ASP.NET – MaxVergelli.com

Create an Excel file in C# without Microsoft Office or Third party plugins

Max — Sat, 18 Apr 2020 18:07:00 +0000

What I’m about to say seems paradoxical, but the reality is that in open environments (as in PHP for example) it is often easier and we have less problems in creating or converting files in proprietary systems, compared to what happens on frameworks such as Microsoft’s .Net; this is the case when we have to create an Excel file (XLS / XLSX) in C# without having a copy of Microsoft Office on the server, or other third party plugins installed, without the right libraries in our project we will have several headaches. A quick solution is to use the open-source library ExcelLibrary. This looks to be a port of the PHP ExcelWriter, it’s very simple, small and easy to use.

Using ExcelLibrary

Workbook workbook = new Workbook();
workbook.Open("Book1.xlsx");
Sheet sheet = workbook.Sheet("Sheet1");
Row row = sheet.Row(2);
Cell cell = row.Cell(3);
string text = cell.Value;

Main features

No dependencies except .NET Framework 4.5. Easy to include in other solutions.
Built and extendable with LINQ. Most collections in the library (e.g. Workbook.Sheets or Row.Cells) is of type IEnumerable, which allows you to use LINQ queries to find exactly what you need.
Respects the visibility of sheets, rows and columns. Set the IncludeHidden option to trueto return hidden objects.
Well-tested. The library is being developed using principles of Test-driven development (TDD). A large set of unit tests verifies that new bugs are not introduced on code changes.
Well-documented. A software library is only as useful as its documentation.

Another valid alternative is EPPLUS5 however it has a new license model from version 5, it’s still free to use in some cases, but will require a commercial license to be used in a commercial business.

Render a Section in a Partial View – ASP.Net MVC

Max — Sun, 12 Apr 2020 15:34:00 +0000

Let’s start with the following configuration to give an example: in a MVC project, you have a “_Layout.vbhtml” file with this code



  
  
  
	
    
    @RenderSection("Scripts", false)

Then, you have a Partial View “ValidationScripts.vbhtml” in the Shared folder with

@Section Scripts
    
    
      
          
End Section

If you call the Partial View from a View like this…

@ModelType MvcExample.MyModel
@Code
    ViewData("Title") = "Test"
End Code

@Html.Partial("ValidationScripts")

Just a Test

However the Section “Scripts” is not rendered on the page, and the output HTML will be…

Solution

To render the Section in the Partial View, you need to create a couple of Extension methods like this:

public static class HtmlHelperExtensions
{
  private const string _jSViewDataName = "RenderJavaScript";
  private const string _styleViewDataName = "RenderStyle";

  public static void AddJavaScript(this HtmlHelper htmlHelper, 
                                   string scriptURL)
  {
    List scriptList = htmlHelper.ViewContext.HttpContext
      .Items[HtmlHelperExtensions._jSViewDataName] as List;
    if (scriptList != null)
    {
      if (!scriptList.Contains(scriptURL))
      {
        scriptList.Add(scriptURL);
      }
    }
    else
    {
      scriptList = new List();
      scriptList.Add(scriptURL);
      htmlHelper.ViewContext.HttpContext
        .Items.Add(HtmlHelperExtensions._jSViewDataName, scriptList);
    }
  }

  public static MvcHtmlString RenderJavaScripts(this HtmlHelper HtmlHelper)
  {
    StringBuilder result = new StringBuilder();

    List scriptList = HtmlHelper.ViewContext.HttpContext
      .Items[HtmlHelperExtensions._jSViewDataName] as List;
    if (scriptList != null)
    {
      foreach (string script in scriptList)
      {
        result.AppendLine(string.Format(
          "", 
          script));
      }
    }

    return MvcHtmlString.Create(result.ToString());
  }

  public static void AddStyle(this HtmlHelper htmlHelper, string styleURL)
  {
    List styleList = htmlHelper.ViewContext.HttpContext
      .Items[HtmlHelperExtensions._styleViewDataName] as List;

   if (styleList != null)
   {
     if (!styleList.Contains(styleURL))
     {
       styleList.Add(styleURL);
     }
   }
   else
   {
     styleList = new List();
     styleList.Add(styleURL);
     htmlHelper.ViewContext.HttpContext
       .Items.Add(HtmlHelperExtensions._styleViewDataName, styleList);
   }
 }

 public static MvcHtmlString RenderStyles(this HtmlHelper htmlHelper)
 {
   StringBuilder result = new StringBuilder();

   List styleList = htmlHelper.ViewContext.HttpContext
     .Items[HtmlHelperExtensions._styleViewDataName] as List;

   if (styleList != null)
   {
     foreach (string script in styleList)
     {
       result.AppendLine(string.Format(
         "", 
         script));
     }
   }

  return MvcHtmlString.Create(result.ToString());
  }
}

So, on any View or Partial View or Display/Edit Template you simply add what you need:

@{
  Html.AddJavaScript("http://cdn.jquerytools.org/1.2.7/full/jquery.tools.min.js");
}

Then, in your Layouts you render it where you want it! Like this markup…



  
  @Html.RenderStyles()
  @Html.RenderJavascripts()

C# code to VB.NET free online converter

Max — Sun, 01 Mar 2020 16:31:43 +0000

Simply paste your C# code and this free online utility will automatically convert it to its equivalent in VB.NET. This utility now support .NET 3.5 syntax:

http://www.developerfusion.com/tools/convert/csharp-to-vb/

You can reverse code from VB.NET to C# too.

