Question

设置

考虑给定的临时程序使用SharpDX（Direct *库的托管包装器）来呈现位图并将其另存为PNG：

namespace ConsoleApplication5
{
    using System;
    using System.Diagnostics;
    using System.IO;
    using SharpDX;
    using SharpDX.Direct2D1;
    using SharpDX.DirectWrite;
    using SharpDX.DXGI;
    using SharpDX.IO;
    using SharpDX.WIC;
    using AlphaMode = SharpDX.Direct2D1.AlphaMode;
    using Bitmap = SharpDX.WIC.Bitmap;
    using D2DPixelFormat = SharpDX.Direct2D1.PixelFormat;
    using WicPixelFormat = SharpDX.WIC.PixelFormat;

    class Program
    {
        static void Main(string[] args)
        {
            var width = 400;
            var height = 100;
            var pixelFormat = WicPixelFormat.Format32bppBGR;

            var wicFactory = new ImagingFactory();
            var dddFactory = new SharpDX.Direct2D1.Factory();
            var dwFactory = new SharpDX.DirectWrite.Factory();

            var wicBitmap = new Bitmap(
                wicFactory,
                width,
                height,
                pixelFormat,
                BitmapCreateCacheOption.CacheOnLoad);

            var renderTargetProperties = new RenderTargetProperties(
                RenderTargetType.Default,
                new D2DPixelFormat(Format.Unknown, AlphaMode.Unknown),
                0,
                0,
                RenderTargetUsage.None,
                FeatureLevel.Level_DEFAULT);
            var renderTarget = new WicRenderTarget(
                dddFactory,
                wicBitmap,
                renderTargetProperties)
            {
                TextAntialiasMode = TextAntialiasMode.Cleartype
            };

            renderTarget.BeginDraw();

            var textFormat = new TextFormat(dwFactory, "Consolas", 48) 
            {
                TextAlignment = TextAlignment.Center, 
                ParagraphAlignment = ParagraphAlignment.Center
            };
            var textBrush = new SolidColorBrush(
                renderTarget,
                Colors.Blue);

            renderTarget.Clear(Colors.White);
            renderTarget.DrawText(
                "Hi, mom!",
                textFormat,
                new RectangleF(0, 0, width, height),
                textBrush);

            renderTarget.EndDraw();

            var stream = new WICStream(
                wicFactory,
                "test.png",
                NativeFileAccess.Write);

            var encoder = new PngBitmapEncoder(wicFactory);
            encoder.Initialize(stream);

            var frameEncoder = new BitmapFrameEncode(encoder);
            frameEncoder.Initialize();
            frameEncoder.SetSize(width, height);
            frameEncoder.PixelFormat = WicPixelFormat.FormatDontCare;
            frameEncoder.WriteSource(wicBitmap);
            frameEncoder.Commit();

            encoder.Commit();

            frameEncoder.Dispose();
            encoder.Dispose();
            stream.Dispose();

            Process.Start(Path.GetFullPath(Path.Combine(Environment.CurrentDirectory, "test.png")));
        }
    }
}

运行此程序会在程序的工作目录中为您提供一个“test.png”文件，其中包含以下精美图像：

Output Image

问题

太棒了，我刚刚在ASP.NET应用程序的上下文中使用Direct2D而不是GDI + which is supposedly more supported渲染了一个图像。另外，Direct2D是新的热点。

假设我想编写一个渲染这样一个图像的函数，并将PNG作为Stream或byte[]数组返回，在内存中执行整个渲染和编码操作，而不是写入文件系统。这是为了响应Web请求;只需直接将其流式传输到浏览器而无需通过文件系统。

在GDI +中，我可以很容易地使用MemoryStream进行此操作，但我不知道如何在不知道缓冲区大小的情况下如何在SharpDX中使用DataStream：

        var bufferSize = 1024 * 3; // how do I know?
        var buffer = new DataStream(
            bufferSize,
            true,
            true);
        var stream = new WICStream(
            wicFactory,
            buffer);

我是否需要P / Invoke到CreateStreamOnHGlobal并使用IntPtr来构建我的DataStream？
我遗失了DataStream的某些重载吗？
是否有一种简单的方法可以预先计算保存编码的PNG图像所需的缓冲区？
或者我应该克服文件系统？

感谢您的帮助！

Answer 1

图书馆的作者added this as a feature。

我会留下问题，因为我认为代码为人们提供了有用的Direct2D示例。

Answer 2

如果有人想在asp.net中这样做：

var memStream = new MemoryStream();
var wicStream = new WICStream(wicFactory, memStream);

//Encode wic bitmap
var encoder = new PngBitmapEncoder(wicFactory);
encoder.Initialize(wicStream);
var frameEncoder = new BitmapFrameEncode(encoder);
frameEncoder.Initialize();
frameEncoder.SetSize(width, height);
var format = WicPixelFormat.FormatDontCare;
frameEncoder.SetPixelFormat(ref format);
frameEncoder.WriteSource(wicBitmap);
frameEncoder.Commit();
encoder.Commit();

//Clean-up
frameEncoder.Dispose();
encoder.Dispose();
wicStream.Dispose();

imgBackdrop.ImageUrl = "data:image/png;base64," + Convert.ToBase64String(memStream.ToArray(), 0, memStream.ToArray().Length);

在通过SharpDX渲染Direct2D图像时，如何使用内存流而不是文件？

设置

问题

2 个答案: