MATLAB: Print contents of uipanel to PNG image - matlab

Question

I don't know how to accomplish the following in MATLAB. I have a figure which looks like this:
In the figure, I have a panel with many subplots and a scrollbar that allows me to view a portion of the panel.
I want to save the whole contents of the panel to a PNG image file (not just the visible portion), i.e. I want to have a file which is a tall rectangle, and doesn't require scrolling.
The code for generating the figure is as follows:
function draw(obj)
figure;
panel1 = uipanel('Parent',1);
panel2 = uipanel('Parent',panel1);
panelheight = obj.nIterations / 2;
set(panel1,'Position',[0 0 0.97 1]);
set(panel2,'Position',[0 1-panelheight 1 panelheight]); %%
nPlot = 1;
for i=1:obj.nIterations
models = obj.iterations{i};
for nModel=1:length(models)
subplot(obj.nIterations,length(models)*2,nPlot);
nPlot = nPlot + 1;
drawTransitions(models{nModel});
set(gca,'Parent',panel2);
subplot(obj.nIterations,length(models)*2,nPlot);
nPlot = nPlot + 1;
drawRewards(models{nModel});
set(gca,'Parent',panel2);
end
end
s = uicontrol('Style','Slider','Parent',1,...
'Units','normalized','Position',[0.97 0 0.03 1],...
'Value',1,'Callback',{#slider_callback1,panel2,panelheight});
end
I have tried the following, without success.
The saveas funstion saves the whole figure, not just the panel. Also, it clips the invisible portion of the panel.
export_fig(panel2.'file.png') gives just a solid gray image.

Answer 1

Why don't you just scroll your panel and grab the frames and concatenate them all together? Here's some code that will basically do that. I would have posted am image, but I guess I don't have enough points for that. You may need to fiddle with the scrolling, and maybe making the slider invisible, but it works.
function printPanel(pnl,filename)
fig = figure(ancestor(pnl,'figure'));
pnl_units = get(pnl,'units');
fig_units = get(fig,'units');
set(pnl,'units','pixels')
set(fig,'units','pixels')
pnl_rect = getpixelposition(pnl);
fig_rect = getpixelposition(fig);
pnl_height = pnl_rect(4);
fig_height = fig_rect(4);
pnl_rect(2) = -pnl_height;
set(pnl,'position',pnl_rect)
N = ceil(pnl_height/fig_height);
CDATA = cell(N,1);
for i = 1:N
F = getframe(fig);
CDATA{i} = F.cdata;
pnl_rect(2) = pnl_rect(2)+fig_height;
set(pnl,'position',pnl_rect)
drawnow
end
set(pnl,'units',pnl_units)
set(fig,'units',fig_units)
imwrite(cat(1,CDATA{:}),filename)
end

Answer 2

You could get rid of the ui elements and just make a figure with all the subplots, and then export that one, using e.g. print -dpng ....
saveas takes a handle as a first argument. Maybe this does not have to be a figure or model handle, but could be a reference to the contents of the panel.