UiApplication

Remarks

The four steps are worth naming, because they are the whole loop: pump the platform's events into the document, run the layout and draw passes, turn the draw list into geometry, and record that geometry into a frame. Only the last of the four knows what a GPU is — which is why Frames means something on a machine with no Vulkan at all.

⚠ This existed three times before it existed once. Samples/02-HelloUi, Tools/Vixen.Templates' AppHost and Vixen.Editor.Host's EditorHost each carried it, and the copies had already diverged in ways nothing failed on: the sample never called Compose, so every translucent subtree in it drew at full strength; two of the three could not open a second window; and one of the three cached its tessellation while the others rebuilt every path in the draw list sixty times a second for a window where nothing had moved. What is here is the union of the correct halves.

⚠ No Vixen.Engine and no Vixen.App, and the absence is the reason this assembly exists. That host owns a frame loop built around an ECS world and a fixed-step accumulator; an interface's loop redraws a document. An application that wanted a window used to choose between writing this file and dragging a scene graph behind it.

⚠ It draws every frame rather than when something changes. Redrawing only on input is the right end state for a desktop application and it is not free: every animation, every timer and every background task's progress has to say that it moved, and one that forgets leaves a progress bar frozen at forty per cent. Said out loud here rather than left to be discovered on a laptop battery. The tessellation is skipped for a window whose drawing did not change — see Tessellate — which is most of the cost of a still frame.

Fields and properties (8)

• public const string ContentClass

  The class the mounted content's host element carries.

• public Component? Content

  The component the interface was built from, once it has been.

• public UiDocument Document

  The document the loop lays out, draws and dispatches into.

• public DiagnosticsPanel? Diagnostics

  A debug panel this loop refreshes at the right moment, if the application made one.

• public IWindow Window

  The window the application was opened on.

• public IPlatform Platform

  Everything the operating system does for this application.

• public int FrameCount

  How many frames have been drawn.

• public BackgroundTaskManager Tasks

  The long operations this application is running, and what they have got to.

Events (3)

• public Action<UiApplication>? Started

  Raised once, after the interface is built and before the first frame is pumped.

• public Action<UiApplication, UiFrame>? Frame

  Raised once a frame, after the events are pumped and before the document is updated.

• public Action<UiApplication>? Stopping

  Raised once, after the loop stops and while the document is still alive.

Methods (5)

• public static int Run(UiApplicationOptions options)

  Opens a window, runs the interface in it, and returns a process exit code.

• public static int Run(UiApplicationOptions options, params ReadOnlySpan<string> arguments)

  The same, having first read the arguments every Vixen application understands.

• public void Stop()

  Asks the loop to stop at the end of this frame.

• public bool Quit(UiCloseReason reason = Quit)

  Asks whether the application may close, and stops the loop if nothing refuses.

• public void Dispose()

  Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.

Used by (11)

• ProgramHelloUi
• ColorSchemeWiringTestsVixen.Ui.Desktop.Tests
• DesktopHotReloadVixen.Ui.Desktop.HotReload
• HotReloadSeamTestsVixen.Ui.Desktop.Tests
• PipelineCachePathTestsVixen.Ui.Desktop.Tests
• PlatformReachTestsVixen.Ui.Desktop.Tests
• QuitRequestTestsVixen.Ui.Desktop.Tests
• TextInputWiringTestsVixen.Ui.Desktop.Tests
• UiApplicationOptionsVixen.Ui.Desktop
• UiApplicationTestsVixen.Ui.Desktop.Tests
• UiDevelopmentVixen.Ui.Desktop