Post-render loop processing really slow ?

[ins0mniaque]

Hi, first time on forum, - "Welcome to the forum", well thank you. Time for substance.

I'm writing a test plugin that write the source surface to a bitmap on disk, waits for an executable to end and then re-reads the bitmap and render it on the destination surface.

The problem is that after my render loop is called, a ProgressDialog apprears with "Rendering...", and it renders for ~15-20 seconds a 50x50px image.

Here is my reduced code [no error checking, etc...] but tested that it still has this behavior.

public override void Render ( EffectConfigToken parameters, RenderArgs destination, RenderArgs source, Rectangle [ ] rois, int startIndex, int length )
{
   // Validate configuration token
   MyEffectConfigToken Token = parameters as MyEffectConfigToken;

   // Retrieve selection
   PdnRegion SelectionRegion = EnvironmentParameters.GetSelection ( source.Bounds );
   Rectangle SelectionBounds = SelectionRegion.GetBoundsInt ( );

   // Create temporary filenames
   string InputFileName  = Path.Combine ( Path.GetTempPath ( ), Path.ChangeExtension ( Path.GetRandomFileName ( ), ".bmp" ) );
   string OutputFileName = Path.Combine ( Path.GetTempPath ( ), Path.ChangeExtension ( Path.GetRandomFileName ( ), ".bmp" ) );

   // Create bitmap and save it to InputFileName
   Bitmap Bitmap = source.Surface.CreateAliasedBitmap ( SelectionBounds, true );
   Bitmap.Save ( InputFileName, ImageFormat.Bmp );

   // Create process
   Process Process = new Process ( );

   Process.StartInfo.FileName  = Path.Combine ( Path.GetDirectoryName ( Assembly.GetExecutingAssembly ( ).Location ), "MyExecutable.exe" );
   Process.StartInfo.Arguments = string.Format ( "-input \"{0}\" -output \"{1}\" {2}", InputFileName, OutputFileName, Token.CommandLine );

   Process.StartInfo.CreateNoWindow  = true;
   Process.StartInfo.UseShellExecute = false;
   Process.StartInfo.WindowStyle     = ProcessWindowStyle.Hidden;

   // Start process
   Process.Start ( );

   // Wait for process to end
   Process.WaitForExit ( );

   // Read OutputFileName and draw bitmap
   using ( Bitmap OutputBitmap = new Bitmap ( OutputFileName ) )
       destination.Graphics.DrawImageUnscaledAndClipped ( OutputBitmap, SelectionBounds );
}

Any help would be greatly appreciated.

[Rick Brewster]

This is because you're completely misunderstanding how the Effect system in Paint.NET works. There's no such thing as a post-render loop: your Render method is the implementation of the inside of the rendering loop.

Your Render() method is going to be called from many threads at once and many times in a row. On a typical system it will be called 200 times from 2 difrerent threads (100 times per thread). So you are opening these input files 200 times and dumping this stuff out to disk 200 times as well, as well as creating 200 processes.

You're also violating the Effect contract by writing outside of the region of interest that is specified in the parameters. When I call your Render() method, you must only and I mean ONLY ever write to the pixels described by the roi array from startIndex through startIndex+length-1. The reason your Render method is called many times is because each time you are called upon to render only a small portion of the roi array (roi stands for region of interest btw).

So to quickly summarize: it's slow because everything is completely wrong. Paint.NET is probably the worst possible harness for what you are trying to do.

[ins0mniaque]

OMG! That's what you get for jumping directly to code...

But let's say I really really wanted to do this, is there a way you would suggest me to do it ? Is there a single-thread effect model ? Or do I have to execute this from my configuration window and read from it from the render thread ?

[Rick Brewster]

You'll need to write your own program to do this.