How to return the state of preivew camera?

thank you for your help in advance.

Is there something like fopen for gige camera "Preview(g)"?

here is what the code looks like.

   Camlist = gigecamlist;
    IP = string(Camlist{1,3});
    g= gigecam(IP,'PixelFormat','mono8');  
    g_Res = [g.Width g.Height];
 %----------------lines to created figure with tabs-------------------------------------------------------
streamingHandle = uicontrol(tab_ini,'Style','PushButton','String', 'Streaming','Position',[135 10 80 20],'Callback', {@streaming,tab_ini,g_Res,g});
%------------------------------------------------------ callback funtion for push button
function streaming(object_handle,event, tab_ini, g_Res, g)
%% How can i return a value from 'preview(g)' to condition "if"  
% if Preview(g) ==1;  is opened
% closePreview(g);
% end
dock_tab = axes(tab_ini,'units','pixels','Position',[35,40,g_Res(1),g_Res(2)],'box','on');
nBands = 1; % grey scale
I = image(zeros(g_Res(2),g_Res(1), nBands),'Parent',dock_tab); 
preview(g, I);

Answer 1

[Walter Roberson]

%avoid warnings about struct() preventing hiding implementation details
old_warning_state = warning('off', 'MATLAB:structOnObject');
gs = struct(g);
gsw = struct(gs.webcamImpl);
gscpc = struct(gsw.CamPreviewController);
warning(old_warning_state);

if gscpc.IsPreviewing
    closePreview(g)
end

Note: you cannot do this directly: several of the properties are hidden properties.

[shin hsu]

The gigecam has the 'CamPreviewController' so it works preferectly.

%avoid warnings about struct() preventing hiding implementation details

old_warning_state = warning('off', 'MATLAB:structOnObject');

gs = struct(g);

%gsw = struct(gs.webcamImpl);

gscpc = struct(gs.CamPreviewController);

warning(old_warning_state);

if gscpc.IsPreviewing

closePreview(g)

end

thank you Walter for you help. I won't be able to figure this out myself.

Sincerely