Screens

Cobalt renders its own UI screens using Skia for hardware-accelerated 2D rendering, rather than Minecraft’s native draw calls.

UIScreen

The base class for custom Cobalt screens. It extends Minecraft’s Screen but redirects rendering through Skia.


class MyScreen : UIScreen() {
 
    init {
        components.add(MyComponent)
    }
 
    override fun renderSkia() {
        SkiaRenderer.rect(0f, 0f, 100f, 100f, theme.backgroundPrimary)
        components.forEach { it.renderComponent() }
    }
}

Open it with:


minecraft.gui.setScreen(MyScreen)

UIComponent

The base class for all UI elements. Components can be nested, and events bubble up from children to parents.


class MyComponent : UIComponent(
    xPos = 10f, yPos = 10f,
    width = 200f, height = 50f
) {
    override fun renderComponent() {
        SkiaRenderer.roundedRect(xPos, yPos, width, height, 5f, theme.backgroundPrimary)
    }
 
    override fun mouseClicked(button: Int): Boolean {
        if (Mouse.isHoveringOver(xPos, yPos, width, height)) {
            // clicked!
            return true
        }
        return false
    }
}

Available overrides


renderComponent()                                 // draw
mouseClicked(button: Int): Boolean                // click
mouseReleased(button: Int): Boolean               // release
mouseDragged(button: Int, dx: Double, dy: Double): Boolean  // drag
mouseScrolled(hAmount: Double, vAmount: Double): Boolean    // scroll
charTyped(input: CharacterEvent): Boolean         // text input
keyPressed(input: KeyEvent): Boolean              // key press
keyReleased(input: KeyEvent): Boolean             // key release

Component helpers


component.updateBounds(x, y)  // reposition, returns self for chaining
component.addChild(child)     // add as a child
component.removeAllChildren() // clear children
theme                         // access active theme

Animations

Components can use animations for smooth transitions:


class SlideComponent : UIComponent(width = 200f, height = 50f) {
 
    private val slideAnim = EaseOutAnimation(200L)
 
    override fun renderComponent() {
        val offset = slideAnim.get(-30f, 0f)
        SkiaRenderer.rect(xPos + offset, yPos, width, height, theme.accentPrimary)
    }
}

Animation	Type	Behavior
`EaseOutAnimation(ms)`	Float	Smooth quadratic ease-out
`BounceAnimation(ms)`	Float	Overshoots then settles
`ColorAnimation(ms)`	Color/Int	Interpolates between two colors

Animation API


anim.start()                    // start the animation
anim.get(start, end, reverse)   // get current value (true = play backwards)
anim.isAnimating()              // check if running

Notifications

Cobalt has a built-in notification system that shows animated toasts:


NotificationManager.queue(
    title = "Fishing Complete",
    description = "Caught 5 fish",
    duration = Duration.seconds(3)
)
 
NotificationManager.clear()  // dismiss all

Notifications stack from the bottom-right, up to 3 visible. They include:

Title and description (word-wrapped)
Sliding animation
Progress bar for the duration

Built-in screens

Screen	How to open
`ConfigScreen`	`.cobalt` command or `O` key
`HudEditorScreen`	`.cobalt hud` command

Both save module config on close.