I don't know how about you, but for me visiting The Code Projects at least once a day have become a pleasant and necessary habit. It's really a valuable web site with a wealth of useful samples and projects for .NET. So, the other day I've stumbled upon this article on the web site. It explains how to create thumbnail images from a directory of Adobe Acrobat PDF documents.  The author gives details on a technique of using a template image for a thumbnail, making it transparent and overlaying it on a top of resized original image.  The code in the article is using available in .NET GDI+ methods like Image.GetThumbnailImage, Bitmap.MakeTransparent, etc… So I asked myself a question: “Is it still possible to implement a similar technique in Compact Framework?” Aside from saving the resulting image to a file I couldn’t see any problems in doing that and in 15 minutes I had this code…

 

The simplified implementation of the GetThumbnailImage goes first:

 

public static Bitmap GetThumbnailImage(Bitmap image, int height, int width)

{

    Bitmap bmp = new Bitmap(height, width);

    //create temp Graphics

    Graphics gx = Graphics.FromImage(bmp);

    //Resize the image

    gx.DrawImage(image, new Rectangle(0, 0, height, width), new Rectangle(0, 0, image.Width, image.Height), GraphicsUnit.Pixel);

    //don't forget the dispose

    gx.Dispose();

    return bmp;

}

 

Now the CF version of the code from the article:

 

int thumbnailWidth = 38;

int thumbnailHeight = 52;

 

//Load original bitmap first

Bitmap orig = new Bitmap(@"\Program Files\ThumbnailProj\today.PNG");

//Create a thumbnailed version

Bitmap thumbOrig = GetThumbnailImage(orig, thumbnailWidth, thumbnailHeight);

//Load a template image

Bitmap thumbTemp = new Bitmap(@"\Program iles\ThumbnailProj\template_portrait.gif");

//Create new blank bitmap

Bitmap thumbnailBitmap = new Bitmap(thumbnailWidth + 7, thumbnailHeight + 7);

                 

Graphics gx = Graphics.FromImage(thumbnailBitmap);

gx.Clear(Color.White);

//Draw a thumbnailed image version  first

gx.DrawImage(thumbOrig, 2, 2);

           

//Draw a template image on the top with transparent attributes.

//This is what we do instead of Bitmap.MakeTransparent()

ImageAttributes attr = new ImageAttributes();

attr.SetColorKey(thumbTemp.GetPixel(5, 5), thumbTemp.GetPixel(5, 5));

gx.DrawImage(thumbTemp, new Rectangle(0, 0, thumbTemp.Width, thumbTemp.Height), 0, 0, thumbTemp.Width, thumbTemp.Height, GraphicsUnit.Pixel, attr);

 

//Draw the final image on the Form/Control

Graphics gxScr = this.CreateGraphics();

gxScr.DrawImage(thumbnailBitmap, 10, 10);

You can download the whole demo project here.