FlowDocument - How to Implement KeepWithNext - wpf

I have a FlowDocument with multiple BlockUIContainers back to back with one another. These UIContainers each represent a different type of content coming from a different source, but are all related and I would like them to stay together on a page. To word it differently, I don't want them split between pages.
The Paragraph class has a property called KeepWithNext that will make sure that the paragraph that follows it always stays on the same page as the given paragraph.
I would like to add this functionality to the BlockUIContainer (or subclass BlockUIContainer to add it) but I don't know how the KeepWithNext property gets used for the Paragraph class.
I've tried using Reflector to get some insight, but as far as I can tell it's just a boolean property with no real usage inside of the Paragraph class. This leads me to believe that the paginator somehow knows what to do with the property.
Does anyone have a clue about how I should approach this? Where should I look to find out what I need to do to match the Paragraph functionality?

I'm not sure how the internal pagination works, but...
Instead of extending BlockUIContainer, it may be much easier to use the existing KeepWithNext property on Paragraph and convert your BlockUIContainers to InlineUIContainers inside Paragraphs.

Related

Protecting custom inline elements in WPF RichTextBox

I'm currently spiking with the WPF RichTextBox before I decide whether or not it can be used in a project of mine.
What I need is to have elements of text representing various objects (other texts or objects), a bit like a WIKI but not quite. Clicking on such a text will make stuff happen, like navigating to other texts or providing additional options.
Anyway, as these little text bits represent other objects I would like to protect them but I have succeeded with this only in part: The user cannot position a caret inside such a text element and edit/delete it but it is still possible to make a selection and delete/replace it, including my custom elements.
Have anyone travelled down this road with the RichTextBox? My latest experiment was to simply record all custom text elements when being part of a selection and then restoring them after the (destructive) edit. That fell apart because I can't find a way to re-insert my custom inline elements (derived from the Run class). The only way I've found to programmatically insert a Run (based) element at a specified position (TextPosition) is via its constructor.
Well, any hints would be greatly appreciated.
You are really looking for a FlowDocument, not a RichTextBox.

How does the ExtJS4 Column class work?

I wrote my own sub-class, for some selection stuff and paging etc. But those all worked with the renderer(), which required them to return a string.
This worked fine, I created some image-tags and returned those.
But how does this class work in detail?
I want a sub-class which displays a chart in a cell, which should technically be no problem, but the renderer() doesn't seem the right place for it, since it only works for strings.
Does the Class get instantiated for every row? or is it really just one instance for a column, which methods get called for every row with the needed data and the instances don't hold any state about the rows?
The renderer() mechanism is actually implemented in Ext.grid.column.Column, for which there is one per column.
As you have mentioned, the renderer() function returns a string, which could be an HTML string (which could be rather complex - have a look at the templates used by ExtJs for the standard columns). But you cannot return a component (chart).
To the best of my knowledge (based on my own understanding and replies to similar questions), ExtJs does not offer a straight-forward way to render components within grid cells. If you really think about it - you are asking a grid for much more than its intended role. It was designed to present records per raw, with the addition of simple user interaction facilities, like checkboxes.
But what you are really asking for is more of a way to layout charts, for which problem i suggest you look into the Table layout.
Alternatively you should be able to render a chart into a dom element, which will be defined in your own custom column template. But I will consider this to be an involved task.

Choosing an Appropriate ViewModel While Avoiding Large Conditional

I'm writing a WPF application while mostly adhering to the MVVM design pattern. The application has various educational modules broken up into different categories to be accomplished by the user. The modules are organized into a hierarchical menu. My ViewModel has a class called MenuPageViewModel which exposes the information needed to render a MenuNode. Naturally, the terminal elements in the menu tree have content that I'd like to display to the user. This content can be one of many different types of modules. Currently, when the user selects a module in the menu, I can't see any way around using a large conditional block to determine what type of ViewModel I'd like to return to be displayed based on the type of the MenuItem's Content Property. For example...
if (CurrentlySelectedMenuItem.Content is Lesson)
return new LessonViewModel(CurrentlySelectedMenuItem.Content as Lesson);
if (CurrentlySelectedMenuItem.Content is SkillsCheck)
return new SkillsCheckViewModel(CurrentlySelectedMenuItem.Content as SkillsCheck);
Can someone give me a hint to a more elegant and maintainable approach? Right now, if I add a new module type, I have to remember to update this conditional block, and that just sort of annoys me.
Thanks.
If you are using Unity/Prism then using the container to resolve the object would be my first preference.
_container.Resolve(Type.GetType(strObjectType)) as BaseViewModel;
where strObjectType is a string with the type of class you want to create (eg "LessionViewModel" )
if you are not using Unity, then reflection works
Activator.CreateInstance(strObjectType) as BaseViewModel;
with both solutions you need to have the string with the class type on your menuItem.
A third option is to have a factory, but it would probably end up having a conditional situation within it or will contain the code i just listed.

flowdocument pagination - forcing elements to appear on a new page

when i print a flow document, I want certain elements - paragraphs, tables - probably marked with some attached property to:
be transferred to a new page if they do not fit entirely on the previous one
or
always appear on a new page.
Has anybody done it already or has an idea how to do it?
Cheers
Seems like you are on the right track for the permanent page break.
The 'Paragraph' object has a property called 'KeepTogether' which would achieve your first bullet point. If the blocks within the 'Paragraph' do not all fit on one page, all of the blocks will be moved to the next page. There is also the similar property 'KeepWithNext' which allows provides the same behavior, but groups 'Paragaph' siblings together.

What's the purpose of Winforms controls tags?

I see a 'Tag' property in the design view for most WinForms controls. I have never used this tag and want to know why I would want to use it.
It allows you to store some of your own data with a control. It mostly useful in tree controls where you might want each node/leaf to have some extra data associated with it. This way when you click on a node you can perform an action relevant to the node.
Its a general "catch-all" for additional data you wish to store with a control.
I too have never used it.
We perform heavy use of tags. We have some methods for checking input, and these methods checks whats in the tags in order to know what control to perform.
IE: if a textbox has RQ=1;DT=int;MAX=100
the automatic method knows that this text can not be left blank, that should accept only integers within 0 and 100.
We have a complete pseudo declarative language for this.
Kind of useful!
More specific for your question, Tags are for your use.
for example you have a lot of buttons with single method handling clicks. then at handler you have do differentiate them from each other. So you put some sort of id (or reference) and then access it there.

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