Watermark better way to generate .NET

In order to protect intellectual property from unauthorized use of resources, watermarks in blog, shop and other scenes are very common.

This paper demonstrates on System.Drawing.Imagedoing normal operation. Then, based on Direct2D/ WIC/ DirectWrite, demonstrate a new, different " show " operation.

Method 1 - `System.Drawing`to add a watermark picture

System.Drawing.ImageNative belong to GDIa part of, is Windows Only, but with NuGet package System.Drawing.Common release, now System.Drawing.Imagehas support for linux:

Install-Package System.Drawing.Common -Version 4.5.1

The following code demonstrates how to add a watermark to the picture from:

// 加水印
var watermarkedStream = new MemoryStream();
using (var img = Image.FromStream(File.OpenRead(@"D:\_\WatermarkDemo.png")))
{
    using (var graphic = Graphics.FromImage(img))
    {
        var font = new Font("微软雅黑", 30, FontStyle.Bold, GraphicsUnit.Pixel);
        var color = Color.FromArgb(128, 255, 255, 255);
        var brush = new SolidBrush(color);
        var point = new Point(img.Width - 130, img.Height - 50);

        graphic.DrawString("水印在此", font, brush, point);
        img.Save(watermarkedStream, ImageFormat.Png);
    }
}

FIG effect (no yellow shear head):

Attached: Edi.Wang made a NuGet package, you can easily configure watermark parameters:

NuGet：https://github.com/EdiWang/Edi.ImageWatermark
Article: https: //edi.wang/post/2018/10/12/add-watermark-to-uploaded-image-aspnet-core

Method 2 `Direct2D`/ `WIC`to images watermarked

Direct2DFrom Windows 8/ IE 10to install IE 10later, Windows 7also can be used. Direct2DBased Direct3D, apparently, it is a Windows Only.

Direct2DIt is Windowsthe next generation of 2D rendering library, as Direct2Dpublished together, as well as Windows Imaging Component(for short WIC) and DirectWrite.

Instructions and document links:

technology	Explanation	link
`Direct2D`	Hardware accelerated 2D graphics rendering	Go
`WIC`	High-performance picture encoding, decoding	Go
`DirectWrite`	Hardware-accelerated text rendering	Go

If you open the link looked at, it is easy to see that these techniques are based on COM, but we use .NET, is not it?

Fortunately, we have`SharpDX`

SharpDXThese DirectXtechniques do packaging, in this Demo, we need to be installed SharpDX.Direct2D1and SharpDX.Mathematicstwo packages:

Install-Package SharpDX.Direct2D1 -Version 4.2.0
Install-Package SharpDX.Mathematics -Version 4.2.0

The following code demonstrates how SharpDX.Direct2D1to add a watermark picture:

using D2D = SharpDX.Direct2D1;
using DWrite = SharpDX.DirectWrite;
using SharpDX;
using SharpDX.IO;
using WIC = SharpDX.WIC;

MemoryStream AddWatermark(Stream fileName, string watermarkText)
{
    using (var wic = new WIC.ImagingFactory2())
    using (var d2d = new D2D.Factory())
    using (var image = CreateWicImage(wic, fileName))
    using (var wicBitmap = new WIC.Bitmap(wic, image.Size.Width, image.Size.Height, WIC.PixelFormat.Format32bppPBGRA, WIC.BitmapCreateCacheOption.CacheOnDemand))
    using (var target = new D2D.WicRenderTarget(d2d, wicBitmap, new D2D.RenderTargetProperties()))
    using (var bmpPicture = D2D.Bitmap.FromWicBitmap(target, image))
    using (var dwriteFactory = new SharpDX.DirectWrite.Factory())
    using (var brush = new D2D.SolidColorBrush(target, new Color(0xff, 0xff, 0xff, 0x7f)))
    {
        target.BeginDraw();
        {
            target.DrawBitmap(bmpPicture, new RectangleF(0, 0, target.Size.Width, target.Size.Height), 1.0f, D2D.BitmapInterpolationMode.Linear);
            target.DrawRectangle(new RectangleF(0, 0, target.Size.Width, target.Size.Height), brush);
            var textFormat = new DWrite.TextFormat(dwriteFactory, "微软雅黑", DWrite.FontWeight.Bold, DWrite.FontStyle.Normal, 30.0f);
            target.DrawText(watermarkText, textFormat, new RectangleF(target.Size.Width - 130, target.Size.Height - 50, int.MaxValue, int.MaxValue), brush);
        }
        target.EndDraw();

        var ms = new MemoryStream();
        SaveD2DBitmap(wic, wicBitmap, ms);
        return ms;
    }
}

void SaveD2DBitmap(WIC.ImagingFactory wicFactory, WIC.Bitmap wicBitmap, Stream outputStream)
{
    using (var encoder = new WIC.BitmapEncoder(wicFactory, WIC.ContainerFormatGuids.Png))
    {
        encoder.Initialize(outputStream);
        using (var frame = new WIC.BitmapFrameEncode(encoder))
        {
            frame.Initialize();
            frame.SetSize(wicBitmap.Size.Width, wicBitmap.Size.Height);

            var pixelFormat = wicBitmap.PixelFormat;
            frame.SetPixelFormat(ref pixelFormat);
            frame.WriteSource(wicBitmap);

            frame.Commit();
            encoder.Commit();
        }
    }
}

WIC.FormatConverter CreateWicImage(WIC.ImagingFactory wicFactory, Stream stream)
{
    using (var decoder = new WIC.PngBitmapDecoder(wicFactory))
    {
        var decodeStream = new WIC.WICStream(wicFactory, stream);
        decoder.Initialize(decodeStream, WIC.DecodeOptions.CacheOnLoad);
        using (var decodeFrame = decoder.GetFrame(0))
        {
            var converter = new WIC.FormatConverter(wicFactory);
            converter.Initialize(decodeFrame, WIC.PixelFormat.Format32bppPBGRA);
            return converter;
        }
    }
}

Invocation:

File.WriteAllBytes(@"D:\_\Demo2.png", AddWatermark(File.OpenRead(@"D:\_\WatermarkDemo.png"), "水印在此").ToArray());

The effect is as usual:

What's the difference?

System.DrawingIt took only 14 lines, Direct2Dit takes a full 60 rows! The complexity of amazing! Why do you want to round it simple Complicated?

Because System.Drawingthere is no hardware acceleration, and the resulting picture is also no anti-aliasing ( Anti-aliasing), which leads to the use of System.Drawingcontrast slower, less effective and the resulting picture:

It is obvious that the Direct2Dresulting image is smoother.

Author: Zhou Jie
Source: https: //www.cnblogs.com/sdflysha
This article uses Creative Commons Attribution - NonCommercial - ShareAlike 2.5 license agreement in China to license, welcome to reprint, but without the author's consent must keep this paragraph statement, and given the original connection in the apparent position of the article page.