Hi Bob,
Using an exception for this is not recommended, in fact an exception should
only be used when an error occur, do never use exceptions to control the
flow of a program, the exceptions are VERY EXPENSIVES !!!.
You have to use a event for this, below I post a code snap that do
precisely that.
Basically I'm resizing images files, I do so in a worker thread and in the
main thread ( UI thread ) I use a progressbar as well as a couple of labels.
I post here the important part of the code, all the code will found below.
// This is the delegate I Will use to notify the interface a new file was
processed
public delegate void ProcessedFileHandler( );
// thre thread
Thread workingThread;
// This will "point" to the function to update the UI
ProcessedFileHandler procfilehandler;
private void ImportImages_Load(object sender, System.EventArgs e)
{
// The method I will call to update the UI
procfilehandler = new ProcessedFileHandler( this.UpdateProgressBar);
//Start the thread
this.workingThread = new Thread( new ThreadStart( this.ImportImage ));
this.workingThread.Start();
}
// This is the working method, I iterate in the file list and process each
file , at the end I call the method to update the interface
// the trick is to use a WinForm control and call Invoke on it, it can be
ANY UI control, all it does is MAKE SURE that the call
// is done in the main thread.
void ImportImage( )
{
foreach(string imageURL in files)
{
try
{
//Update the interface, this MAKE SURE the call is done in the main
thread
this.progressBar1.Invoke( procfilehandler, null);
}
catch(Exception e)
{
continue;
}
}
}
//The update UI method:
void UpdateProgressBar( )
{
this.progressBar1.Value++;
FileNameLBL.Text = currentfile;
currentLBL.Text = currentpos.ToString();
}
Here is the code completed, just for reference !!!.
Hope this help,
--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation
//*********************** CODE START
using System;
using System.Data;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Text;
using System.IO;
using System.Threading;
namespace WindowsApplication1
{
/// <summary>
/// Summary description for ImportImages.
/// </summary>
public class ImportImages : System.Windows.Forms.Form
{
public delegate void ProcessedFileHandler( );
Thread workingThread;
object syslock = new object();
int currentpos=0;
string currentfile="";
string[] files;
ProcessedFileHandler procfilehandler;
private System.Windows.Forms.ProgressBar progressBar1;
private System.Windows.Forms.Label FileNameLBL;
private System.Windows.Forms.Label currentLBL;
private System.Windows.Forms.Label label3;
private System.Windows.Forms.Label label1;
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.Container components = null;
public ImportImages(string[] files)
{
//
// Required for Windows Form Designer support
//
InitializeComponent();
//
// TODO: Add any constructor code after InitializeComponent call
//
this.files = files;
}
/// <summary>
/// Clean up any resources being used.
/// </summary>
protected override void Dispose( bool disposing )
{
if( disposing )
{
if(components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.progressBar1 = new System.Windows.Forms.ProgressBar();
this.FileNameLBL = new System.Windows.Forms.Label();
this.currentLBL = new System.Windows.Forms.Label();
this.label3 = new System.Windows.Forms.Label();
this.label1 = new System.Windows.Forms.Label();
this.SuspendLayout();
//
// progressBar1
//
this.progressBar1.Location = new System.Drawing.Point(16, 144);
this.progressBar1.Name = "progressBar1";
this.progressBar1.Size = new System.Drawing.Size(264, 23);
this.progressBar1.TabIndex = 1;
//
// FileNameLBL
//
this.FileNameLBL.Location = new System.Drawing.Point(16, 208);
this.FileNameLBL.Name = "FileNameLBL";
this.FileNameLBL.Size = new System.Drawing.Size(208, 16);
this.FileNameLBL.TabIndex = 2;
this.FileNameLBL.Text = "label1";
//
// currentLBL
//
this.currentLBL.Location = new System.Drawing.Point(176, 184);
this.currentLBL.Name = "currentLBL";
