copy method
Implementation
void copy(int toIndex, int fromIndex) {
var index0 = toIndex * bytesPerElement;
var fromIndex0 = fromIndex * bytesPerElement - bytesPerElement;
data[index0] = data[fromIndex0];
data[index0 + 1] = data[fromIndex0 + 1];
data[index0 + 2] = data[fromIndex0 + 2];
data[index0 + 3] = data[fromIndex0 + 3];
}