这个小型实用程序库需要将 NuGet SixLabors.ImageSharp包（版本 1.0.4）添加到.NET Core 3.1/ .NET 6 / .NET 8项目中。它与Windows、Linux和 MacOS兼容。
这已针对 ImageSharp v3.0.1 进行了重新设计。
它可以根据百万像素数或长度乘以宽度来调整图像大小，并根据需要保留纵横比。
它根据EXIF数据旋转/翻转图像。这是为了适应移动设备。
它还创建散点图和直方图。
另请参阅：MVC 应用程序的位图图像创建和下载
using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Metadata.Profiles.Exif;
using SixLabors.ImageSharp.Processing;
using SixLabors.ImageSharp.PixelFormats;
using SixLabors.ImageSharp.Formats.Png;
using System.IO;
using System;
using SixLabors.ImageSharp.Formats.Jpeg;
namespace ImageUtil
{
public class GetSize
{
public GetSize(Stream stream)
{
using (Image iOriginal = Image.Load(stream))
{
stream.Position = 0;
Width = iOriginal.Width;
Height = iOriginal.Height;
}
}
/// <summary>
/// The width of the image specified in the class constructor's Stream parameter
/// </summary>
public int Width { get; }
/// <summary>
/// The height of the image specified in the class constructor's Stream parameter
/// </summary>
public int Height { get; }
}
public static class Resize
{
/// <summary>
/// Resize and save an image to a Stream specifying its new width and height
/// </summary>
public static void SaveImage(Stream imageStream, int newWidth, int newHeight, bool preserveImageRatio, Stream saveToStream, int jpegQuality = 100)
{
using (Image iOriginal = Image.Load(imageStream))
{
imageStream.Position = 0;
if (preserveImageRatio)
{
float percentWidth = newWidth / (float)iOriginal.Width;
float percentHeight = newHeight / (float)iOriginal.Height;
float percent = percentHeight < percentWidth ? percentHeight : percentWidth;
newWidth = (int)Math.Round(iOriginal.Width * percent, 0);
newHeight = (int)Math.Round(iOriginal.Height * percent, 0);
}
resize(imageStream, iOriginal, newWidth, newHeight, saveToStream, jpegQuality);
}
}
/// <summary>
/// Resize and save an image to a Stream specifying the number of pixels to resize to
/// </summary>
public static void SaveImage(Stream imageStream, int newNumberOfPixels, Stream saveToStream, int jpegQuality = 100)
{
using (Image iOriginal = Image.Load(imageStream))
{
imageStream.Position = 0;
double ratio = Math.Sqrt(newNumberOfPixels / (double)(iOriginal.Width * iOriginal.Height));
resize(imageStream, iOriginal, (int)Math.Round(iOriginal.Width * ratio, 0), (int)Math.Round(iOriginal.Height * ratio, 0), saveToStream, jpegQuality);
}
}
private static void resize(Stream origSource, Image image, int newWidth, int newHeight, Stream saveTo, int jpegQuality)
{
image.Mutate(x => x.Resize(newWidth, newHeight));
transformImage(image); // NOTE: transform image AFTER resizing it!!!
