LoadPartialPixels

RasterImage.LoadPartialPixels method

Loads pixels partially by packs.

public void LoadPartialPixels(Rectangle desiredRectangle, IPartialPixelLoader pixelLoader)
Parameter Type Description
desiredRectangle Rectangle The desired rectangle.
pixelLoader IPartialPixelLoader The pixel loader.

Examples

The following example shows how to load and process pixels of a raster image using your own partial processor. For example, consider a problem of counting of fully transparent pixels of an image. In order to count transparent using partial loading mechanism, a separate class TransparentPixelCounter implementing Aspose.Imaging.IPartialPixelLoader is introduced.

[C#]

using (Aspose.Imaging.Image image = Aspose.Imaging.Image.Load(@"c:\temp\alpha.png"))
{
    Aspose.Imaging.RasterImage rasterImage = (Aspose.Imaging.RasterImage)image;

    // Create an instance of the Aspose.Imaging.IPartialPixelLoader and pass it to the Aspose.Imaging.RasterImage.LoadPartialPixels
    TransparentPixelCounter counter = new TransparentPixelCounter();

    // Load pixels for the whole image. Any rectangular part of the image can be specified as the first parameter of the Aspose.Imaging.RasterImage.LoadPartialPixels method.
    rasterImage.LoadPartialPixels(rasterImage.Bounds, counter);

    System.Console.WriteLine("The number of fully transparent pixels is {0}", counter.Count);
    System.Console.WriteLine("The total number of pixels is {0}", image.Width * image.Height);
}

// The counter may look like this:
/// <summary>
/// Counts the number of fully transparent pixels with alpha channel value of 0.
/// </summary>
private class TransparentPixelCounter : IPartialPixelLoader
{
    /// <summary>
    /// The number of fully transparent pixels.
    /// </summary>
    private int count;

    /// <summary>
    /// Gets the number of fully transparent pixels.
    /// </summary>
    public int Count
    {
        get { return this.count; }
    }

    /// <summary>
    /// Processes the loaded pixels. This method is called back every time when a new portion of pixels is loaded.
    /// </summary>
    /// <param name="pixelsRectangle">The pixels rectangle.</param>
    /// <param name="pixels">The 32-bit ARGB pixels.</param>
    /// <param name="start">The start pixels point.</param>
    /// <param name="end">The end pixels point.</param>
    public void Process(Aspose.Imaging.Rectangle pixelsRectangle, Aspose.Imaging.Color[] pixels, Aspose.Imaging.Point start, Aspose.Imaging.Point end)
    {
        foreach (Color pixel in pixels)
        {
            if (pixel.A == 0)
            {
                this.count++;
            }
        }
    }
}

See Also