output=rotateAround(image, pointY, pointX, angle, varargin)

function output=rotateAround(image, pointY, pointX, angle, varargin)
% ROTATEAROUND rotates an image.
%   ROTATED=ROTATEAROUND(IMAGE, POINTY, POINTX, ANGLE) rotates IMAGE around
%   the point [POINTY, POINTX] by ANGLE degrees. To rotate the image
%   clockwise, specify a negative value for ANGLE.
%
%   ROTATED=ROTATEAROUND(IMAGE, POINTY, POINTX, ANGLE, METHOD) rotates the
%   image with specified method:
%       'nearest'       Nearest-neighbor interpolation
%       'bilinear'      Bilinear interpolation
%       'bicubic'       Bicubic interpolation
%    The default is 'nearest'.
%
%   Example
%   -------
%       image=imread('eight.tif');
%       imshow(rotateAround(image, 1, 1, 10));
%
%   See also IMROTATE, PADARRAY.

%   Contributed by Jan Motl ([e-mail])
%   $Revision: 1.0 $  $Date: 2013/02/22 16:58:01 $

% Parameter checking.
numvarargs = length(varargin);
if numvarargs > 1
    error('myfuns:somefun2Alt:TooManyInputs', ...
        'requires at most 1 optional input');
end
optargs = {'nearest'};    % Set defaults for optional inputs
optargs(1:numvarargs) = varargin;
[method] = optargs{:};    % Place optional args in memorable variable names

% Initialization.
[imageHeight imageWidth] = size(image);
centerX = floor(imageWidth/2+1);
centerY = floor(imageHeight/2+1);

dy = centerY-pointY;
dx = centerX-pointX;

% How much would the watched point shift if rotated around the img center. 
[theta, rho] = cart2pol(-dx,dy);
[newX, newY] = pol2cart(theta+deg2rad(angle), rho);
shiftX = round(pointX-(centerX+newX));
shiftY = round(pointY-(centerY-newY));

% Pad the image to preserve the whole image during the rotation.
padX = abs(shiftX);
padY = abs(shiftY);

padded = padarray(image, [padY padX]);

% Rotate the image around the center.
rot = imrotate(padded, angle, 'crop', method);

% Crop the image.
output = rot(padY+1-shiftY:end-padY-shiftY, padX+1-shiftX:end-padX-shiftX);