How can i update the color of my initial band of my resistor?

Hello,

i already tried a bit but at some point i cant come further. I already got my initial bands and the value

for them but the next step would be to update the color of my bands so that when i chose the color value in the popupmenu

the right image pops up. I already did the initial bands with color images that had in my file

This is how the bands look now but i need to update the color of my bands

which i dont know how to do. I tried it with this code but it didnt work.

Can somebody please help me i really want it to work.

Thank you very much for every help

Answer 1

[Nick]

Its hard to tell how you implemented it based on only those screenshots. But the idea is relatively simpel:

You add a callback to your dropdowns, in that callback you grab the color that is linked to the dropdown value. Then you update the axes/image with that color

Below is a small example that illustrates the idea of how this could work, out of lazyness i just used a nested function to share the handles variable. It might be that its a property of a class or the variable that gets passed around in GUIDE in your situation.

function exampleCode
% create a struct that will be used directly inside the nested function - to make example work out of the box without boilerplate
handles = struct;

% initialize example gui
handles.fig = figure;
handles.axes.left = axes(handles.fig, 'units','norm','Position',[0.1 0.5 0.3 0.4]);
handles.axes.right = axes(handles.fig, 'units','norm','Position',[0.6 0.5 0.3 0.4]);
handles.dropdown.left = uicontrol(handles.fig, 'Style','popupmenu','String',{'blue','green', 'red'},'units','norm','Position',[0.1 0.3 0.3 0.18], 'Callback',@updateColor, 'Tag','left');
handles.dropdown.right = uicontrol(handles.fig, 'Style','popupmenu','String',{'blue','green', 'red'},'units','norm','Position',[0.6 0.3 0.3 0.18], 'Callback',@updateColor, 'Tag','right');
handles.colorSize = [500 500 3];
  
% set initial colors 2x blue
initialColor = grabColor('blue', handles.colorSize);
imshow(initialColor, 'Parent', handles.axes.left);
imshow(initialColor, 'Parent', handles.axes.right);

    function updateColor(src, ~)
        color = grabColor(src.String{src.Value}, handles.colorSize);
        
        switch src.Tag
            case 'left'
                parentAx = handles.axes.left;
            case 'right'
                parentAx = handles.axes.right;
        end
        
        parentAx.Children.CData = color; 
        % you could imshow every time, which is quite a bit slower but still fast enough for what you try to achieve here
        % it would look like this:
        % imshow(color, 'Parent', parentAx);
    end
end

 function color = grabColor(colorId, colorSize)
 % depending on the amount of colors you could just work with imread here
 % but make sure you do a check for the size and resize accordingly
 switch colorId
     case 'green'
         % could be color = imread('pathtogreen.jpg')
         green(:,:,3) =  zeros(500,500);
         green(:,:,1) =  zeros(500,500);
         green(:,:,2) =  255*ones(500,500);
         color = uint8(green);
     case 'blue'
         blue(:,:,3) =  255*ones(500,500);
         blue(:,:,1) =  zeros(500,500);
         blue(:,:,2) =  zeros(500,500);
         color = uint8(blue);
     case 'red'
         red(:,:,3) =  zeros(500,500);
         red(:,:,1) =  255*ones(500,500);
         red(:,:,2) =  zeros(500,500);
         color = uint8(red);
 end
 
 if ~all(size(color)==colorSize)
     if size(color,3) < 3
         % should be rgb but incase you load in a gray image with only one channel 
         repmat(color(:,:,1), 1, 1, 3);
     end
     color = imresize(color, [colorSize(1), colorSize(2)]);
 end
end

Hopefully this example can set you on your way to solve your problem.