MATLAB: Updating a string inside a callback

callbackMATLABstringsswitch

The following code is a graphic rendering of the Earth globe spinning eastward. I have two push buttons, Spin and Stop. Both share the same callback function, hAnimaCallback. In particular, this latter does not work. I pretend to use the strings (names) of the push buttons to create a switch that stops the movement. However, I can not get to change the string name inside the while loop and I do not understand why my method is wrong.
   function example
      fh = figure('Menu','none','Toolbar','none','Units','characters');
      T = 0:pi/100:2*pi;
      Y = zeros(numel(T),3);
      Y(:,1) = 7000*cos(T);
      Y(:,2) = 7000*sin(T);
      hPanAni = uipanel('parent',fh,'Units','characters','Position',...
          [22.6 10.4 53 23],'title','Controls','FontSize',11,...
          'FontAngle','italic','FontWeight','bold');
      hIniAni = uicontrol(hPanAni,'Style','pushbutton','Units','normalized',...
          'Position',[0.14 0.64 0.5 0.12],'String','Spin',...
          'FontSize',10,'Callback',@hAnimaCallback);
      hFinAni = uicontrol(hPanAni,'Style','pushbutton','Units','normalized',...
          'Position',[0.14 0.26 0.5 0.12],'String','Stop',...
          'FontSize',10,'Callback',@hAnimaCallback);
      hPantSim = uipanel('Parent',fh,'Units','characters',...
          'Position',[107.87 8 157.447 42],'BorderType','none','title',...
          'Screen','FontSize',11,'FontAngle','italic',...
          'FontWeight','bold');
      hPantSimInt = uipanel('Parent',hPantSim,'Units','normalized','Position',...
          [0 0 1 1],'BorderType','line','BackgroundColor','black');
      ah4 = axes('Parent',hPantSimInt,'Units','normalized','Position',...
          [0 0 1 1],'Color','none','Visible','off','DataAspectRatio',...
          [1 1 1],'NextPlot','add');
      rotate3d(ah4);
      hgrot = hgtransform('Parent',ah4);
      Resf = 6378;
      maptext = imread('tierra.jpg');
      [X, map] = rgb2ind(maptext,128);
      [x,y,z] = sphere(50);
      x = Resf*x;
      y = Resf*y;
      z = Resf*z;
      props.FaceColor= 'texture';
      props.EdgeColor = 'none';
      props.Parent = hgrot;
      props.Cdata = flipud(X); % it is necesary to do this for getting the 
      % appropiate image on the sphere
      hsurf = surface(x,y,z,props);
      colormap(map);
      axis equal;
      view([71 14]);
      set(gcf,'Renderer','opengl')
      drawnow;
      line('parent',ah4,'XData',Y(:,1),'YData',Y(:,2),'ZData',...
          Y(:,3),'Color','red','LineWidth',2);
      line('parent',ah4,'XData',Y(end,1),'YData',Y(end,2),...
          'ZData',Y(end,3),'Marker','o','MarkerSize',6,'MarkerFaceColor','b');
      axis square equal vis3d;
      view(3);
      handles.XLim = get(ah4,'XLim');
      handles.YLim = get(ah4,'YLim');
      handles.ZLim = get(ah4,'ZLim');
      xmin = handles.XLim(1);
      ymin = handles.YLim(1);
      zmin = handles.ZLim(1);
      xmax = handles.XLim(2);
      ymax = handles.YLim(2);
      zmax = handles.ZLim(2);
      set(ah4, 'XLim', [xmin xmax],'YLim', [ymin ymax],'Zlim',[zmin zmax]);
      az = 0;
          function hAnimaCallback(hObject,evt)
              while (ishandle(fh))
                  state = get(hObject,'String'), % state should change between the states of Spin and Stop but this does not occur
                  if (strcmp(state,'Stop'))
                      break;
                  else
                  az = az + 0.01745329252;
                  set(hgrot,'Matrix',makehgtform('zrotate',az));
                  drawnow;  
                  end  
              end
          end
      end

Best Answer

Instead of using a while-loop I would highly recommend using a timer.
          function hAnimaCallback(hObject,evt)
              if isempty(timerfind) %spin
                  T = timer('tag','T','Period',0.001,'executionmode','fixedrate',...
                      'timerfcn',@make_her_spin);
                  start(T)
              else %stop
                  T = timerfind('tag','T');
                  stop(T);
                  delete(T)
              end    
          end
       function make_her_spin(hObject,evt)
            az = az + 0.01745329252;
            set(hgrot,'Matrix',makehgtform('zrotate',az));
            drawnow;  
       end
Related Question