var format = Image.DetectFormat(origSource);
if (format.Name.ToLower() == "jpeg")
{
var encoder = new JpegEncoder();
encoder.Quality = jpegQuality;
image.SaveAsJpeg(saveTo, encoder);
}
else
image.Save(saveTo, format);
}
private static void transformImage(Image image)
{
IExifValue exifOrientation = image.Metadata?.ExifProfile?.GetValue(ExifTag.Orientation);
if (exifOrientation == null)
return;
RotateMode rotateMode;
FlipMode flipMode;
setRotateFlipMode(exifOrientation, out rotateMode, out flipMode);
image.Mutate(x => x.RotateFlip(rotateMode, flipMode));
image.Metadata.ExifProfile.SetValue(ExifTag.Orientation, (ushort)1);
}
private static void setRotateFlipMode(IExifValue exifOrientation, out RotateMode rotateMode, out FlipMode flipMode)
{
var orientation = (ushort)exifOrientation.GetValue();
switch (orientation)
{
case 2:
rotateMode = RotateMode.None;
flipMode = FlipMode.Horizontal;
break;
case 3:
rotateMode = RotateMode.Rotate180;
flipMode = FlipMode.None;
break;
case 4:
rotateMode = RotateMode.Rotate180;
flipMode = FlipMode.Horizontal;
break;
case 5:
rotateMode = RotateMode.Rotate90;
flipMode = FlipMode.Horizontal;
break;
case 6:
rotateMode = RotateMode.Rotate90;
flipMode = FlipMode.None;
break;
case 7:
rotateMode = RotateMode.Rotate90;
flipMode = FlipMode.Vertical;
break;
case 8:
rotateMode = RotateMode.Rotate270;
flipMode = FlipMode.None;
break;
default:
rotateMode = RotateMode.None;
flipMode = FlipMode.None;
break;
}
}
}
/* CREATE A SCATTER PLOT JPEG/PNG IMAGE */
public static class ScatterPlot
{
static readonly Rgba32 WHITE = new Rgba32(255, 255, 255);
static readonly Rgba32 BLACK = new Rgba32(0, 0, 0);
static readonly Rgba32 RED = new Rgba32(255, 0, 0);
static readonly Rgba32 BLUE = new Rgba32(0, 0, 255);
static readonly Rgba32 GREEN = new Rgba32(0, 192, 0);
static readonly Rgba32 PURPLE = new Rgba32(128, 0, 128);
static readonly Rgba32 ORANGE = new Rgba32(255, 164, 0);
static readonly Rgba32 YELLOW = new Rgba32(255, 225, 0);
static readonly Rgba32 MAGENTA = new Rgba32(255, 0, 255);
static readonly Rgba32 AQUA = new Rgba32(0, 225, 255);
static readonly Rgba32 BLUEJEAN = new Rgba32(0, 128, 255);
static readonly Rgba32 BROWN = new Rgba32(150, 75, 50);
static readonly Rgba32 CHARTREUSE = new Rgba32(223, 255, 0);
static readonly Rgba32 DODGERBLUE = new Rgba32(30, 144, 255);
static readonly Rgba32 NAVY = new Rgba32(0, 0, 128);
static readonly Rgba32 DARKRED = new Rgba32(139, 0, 0);
static readonly Rgba32[] colors = new Rgba32[] { WHITE, BLACK, RED, BLUE, GREEN, PURPLE, ORANGE, YELLOW, MAGENTA, AQUA, BLUEJEAN, BROWN, DODGERBLUE, CHARTREUSE, NAVY, DARKRED };
public static void CreateJPEG(Stream stream, ScatterPlotColors backgroundColor, IEnumerable<PlotPoint> points, int width, int height, int pointSize, int jpegQuality = 100)
{
using (var bmp = new Image<Rgba32>(width / pointSize + 6, height / pointSize + 6, colors[(int)backgroundColor]))
create(stream, width, height, bmp, points, pointSize, new JpegEncoder() { Quality = jpegQuality });
}
public static void CreateJPEG(string filename, ScatterPlotColors backgroundColor, IEnumerable<PlotPoint> points, int width, int height, int pointSize, int jpegQuality = 100)
{
using (var stream = File.Create(filename))
CreateJPEG(stream, backgroundColor, points, width, height, pointSize, jpegQuality);
}
public static void CreatePNG(Stream stream, IEnumerable<PlotPoint> points, int width, int height, int pointSize)
{
using (var bmp = new Image<Rgba32>(width / pointSize + 6, height / pointSize + 6))
create(stream, width, height, bmp, points, pointSize, new PngEncoder());
}
