Avalonia/src/Skia/Avalonia.Skia/PlatformRenderInterface.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Avalonia.Controls.Platform.Surfaces;
using Avalonia.Media;
using Avalonia.Platform;
using SkiaSharp;

namespace Avalonia.Skia
{
    public partial class PlatformRenderInterface : IPlatformRenderInterface
    {
        public IBitmapImpl CreateBitmap(int width, int height)
        {
            return CreateRenderTargetBitmap(width, height, 96, 96);
        }

        public IFormattedTextImpl CreateFormattedText(
            string text,
            Typeface typeface,
            TextAlignment textAlignment,
            TextWrapping wrapping,
            Size constraint,
            IReadOnlyList<FormattedTextStyleSpan> spans)
        {
            return new FormattedTextImpl(text, typeface, textAlignment, wrapping, constraint, spans);
        }

        public IStreamGeometryImpl CreateStreamGeometry()
        {
            return new StreamGeometryImpl();
        }

        public IBitmapImpl LoadBitmap(System.IO.Stream stream)
        {
            using (var s = new SKManagedStream(stream))
            {
                var bitmap = SKBitmap.Decode(s);
                if (bitmap != null)
                {
                    return new BitmapImpl(bitmap);
                }
                else
                {
                    throw new ArgumentException("Unable to load bitmap from provided data");
                }
            }
        }

        public IBitmapImpl LoadBitmap(string fileName)
        {
            using (var stream = File.OpenRead(fileName))
            {
                return LoadBitmap(stream);
            }
        }

        public IBitmapImpl LoadBitmap(PixelFormat format, IntPtr data, int width, int height, int stride)
        {
            using (var tmp = new SKBitmap())
            {
                tmp.InstallPixels(new SKImageInfo(width, height, format.ToSkColorType(), SKAlphaType.Premul)
                    , data, stride);
                return new BitmapImpl(tmp.Copy());
            }
        }

        public IRenderTargetBitmapImpl CreateRenderTargetBitmap(
            int width,
            int height,
            double dpiX,
            double dpiY)
        {
            if (width < 1)
                throw new ArgumentException("Width can't be less than 1", nameof(width));
            if (height < 1)
                throw new ArgumentException("Height can't be less than 1", nameof(height));

            return new BitmapImpl(width, height, new Vector(dpiX, dpiY));
        }

        public virtual IRenderTarget CreateRenderTarget(IEnumerable<object> surfaces)
        {
            var fb = surfaces?.OfType<IFramebufferPlatformSurface>().FirstOrDefault();
            if (fb == null)
                throw new Exception("Skia backend currently only supports framebuffer render target");
            return new FramebufferRenderTarget(fb);
        }

        public IWritableBitmapImpl CreateWritableBitmap(int width, int height, PixelFormat? format = null)
        {
            return new BitmapImpl(width, height, new Vector(96, 96), format);
        }
    }
}