Question

Looking for a simple example or link to a tutorial.

Say I have a bunch of values stored in an array. I would like to create an image and update the image data from my array. Assume the array values are intensity data and will be updating a grayscale image. Assume the array values are between 0 and 255 — or that I will convert it to that range.

This is not for purposes of animation. Rather the image would be updated based on user interaction. This is something I know how to do well in Java, but am very new to iPhone programming. I’ve googled some information about CGImage and UIImage — but am confused as to where to start.

Any help would be appreciated.

Answer 1

I have sample code from one of my apps that takes data stored as an array of unsigned char and turns it into a UIImage:

// unsigned char *bitmap; // This is the bitmap data you already have.
// int width, height; // bitmap length should equal width * height

// Create a bitmap context with the image data
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceGray();
CGContextRef context = CGBitmapContextCreate(bitmap, width, height, 8, width, colorspace, kCGImageAlphaNone);
CGImageRef cgImage = nil;
if (context != nil) {
    cgImage = CGBitmapContextCreateImage (context);
    CGContextRelease(context);
}
CGColorSpaceRelease(colorspace);

// Release the cgImage when done
CGImageRelease(cgImage);