how to get the thumbnail of picture in windows mobile application - vb.net

Question

I am delveloping a small application in VB.NET, where I need to load an image from the phone into a picture box. I am not able to add the picture into picturebox, though. It throws an OutOfMemoryException. I am wondering if there is any way to reduce the size of the picture by changing it to thumbnail.
Dim srcmap As New Bitmap(OpenFileDialog1.FileName)
Dim destbit As New Bitmap(220, 220)
Dim srcRec As New Rectangle(0, 0, srcmap.Width, srcmap.Height)
Dim destRec As New Rectangle(0, 0, 220, 220)
Dim g As Graphics
g = Graphics.FromImage(destbit)
g.DrawImage(srcmap, destRec,srcRec, GraphicsUnit.Pixel)
picturebox.Image = destbit

Answer 1

Here is my OpenNetCF C# snippet for that issue:
...
//imagefactory
using OpenNETCF.Drawing;
using OpenNETCF.Drawing.Imaging;
...
OpenNETCF.Drawing.Imaging.StreamOnFile m_stream;
Size m_size;
///
/// this will handle also large bitmaps and show a thumbnailed version on a picturebox
/// see http://blog.opennetcf.com/ctacke/2010/10/13/LoadingPartsOfLargeImagesInTheCompactFramework.aspx
///
/// the name of the file to load
private void showImage(string sFileName)
{
var stream = File.Open(sFileName, FileMode.Open);
m_stream = new StreamOnFile(stream);
m_size = ImageHelper.GetRawImageSize(m_stream);
System.Diagnostics.Debug.WriteLine("showImage loading " + sFileName + ", width/height = " + m_size.Width.ToString() + "/"+ m_size.Height.ToString());
//CameraPreview.Image = ImageHelper.CreateThumbnail(m_stream, CameraPreview.Width, CameraPreview.Height);
CameraSnapshot.Image = ImageHelper.CreateThumbnail(m_stream, CameraPreview.Width, CameraPreview.Height);
showSnapshot(true); //show still image
m_stream.Dispose();
stream.Close();
}
with imagehelper.cs:http://code.google.com/p/intermeccontrols/source/browse/DPAG7/Hasci.TestApp.And_Controls/IntermecControls/Hasci.TestApp.IntermecCamera3/ImageHelper.cs