this.currentLBL.Size = new System.Drawing.Size(56, 16);
this.currentLBL.TabIndex = 3;
this.currentLBL.Text = "label2";
this.currentLBL.TextAlign = System.Drawing.ContentAlignment.TopRight;
//
// label3
//
this.label3.Location = new System.Drawing.Point(240, 184);
this.label3.Name = "label3";
this.label3.TabIndex = 4;
this.label3.Text = "label3";
//
// label1
//
this.label1.Location = new System.Drawing.Point(16, 176);
this.label1.Name = "label1";
this.label1.TabIndex = 5;
this.label1.Text = "Processing:";
this.label1.TextAlign = System.Drawing.ContentAlignment.BottomLeft;
//
// ImportImages
//
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(292, 273);
this.Controls.Add(this.label1);
this.Controls.Add(this.label3);
this.Controls.Add(this.currentLBL);
this.Controls.Add(this.FileNameLBL);
this.Controls.Add(this.progressBar1);
this.Name = "ImportImages";
this.Text = "ImportImages";
this.Load += new System.EventHandler(this.ImportImages_Load);
this.ResumeLayout(false);
}
#endregion
void UpdateProgressBar( )
{
this.progressBar1.Value++;
FileNameLBL.Text = currentfile;
currentLBL.Text = currentpos.ToString();
}
void Done()
{
MessageBox.Show("Done");
this.Close();
}
void ImportImage( )
{
Image.GetThumbnailImageAbort myCallback =
new Image.GetThumbnailImageAbort(ThumbnailCallback);
//Images are in the form ID.extension
foreach(string imageURL in files)
{
try
{
DataRow prow = GetProductRow( Path.GetFileNameWithoutExtension(
imageURL) );
// if ( prow == null)
// continue; //product not found.
//See if the Image is correct in size, if not try to resize it
Image image = new Bitmap( imageURL);
if ( (image.Width> Config.MaxImageWidth) || (image.Height>
Config.MaxImageHeight) )
{
//Resize the image
Image newimage = image.GetThumbnailImage( Math.Min( image.Width,
Config.MaxImageWidth) ,
Math.Min( image.Height, Config.MaxImageHeight) ,
myCallback, IntPtr.Zero);
ExportImage( newimage,
Path.GetFileName(imageURL) );//prow["ProductID"].ToString() );
}
else
ExportImage( image,
Path.GetFileName(imageURL) );//prow["ProductID"].ToString() );
lock( this.syslock)
{
this.currentpos++;
this.currentfile = Path.GetFileName(imageURL);
}
//Update the interface
this.progressBar1.Invoke( procfilehandler, null);
}
catch(Exception e)
{
continue;
}
}
this.progressBar1.Invoke( new ProcessedFileHandler( this.Done), null);
}
//Just save the image to the new directory under the new name
void ExportImage( Image image, string newname)
{
image.Save( Config.ExportImageDirectory + @"\" + newname,
System.Drawing.Imaging.ImageFormat.Jpeg);
}
DataRow GetProductRow( string origID )
{
// foreach(DataRow prow in DataProvider.StaticData.Tables["Product"].Rows)
// if ( prow["OriginalID"].ToString() == origID)
// return prow;
return null;
}
public bool ThumbnailCallback()
{
return false;
}
private void ImportImages_Load(object sender, System.EventArgs e)
{
this.label3.Text = "of " + files.Length.ToString();
this.progressBar1.Minimum = 0;
this.progressBar1.Maximum = files.Length;
procfilehandler = new ProcessedFileHandler( this.UpdateProgressBar);
//Start the thread
this.workingThread = new Thread( new ThreadStart( this.ImportImage ));
this.workingThread.Start();
}
}
class Config
{
public static int MaxImageWidth = 200;
public static int MaxImageHeight = 200;
public static string ExportImageDirectory = @"c:\temp";
public static string ExportImageDirectoryPPC = @"c:\temp";
}
}
//********************** CODE END
"bob" <bo**********@hotmail.com> wrote in message
news:b0**************************@posting.google.c om...
Hello,
I want to show progress to the user while some method is running so I
thought I'd use a progress bar.
But I don't see how I can do this without writing GUI code in the
model?
In Smalltalk I would fire of notification exceptions that a progress
bar would catch, increment progress, and then allow to continue (or no
one would catch and would perform their default behaviour which was to
continue). I gather that's not possible because Exceptions in C#
cannot be resumable?
Any ideas?
Thanks,
Bob
