C#实现：基于背景图与二维码图生成指定位置的新图片

No problem! Below is a practical, reusable C# function that lets you merge your background image with a QR code, with full control over where the QR code is placed on the final image.

Step 1: Prerequisites #

First, make sure you have the System.Drawing.Common NuGet package installed (required for .NET Core/.NET 5+; .NET Framework has this built-in).

Step 2: Complete Implementation #

using System.Drawing;
using System.Drawing.Imaging;

public static class ImageComposer
{
    /// <summary>
    /// Combines a background image with a QR code at a specified position
    /// </summary>
    /// <param name="backgroundPath">File path to the background image</param>
    /// <param name="qrCodePath">File path to the QR code image</param>
    /// <param name="qrPosition">Position (X,Y coordinates) where the QR code should be placed</param>
    /// <param name="outputPath">File path to save the composed image</param>
    /// <param name="imageFormat">Output image format (default: PNG)</param>
    public static void CombineImages(string backgroundPath, string qrCodePath, Point qrPosition, string outputPath, ImageFormat imageFormat = null)
    {
        // Use using statements to automatically dispose of image resources and avoid memory leaks
        using (var backgroundImage = Image.FromFile(backgroundPath))
        using (var qrCodeImage = Image.FromFile(qrCodePath))
        using (var composedImage = new Bitmap(backgroundImage.Width, backgroundImage.Height))
        using (var graphics = Graphics.FromImage(composedImage))
        {
            // Draw the background image first (covers the entire canvas)
            graphics.DrawImage(backgroundImage, new Rectangle(0, 0, composedImage.Width, composedImage.Height));
            
            // Draw the QR code at your specified X/Y coordinates
            // Use the QR code's original size by default
            graphics.DrawImage(qrCodeImage, qrPosition.X, qrPosition.Y);
            
            // Fall back to PNG if no format is provided
            imageFormat ??= ImageFormat.Png;
            
            // Save the final combined image to your desired path
            composedImage.Save(outputPath, imageFormat);
        }
    }
}

How to Use It #

Call the function in your code like this (adjust paths and position to match your needs):

// Example: Place QR code at X=50, Y=100 on the background image
ImageComposer.CombineImages(
    @"C:\assets\background.jpg",
    @"C:\assets\qrcode.png",
    new Point(50, 100),
    @"C:\output\final_image.png"
);

Customization Tips #

• Resize QR Code: If you need to adjust the QR code's dimensions, replace the QR code DrawImage call with this (example resizes to 150x150 pixels):

  graphics.DrawImage(qrCodeImage, new Rectangle(qrPosition.X, qrPosition.Y, 150, 150));
  

• Transparent QR Codes: The function works seamlessly with transparent PNG QR codes—no extra configuration needed.
• Error Handling: Add try-catch blocks to handle edge cases like missing files or invalid image formats, depending on your application's requirements.

内容的提问来源于stack exchange，提问作者Claudio Gareca