(How to add Watermark Image to an image dynamically while uploading in ASP.NET) – Việc bảo vệ bản quyền đối với các bài viết cả nội dung và hình ảnh luôn được tác giả quan tâm. Vì tác giả bỏ nhiều công sức, thời gian để viết bài mà hoàn toàn không được tôn trọng bản quyền. Hiện có nhiều cách để bảo vệ và kiểm soát bài viết nhưng có 1 cách đơn giản và nhanh chóng để góp một phần trong việc bảo vệ bản quyền. Đó là việc tự động đóng dấu bản quyền vào các hình ảnh khi được Upload, hình ảnh về bản quyền được đặt sẵn vào 1 thư mục và nó sẽ được chèn vào hình ảnh mỗi khi người dùng Upload. Dưới đây là các bước thực hiện.
- B1: Tạo Project trong Microsoft Visual Studio 2010
- B2: Mở file Default.aspx dưới dạng HTML và nhập mã HTML
C# Code
<%@ PageTitle="Add Watermark Image on Uploaded Image in Asp.Net" Language="C#"MasterPageFile="~/Site.master"AutoEventWireup="true"CodeBehind="Default.aspx.cs"Inherits="AddWatermarkImageonUploaded._Default"%>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
<table cellpadding="3"cellspacing="5"border="0"width="50%">
<tr>
<td>
<divclass="panel panel-default">
<divclass="panel-heading">
<asp:label id="lblHeader" runat="server" Text="Add Watermark Image on Uploaded Image in Asp.Net"></asp:label>
</div>
<divclass="panel-body">
<table cellspacing="2"cellpadding="3"border="0"width="100%">
<tr>
<td style="width:25%;">
<asp:label id="plFileName"runat="server"Text="File Name (*)"></asp:label>
</td>
<td>
<asp:FileUpload ID="FileUpload"runat="server"Width="150px"/><br />
<asp:CustomValidator id="valFile"runat="server"CssClass="NormalRed"ValidationGroup="validate"OnServerValidate="valFile_ServerValidate"ErrorMessage="You Must Upload A File" Display="Dynamic"></asp:CustomValidator>
<asp:CustomValidator id="valType"runat="server"CssClass="NormalRed"ValidationGroup="validate"OnServerValidate="valType_ServerValidate"ErrorMessage="You must upload a file that is either a JPG" Display="Dynamic"></asp:CustomValidator>
</td>
</tr>
<tr>
<td colspan="2">
<asp:label id="lblMessage"runat="server"Visible="false"></asp:label><br />
</td>
</tr>
</table>
</div>
<divclass="modal-footer">
<div class="btn-group">
<asp:LinkButton id="cmdUpload"runat="server"CssClass="btn btn-small" OnClick="cmdUpload_Click" ValidationGroup="validate" Causesvalidation="true">
<i class="icon-upload"></i> <asp:label id="lblUpload" runat="server" Text="Upload"></asp:label>
</asp:LinkButton>
</div>
</div>
</div>
</td>
</tr>
</table>
</asp:Content>VB.NET Code
<%@ PageTitle="Add Watermark Image on Uploaded Image in Asp.Net" Language="vb"MasterPageFile="~/Site.Master"AutoEventWireup="false"CodeBehind="Default.aspx.vb"Inherits="AddWatermarkImageonUploaded._Default"%>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
<table cellpadding="3"cellspacing="5"border="0"width="50%">
<tr>
<td>
<divclass="panel panel-default">
<divclass="panel-heading">
<asp:label id="lblHeader" runat="server" Text="Add Watermark Image on Uploaded Image in Asp.Net"></asp:label>
</div>
<divclass="panel-body">
<table cellspacing="2"cellpadding="3"border="0"width="100%">
<tr>
<td style="width:25%;">
<asp:label id="plFileName"runat="server"Text="File Name (*)"></asp:label>
</td>
<td>
<asp:FileUpload ID="FileUpload" runat="server" Width="150px" /><br />
<asp:CustomValidator id="valFile"runat="server"CssClass="NormalRed"ValidationGroup="validate"ErrorMessage="You Must Upload A File" Display="Dynamic"></asp:CustomValidator>
