Render MATLAB figure in memory

Solution 1:

I realize this is an old thread, but I ran into this problem again lately, so I wanted to summarize my findings. My main source is this page (cached). According to it, there are three alternatives:

1. using ADDFRAME directly with the figure handle (without using GETFRAME). This is exactly what @rescdsk has shown in his answer.

   hFig = figure('Visible','off');
   
   aviobj = avifile('file.avi');
   for k=1:N
       %#plot(...)
       aviobj = addframe(aviobj, hFig);
   end
   aviobj = close(aviobj);
   

2. using PRINT/SAVEAS/HGEXPORT to export the figure to an image file, then reading the image back from disk. This is approach#2 that you listed yourself in the question above.

   hFig = figure('Visible','off');
   set(hFig, 'PaperPositionMode','auto', 'InvertHardCopy','off')
   
   aviobj = avifile('file.avi');
   for k=1:N
       %#plot(...)
       print(['-f' num2str(hFig)], '-zbuffer', '-r0', '-dpng', 'file.png')
       img = imread('file.png');
       aviobj = addframe(aviobj, im2frame(img));
   end
   aviobj = close(aviobj);
   

3. using the undocumented HARDCOPY function to capture the figure in-memory.

   hFig = figure('Visible','off');
   set(hFig, 'PaperPositionMode','auto')
   
   aviobj = avifile('file.avi');
   for k=1:N
       %#plot(...)
       img = hardcopy(hFig, '-dzbuffer', '-r0');
       aviobj = addframe(aviobj, im2frame(img));
   end
   aviobj = close(aviobj);
   

   In fact, this is the underlying function that other functions use either directly or indirectly. By inspecting the source codes where possible, here is an illustration of the dependencies of the related functions where A --> B denotes A calls B:

   saveas [M-file] --> print [M-file] --> render [private M-file] --> hardcopy [P-file]
   hgexport [P-file] --> print [M-file] --> ...
   @avifile/addframe [M-file] --> hardcopy [P-file]
   

   On the other hand, GETFRAME does not call HARDCOPY but an undocumented built-in function named CAPTURESCREEN (although it seems that it will be using PRINT for the upcoming HG2 system where there is a new -RGBImage print flag):

   getframe [M-file] --> capturescreen [builtin]
   

Note: Since AVIFILE is now deprecated, you can replace it with the newer VIDEOWRITER in (2) and (3), but not in (1) since it does not support passing figure handle directly.

Solution 2:

If you create an avi file with avifile, and then add frames to it with addframe, MATLAB doesn't open up extra visible figures like it does with getframe.

avi = avifile('/path/to/output');
figure_handle = figure('visible', 'off');

% ...
for something = 1:1000
    cla
    % (draw stuff...)
    avi = addframe(avi, figure_handle);
end