C#如何实现图片的剪裁并保存

最近需要将一张图片上传并按指定位置剪裁，后来在网上找了一个剪裁图片的插件，但是只有前台没有后端，然后我各种百度，并最终完成，特此写一篇博客略表纪念。

前台我就不说了，用的cropper插件，有兴趣的自己去百度找找吧。 有这个插件。

下面是代码：

httppostedfile file = context.request.files["avatar_file"];
string datasize = context.request.params["avatar_data"];
//{"x":30.003846153846148,"y":16.715384615384625,"height":300.8,"width":300.8,"rotate":0} 剪裁之后参数
javascriptserializer jss = new javascriptserializer();
imgsize imagesize = jss.deserialize<imgsize>(datasize);
byte[] filebyte = setfiletobytearray(file);//图片数组
string strtextension = system.io.path.getextension(file.filename);//图片格式
memorystream ms1 = new memorystream(filebyte);
bitmap sbitmap = (bitmap)image.fromstream(ms1);
rectangle section = new rectangle(new point(imagesize.toint(imagesize.x), imagesize.toint(imagesize.y)), new size(imagesize.toint(imagesize.width), imagesize.toint(imagesize.height)));
bitmap croppedimage = makethumbnailimage(sbitmap, section.width, section.height, section.width, section.height, section.x, section.y);

上面代码中用到我自己创建了一个imgsize类，代码如下：

class imgsize
{
//{"x":30.003846153846148,"y":16.715384615384625,"height":300.8,"width":300.8,"rotate":0}
public double x { get; set; }
public double y { get; set; }
public double width { get; set; }
public double height { get; set; }
public int rotate { get; set; }
public int toint(double doublevalue)
{
return convert.toint32(doublevalue);
}
}

上面代码中使用到的几个方法：

文件转化：

/// <summary>
/// 将from表单file文件转化为byte数组
/// </summary>
/// <param name="file">from提交文件流</param>
/// <returns></returns>
private byte[] setfiletobytearray(httppostedfile file)
{
stream stream = file.inputstream;
byte[] ayyaybyte = new byte[file.contentlength];
stream.read(ayyaybyte, 0, file.contentlength);
stream.close();
return ayyaybyte;
}

核心剪裁方法：

/// <summary>
/// 裁剪图片并保存
/// </summary>
/// <param name="image">图片信息</param>
/// <param name="maxwidth">缩略图宽度</param>
/// <param name="maxheight">缩略图高度</param>
/// <param name="cropwidth">裁剪宽度</param>
/// <param name="cropheight">裁剪高度</param>
/// <param name="x">x轴</param>
/// <param name="y">y轴</param>
public static bitmap makethumbnailimage(image originalimage, int maxwidth, int maxheight, int cropwidth, int cropheight, int x, int y)
{
bitmap b = new bitmap(cropwidth, cropheight);
try
{
using (graphics g = graphics.fromimage(b))
{
//清空画布并以透明背景色填充
g.clear(color.transparent);
//在指定位置并且按指定大小绘制原图片的指定部分
g.drawimage(originalimage, new rectangle(0, 0, cropwidth, cropheight), x, y, cropwidth, cropheight, graphicsunit.pixel);
image displayimage = new bitmap(b, maxwidth, maxheight);
displayimage.save("e:\\cutimg.jpg", system.drawing.imaging.imageformat.jpeg);
bitmap bit = new bitmap(b, maxwidth, maxheight);
return bit;
}
}
catch (system.exception e)
{
throw e;
}
finally
{
originalimage.dispose();
b.dispose();
}
}

最后的结果是把存到了e盘根目录下面

以上所述是小编给大家介绍的c#如何实现图片的剪裁并保存，希望对大家有所帮助