Add Watermark Image on Uploaded Image in Asp.Net

By Unknown - Monday, September 14, 2015 - No Comments

(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

<%@ Page Title="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">

<tr>

<td>

<asp:label id="lblHeader" runat="server" Text="Add Watermark Image on Uploaded Image in Asp.Net"></asp:label>

</div>

<tr>

<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>

<asp:label id="lblMessage" runat="server" Visible="false"></asp:label><br />

</td>

</tr>

</table>

</div>

<asp:LinkButton id="cmdUpload" runat="server" CssClass="btn btn-small" OnClick="cmdUpload_Click" ValidationGroup="validate" Causesvalidation="true">

</asp:LinkButton>

</div>

</td>

</tr>

</table>

</asp:Content>

VB.NET Code

<%@ Page Title="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">

<tr>

<td>

<asp:label id="lblHeader" runat="server" Text="Add Watermark Image on Uploaded Image in Asp.Net"></asp:label>

</div>

<tr>

<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>

<asp:label id="lblMessage" runat="server" Visible="false"></asp:label><br />

</td>

</tr>

</table>

</div>

<asp:LinkButton id="cmdUpload" runat="server" CssClass="btn btn-small" ValidationGroup="validate" Causesvalidation="true">

</asp:LinkButton>

</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 string FilePath;

private string FileFilter = "jpg,jpeg";

#endregion

#region "Private Methods"

protected string UploadFile(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 void SetFilePath()

{

FilePath = MapPath("~/Upload/");

//Create Folder

if (!Directory.Exists(FilePath))

{

Directory.CreateDirectory(FilePath);

}

#endregion

#region "Event Handles"

protected void cmdUpload_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 (Exception ex)

{

lblMessage.Text = ex.Message;

lblMessage.ForeColor = System.Drawing.Color.Red;

lblMessage.Visible = true;

return;

}

protected void valFile_ServerValidate(object source, ServerValidateEventArgs args)

{

if (FileUpload.PostedFile != null)

{

if (FileUpload.PostedFile.ContentLength > 0)

{

args.IsValid = true;

}

else

{

args.IsValid = false;

}

protected void valType_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 As String = "jpg"

#End Region

#Region "Private Methods"

Protected Function UploadFile(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 As New Bitmap(ImagePath)

Dim bmpUpload As New Bitmap(Upload.PostedFile.InputStream, False)

Dim graphicsObj As Graphics = 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 Sub SetFilePath()

FilePath = MapPath("~/Upload/")

'Create Folder

If Not Directory.Exists(FilePath) Then

Directory.CreateDirectory(FilePath)

End If

End Sub

#End Region

#Region "Event Handles"

Private Sub cmdUpload_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdUpload.Click

If Page.IsValid Then

Try

Dim fileName As String = ""

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

Catch ex As Exception

lblMessage.Text = ex.Message

lblMessage.ForeColor = System.Drawing.Color.Red

lblMessage.Visible = True

Exit Sub

End Try

End If

End Sub

Private Sub valFile_ServerValidate(ByVal source As System.Object, ByVal args As System.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

args.IsValid = False

Catch exc As Exception

End Try

End Sub

Private Sub valType_ServerValidate(ByVal source As System.Object, ByVal args As System.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

Catch exc As Exception

End Try

End Sub

#End Region

End Class

End Namespace

Chúc các bạn thành công!

Quang Bình

News Ticker