Summary: Jetpack Compose’s low-level graphics API leverages Skia for drawing primitives, paths, and shapes via Canvas and drawing modifiers, while Layout and Modifier.layout enable custom arrangement of UI elements (turn0search6) (developer.android.com). Graphics layers (Modifier.graphicsLayer) provide hardware-accelerated transforms, clipping, and RenderEffect support for blur and color filters (turn0search2, turn0search18) (developer.android.com, developer.android.com). Brush APIs like LinearGradient and RadialGradient enable gradients and custom shaders for rich visuals (turn0search4) (developer.android.com). Performance features such as drawWithCache, drawBehind, and drawIntoCanvas enable caching of expensive drawings and minimization of overdraw, while modern GPUs handle deferred rendering to reduce wasted work (turn0search0, turn0search5) (developer.android.com, developer.android.com). Libraries like ComposeCharts and community shaders demonstrate animated charts and custom effects in Compose (turn0search10, turn0search21) (github.com, medium.com).

Canvas API Implementation

The Canvas composable enables direct shape drawing:

Canvas(modifier = Modifier.fillMaxSize()) {
    drawCircle(Color.Red, radius = size.minDimension / 4, center = center)
    drawRect(
        color = Color.Green,
        topLeft = Offset(10f, 10f),
        size = Size(100f, 50f)
    )
    val path = Path().apply {
        moveTo(50f, 150f)
        arcTo(
            rect = Rect(Offset(0f, 100f), Size(100f, 100f)),
            startAngleDegrees = 0f,
            sweepAngleDegrees = 180f,
            forceMoveTo = false
        )
    }
    drawPath(path, brush = SolidColor(Color.Blue))
}

This approach provides full control over drawing primitives and paths in the UI (developer.android.com).

Custom Layout Implementation

Compose’s Layout composable enables manual measurement and placement of children:

@Composable
fun CustomRow(
    modifier: Modifier = Modifier,
    content: @Composable () -> Unit
) {
    Layout(
        content = content,
        modifier = modifier
    ) { measurables, constraints ->
        val placeables = measurables.map { it.measure(constraints) }
        val width = placeables.sumOf { it.width }
        val height = placeables.maxOfOrNull { it.height } ?: 0
        layout(width, height) {
            var xPosition = 0
            placeables.forEach { placeable ->
                placeable.placeRelative(x = xPosition, y = 0)
                xPosition += placeable.width
            }
        }
    }
}

MeasurePolicy overrides enable precise layout control when needed (developer.android.com, developer.android.com).

Graphics Layers & Effects Implementation

Modifier.graphicsLayer enables transforms and clipping without affecting layout:

Box(
    modifier = Modifier
        .size(120.dp)
        .graphicsLayer(
            rotationZ = 45f,
            scaleX = 1.2f,
            clip = true,
            renderEffect = RenderEffect.createBlurEffect(
                8f, 8f, Shader.TileMode.CLAMP
            )
        )
) {
    Text("Blurred Box")
}

Gradient brushes are applied through:

Canvas(modifier = Modifier.fillMaxSize()) {
    drawCircle(
        brush = Brush.radialGradient(
            colors = listOf(Color.Yellow, Color.Transparent),
            center = center,
            radius = size.minDimension
        ),
        radius = size.minDimension,
        center = center
    )
}

These APIs enable efficient layering of visual effects (developer.android.com, developer.android.com).

Performance Optimization Implementation

drawWithCache minimizes overdraw by caching computed paths and paints:

Box(
    modifier = Modifier
        .size(100.dp)
        .drawWithCache {
            val path = Path().apply { /* expensive path */ }
            onDrawWithContent {
                drawContent()
                drawPath(path, color = Color.Magenta)
            }
        }
)

drawIntoCanvas renders precomputed ImageBitmaps, avoiding repeated layout calculations within tight draw loops (developer.android.com, developer.android.com). Skia Perf and Layout Inspector profiling reveals expensive draw calls and overdraw hotspots, guiding optimization efforts (turn0search23) (medium.com).

Implementation Examples

  • ComposeCharts: Animated, flexible charts in Compose, pie, line, bar, donut, demonstrating custom drawing and animation (github.com).
  • dautovicharis Charts: Community chart library with M3 theme support and robust animations (turn0search3) (reddit.com).
  • Learning to Paint in Compose: Custom shaders and GraphicsLayer.renderEffect examples for advanced FFI rendering (turn0search21) (medium.com).
  • Yin & Yang Tutorial: Step-by-step guide drawing complex shapes with Path and arcTo() in Compose (turn0search14) (medium.com).

Conclusion

Compose’s Canvas, Layout, graphics layers, and performance tools enable creation of unique, high-performance UIs, from custom charts to shader-driven effects, extending Android design beyond standard components.