Convenience class for iterating the pixels of a Channel.
The Iter class can be used to walk the pixels of a Channel using a nested for-loop, where the outer loop calls line(), and the inner calls pixel().
The code below implements an invert on the Area \a area of \a channel:
Channel::Iter iter = channel.getIter( area );
while( iter.line() ) {
while( iter.pixel() ) {
iter.v() = 255 - iter.v();
}
}In addition to v(), the Iter provides an accessor which accepts an offset in x & y relative to the current location:
inputIter.v(1, 1); // will return the value of the pixel to the lower right of the current pixel
inputIter.v(0, -1); // will return the value of the pixel directly above the current pixel
A final accessor, vClamped() also accepts an x & y relative offset, but will not sample outside of the bounds of the iterator.
inputIter.vClamped(-2,0); // when called on the left edge of a row,
// this will simply return the left-most pixel's value
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