Currently the "value" property of Slider is required, however I was wondering if it is possible to create a Slider such that it initially has no value and the thumb is hidden. Then when the user presses along the line, the thumb appears at that point.
I looked at https://pub.dev/packages/flutter_xlider but it seems like that package also required values to be set.
I think not, and for good reason. The function of the Slider and the understanding of how it is used is interpreted by the user primarily based on seeing the thumb indicator on a line. So regardless how you set up the requirements for the slider's usage in your app, the Slider control needs to always have a value represented. You could default the slider value to the min, the max, the middle(-ish), or any valid value.
If you want to ensure the user makes a selection (making it a required field sort of), you could set a bool state variable on an ancestor widget (perhaps named sliderWasTouched) to true when any part of the Slider is tapped and whenever the Slider changes value (after initialization), and then make that state variable being true part of your form field validation.
I run a very completed piece of MATLAB code containing hundreds of variables and sometimes I forget to change value of variables/parameters. I want to create a dialog box that pops up and notifies me about values of my variables prior to execution of the program.
You could use one of the predefined dialog boxes, such as inputdlg. The first example in the documentation shows how you can allow the user to modify multiple values (with defaults):
I have built a bokeh app that allows users to select windows in data and run python code to find and label (with markers) extreme values within these limits. For ease of interaction, I use the box select tool for the range selection. My problem arises when repeating this process for subsequent cases. After markers are placed for the results, they are rendered invisible by setting alpha to zero and another case needs to be chosen. When the new select box includes previous markers, they become visible based on the selection. How do I override this default behavior? Can markers be made unselectable? or can I add code to the customJS to hide them after they are selected?
Thanks in advance for any help!
There are a few possible approaches. If you just want non-selected glyphs to "disappear" visually, you can set a policy to do that as described here:
http://docs.bokeh.org/en/latest/docs/user_guide/styling.html#selected-and-unselected-glyphs
Basically, for bokeh.plotting, pass
nonselection_fill_alpha=0.0,
nonselection_line_alpha=0.0,
as arguments to your plot.circle call or whatever. Or if you are using the low level bokeh.models interface, something like:
renderer.nonselection_glyph = Circle(fill_alpha=0.0, line_alpha=0.0)
But be aware (I think you already are) that the invisible markers are still there, and still selectable if the user happens to draw a box over them with the selection tool.
If you truly want only a subset of the data to be visible and selectable after a selection, I'd say you want to replace the data in the column data source wholesale with the subset in your selection callback.
I'm having a bit of trouble with Matlab's uicontrol handling. Here's the situation:
My (programmatic) GUI contains an editable text field. This field originally contains a numeric value and is supposed to always contain one. In order to ensure that, the 'String' parameter is to be repeatedly checked, converted to numeric, and re-entered into the 'String' property of the uicontrol. This is supposed to happen whenever a user enters a visible character into the text field.
Additionally, the program is supposed to notice at any point whether the current value of said text field differs from the original value, which is stored in memory. If the user closes the figure, a modal dialog opens and asks if he wants to save the change to that value or discard it. If the figure is then reopened (through the rest of the GUI), the value of the text field starts out as either the same it started out as before (if the user discarded the changes) or the changed value defined by the user.
Both of these things fail in some instances because of a strange behaviour: The uicontrol's 'String' property is only updated after the uicontrol loses focus. This is not a problem if the user wants to do other things on that GUI or knows how to handle this. I can also live with my text field only updating to a meaningful numeric value after it loses focus.
The problem is, when I close the figure via Windows' red X button in the top right corner after changing the value of the text field, but without first clicking somewhere else, the 'String' value is never updated, so the CloseRequestFcn doesn't notice the change and simply closes the window. Even pausing for a whopping 100ms and then explicitly calling the text field's Callback from within the CloseRequestFcn doesn't help, it just closes without my dialog. The reverse is also true, if I do change the value, click somewhere else, and then change it back, it will display the dialog unless I first click somewhere else again.
So the question is this: How do I ensure the uicontrol correctly updates/executes its Callback when I click the red X button provided by Windows?
And bonus question: How do I execute this Callback "on the fly" in order to correct any impossible values the user enters as soon as he does (e.g. letters other than e and i)?
Here's the isolated part of my GUI that causes the problem, copy into a file called 'guitest.m' and run in order to test what I'm talking about.
function guitest
changed = false; %// tracks changes to catch closing without saving
startval = 1; %// the starting value
handles.figure = figure('Resize','off','Toolbar','none','Menu',...
'none','Name','Change text field value','CloseRequestFcn',...
#closefig,'Visible','off'); %// not visible until fully created
handles.textfield = uicontrol('Style','edit','Units','normalized',...
'Parent',handles.figure,'String',startval,...
'Position',[.4 .6 .2 .1],'Callback',#changedValue);
handles.button = uicontrol('String','Push me','Units','normalized',...
'Parent',handles.figure,'Position',[.4 .3 .2 .2],'Callback',#dispval);
%// all done, display GUI
set(handles.figure,'Visible','on');
%// callback functions
function closefig(~,~) %// Quit program
pause(0.1);
changedValue(handles.textfield); %// update fields
if changed
disp('Do you really want to close?'); %// save dialog
else
delete(handles.figure); %// this is used as CloseRequestFcn!
end
end
function changedValue(hObject,~)
newval = uint16(str2double(get(hObject,'String')));
changed = (startval ~= newval);
end
function dispval(~,~)
disp('With buttons inside the GUI, it works properly:');
disp(get(handles.textfield,'String'));
disp(changed);
end
end
Will forcing a GUI focus change with uicontrol in your closing function provide the correct behavior? From the documentation:
uicontrol(uich) gives focus to the uicontrol specified by the handle,
uich
For the 'bonus' you're likely going to have to leverage the underlying Java. See the article on editbox data input validation from Undocumented Matlab.
I have a dataPointGrid and I want to check if a record from it is being selected (mouse clicked on)
Data point grid above. I want to check if a folder (record) is being selected.
Is there a method that does this?
Add ListGrid#addSelectionChangedHandler() on list grid that is called when (row-based) selection changes within this grid. Note this method fires for each record for which selection is modified - so when a user clicks inside a grid this method will typically fire twice (once for the old record being deselected, and once for the new record being selected).
Look at the ListGrid#setSelectionType() as well that defines a listGrid's clickable-selection behavior (MULTIPLE, SINGLE, SIMPLE or NONE)