.NET 采用 SkiaSharp 生成二维码和图形验证码及图片进行指定区域截取方法实 - ToB企服应用市场:ToB评测及商务社交产业平台

using SkiaSharp.QrCode;
namespace Common
{
public class ImgHelper
{
/// <summary>
/// 生成二维码
/// </summary>
/// <param name="text">二维码内容</param>
/// <returns></returns>
public static byte[] GetQrCode(string text)
{
using QRCodeGenerator generator = new();
using var qr = generator.CreateQrCode(text, ECCLevel.L);
SKImageInfo info = new(500, 500);
using var surface = SKSurface.Create(info);
using var canvas = surface.Canvas;
canvas.Render(qr, info.Width, info.Height, SKColors.White, SKColors.Black);
using var image = surface.Snapshot();
using var data = image.Encode(SKEncodedImageFormat.Png, 100);
return data.ToArray();
}
/// <summary>
/// 从图片截取部分区域
/// </summary>
/// <param name="fromImagePath">源图路径</param>
/// <param name="offsetX">距上</param>
/// <param name="offsetY">距左</param>
/// <param name="width">宽度</param>
/// <param name="height">高度</param>
/// <returns></returns>
public static byte[] Screenshot(string fromImagePath, int offsetX, int offsetY, int width, int height)
{
using var original = SKBitmap.Decode(fromImagePath);
using SKBitmap bitmap = new(width, height);
using SKCanvas canvas = new(bitmap);
SKRect sourceRect = new(offsetX, offsetY, offsetX + width, offsetY + height);
SKRect destRect = new(0, 0, width, height);
canvas.DrawBitmap(original, sourceRect, destRect);
using var img = SKImage.FromBitmap(bitmap);
using SKData p = img.Encode(SKEncodedImageFormat.Png, 100);
return p.ToArray();
}
/// <summary>
/// 获取图像数字验证码
/// </summary>
/// <param name="text">验证码内容，如4为数字</param>
/// <returns></returns>
public static byte[] GetVerifyCode(string text)
{
int width = 128;
int height = 45;
Random random = new();
//创建bitmap位图
using SKBitmap image = new(width, height, SKColorType.Bgra8888, SKAlphaType.Premul);
//创建画笔
using SKCanvas canvas = new(image);
//填充背景颜色为白色
canvas.DrawColor(SKColors.White);
//画图片的背景噪音线
for (int i = 0; i < (width * height * 0.015); i++)
{
using SKPaint drawStyle = new();
drawStyle.Color = new(Convert.ToUInt32(random.Next(Int32.MaxValue)));
canvas.DrawLine(random.Next(0, width), random.Next(0, height), random.Next(0, width), random.Next(0, height), drawStyle);
}
//将文字写到画布上
using (SKPaint drawStyle = new())
{
drawStyle.Color = SKColors.Red;
drawStyle.TextSize = height;
drawStyle.StrokeWidth = 1;
float emHeight = height - (float)height * (float)0.14;
float emWidth = ((float)width / text.Length) - ((float)width * (float)0.13);
canvas.DrawText(text, emWidth, emHeight, drawStyle);
}
//画图片的前景噪音点
for (int i = 0; i < (width * height * 0.6); i++)
{
image.SetPixel(random.Next(0, width), random.Next(0, height), new SKColor(Convert.ToUInt32(random.Next(Int32.MaxValue))));
}
using var img = SKImage.FromBitmap(image);
using SKData p = img.Encode(SKEncodedImageFormat.Png, 100);
return p.ToArray();
}
}
}

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