rgbgui.adjGamma(hObject,event)

function adjGamma(hObject,event)
% ADJGAMMA Interface for adjusting image gamma values.

% Copyright 2010 The MathWorks, Inc.

    data = guidata(hObject);
    
    % Color channel
    k = data.k;

    % Axes bounds
    ax = data.ax;
    xlim(ax,[0 1]);
    ylim(ax,[0 1]);

    % Create gamma line and end points
    P       = data.P;
    xPts    = P{k}(:,1);
    yPts    = P{k}(:,2);
    [hl,hp] = createPlots(ax,xPts,yPts);
    data.hl = hl;
    data.hp = hp;
    % Save to GUIDATA
    guidata(hObject,data);

    % Set up callbacks
    set(hl, 'ButtonDownFcn', @lineBtnDown);

end


% ADJGAMMA specific utility and callback functions
% ------------------------------------------------

function ptButtonDown(h,e)
% PTBUTTONDOWN responds to gamma point mouse clicks.

    data = guidata(h);
    hf   = data.fig;

    % Set the figure motion function accordingly
    f = @(hh,ee)figMotionFcn(hh,ee,h);
    set(hf,'WindowButtonMotionFcn',f);
    set(hf,'WindowButtonUpFcn',@figButtonUp);

end


function lineBtnDown(h,e)
% LINEBTNDOWN responds to mouse clicks on the line.

    data = guidata(h);
    ax   = data.ax;
    hl   = data.hl;
    hp   = data.hp;

    [x,y,b] = tools.currentPoint(ax);

    % Bail if out of bounds
    if ~b, return, end

    % Add a new gamma point, and link to line.
    hpNew     = addPoint(ax,x,y);
    hp(end+1) = hpNew;
    data.hp   = hp;
    guidata(h,data);

    link(hl,hp);

    % Trigger the gamma point callback immediately
    ptButtonDown(hpNew,[]);

end


function figButtonUp(h,e)
% FIGBUTTONUP stops dragging a gamma point.
    set(h,'WindowButtonMotionFcn',{});
    set(h,'WindowButtonUpFcn',{});
end


function figMotionFcn(h,e,hUpdate)
% FIGMOTIONFCN drags a gamma marker.

    data = guidata(h);
    ax   = data.ax;
    hl   = data.hl;
    hp   = data.hp;

    % Update gamma marker and line
    [x,y] = tools.currentPoint(ax,'snap',0.01);

    set(hUpdate,'XData',x,'YData',y);
    link(hl,hp);
    
    % Update the image
    setGamma(h,e);
    
end


function [hl,hp] = createPlots(ax,X,Y)
% CREATEPLOTS creates the gamma line and marker plots.

    nPts = numel(X);

    % Sort points by ascending X
    M = [X(:) Y(:)];
    M = sortrows(M,1);
    X = M(:,1);
    Y = M(:,2);

    % Line connecting gamma points
    hl = plot(ax,X,Y,'-b');

    % Plot a separate marker for each gamma point
    hp = zeros(nPts,1);
    hold(ax,'on');
    for i = 1:nPts
        x = X(i);
        y = Y(i);
        hp(i) = plot(ax,x,y,'-dk');
        set(hp(i), 'Markersize'     , 8  , ...
                   'MarkerEdgeColor', 'k', ...
                   'MarkerFaceColor', 'k'  );
        % If this is not an endpoint, set callback
        if i > 1 && i < nPts
            set(hp(i),'ButtonDownFcn',@ptButtonDown);
        end
    end
    hold(ax,'off');

    % Apply curvature to the line
    link(hl,hp);
    
end


function link(hl,hp)
% LINK syncs the line data with gamma points.

    [x,y]  = getPoints(hp);

    % Color adjustment curve
    % NOTE: This curve is an approximation of
    % the full gamma curve. The actual gamma curve
    % has 2^N elements, where N is the bit depth
    % of each pixel.
    [c,xi] = tools.gamma.curve(x,y,100);

    % Set gamma line
    set(hl,'XData',xi,'YData',c);
    
end


function hp = addPoint(ax,x,y)
% ADDPOINT adds a gamma control point.
%    HP = ADD(AX,X,Y,FUN) adds a gamma control point
%    to axes AX at [X,Y]. FUN is the handle of the
%    function to call when the point is clicked.

    hold(ax,'on');
    hp = plot(ax,x,y,'-dk');
    set(hp, 'Markersize'     , 8  , ...
            'MarkerEdgeColor', 'k', ...
            'MarkerFaceColor', 'k', ...
            'ButtonDownFcn'  , @ptButtonDown);
    hold(ax,'off');

end


function hp = deletePoints(hp,h)
% DELETE removes the markers H from the gamma points.
    hp(hp == h) = [];
end


function [x,y] = getPoints(hp)
% GETPOINTS Returns X and Y gamma curve coordinates.

    % Gamma points
    x = get(hp,'XData');  x = cell2mat(x);
    y = get(hp,'YData');  y = cell2mat(y);
    % Ensure X and Y are column vectors
    x = x(:);
    y = y(:);
    % Sort in order of increasing X
    M = [x y];
    M = sortrows(M,1);
    x = M(:,1);
    y = M(:,2);

end


function setGamma(h,e)
% SETGAMMA adjusts a color channel

    data = guidata(h);
    hi   = data.hi;
    hp   = data.hp;
    k    = data.k;
    
    [x,y] = getPoints(hp);

    % Image to work with. Use the adjusted data
    % for inactive channels, unadjusted data for
    % active channel.
    I = get(hi,'CData');
    % Replace active channel with unmodified data
    I(:,:,k) = data.I(:,:,k);
    I(:,:,k) = tools.gamma.apply(x,y,I(:,:,k));

    % Update image
    set(hi,'CData',I);

    % Update point list
    data.P{k} = [x(:) y(:)];
    guidata(h,data);

end