SlateIM

About

SlateIM widgets/windows are meant to be constructed from commands. But you can also use SlateIM to build a SWidget and get it (see How it works section)

Commands

• SlateIM.ToggleSlateStyleBrowser: A window showing the engine existing brushes, rich text, button styles, etc
• SlateIM.ToggleTestSuiteWindow: A ton of examples in a single window
• SlateIM.ToggleTestSuiteViewport: Same as above but the widget is “linked” to the viewport

Examples

See the Commands section and FSlateIMTestWindowWidget with FSlateIMTestWidget.

How it works

Arrows points to parent

flowchart TD


    FSlateIMWidgetWithCommandBase --> FSlateIMWidgetBase
    FSlateIMWindowBase --> FSlateIMWidgetWithCommandBase
    FSlateIMExposedBase --> FSlateIMWidgetBase

From this hierarchy we can understand the following:

• If you want a standalone window (which holds a widget) that is created from a command, use FSlateIMWindowBase or directly subclass FSlateIMWidgetWithCommandBase.
• If you want to use the SlateIM API and get the generated SWidget to use it elsewhere, use FSlateIMExposedBase.

For FSlateIMWidgetBase, the widget is constructed from the command that runs FSlateIMWidgetWithCommandBase::ToggleWidget. This will execute FSlateIMWidgetBase::DrawWidget on Slate PreTick until the window is disabled. If conditions are met FSlateIMWindowBase::DrawWindow runs (which needs to be overridden, for example FSlateIMTestWindowWidget does it).

But for FSlateIMExposedBase, its different. FSlateIMExposedBase::DrawContent is the functions that has to be overridden to build the widget.

How to use FSlateIMExposedBase to embed it in other widgets?

This might not be the case since 5.7 and above

Without editing the plugin: Since after enabling the widget it needs at least 1 Slate PreTick to hold a valid SWidget, you have to enable the widget BEFORE you use GetExposedWidget. To avoid unnecessary calls, you also have to manually handle its active/inactive state depending on if the widget is displayed or not (since DrawContent is called regardless of its visibility).

If you can edit the plugin: In SlateIMWidgetBase.h, remove the private for DrawWidget. Then you can simply call EnableWidget and DrawWidget(FApp::GetDeltaTime()) on your FSlateIMExposedBase when you need to initialize one and directly access its internal widget (for example I do this for editor utilities which are in engine-managed tab managers).

Troubleshoot

Text not filling space after resizing ? Use SlateIM::HAlign(HAlign_Fill);