if 循环就是为了画直线  点击两点画直线。应该是在红 {MOD}部分加算平均值   且是完成每个if循环后，即直线画完后求平均handles.lengthPoints = [handles.lengthPoints ; x y];
hPlot = plot(x*A,y*A,'g.','markersize',10,'tag','point');
handles.hLengthPointsPlot = [handles.hLengthPointsPlot ; hPlot];

for j=1:2:100
if size(handles.lengthPoints,1)==j+1

points = A*handles.lengthPoints([j j+1],:);
hLine = plot(points(:,1), points(:,2), 'g', 'linewidth',2, 'ButtonDownFcn','calcArea(''axes1_ButtonDownFcn'',gca,[],guidata(gcbo))');
handles.lengthLines = [handles.lengthLines hLine];
dist = sqrt( sum((diff(points).^2)) );%前面有diff的定义

orientation = angle( diff(points) * [1 ; i] );%angle()是求相位角，angle（）的取值是-pi到pi
h = text(mean( points(:,1) ), mean( points(:,2) ) , num2str(dist), 'Rotation', orientation);% 在中点位置显示直线长度

handles.hLengthData = [handles.hLengthData h];
temp = get(handles.totalArea,'userdata');

temp(3) = (temp(3) +dist);%求总和
set(handles.totalArea,'userdata',temp);

end

set(handles.totalArea,'userdata',temp);

updateTitle(handles);


end

guidata(hObject,handles);% guidata保存数据 更新数据