Simple question with slider in GUI interface

I have a GUI interface with an edit text box (tag edit1) and a slider (tag slider 1). At a certain point of the program, a number is shown in the edit text box. What I want to do is to increase by 1 unit the number in edit1 when pressing the up arrow of the slider and decrease it by 1 unit when pressing the down arrow of the slider. What is the code to write into the function

function slider1_Callback(hObject, eventdata, handles)

? Thank you

Answer 1

[Image Analyst]

Try this:

% Get string from edit box.
editBoxValue = get(handles.edit1, 'String');
% Convert string to number.
theNumber = str2double(editBoxValue);
% Increment the number.
theNumber = theNumber + 1;
% Send new number back into the edit box.
set(handles.edit1, 'String', theNumber);

You might want to consider use of a slider instead of edit boxes and keystrokes.

[aurc89]

In this way I can only increase the number by pressing both up and down arrows of the slider, while I would like to increase it with the up arrow and decrease it with the down arrow

[Image Analyst]

For a slider, you get the value directly and just use it immediately. There is no incrementing or decrementing needed.

[Joseph Cheng]

I wonder if you need a slider if you're just using the arrows. two push buttons would do exactly what you want. Or a quick modification of what Image Analysis has supplied

%if you edit the slider to nominal value at 1 and has range/step of 0:1:2

editBoxValue = get(handles.edit1, 'String');
% Convert string to number.
theNumber = str2double(editBoxValue);
%Determine up or down and increment
theNumber = theNumber + get(handles.slider1,'value')-1;

% Send new number back into the edit box.
set(handles.edit1, 'String', theNumber);
%reset slider to 1;
set(handles.slider1,'value',1);

[Image Analyst]

Here's a snippet from one of my programs. I have 3 sliders. In each slider's callback, it calls this function which reads all the sliders and updates the label above the slider with the current value of the sliders.

% Gets called in the callback of each of the 3 sliders on the GUI.
% Reads the value of each slider and sets the 
% caption (static text label) above each slider.
function SliderMoved(handles)
  try
    % Set the caption for the smallest dot.
    scrollbarValue = round(get(handles.sldSmallest,'Value')); % Round to nearest integer.
    set(handles.sldSmallest, 'Value', scrollbarValue); % Send rounded value back in.
    caption = sprintf('Smallest Allowable Dot = %d pixels.', scrollbarValue);
    set(handles.txtSmallest, 'string', caption);
    
    % Set the caption for the largest dot.
    scrollbarValue = round(get(handles.sldLargest,'Value')); % Round to nearest integer.
    set(handles.sldLargest, 'Value', scrollbarValue); % Send rounded value back in.
    caption = sprintf('Largest Allowable Dot = %d pixels.', scrollbarValue);
    set(handles.txtLargest, 'string', caption);
    
    % Set the caption for the threshold.
    scrollbarValue = round(get(handles.sldThreshold,'Value')); % Round to nearest integer.
    set(handles.sldThreshold, 'Value', scrollbarValue); % Send rounded value back in.
    caption = sprintf('Threshold = %d gray levels.', scrollbarValue);
    set(handles.txtThreshold, 'string', caption);
  catch ME
    errorMessage = sprintf('Error in function %s() at line %d.\n\nError Message:\n%s', ...
      ME.stack(1).name, ME.stack(1).line, ME.message);
    fprintf(1, '%s\n', errorMessage);
    WarnUser(errorMessage);
  end
  return; % from SliderMoved()

Note: You need to set up the slider step first to get exactly 1.

sliderMin = get(handles.slider1, 'Min');
sliderMax = get(handles.slider1, 'Max');
stepValue = 1 / (sliderMax - sliderMin);
set(handles.slider1, 'SliderStep', [stepValue, 3*stepValue]);

You might do that in the yourGui_OpeningFcn() function.