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
<STAThread()> _
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 🙂
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