放大图片 Canvas

Question

有没有使用System.Drawing快速放大.png图片canvas的快捷方式？（见下面的例子）。警告是背景可能是透明的，我想保持透明。

编辑：需要在 ASP.Net CORE

或者，有没有办法将图像放在比图像稍大的白色背景上？

Answer 1

经过几天的反复试验，我想我找到了一些有用的东西

Image overlayImage = //get your image here from file or url.
xloc = //x coord where to start overlay image.  
yloc = //y coord where to start overlay image.  
canvasWidth = //width of background canvas  
canvasHeight = //height of background canvas  
Bitmap baseImage = new Bitmap(canvasWidth, canvasHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb); 

using (Graphics graphics = Graphics.FromImage(baseImage))
{
    using (System.Drawing.SolidBrush myBrush = new System.Drawing.SolidBrush(System.Drawing.Color.White))
    {
        graphics.FillRectangle(myBrush, new Rectangle(0, 0, canvasWidth, canvasHeight));  // white rectangle

    }
    graphics.CompositingMode = CompositingMode.SourceOver;
    graphics.DrawImage(overlayImage, xloc, yloc);

} // graphics will be disposed at this line

放大图片 Canvas

Enlarge Image Canvas

asp.net

asp.net-core

system.drawing