Contents tagged with ASP.NET

  • Implementing Delete Confirmation Dialog in ListView Control (ASP.Net)

    Listview control is one of my favorite controls added in asp.net version 3.5. It provides easy way to implement view (list), update, insert and delete functionality. Using SQL Data Source or LINQ Data Source control, you can create a page that will display data from database in your desired format. It will also allow you to edit, insert or delete a record from the listview itself. And the good part is that you don't need to write any code. This may be disappointing to a hard core programmer like me. But again this saves lot of development time.

    But one of the lacking feature in the listview control is delete confirmation. If somebody clicks on the delete button by mistake, there is no way to cancel the delete action. To solve this issue, I used client side JavaScript and confirm function.

    JavaScript's confirm function display an modal alert popup with the user specified confirmation message. It also have two buttons - OK and Cancel. Pressing OK or Cancel return boolean true or false. When confirm function is used with form submission, it cancels the form submission if Cancel button is pressed by the user. If user presses OK button, form submits as usual.

    I used confirm function in the OnClientClick event of the ListView's delete button.The code to use this is given below. Please note that in the code I used LinkButton instead of auto generated Button. This is for usability purpose and the code works well with the Button also.

    <asp:LinkButton ID="DeleteButton" runat="server" CommandName="Delete" ForeColor="Red" Text="Delete"
    OnClientClick="return confirm('Are you certain you want to delete?');" />

    And the dialog box shown by this code is :

    image

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  • Converting Text into Image On-The-Fly

    Sometimes we need to convert text into the images on the fly. This code converts the text into image and displays it onto the web page without saving it into a file on the disk. It also takes care of text wrapping.

     

    TextToImageConvertor can either be used in a web page or in a module. I have used this code in a web page. To use TextToImageConvertor in a module, you will need to make some changes in the step 8.

    The code for TextToImageConvertor is self explanatory. However, I am going to describe this step-by-step.

    Step 0 - Include Namespaces

    using System.Drawing;
    using System.Drawing.Imaging;

    Step 1 - Declare Properties

    Declare some variables that will control the behavior and color of the image.

    string Text = Request.QueryString["Text"];
    Color FontColor = Color.Blue;
    Color BackColor = Color.White;
    String FontName = "Times New Roman";
    int FontSize = 10;
    int Height = 150;
    int Width = 150;

    Step 2 - Create a Bitmap Object to Hold The Image

    Bitmap bitmap = new Bitmap(Width, Height);

    Step 3 - Create a Graphics object using this Bitmap object

    Graphics graphics = Graphics.FromImage(bitmap);

    Step 4 - Create Color, Font, and  PointF objects.

    Color color = Color.Gray; ;
    Font font = new Font(FontName, FontSize);
    //define where the text will be displayed in the specified area of the image
    PointF point = new PointF(5.0F, 5.0F);

    Step 5 - Create Brushes and Pen

    SolidBrush BrushForeColor = new SolidBrush(FontColor);
    SolidBrush BrushBackColor = new SolidBrush(BackColor);
    Pen BorderPen = new Pen(color);

    Step 6 - Draw Rectangle using Graphics object

    Rectangle displayRectangle = new Rectangle(new Point(0, 0), new Size(Width - 1, Height - 1));
    graphics.FillRectangle(BrushBackColor, displayRectangle);
    graphics.DrawRectangle(BorderPen, displayRectangle);
    Step 7 - Draw Text string on the specified rectangle using Graphics object
    //Define string format 
    StringFormat format1 = new StringFormat(StringFormatFlags.NoClip);
    StringFormat format2 = new StringFormat(format1);
    //Draw text string using the text format
    graphics.DrawString(Text, font, Brushes.Red, (RectangleF)displayRectangle, format2);
    Step 8 - Send the bitmap to page output stream in JPEG format
    Response.ContentType = "image/jpeg";
    bitmap.Save(Response.OutputStream, ImageFormat.Jpeg);

     

    Using TextToImageConvertor

    TextToImageConvertor is developed as a web page which can be accessed directly by passing the text in he query string.

    To demonstrate the use of this tool, create a webpage with a textbox, a button and an image control. On the click event of the button, set the image URL to the convertor page and pass the text of text box into the query string. In the example code below, I have named my image control as img1 and text box as txtNote.

    img1.ImageUrl = "default2.aspx?Text=" + txtNote.Text;

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