Maybe this is still helpful. I wrote a function for exactly that with vertical line called slideScale. If you want to see how it works see the test script.
Code:
function [position, RT, answer] = slideScale(screenPointer, question, rect, endPoints, varargin)
%SLIDESCALE This funtion draws a slide scale on a PSYCHTOOLOX 3 screen and returns the
% position of the slider in pixel as well as the rection time and if an answer was given.
%
% Usage: [position, secs] = slideScale(ScreenPointer, question, center, rect, endPoints, varargin)
% Mandatory input:
% ScreenPointer -> pointer to the window
% question -> Text string containing the question
% rect -> Double contatining the screen size.
% Obtained with [myScreen, rect] = Screen('OpenWindow', 0);
% endPoints -> Cell containg the two text string of the left and right
% end of the scala. Exampe: endPoints = {'left, 'right'};
%
% Varargin:
% 'linelength' -> An integer specifying the lengths of the ticks in
% pixels. The default is 10.
% 'width' -> An integer specifying the width of the scala leine in
% pixels. The default is 3.
% 'scalalength' -> Double value between 0 and 1 for the length of the
% scale. The default is 0.9.
% 'scalaposition' -> Double value between 0 and 1 for the position of the
% scale. 0 is top and 1 is bottom.
% 'device' -> A string specifying the response device. Either 'mouse'
% or 'keyboard'. The default is 'mouse'.
% 'responsekey' -> String containing name of the key from the keyboard to log the
% response. Example. The default is 'return'.
% 'slidecolor' -> Vector for the color value of the slider [r g b]
% from 0 to 255. The dedult is red [255 0 0].
% 'scalacolor' -> Vector for the color value of the scale [r g b]
% from 0 to 255.The dedult is black [0 0 0].
% 'aborttime' -> Double specifying the time in seconds after which
% the function should be aborted. In this case no
% answer is saved. The default is 8 secs.
% 'image' -> An image saved in a uint8 matrix. Use
% imread('image.png') to load an image file.
%
% Output:
% 'position' -> Deviation from zero in percentage,
% with -100 <= position <= 100 to indicate left-sided
% and right-sided deviation.
% 'RT' -> Reaction time in milliseconds.
% 'answer' -> If 0, no answer has been given. Otherwise this
% variable is 1.
%
% Author: Joern Alexander Quent
% e-mail: alexander.quent@rub.de
% Version history:
% 1.0 - 01/04/2016 - First draft
% 1.1 - 02/18/2016 - Added abort time and option to
% choose between mouse and key board
% 1.2 - 05/10/2016 - End points will be aligned to end
% ticks
% 1.3 - 06/01/2016 - Added the possibility to display an
% image
%% Return error if in multi display mode!
screens = Screen('Screens');
if length(screens) > 1
error('Multi display mode not supported.');
end
%% Parse input arguments
% Default values
center = round([rect(3) rect(4)]/2);
lineLength = 10;
width = 3;
scalaLength = 0.9;
scalaPosition = 0.8;
sliderColor = [255 0 0];
scaleColor = [0 0 0];
device = 'mouse';
aborttime = 8;
responseKey = KbName('return');
drawImage = 0;
i = 1;
while(i<=length(varargin))
switch lower(varargin{i})
case 'linelength'
i = i + 1;
lineLength = varargin{i};
i = i + 1;
case 'width'
i = i + 1;
width = varargin{i};
i = i + 1;
case 'scalalength'
i = i + 1;
scalaLength = varargin{i};
i = i + 1;
case 'scalaposition'
i = i + 1;
scalaPosition = varargin{i};
i = i + 1;
case 'device'
i = i + 1;
device = varargin{i};
i = i + 1;
case 'responsekey'
i = i + 1;
responseKey = KbName(varargin{i});
i = i + 1;
case 'slidecolor'
i = i + 1;
sliderColor = varargin{i};
i = i + 1;
case 'scalacolor'
i = i + 1;
scaleColor = varargin{i};
i = i + 1;
case 'aborttime'
i = i + 1;
