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?
Without editing the plugin: Since after enabling the widget it needs at least 1 Slate PreTick to hold a valid SWidget, you have to enabled 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);