29 December 2009

Creating layered images in C#

I'm currently developing a mobile site for a client. The site is the frontend for a competition that they will be running in 2010.

Part of the project specification requires the user to be able to build an image by choosing a background, foreground, and slogan. The site will then composite these images and enter the result into the competition.

In addition the site will send text messages to the users cellphone informing them of their status and (if they elect to receive it) a "word of the day"

This is probably the closest C# solution to what I was looking for:

public Image LayerImage(Image Current, Image Layer, Int32 LayerOpacity)
{
Bitmap bitmap = new Bitmap(Current);
Bitmap layer = new Bitmap(Layer);
Color pixel = new Color();

for (int x = 0; x < layer.Width; x++)
{
for (int y = 0; y < layer.Height; y++)
{
pixel = layer.GetPixel(x, y);
bitmap.SetPixel(x, y, Color.FromArgb(LayerOpacity, pixel));
}
}

return bitmap;
}

The PHP solution is slightly more easy:

$layers[] = imagecreatefromjpeg("images/example_background.jpg");
$layers[] = imagecreatefromgif("images/example_foreground.gif");
$layers[] = imagecreatefromgif("images/example_motto.gif");
for ($i = 0; $i < count($layers); $i++)
{
imagecopy($image, $layers[$i], 0, 0, 0, 0, 600, 550);
}
header('Content-type: image/jpeg');
imagejpeg($image);

We don't use the .PNG format when coding a .mobi website because not all handsets support this format. Similarly we cannot assume that Javascript will be supported and so we cannot rely on this as a solution. Everything must happen at the server and be sent in the most simple format to the mobile phone.

Further references


http://www.dreamincode.net/forums/showtopic53101.htm
http://msdn.microsoft.com/en-us/library/system.drawing.aspx
http://www.microsoft.com/msdownload/platformsdk/sdkupdate/psdk-full.htm
Tip

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