Winform+.Net6实现图片拖拽上传功能
作者：Csharp小记
这篇文章主要为大家详细介绍了如何使用WinformPictureBox控件+.Net6 WebApi实现图片拖拽上传功能,文中的示例代码讲解详细,感兴趣的可以学习一下
前言
如题，跟你使用过的某些拖拽上传的网站或者Web框架一样，将图片拖拽到指定位置后直接进行上传以及预览，减少找文件、操作的时间。本文主要使用WinformPictureBox控件+.Net6 WebApi实现。
开发环境：.NET Framework4.8+.Net6
开发工具：Visual Studio 2022
实现步骤
1.创建自定义控件，继承自PictureBox,然后定义以下属性
private string _NullDesc;
[Description("没有图像时的描述")]
public string NullDesc { get { return _NullDesc; } set { _NullDesc = value; Invalidate(); } }
private Font _NullDescFont;
[Description("没有图像时的描述字体")]
public Font NullDescFont { get { return _NullDescFont; } set { _NullDescFont = value; Invalidate(); } }
private Color _NullDescFontColor;
[Description("没有图像时的描述字体颜色")]
public Color NullDescFontColor { get { return _NullDescFontColor; } set { _NullDescFontColor = value; Invalidate(); } }
[Description("上传事件")]
public event EventHandler Upload;
public new Image Image
{
get
{
return base.Image;
}
set
{
base.Image = value;
if (value != null)
{
Upload?.Invoke(this, new EventArgs());
}
}
}2.处理拖拽事件
protected override void OnDragEnter(DragEventArgs drgevent)
{
base.OnDragEnter(drgevent);
if (drgevent.Data.GetDataPresent(DataFormats.FileDrop) || drgevent.Data.GetDataPresent(DataFormats.Bitmap))
{
drgevent.Effect = DragDropEffects.Copy;
}
else
{
drgevent.Effect = DragDropEffects.None;
}
}
protected override void OnDragDrop(DragEventArgs drgevent)
{
base.OnDragDrop(drgevent);
Image = GetImage(drgevent.Data);
}3.重写OnPaint事件，做以下处理
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
Graphics g = e.Graphics;
if (Image == null && BackgroundImage == null && !string.IsNullOrWhiteSpace(NullDesc))
{
SizeF sf = g.MeasureString(NullDesc, NullDescFont, Size);
float x = (Width - sf.Width) / 2;
float y = (Height - sf.Height) / 2;
g.DrawString(NullDesc, Font, new SolidBrush(NullDescFontColor), new PointF(x, y));
}
}4.在Upload事件中完成上传
private async void PictureBoxEx1_Upload(object sender, EventArgs e)
{
HttpClient client = new HttpClient();
MemoryStream memoryStream = new MemoryStream();
Image img = (Image)pictureBoxEx1.Image.Clone();
img.Save(memoryStream, img.RawFormat);
memoryStream.Seek(0, SeekOrigin.Begin);
MultipartFormDataContent content = new MultipartFormDataContent();
StreamContent streamContent = new StreamContent(memoryStream);
streamContent.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("form-data")
{
Name = "file",
FileName = "upload" + GetExtension(img)
};
content.Add(streamContent);
var result =await client.PostAsync("https://localhost:7075/Default/Upload", content);
MessageBox.Show(await result.Content.ReadAsStringAsync());
}5.后台接收文件
public string Upload(IFormFile file)
{
string basePath = AppContext.BaseDirectory + "upload\\";
if (file == null || file.Length == 0)
{
return "文件不可为空";
}
if (!Directory.Exists(basePath))
{
Directory.CreateDirectory(basePath);
}
string filter = Path.GetExtension(file.FileName);
string fileName = DateTime.Now.Ticks + filter;
string savePath = basePath + fileName;
using var stream = new FileStream(savePath, FileMode.OpenOrCreate, FileAccess.ReadWrite);
file.CopyTo(stream);
return "上传成功";
}实现效果
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