🙂

New Associative Array Class for VB.NET / ASP.NET and C#

Max — Wed, 26 Feb 2020 16:30:19 +0000

I have coded the “Associative Array Class” also for VB.NET and ASP.NET so You can add this class to your .NET projects;

Download the VB.NET/ASP.NET Associative Array Class from:

https://sourceforge.net/projects/vbnetassocarray/

You will find a tutorial inside the archive.

vb.net Bitmap object locks images (impossible to move/delete jpg/gif files) – .Dispose() Method common problem

Max — Tue, 14 Jan 2020 15:47:04 +0000

Many people are in trouble and on forums asking why the .Net Bitmap object does not release an image with its .Dispose() method. The Bitmap object (after its destruction too) seems to lock the image file, then we are not able to move or delete that image file through the file system.

This is a known problem and it occurs when we declare and instantiate a Bitmap object and destruct that like in the following code:

[sourcecode language=”vb”]

‘create a bitmap object
Dim myBitmap As New Bitmap("c:myimage.jpg")

‘editing image routines, right here
‘…

‘release all Bitmap object resources
myBitmap.Dispose()

[/sourcecode]

The above code it is formally correct, however in same circumstances the .net garbage collector cannot recognize bitmap’s disposing; Dispose() method leaves the image file in an unusable state, then as MSDN said, we MUST release explicitly any reference after a Dispose() call;

with the following code, You will not encounter any problem, and after Dispose() You can edit, move, delete the image file by the filesystem functions…

[sourcecode language=”vb”]
‘create a bitmap object
Dim myBitmap As New Bitmap("c:myimage.jpg")

‘editing image routines, right here
‘…

‘release image reference
While myBitmap IsNot Nothing
myBitmap.Dispose()
myBitmap = Nothing ‘<– tells .net garbage collector to release resources
End While

[/sourcecode]

Happy image editing! 🙂

How to draw a shadow for a bitmap (Drop Shadow Effect in VB.NET / ASP.NET)

Max — Thu, 09 Jan 2020 15:41:16 +0000

I wrote a vb.net subroutine to draw easly a shadow for a Bitmap object; It is possible get a charming shadow in different ways…

Normal black shadow to the bottom right corner
Red shadow to the bottom right corner
Shadow to the bottom left corner
Shadow to the top left corner
Shadow to the top right corner
Shadow with Opacity: “128”
Shadow with Opacity: “128” and Softness: “8”
Shadow with Opacity: “128”, Softness: “8” and Distance: “10”
Shadow without rounded edges

Copy and paste my following vb.net code in your application. it does all the hard job…

[sourcecode language=”vb”]

‘ShadowDirection:
‘ TOP_RIGHT = 1
‘ BOTTOM_RIGHT = 2
‘ BOTTOM_LEFT = 3
‘ TOP_LEFT = 4
‘ShadowOpacity: from 0 to 255
‘ShadowSoftness: from 1 to 30
‘ShadowDistance: from 1 to 50
‘ShadowRoundedEdges: True or False

‘Note:
‘If You set "transparent" as background color, this is replaced with white color.

Public Enum ShadowDirections As Integer
TOP_RIGHT = 1
BOTTOM_RIGHT = 2
BOTTOM_LEFT = 3
TOP_LEFT = 4
End Enum

_
Public Sub DropShadow(ByRef SourceImage As Drawing.Bitmap, _
ByVal ShadowColor As Drawing.Color, _
ByVal BackgroundColor As Drawing.Color, _
Optional ByVal ShadowDirection As ShadowDirections = _
ShadowDirections.BOTTOM_RIGHT, _
Optional ByVal ShadowOpacity As Integer = 190, _
Optional ByVal ShadowSoftness As Integer = 4, _
Optional ByVal ShadowDistance As Integer = 5, _
Optional ByVal ShadowRoundedEdges As Boolean = True)
Dim ImgTarget As Bitmap = Nothing
Dim ImgShadow As Bitmap = Nothing
Dim g As Graphics = Nothing
Try
If SourceImage IsNot Nothing Then
If ShadowOpacity < 0 Then
ShadowOpacity = 0
ElseIf ShadowOpacity > 255 Then
ShadowOpacity = 255
End If
If ShadowSoftness < 1 Then
ShadowSoftness = 1
ElseIf ShadowSoftness > 30 Then
ShadowSoftness = 30
End If
If ShadowDistance < 1 Then
ShadowDistance = 1
ElseIf ShadowDistance > 50 Then
ShadowDistance = 50
End If
If ShadowColor = Color.Transparent Then
ShadowColor = Color.Black
End If
If BackgroundColor = Color.Transparent Then
BackgroundColor = Color.White
End If