public static void CreatePNG(string filename, IEnumerable<PlotPoint> points, int width, int height, int pointSize)
{
using (var stream = File.Create(filename))
CreatePNG(stream, points, width, height, pointSize);
}
private static double normalize(float min, float max, float value)
{
double x = max - min;
if(x == 0)
return 0;
return (value - min) / x;
}
private static void create(Stream stream, int width, int height, Image<Rgba32> bmp, IEnumerable<PlotPoint> points, int pointSize, SixLabors.ImageSharp.Formats.IImageEncoder imageEncoder)
{
float xMax = float.MinValue, xMin = float.MaxValue, yMax = float.MinValue, yMin = float.MaxValue;
foreach (var pt in points)
{
xMax = Math.Max(pt.x, xMax);
xMin = Math.Min(pt.x, xMin);
yMax = Math.Max(pt.y, yMax);
yMin = Math.Min(pt.y, yMin);
}
float xDelta = Math.Max(1, xMax - xMin), yDelta = Math.Max(1, yMax - yMin);
int w = width / pointSize;
int h = height / pointSize;
foreach (var pt in points)
{
int x = (int)(w * normalize(xMin, xMax, pt.x));
int y = (int)(h * normalize(yMin, yMax, pt.y));
bmp[x + 3, y + 3] = colors[((int)pt.color) % colors.Length];
}
bmp.Mutate(x => x.Flip(FlipMode.Vertical));
bmp.Mutate(x => x.Resize(width, height));
bmp.Save(stream, imageEncoder);
}
}
public class PlotPoint
{
public ScatterPlotColors color { get; }
public float x { get; }
public float y { get; }
public PlotPoint(float x, float y, ScatterPlotColors color)
{
this.x = x;
this.y = y;
this.color = color;
}
}
public enum ScatterPlotColors
{
WHITE,
BLACK,
RED,
BLUE,
GREEN,
PURPLE,
ORANGE,
YELLOW,
MAGENTA,
AQUA,
BLUEJEAN,
BROWN,
CHARTREUSE,
DODGERBLUE,
NAVY,
DARKRED
}
/* CREATE A PNG HISTOGRAM OF AN IMAGE */
public static class Histogram
{
/// <summary>
/// Create a histogram from the data in a stream
/// </summary>
public static MemoryStream CreatePNG(Stream stream, int width, int height, LRGB lrgb, byte alphaChannel = 128, bool clipBlackAndWhite = true, byte luminanceShade = 255)
{
using (var bmp = Image<Rgb24>.Load(stream))
{
return create(bmp, width, height, lrgb, alphaChannel, clipBlackAndWhite, luminanceShade);
}
}
/// <summary>
/// Create a histogram from the data in a file
/// </summary>
public static MemoryStream CreatePNG(string filename, int width, int height, LRGB lrgb, byte alphaChannel = 128, bool clipBlackAndWhite = true, byte luminanceShade = 255)
{
using (var bmp = Image<Rgb24>.Load(filename))
{
return create(bmp, width, height, lrgb, alphaChannel, clipBlackAndWhite, luminanceShade);
}
}
private static MemoryStream create(Image bmp, int width, int height, LRGB lrgb, byte alpha, bool clip, byte shade)
{
ulong[] lumin = new ulong[256];
ulong[] red = new ulong[256];
ulong[] green = new ulong[256];
ulong[] blue = new ulong[256];
var bred = (lrgb & LRGB.RED) != 0;
var bgreen = (lrgb & LRGB.GREEN) != 0;
var bblue = (lrgb & LRGB.BLUE) != 0;
var blumin = (lrgb == LRGB.LUMINANCE);
int w = bmp.Width;
int h = bmp.Height;
var bmp2 = bmp.CloneAs<Rgb24>();
for (int y = 0; y < h; y++)
{
Span<Rgb24> pixelRow = bmp2.GetPixelRowSpan(y);
for (int x = 0; x < w; x++)
{
var c = pixelRow[x];
lumin[(int)Math.Round((c.R + c.G + c.B) / 3.0)]++;
red[c.R]++;
green[c.G]++;
blue[c.B]++;
}
}
ulong max = 0;
int a = (clip ? 1 : 0), b = (clip ? 255 : 256);
for (int i = a; i < b; i++)
{
if (!blumin)
{
if (bred)
if (max < red[i])
max = red[i];
if (bgreen)
if (max < green[i])
max = green[i];
if (bblue)
if (max < blue[i])
max = blue[i];
}
else if (max < lumin[i])
max = lumin[i];
}
double HEIGHTFACTOR = 256.0 / max;
if (blumin)
{
using (var bmplum = new Image<Rgba32>(256, 256))
{
var penlum = new VerticalPen(new Rgba32(shade, shade, shade, alpha));