aborttime = varargin{i};
i = i + 1;
case 'image'
i = i + 1;
image = varargin{i};
i = i + 1;
imageSize = size(image);
stimuli = Screen('MakeTexture', screenPointer, image);
drawImage = 1;
end
end
% Sets the default key depending on choosen device
if strcmp(device, 'mouse')
responseKey = 1; % X mouse button
end
%% Coordinates of scale lines and text bounds
midTick = [center(1) rect(4)*scalaPosition - lineLength - 5 center(1) rect(4)*scalaPosition + lineLength + 5];
leftTick = [rect(3)*(1-scalaLength) rect(4)*scalaPosition - lineLength rect(3)*(1-scalaLength) rect(4)*scalaPosition + lineLength];
rightTick = [rect(3)*scalaLength rect(4)*scalaPosition - lineLength rect(3)*scalaLength rect(4)*scalaPosition + lineLength];
horzLine = [rect(3)*scalaLength rect(4)*scalaPosition rect(3)*(1-scalaLength) rect(4)*scalaPosition];
textBounds = [Screen('TextBounds', screenPointer, endPoints{1}); Screen('TextBounds', screenPointer, endPoints{2})];
if drawImage == 1
rectImage = [center(1) - imageSize(2)/2 rect(4)*(scalaPosition - 0.2) - imageSize(1) center(1) + imageSize(2)/2 rect(4)*(scalaPosition - 0.2)];
if rect(4)*(scalaPosition - 0.2) - imageSize(1) < 0
error('The height of the image is too large. Either lower your scale or use the smaller image.');
end
end
%% Loop for scale loop
t0 = GetSecs;
answer = 0;
while answer == 0
[x,y,buttons,focus,valuators,valinfo] = GetMouse(screenPointer, 1);
if x > rect(3)*scalaLength
x = rect(3)*scalaLength;
elseif x < rect(3)*(1-scalaLength)
x = rect(3)*(1-scalaLength);
end
% Draw image if provided
if drawImage == 1
Screen('DrawTexture', screenPointer, stimuli,[] , rectImage, 0);
end
% Drawing the question as text
DrawFormattedText(screenPointer, question, 'center', rect(4)*(scalaPosition - 0.1));
% Drawing the end points of the scala as text
DrawFormattedText(screenPointer, endPoints{1}, leftTick(1, 1) - textBounds(1, 3)/2, rect(4)*scalaPosition+10, [],[],[],[],[],[],[]); % Left point
DrawFormattedText(screenPointer, endPoints{2}, rightTick(1, 1) - textBounds(2, 3)/2, rect(4)*scalaPosition+10, [],[],[],[],[],[],[]); % Right point
% Drawing the scala
Screen('DrawLine', screenPointer, scaleColor, midTick(1), midTick(2), midTick(3), midTick(4), width); % Mid tick
Screen('DrawLine', screenPointer, scaleColor, leftTick(1), leftTick(2), leftTick(3), leftTick(4), width); % Left tick
Screen('DrawLine', screenPointer, scaleColor, rightTick(1), rightTick(2), rightTick(3), rightTick(4), width); % Right tick
Screen('DrawLine', screenPointer, scaleColor, horzLine(1), horzLine(2), horzLine(3), horzLine(4), width); % Horizontal line
% The slider
Screen('DrawLine', screenPointer, sliderColor, x, rect(4)*scalaPosition - lineLength, x, rect(4)*scalaPosition + lineLength, width);
% Flip screen
onsetStimulus = Screen('Flip', screenPointer);
% Check if answer has been given
if strcmp(device, 'mouse')
secs = GetSecs;
if buttons(responseKey) == 1
answer = 1;
end
elseif strcmp(device, 'keyboard')
[keyIsDown, secs, keyCode] = KbCheck;
if keyCode(responseKey) == 1
answer = 1;
end
else
error('Unknown device');
end
% Abort if answer takes too long
if secs - t0 > aborttime
break
end
end
%% Calculating the rection time and the position
RT = (secs - t0)*1000; % converting RT to millisecond
scaleRange = round(rect(3)*(1-scalaLength)):round(rect(3)*scalaLength); % Calculates the range of the scale
scaleRangeShifted = round((scaleRange)-mean(scaleRange)); % Shift the range of scale so it is symmetrical around zero
position = round((x)-mean(scaleRange)); % Shift the x value according to the new scale
position = (position/max(scaleRangeShifted))*100; % Converts the value to percentage
end
