User`s guide

2 Introduction
2-18
'Callback', 'stoppreview(vid)',...
'Units','normalized',...
'Position',[.17 0 .15 .07]);
uicontrol('String', 'Close',...
'Callback', 'close(gcf)',...
'Units','normalized',...
'Position',[0.34 0 .15 .07]);
% Create the text label for the timestamp
hTextLabel = uicontrol('style','text','String','Timestamp', ...
'Units','normalized',...
'Position',[0.85 -.04 .15 .08]);
% Create the image object in which you want to
% display the video preview data.
vidRes = vid.VideoResolution;
imWidth = vidRes(1);
imHeight = vidRes(2);
nBands = vid.NumberOfBands;
hImage = image( zeros(imHeight, imWidth, nBands) );
% Specify the size of the axes that contains the image object
% so that it displays the image at the right resolution and
% centers it in the figure window.
figSize = get(hFig,'Position');
figWidth = figSize(3);
figHeight = figSize(4);
gca.unit = 'pixels';
gca.position = [ ((figWidth - imWidth)/2)...
((figHeight - imHeight)/2)...
imWidth imHeight ];
% Set up the update preview window function.
setappdata(hImage,'UpdatePreviewWindowFcn',@mypreview_fcn);
% Make handle to text label available to update function.
setappdata(hImage,'HandleToTimestampLabel',hTextLabel);
preview(vid, hImage);
When you run this example, it creates the GUI shown in the following figure. Each time
preview receives a video frame, it calls the update preview window function that you
specified, which updates the timestamp text label in the GUI.