBMask(alphaTex);
+                            return tex;
                         case SpriteMaskMode.MaskOnly:
                             tex.Dispose();
                             return alphaTex;
@@ -58,10 +58,16 @@ namespace AssetStudio
             return null;
         }
 
-        private static Image<Bgra32> ApplyRGBMask(Image<Bgra32> tex, Image<Bgra32> texMask)
+        private static void ApplyRGBMask(this Image<Bgra32> tex, Image<Bgra32> texMask, bool isPreview = false)
         {
             using (texMask)
             {
+                if (tex.Width != texMask.Width || tex.Height != texMask.Height)
+                {
+                    var resampler = isPreview ? KnownResamplers.NearestNeighbor : KnownResamplers.Bicubic;
+                    texMask.Mutate(x => x.Resize(tex.Width, tex.Height, resampler));
+                }
+
                 tex.ProcessPixelRows(texMask, (sourceTex, targetTexMask) =>
                 {
                     for (int y = 0; y < texMask.Height; y++)
@@ -75,8 +81,6 @@ namespace AssetStudio
                         }
                     }
                 });
-
-                return tex;
             }
         }