<asp:CustomValidator id="valType"runat="server"CssClass="NormalRed"ValidationGroup="validate"ErrorMessage="You must upload a file that is either a JPG" Display="Dynamic"></asp:CustomValidator>
</td>
</tr>
<tr>
<td colspan="2">
<asp:label id="lblMessage"runat="server"Visible="false"></asp:label><br />
</td>
</tr>
</table>
</div>
<divclass="modal-footer">
<div class="btn-group">
<asp:LinkButton id="cmdUpload"runat="server"CssClass="btn btn-small" ValidationGroup="validate" Causesvalidation="true">
<i class="icon-upload"></i> <asp:label id="lblUpload" runat="server" Text="Upload"></asp:label>
</asp:LinkButton>
</div>
</div>
</div>
</td>
</tr>
</table>
</asp:Content>- B3: Viết Code cho file Default.aspx
C# Code
//Visit http://www.laptrinhdotnet.com for more ASP.NET Tutorials
using Microsoft.VisualBasic;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Diagnostics;
using System.Web.UI;
using System.Web;
using System.Drawing;
using System.Web.UI.WebControls;
namespace AddWatermarkImageonUploaded
{
public partial class _Default : System.Web.UI.Page
{
#region"Private Members"
private stringFilePath;
private stringFileFilter = "jpg,jpeg";
#endregion
#region"Private Methods"
protected stringUploadFile(FileUpload Upload)
{
string fileName = "";
string fileExtension = "";
string ImagePath = Server.MapPath("Images") + "\\"+ "Copyright.png";
if (File.Exists(ImagePath))
{
Bitmap bmpStamp = new Bitmap(ImagePath);
Bitmap bmpUpload = new Bitmap(Upload.PostedFile.InputStream, false);
Graphics graphicsObj = Graphics.FromImage(bmpUpload);
Point postionWaterMark = new Point((bmpUpload.Width / 15), (bmpUpload.Height / 15));
graphicsObj.DrawImage(bmpStamp, postionWaterMark);
SetFilePath();
fileExtension = Path.GetExtension(Upload.FileName).Replace(".", "");
fileName = Upload.FileName.Substring(Upload.FileName.LastIndexOf("\\\\") + 1);
fileName = fileName.Substring(0, fileName.LastIndexOf(fileExtension)) + fileExtension;
FilePath = FilePath + fileName;
bmpUpload.Save(FilePath);
}
return fileName;
}
private voidSetFilePath()
{
FilePath = MapPath("~/Upload/");
//Create Folder
if (!Directory.Exists(FilePath))
{
Directory.CreateDirectory(FilePath);
}
}
#endregion
#region"Event Handles"
protected voidcmdUpload_Click(object sender, System.EventArgs e)
{
if (Page.IsValid)
{
try
{
string fileName = "";
if (!string.IsNullOrEmpty(FileUpload.PostedFile.FileName))
{
fileName = UploadFile(FileUpload);
if (!string.IsNullOrEmpty(fileName))
{
lblMessage.Text = "Upload file Sucessfully";
lblMessage.ForeColor = System.Drawing.Color.Green;
lblMessage.Visible = true;
}
}
}
catch (Exceptionex)
{
lblMessage.Text = ex.Message;
lblMessage.ForeColor = System.Drawing.Color.Red;
lblMessage.Visible = true;
return;
}
}
}
protected voidvalFile_ServerValidate(object source, ServerValidateEventArgs args)
{
if (FileUpload.PostedFile != null)
{
if (FileUpload.PostedFile.ContentLength > 0)
{
args.IsValid = true;
}
else
{
args.IsValid = false;
}
}
}
protected voidvalType_ServerValidate(object source, ServerValidateEventArgs args)
{
if (FileUpload.PostedFile != null)
{
lblMessage.Visible = false;
if (FileUpload.PostedFile.ContentLength > 0)
{
string[] arr = FileUpload.PostedFile.FileName.Split(Convert.ToChar('.'));
string FileType = arr[arr.Length - 1].ToLower();
