magnifier

fun Modifier.magnifier(
    sourceCenter: Density.() -> Offset,
    magnifierCenter: (Density.() -> Offset)? = null,
    onSizeChanged: ((DpSize) -> Unit)? = null,
    zoom: Float = Float.NaN,
    size: DpSize = DpSize.Unspecified,
    cornerRadius: Dp = Dp.Unspecified,
    elevation: Dp = Dp.Unspecified,
    clip: Boolean = true
): Modifier

import androidx.compose.foundation.gestures.detectDragGestures
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.magnifier
import androidx.compose.material3.Text
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.drawBehind
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.drawscope.Stroke
import androidx.compose.ui.input.pointer.pointerInput

// When the magnifier center position is Unspecified, it is hidden.
// Hide the magnifier until a drag starts.
var magnifierCenter by remember { mutableStateOf(Offset.Unspecified) }

if (Build.VERSION.SDK_INT < 28) {
    Text("Magnifier is not supported on this platform.")
} else {
    Box(
        Modifier.magnifier(sourceCenter = { magnifierCenter }, zoom = 2f)
            .pointerInput(Unit) {
                detectDragGestures(
                    // Show the magnifier at the original pointer position.
                    onDragStart = { magnifierCenter = it },
                    // Make the magnifier follow the finger while dragging.
                    onDrag = { _, delta -> magnifierCenter += delta },
                    // Hide the magnifier when the finger lifts.
                    onDragEnd = { magnifierCenter = Offset.Unspecified },
                    onDragCancel = { magnifierCenter = Offset.Unspecified },
                )
            }
            .drawBehind {
                // Some concentric circles to zoom in on.
                for (diameter in 2 until size.maxDimension.toInt() step 10) {
                    drawCircle(color = Color.Black, radius = diameter / 2f, style = Stroke())
                }
            }
    )
}