webcam preview in a gui

Hi,

I have been trying to include a webcam preview in a gui but I didn't success.

I have used the userData field within the main figure to store all the revelant informaiton and the 'fig' is a global variable.

When I launch the app and turn on the camera (video button), I get a solid color image (black, white...it depends) but not the webcam preview.

I have tested the preview function outside of the gui and it works.

My code is as follows:

clear all, close all, clc
global fig

fig = uifigure('Name','Gui');
fig.Position = [50 50 1700 800];
fig.UserData.g = uigridlayout(fig);
fig.UserData.g.RowHeight = {30,30,30,30,30,30,30,'1x'};
fig.UserData.g.ColumnWidth = {150,150,'1x','1x'};

fig.UserData.ax3 = uiaxes(fig.UserData.g);
fig.UserData.ax3.Layout.Row = length(fig.UserData.g.RowHeight);
fig.UserData.ax3.Layout.Column = 4;
title(fig.UserData.ax3,'Video','FontSize',14)

bt6 = uibutton(fig.UserData.g, 'Text', 'Video', 'ButtonPushedFcn', @(bt6,event) fun_Video(bt6, fig));
bt6.Layout.Row = 1;
bt6.Layout.Column = 2;
fig.UserData.bt6=bt6;

bt2 = uibutton(fig.UserData.g, 'Text', 'Stop', 'ButtonPushedFcn', @(bt2,event) fun_Stop(bt2, fig));
bt2.Layout.Row = 4;
bt2.Layout.Column = [1 2];
fig.UserData.bt2=bt2;

function fun_Video(bt6, fig)
    global fig
    fig.UserData.dev_info = imaqhwinfo('winvideo',1)
    fig.UserData.vid = videoinput('winvideo',1,fig.UserData.dev_info.SupportedFormats{1})
    
    fig.UserData.vidRes = fig.UserData.vid.VideoResolution;
    fig.UserData.nBands = fig.UserData.vid.NumberOfBands;
    fig.UserData.himage=image(zeros(fig.UserData.vidRes(2), fig.UserData.vidRes(1), fig.UserData.nBands), 'Parent', fig.UserData.ax3);

    preview(fig.UserData.vid, fig.UserData.himage);
end

function fun_Stop(bt2, fig)
    global fig
    closepreview(fig.UserData.vid);
end

Does anyone faced a similar problem?

I also tried the code indicated in https://es.mathworks.com/help/imaq/previewing-data.html using "setappdata(hImage,'UpdatePreviewWindowFcn',@mypreview_fcn)" but the problem remains.

Thanks.

Oscar

Answer 1

[Oscar Gonzalo]

Just in case anyone has the same problem.... I found a functional solution using axes instead of uiaxes:

fig.UserData.ax3 = uiaxes(fig.UserData.g); -------> fig.UserData.ax3 = axes(fig.UserData.g);

I don't know why, but with uiaxes it doesn't work.