valType.ErrorMessage = "You must upload a file that is either a JPG, JPEG";
if (FileFilter.IndexOf(FileType) > -1)
{
args.IsValid = true;
}
else
{
args.IsValid = false;
}
}
else
{
args.IsValid = false;
}
}
}
#endregion
}
}VB.NET Code
'Visit http://www.laptrinhdotnet.com for more ASP.NET Tutorials
Imports System.IO
Imports System.Drawing
Namespace AddWatermarkImageonUploaded
Public Class _Default
Inherits System.Web.UI.Page
#Region "Private Members"
Private FilePath As String = ""
Private FileFilter AsString = "jpg"
#End Region
#Region "Private Methods"
Protected FunctionUploadFile(ByVal Upload As FileUpload) As String
Dim fileName As String = ""
Dim fileExtension As String = ""
Dim ImagePath As String = Server.MapPath("Images") + "\" + "Copyright.png"
If File.Exists(ImagePath) Then
Dim bmpStamp AsNew Bitmap(ImagePath)
Dim bmpUpload AsNew Bitmap(Upload.PostedFile.InputStream, False)
Dim graphicsObj AsGraphics = Graphics.FromImage(bmpUpload)
Dim postionWaterMark As New Point((bmpUpload.Width / 15), (bmpUpload.Height / 15))
graphicsObj.DrawImage(bmpStamp, postionWaterMark)
SetFilePath()
fileExtension = Replace(Path.GetExtension(Upload.FileName), ".", "")
fileName = Upload.FileName.Substring(Upload.FileName.LastIndexOf("\\") + 1)
fileName = fileName.Substring(0, fileName.LastIndexOf(fileExtension)) & fileExtension
FilePath = FilePath + fileName
bmpUpload.Save(FilePath)
End If
Return fileName
End Function
Private SubSetFilePath()
FilePath = MapPath("~/Upload/")
'Create Folder
If Not Directory.Exists(FilePath) Then
Directory.CreateDirectory(FilePath)
End If
End Sub
#End Region
#Region "Event Handles"
Private SubcmdUpload_Click(ByVal sender As Object, ByVal e As System.EventArgs) HandlescmdUpload.Click
If Page.IsValid Then
Try
Dim fileName AsString = ""
If FileUpload.PostedFile.FileName <> "" Then
fileName = UploadFile(FileUpload)
If fileName <> ""Then
lblMessage.Text = "Upload file Sucessfully"
lblMessage.ForeColor = System.Drawing.Color.Green
lblMessage.Visible = True
End If
End If
Catch ex AsException
lblMessage.Text = ex.Message
lblMessage.ForeColor = System.Drawing.Color.Red
lblMessage.Visible = True
Exit Sub
End Try
End If
End Sub
Private SubvalFile_ServerValidate(ByVal source As System.Object, ByVal args AsSystem.Web.UI.WebControls.ServerValidateEventArgs) Handles valFile.ServerValidate
Try
If Not(FileUpload.PostedFile Is Nothing) Then
If (FileUpload.PostedFile.ContentLength > 0) Then
args.IsValid = True
Return
End If
End If
args.IsValid = False
Catch exc As Exception
End Try
End Sub
Private SubvalType_ServerValidate(ByVal source As System.Object, ByVal args AsSystem.Web.UI.WebControls.ServerValidateEventArgs) Handles valType.ServerValidate
Try
If Not(FileUpload.PostedFile Is Nothing) Then
lblMessage.Visible = False
If (FileUpload.PostedFile.ContentLength > 0) Then
Dim arr As String() = FileUpload.PostedFile.FileName.Split(Convert.ToChar("."))
Dim fileType As String = arr(arr.Length - 1).ToLower()
valType.ErrorMessage = "You must upload a file that is either a JPG, JPEG"
If FileFilter <> ""And Not InStr("," & FileFilter.ToLower, "," & fileType.ToLower) = 0 Then
args.IsValid = True
Return
Else
args.IsValid = False
End If
args.IsValid = False
End If
End If
Catch exc As Exception
End Try
End Sub
#End Region
End Class
End Namespace
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