Answer 2

Here is the VB code of the above:
Imports System
Imports System.Drawing
Imports System.Drawing.Imaging
Imports OpenNETCF.Drawing
Imports OpenNETCF.Drawing.Imaging
Imports System.Runtime.InteropServices
Imports System.Resources
Imports System.Reflection
Public Class ImageHelper
Private Shared m_factory As ImagingFactory
Private Shared Function GetFactory() As ImagingFactory
If (m_factory Is Nothing) Then
m_factory = New ImagingFactory
End If
Return m_factory
End Function
Public Shared Function CreateClip(ByVal sof As StreamOnFile, ByVal x As Integer, ByVal y As Integer, ByVal width As Integer, ByVal height As Integer) As Bitmap
Dim original As IBitmapImage = Nothing
Dim image As IImage = Nothing
Dim info As ImageInfo
GetFactory.CreateImageFromStream(sof, image)
Try
image.GetImageInfo(info)
GetFactory.CreateBitmapFromImage(image, info.Width, info.Height, info.PixelFormat, InterpolationHint.InterpolationHintDefault, original)
Try
Dim ops As IBasicBitmapOps = CType(original, IBasicBitmapOps)
Dim clip As IBitmapImage = Nothing
Try
Dim rect As RECT = New RECT(x, y, (x + width), (y + height))
ops.Clone(rect, clip, True)
Return ImageUtils.IBitmapImageToBitmap(clip)
Finally
Marshal.ReleaseComObject(clip)
End Try
Finally
Marshal.ReleaseComObject(original)
End Try
Finally
Marshal.ReleaseComObject(image)
End Try
End Function
Public Shared Function getScaledBitmap(ByVal sof As StreamOnFile, ByVal scalePercent As Integer) As Bitmap
Dim thumbnail As IBitmapImage = Nothing
Dim image As IImage = Nothing
Dim info As ImageInfo
Dim fScale As Decimal = (scalePercent / 100)
' m()
' do not remove the m specifier!
GetFactory.CreateImageFromStream(sof, image)
Try
image.GetImageInfo(info)
Dim newWidth As UInteger = CType((info.Width * fScale), UInteger)
Dim newHeight As UInteger = CType((info.Height * fScale), UInteger)
GetFactory.CreateBitmapFromImage(image, newWidth, newHeight, info.PixelFormat, InterpolationHint.InterpolationHintDefault, thumbnail)
Try
Return ImageUtils.IBitmapImageToBitmap(thumbnail)
Catch ex As Exception
Dim stream As System.IO.Stream = System.Reflection.Assembly.GetExecutingAssembly.GetManifestResourceStream("CameraCx7x.oom.png")
Return New Bitmap(stream)
' (400, 300);
Finally
Marshal.ReleaseComObject(thumbnail)
End Try
Finally
Marshal.ReleaseComObject(image)
End Try
End Function
Public Shared Function CreateThumbnail(ByVal sof As StreamOnFile, ByVal width As Integer, ByVal height As Integer) As Bitmap
Dim thumbnail As IBitmapImage = Nothing
Dim image As IImage = Nothing
Dim info As ImageInfo
GetFactory.CreateImageFromStream(sof, image)
Try
image.GetImageInfo(info)
GetFactory.CreateBitmapFromImage(image, CType(width, UInteger), CType(height, UInteger), info.PixelFormat, InterpolationHint.InterpolationHintDefault, thumbnail)
Try
Return ImageUtils.IBitmapImageToBitmap(thumbnail)
Finally
Marshal.ReleaseComObject(thumbnail)
End Try
Finally
Marshal.ReleaseComObject(image)
End Try
End Function
Public Shared Function saveScaledBitmap(ByVal sof As StreamOnFile, ByVal width As Integer, ByVal height As Integer, ByVal sNewFile As String) As Boolean
Dim bRet As Boolean = True
Try
Dim bmp As Bitmap = CreateThumbnail(sof, width, height)
bmp.Save(sNewFile, System.Drawing.Imaging.ImageFormat.Jpeg)
Catch ex As Exception
System.Diagnostics.Debug.WriteLine(("Exception in saveScaledBitmap(): " + ex.Message))
bRet = False
End Try
Return bRet
End Function
Public Shared Function GetRawImageSize(ByVal sof As StreamOnFile) As Size
Dim image As IImage = Nothing
Dim info As ImageInfo
GetFactory.CreateImageFromStream(sof, image)
Try
image.GetImageInfo(info)
Return New Size(CType(info.Width, Integer), CType(info.Height, Integer))
Finally
Marshal.ReleaseComObject(image)
End Try
End Function
End Class
and this is how to call it from a form with a lable, a button and a picturebox
Imports OpenNETCF.Drawing
Imports OpenNETCF.Drawing.Imaging
Imports System.IO
Public Class Form1
Dim _Bitmap As Bitmap
Private Sub showImage(ByVal filePath As String)
'do not load the full image!
If File.Exists(filePath) Then
label1.Text = filePath
If (Not (_Bitmap) Is Nothing) Then
_Bitmap.Dispose()
End If
' a 1944x2593 image is about 15MByte !
'create a scaled down image file
Dim _filestream As FileStream = File.Open(filePath, FileMode.Open)
Dim _stream As StreamOnFile = New StreamOnFile(_filestream)
Dim fi As System.IO.FileInfo = New FileInfo(filePath)
Dim sizeBmp As Size = ImageHelper.GetRawImageSize(_stream)
'allow 640 hight
Dim ratio As Integer = (sizeBmp.Height / 640)
Dim scale As Integer = (ratio * 10)
If (ratio > 1) Then
_Bitmap = ImageHelper.getScaledBitmap(_stream, scale)
End If
Me.pictureBox1.Image = CType(_Bitmap, Image)
_filestream.Close()
End If
End Sub
Private Sub btnLoad_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLoad.Click
Dim ofd As New OpenFileDialog
ofd.InitialDirectory = "\My Documents"
ofd.Filter = "Jpg image|*.jpg|Bmp image|*.bmp|Gif image|*.gif|All files|*.*"
ofd.FilterIndex = 0
Dim sFile As String
If (ofd.ShowDialog = Windows.Forms.DialogResult.OK) Then
sFile = ofd.FileName
ofd.Dispose()
showImage(sFile)
End If
End Sub
End Class