How can I change uipanel dimensions by using user input?

Question

I'm trying to change panel and axes width and height values by using user input. These values will represent a photograph's resolution. For example, if a user inputs 512*512, the uipanel and Axes' width and height will change to 512 and the user will work on this workspace.

What I tried so far:

prompt = {'Enter width', 'Enter height'}; 
dlg_title = 'Input'; num_lines = 1; def = {'256','256'};
answer = inputdlg(prompt,dlg_title,num_lines,def); 
uipanel1.width = str2num(answer{1}); 
uipanel1.height = str2num(answer{2});

but the size of uipanel1 does not change.

Answer 1

Here's code that demonstrates how what you want can be done, which works with matlab-hg2 (default from MATLAB 2014b and onward).

%% //Create a figure with a uipanel & axes
hFig = figure('Units','pixels');       %// Create a new figure
hFig.Position = [100 100 600 600];     %// Adjust figure's position
hPan = uipanel(hFig,'Units','pixels'); %// Create a new panel
hPan.Position = [150 150 300 300];     %// Adjust panel's position
hAx = axes('Parent',hPan,'Units','normalized','Position',[0 0 1 1]); %// New axes
%% //Ask for user input
prompt = {'Enter width', 'Enter height'}; 
dlg_title = 'Input'; num_lines = 1; def = {'256','256'};
answer = cellfun(@str2double,inputdlg(prompt,dlg_title,num_lines,def)); 
%% //Modify the panel's position (axes will stretch\shrink automatically to fit)
hPan.Position(3:4) = answer;

On older versions of MATLAB, you may need slightly different steps:

new_pos_vec = get(hPan,'Position'); %// Get the existing values
new_pos_vec(3:4) = answer;          %// Modify just the width & height
set(hPan,'Position', new_pos_vec);  %// Update graphical properties

Answer 2

You should use setcommand to modify the UI component properties (and get command to retrieve information). In your case:

% get current position
currentPosition = get(uipanel1, 'position');

% update the position with the entered values
set(uipanel1, 'position', [currentPosition(1), currentPosition(2), str2num(answer{1}), str2num(answer{2})]);