如何使用c#裁剪图像?
当前回答
使用bmp.SetResolution(形象。HorizontalResolution, image .VerticalResolution);
这可能是必要的，即使你在这里实现了最佳答案 特别是如果你的图像真的很好，分辨率不是96.0
我的测试示例:
static Bitmap LoadImage()
{
return (Bitmap)Bitmap.FromFile( @"e:\Tests\d_bigImage.bmp" ); // here is large image 9222x9222 pixels and 95.96 dpi resolutions
}
static void TestBigImagePartDrawing()
{
using( var absentRectangleImage = LoadImage() )
{
using( var currentTile = new Bitmap( 256, 256 ) )
{
currentTile.SetResolution(absentRectangleImage.HorizontalResolution, absentRectangleImage.VerticalResolution);
using( var currentTileGraphics = Graphics.FromImage( currentTile ) )
{
currentTileGraphics.Clear( Color.Black );
var absentRectangleArea = new Rectangle( 3, 8963, 256, 256 );
currentTileGraphics.DrawImage( absentRectangleImage, 0, 0, absentRectangleArea, GraphicsUnit.Pixel );
}
currentTile.Save(@"e:\Tests\Tile.bmp");
}
}
}
其他回答
如果你在使用AForge。NET:
using(var croppedBitmap = new Crop(new Rectangle(10, 10, 10, 10)).Apply(bitmap))
{
// ...
}
假设您想要获取一个图像文件(JPEG、BMP、TIFF等)并将其裁剪，然后将其保存为一个较小的图像文件，我建议使用具有. net API的第三方工具。以下是我喜欢的一些流行的说法:
LeadTools Accusoft珀加索斯 雪地成像SDK
这很简单:
创建一个裁剪大小的新位图对象。 使用图形。为新的位图创建一个图形对象。 使用DrawImage方法将图像绘制到具有负X和负Y坐标的位图上。
这里是github上的工作演示
https://github.com/SystematixIndore/Crop-SaveImageInCSharp
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication1.WebForm1" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<link href="css/jquery.Jcrop.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js"></script>
<script type="text/javascript" src="js/jquery.Jcrop.js"></script>
</head>
<body>
<form id="form2" runat="server">
<div>
<asp:Panel ID="pnlUpload" runat="server">
<asp:FileUpload ID="Upload" runat="server" />
<br />
<asp:Button ID="btnUpload" runat="server" OnClick="btnUpload_Click" Text="Upload" />
<asp:Label ID="lblError" runat="server" Visible="false" />
</asp:Panel>
<asp:Panel ID="pnlCrop" runat="server" Visible="false">
<asp:Image ID="imgCrop" runat="server" />
<br />
<asp:HiddenField ID="X" runat="server" />
<asp:HiddenField ID="Y" runat="server" />
<asp:HiddenField ID="W" runat="server" />
<asp:HiddenField ID="H" runat="server" />
<asp:Button ID="btnCrop" runat="server" Text="Crop" OnClick="btnCrop_Click" />
</asp:Panel>
<asp:Panel ID="pnlCropped" runat="server" Visible="false">
<asp:Image ID="imgCropped" runat="server" />
</asp:Panel>
</div>
</form>
<script type="text/javascript">
jQuery(document).ready(function() {
jQuery('#imgCrop').Jcrop({
onSelect: storeCoords
});
});
function storeCoords(c) {
jQuery('#X').val(c.x);
jQuery('#Y').val(c.y);
jQuery('#W').val(c.w);
jQuery('#H').val(c.h);
};
</script>
</body>
</html>
用于上传和裁剪的c#代码逻辑。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
using SD = System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
namespace WebApplication1
{
public partial class WebForm1 : System.Web.UI.Page
{
String path = HttpContext.Current.Request.PhysicalApplicationPath + "images\\";
protected void Page_Load(object sender, EventArgs e)
{
}
protected void btnUpload_Click(object sender, EventArgs e)
{
Boolean FileOK = false;
Boolean FileSaved = false;
if (Upload.HasFile)
{
Session["WorkingImage"] = Upload.FileName;
String FileExtension = Path.GetExtension(Session["WorkingImage"].ToString()).ToLower();
String[] allowedExtensions = { ".png", ".jpeg", ".jpg", ".gif" };
for (int i = 0; i < allowedExtensions.Length; i++)
{
if (FileExtension == allowedExtensions[i])
{
FileOK = true;
}
}
}
if (FileOK)
{
try
{
Upload.PostedFile.SaveAs(path + Session["WorkingImage"]);
FileSaved = true;
}
catch (Exception ex)
{
lblError.Text = "File could not be uploaded." + ex.Message.ToString();
lblError.Visible = true;
FileSaved = false;
}
}
else
{
lblError.Text = "Cannot accept files of this type.";
lblError.Visible = true;
}
if (FileSaved)
{
pnlUpload.Visible = false;
pnlCrop.Visible = true;
imgCrop.ImageUrl = "images/" + Session["WorkingImage"].ToString();
}
}
protected void btnCrop_Click(object sender, EventArgs e)
{
string ImageName = Session["WorkingImage"].ToString();
int w = Convert.ToInt32(W.Value);
int h = Convert.ToInt32(H.Value);
int x = Convert.ToInt32(X.Value);
int y = Convert.ToInt32(Y.Value);
byte[] CropImage = Crop(path + ImageName, w, h, x, y);
using (MemoryStream ms = new MemoryStream(CropImage, 0, CropImage.Length))
{
ms.Write(CropImage, 0, CropImage.Length);
using (SD.Image CroppedImage = SD.Image.FromStream(ms, true))
{
string SaveTo = path + "crop" + ImageName;
CroppedImage.Save(SaveTo, CroppedImage.RawFormat);
pnlCrop.Visible = false;
pnlCropped.Visible = true;
imgCropped.ImageUrl = "images/crop" + ImageName;
}
}
}
static byte[] Crop(string Img, int Width, int Height, int X, int Y)
{
try
{
using (SD.Image OriginalImage = SD.Image.FromFile(Img))
{
using (SD.Bitmap bmp = new SD.Bitmap(Width, Height))
{
bmp.SetResolution(OriginalImage.HorizontalResolution, OriginalImage.VerticalResolution);
using (SD.Graphics Graphic = SD.Graphics.FromImage(bmp))
{
Graphic.SmoothingMode = SmoothingMode.AntiAlias;
Graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
Graphic.PixelOffsetMode = PixelOffsetMode.HighQuality;
Graphic.DrawImage(OriginalImage, new SD.Rectangle(0, 0, Width, Height), X, Y, Width, Height, SD.GraphicsUnit.Pixel);
MemoryStream ms = new MemoryStream();
bmp.Save(ms, OriginalImage.RawFormat);
return ms.GetBuffer();
}
}
}
}
catch (Exception Ex)
{
throw (Ex);
}
}
}
}
有一个开源的c#包装器，托管在Codeplex上，叫做Web Image裁剪
注册控件
<%@注册程序集="CS.Web.UI. "CropImage CS.Web“Namespace =”。UI" TagPrefix="cs" %>
调整
<asp:Image ID="Image1" runat="server" ImageUrl="images/328.jpg" />
<cs:CropImage ID="wci1" runat="server" Image="Image1"
X="10" Y="10" X2="50" Y2="50" />
在代码后面裁剪-当按钮点击时调用裁剪方法为例;
wci1.Crop (Server.MapPath(“图像/ sample1.jpg”));
