Update slider Limits after loading data?

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Ian
Ian 2024-1-6
回答： Voss 2024-1-7
I am using app designer and I created a slider called "FrameSelect".
The function called just before returns numFrames which I store to the app's properties. The line only works if I hard code the limits. How do I update the limits of this slider?
function OpenMenuSelected(app, event)
[file, path] = uigetfile('*.jpg;*.seq',"Select `.seq` file for analysis");
[app.imageSequence, app.minTemp, app.maxTemp, app.numFrames, app.frameRate] = load_image_sequence(app, strcat(path,file));
app.numFrames
app.FrameSelect.Value = 1;
limits = [1 app.numFrames]
app.FrameSelect.Limits = limits;
app.FrameSelect.MajorTicks = 1:15:app.numFrames;
notify(app.FrameSelect, 'ValueChanged');
end
Error using thermal_image_viewer/OpenMenuSelected
'Limits' must be a 1-by-2 array of real finite numbers that are increasing.
limits =
1×2 int32 row vector
1 317
And yes, numFrames is an int32 value between [200, 1500] after the load_image call.
When I hard code in a value, there is no error.

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采纳的回答

Voss
Voss 2024-1-7
MATLAB doesn't appear to allow the Limits property of a uislider to take on int32 values, at least in R2016b.
So it's worth a shot to try casting the value to double before using it in Limits:
app.FrameSelect.Limits = [1 double(app.numFrames)];

更多回答（1 个）

Ian
Ian 2024-1-7
I created a min reproducable example (min_example.mlapp) that has no issues updating the sliders limits, so there must a problem with how the dll I am using is interfaced with Matlab.
In my code doing the following worked.
function OpenMenuSelected(app, event)
[file, path] = uigetfile('*.jpg;*.seq',"Select `.seq` file for analysis");
[app.imageSequence, app.minTemp, app.maxTemp, app.numFrames, app.frameRate] = load_image_sequence(app, strcat(path,file));
x = int2str(app.numFrames);
y = str2num(x);
UpdateSlider(app, y);
end
function UpdateSlider(app, maxFrame)
app.FrameSelect.Limits = [1 maxFrame];
app.FrameSelect.MajorTicks = 1:15:app.numFrames;
app.FrameSelect.Value = 1;
UpdateImage(app, 1);
end
I am going to change my load function to calculate the number of frames instead of using the dll's functions.

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