for (int i = 0; i < 256; i++)
penlum.Draw(bmplum, i, (int)(lumin[i] * HEIGHTFACTOR));
bmplum.Mutate(x => x.Resize(width, height));
MemoryStream ms = new MemoryStream();
bmplum.Save(ms, new PngEncoder());
return ms;
}
}
else
{
using (var bmppre = new Image<Rgba32>(256, 256))
{
Image<Rgba32>? bmpred = null, bmpgreen = null, bmpblue = null;
VerticalPen? penred = null, pengreen = null, penblue = null;
if (bred)
{
bmpred = new Image<Rgba32>(256, 256);
penred = new VerticalPen(new Rgba32(255, 0, 0, alpha));
}
if (bgreen)
{
bmpgreen = new Image<Rgba32>(256, 256);
pengreen = new VerticalPen(new Rgba32(0, 255, 0, alpha));
}
if (bblue)
{
bmpblue = new Image<Rgba32>(256, 256);
penblue = new VerticalPen(new Rgba32(0, 0, 255, alpha));
}
for (int i = 0; i < 256; i++)
{
if (bred)
penred.Draw(bmpred, i, (int)(red[i] * HEIGHTFACTOR));
if (bgreen)
pengreen.Draw(bmpgreen, i, (int)(green[i] * HEIGHTFACTOR));
if (bblue)
penblue.Draw(bmpblue, i, (int)(blue[i] * HEIGHTFACTOR));
}
if (bred)
{
bmppre.Mutate(x => x.DrawImage(bmpred, 1));
bmpred.Dispose();
}
if (bgreen)
{
bmppre.Mutate(x => x.DrawImage(bmpgreen, 1));
bmpgreen.Dispose();
}
if (bblue)
{
bmppre.Mutate(x => x.DrawImage(bmpblue, 1));
bmpblue.Dispose();
}
bmppre.Mutate(x => x.Resize(width, height));
MemoryStream ms = new MemoryStream();
bmppre.Save(ms, new PngEncoder());
return ms;
}
}
}
internal class VerticalPen
{
private readonly Rgba32 color;
public VerticalPen(Rgba32 color)
{
this.color = color;
}
public void Draw(Image<Rgba32> bmp, int row, int height)
{
if (height <= bmp.Height)
for (int y = height - 1; y >= 0; y--)
bmp[row, bmp.Height - 1 - y] = color;
}
}
public enum LRGB
{
LUMINANCE = 0,
RED = 1,
GREEN = 2,
BLUE = 4,
REDBLUE = 1 | 4,
REDGREEN = 1 | 2,
BLUEGREEN = 2 | 4,
REDGREENBLUE = 1 | 2 | 4
}
}
}
示例用法
另请参阅：控制台应用程序示例
这是MVC Web 应用程序中的视图。
@{
ViewData["Title"] = "/Home/UploadImages";
}
<div class="text-center">
<h1 class="display-4">UploadImages</h1>
<form enctype="multipart/form-data" method="post">
<div>
<input type="file" name="images" accept="image/jpeg, image/gif, image/png" multiple />
</div>
<div>
<button type="submit" class="btn btn-primary">UPLOAD</button>
</div>
</form>
@if(Model is int)
{
<p>@Model images saved.</p>
}
</div>
现在介绍控制器代码：
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.TagHelpers;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
using WebApplication1.Models;
namespace WebApplication1.Controllers
{
public class HomeController : Controller
{
private readonly ILogger<HomeController> _logger;
public HomeController(ILogger<HomeController> logger)
{
_logger = logger;
}
public IActionResult UploadImages()
{
return View();
}
[HttpPost]
[DisableRequestSizeLimit] // NOTE: NOT RECOMMENDED - SET A LIMIT
public IActionResult UploadImages(IFormCollection form)
{
int count = 0;
foreach(var image in form.Files)
{
if(image.ContentType.StartsWith("image/"))
{
using (var openfs = image.OpenReadStream())
{
string filename = "thumbnail-" + image.FileName;
if (System.IO.File.Exists(filename))
System.IO.File.Delete(filename);
using (var savefs = System.IO.File.OpenWrite(filename))
{
// NOTE: RESIZE IMAGE TO 10K PIXEL THUMBNAIL; THIS WILL ALSO FLIP AND ROTATE IMAGE AS NEEDED
ImageUtil.Resize.SaveImage(openfs, 10000, savefs);
count++;
}
}
}
}
return View(count);
}
public IActionResult Index()
{
return View();
}
public IActionResult Privacy()
{
return View();
}
[ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
public IActionResult Error()
{
return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
}
}
}
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