How it's done?

[ReMake]

I'm trying to write an image loading procedure in CodeLab. This works when loading an image for the first time. When I load a new image, the canvas remains unchanged and contains the image that was loaded for the first time.

This is the source code:

Spoiler

// Name:
// Submenu:
// Author:
// Title:
// Version:
// Desc:
// Keywords:
// URL:
// Help:
#region UICode
FilenameControl image = @""; // Image|png|jpg|gif|bmp
#endregion

private Surface _img = null;
private string imgPath;

protected Surface img
{
    get
    {
        if (_img != null)
        {
            return _img;
        }
        GetImageFromFile();
        return _img;
    }
}

private void GetImageFromFile()
{
    imgPath = image;
    Bitmap bitmap = null;
    try
    {
        bitmap = (Bitmap)Image.FromFile(imgPath, false);
    }
    catch (Exception)
    {
    }
    if (bitmap != null)
    {
        _img = Surface.CopyFromBitmap(bitmap);
        return;
    }
    _img = null;
}

void Render(Surface dst, Surface src, Rectangle rect)
{
    // Delete any of these lines you don't need
    Rectangle selection = EnvironmentParameters.SelectionBounds;
    
    ColorBgra CurrentPixel;
    for (int y = rect.Top; y < rect.Bottom; y++)
    {
        if (IsCancelRequested) return;
        for (int x = rect.Left; x < rect.Right; x++)
        {
            CurrentPixel = src[x,y];

            if (img != null) CurrentPixel = img.GetBilinearSampleWrapped(x,y);

            dst[x,y] = CurrentPixel;
        }
    }
}

 

 

How can I fix this?

[toe_head2001]

This code has two issues:

 

- After _img is successfully set, it never gets invalidated (set to null), so GetImageFromFile() will never run more than once.

- Conversely, if an image file is not successfully loaded into _img, GetImageFromFile() will run on every single pixel, and fail over and over again. A serious performance issue.

 

Did you find this code somewhere on the forum? If so, it needs to dealt with. It's bad code, and shouldn't be used.

 

I would just recommend doing this stuff in PreRender().

[ReMake]

47 minutes ago, toe_head2001 said:

Did you find this code somewhere on the forum?

No. I tried to create it myself using loading an image from the Clipboard, as described in Part 4 of BoltBait's CodeLab Tutorial.

[toe_head2001]

Yup, that example code also has the same two issues I pointed out.

@Illnab1024 wrote that code a very long time ago; before IClipboardService and OnSetRenderInfo() existed in Paint.NET.