‘get shadow
Dim shWidth As Integer = CInt(SourceImage.Width / ShadowSoftness)
Dim shHeight As Integer = CInt(SourceImage.Height / ShadowSoftness)
ImgShadow = New Bitmap(shWidth, shHeight)
g = Graphics.FromImage(ImgShadow)
g.Clear(Color.Transparent)
g.InterpolationMode = InterpolationMode.HighQualityBicubic
g.SmoothingMode = SmoothingMode.AntiAlias
Dim sre As Integer = 0
If ShadowRoundedEdges = True Then sre = 1
g.FillRectangle(New SolidBrush(Color.FromArgb(ShadowOpacity, ShadowColor)), _
sre, sre, shWidth, shHeight)
g.Dispose()

‘draw shadow
Dim d_shWidth As Integer = SourceImage.Width + ShadowDistance
Dim d_shHeight As Integer = SourceImage.Height + ShadowDistance
ImgTarget = New Bitmap(d_shWidth, d_shHeight)
g = Graphics.FromImage(ImgTarget)
g.Clear(BackgroundColor)
g.InterpolationMode = InterpolationMode.HighQualityBicubic
g.SmoothingMode = SmoothingMode.AntiAlias
g.DrawImage(ImgShadow, New Rectangle(0, 0, d_shWidth, d_shHeight), _
0, 0, ImgShadow.Width, ImgShadow.Height, GraphicsUnit.Pixel)
Select Case ShadowDirection
Case ShadowDirections.BOTTOM_RIGHT
g.DrawImage(SourceImage, _
New Rectangle(0, 0, SourceImage.Width,SourceImage.Height), _
0, 0, SourceImage.Width, SourceImage.Height, GraphicsUnit.Pixel)
Case ShadowDirections.BOTTOM_LEFT
g.Dispose()
ImgTarget.RotateFlip(RotateFlipType.RotateNoneFlipX)
g = Graphics.FromImage(ImgTarget)
g.DrawImage(SourceImage, _
New Rectangle(ShadowDistance, 0, SourceImage.Width, SourceImage.Height), _
0, 0, SourceImage.Width, SourceImage.Height, GraphicsUnit.Pixel)
Case ShadowDirections.TOP_LEFT
g.Dispose()
ImgTarget.RotateFlip(RotateFlipType.Rotate180FlipNone)
g = Graphics.FromImage(ImgTarget)
g.DrawImage(SourceImage, _
New Rectangle(ShadowDistance, ShadowDistance, _
SourceImage.Width, SourceImage.Height), _
0, 0, SourceImage.Width, SourceImage.Height, GraphicsUnit.Pixel)
Case ShadowDirections.TOP_RIGHT
g.Dispose()
ImgTarget.RotateFlip(RotateFlipType.RotateNoneFlipY)
g = Graphics.FromImage(ImgTarget)
g.DrawImage(SourceImage, _
New Rectangle(0, ShadowDistance, SourceImage.Width, SourceImage.Height), _
0, 0, SourceImage.Width, SourceImage.Height, GraphicsUnit.Pixel)
End Select

g.Dispose()
g = Nothing
ImgShadow.Dispose()
ImgShadow = Nothing

SourceImage = New Bitmap(ImgTarget)
ImgTarget.Dispose()
ImgTarget = Nothing
End If

Catch ex As Exception
If g IsNot Nothing Then
g.Dispose()
g = Nothing
End If
If ImgShadow IsNot Nothing Then
ImgShadow.Dispose()
ImgShadow = Nothing
End If
If ImgTarget IsNot Nothing Then
ImgTarget.Dispose()
ImgTarget = Nothing
End If
End Try

End Sub
[/sourcecode]

Besides, You can use this sub as in the following example (take a look at the comments…) :

[sourcecode language=”vb”]
Dim file_input As String = "c:myfile.jpg"
Dim file_output As String = "c:myfilewithshadow.jpg"

‘get bitmap…
Dim sourceImage As System.Drawing.Image = System.Drawing.Image.FromFile(file_input)
Dim format As System.Drawing.Imaging.ImageFormat = sourceImage.RawFormat
Dim bmpOut As System.Drawing.Bitmap = New Bitmap(sourceImage)

‘release any reference to the original file…
While sourceImage IsNot Nothing
sourceImage.Dispose()
sourceImage = Nothing
End While

‘drop black shadow on new bitmap with white background…
DropShadow(bmpOut, Color.Black, Color.White)

‘save file…
If bmpOut IsNot Nothing Then
bmpOut.Save(file_output, format)
bmpOut.Dispose()
bmpOut = Nothing
End If
[/sourcecode]

PS:
The subroutine executes only in “STAThread” so it’s thread-safe drawing.

Happy coding…

Max 🙂