Android 如何在 Jetpack Compose 中将文本绘制在另一个对象的中心

您可以获取TextLayoutResult，它返回包含文本的矩形的大小.安迪，通过将宽度的一半向左偏移，高度的一半向上偏移，可以使文本在画布内居中.

val textMeasurer = rememberTextMeasurer()

val textToDraw = "A"

val style = TextStyle(
    fontSize = 150.sp,
    color = Color.Black,
    background = Color.Red.copy(alpha = 0.2f)
)
// Keys are to demonstrate that you can re-calculate block inside
// when any of them change. Otherwise remember results on each recomposition
val textLayoutResult = remember(textToDraw, style) {
    textMeasurer.measure(textToDraw, style)
}

完整样品

@Preview
@Composable
private fun DrawTextAtCenterSample() {
    Box(
        modifier = Modifier
            .fillMaxSize()
            .background(Color.Green.copy(alpha = 0.2f))
            .padding(36.dp),
        contentAlignment = Alignment.Center
    ) {
        val textMeasurer = rememberTextMeasurer()

        val textToDraw = "A"

        val style = TextStyle(
            fontSize = 150.sp,
            color = Color.Black,
            background = Color.Red.copy(alpha = 0.2f)
        )

        val textLayoutResult = remember(textToDraw) {
            textMeasurer.measure(textToDraw, style)
        }

        Canvas(modifier = Modifier.fillMaxSize()) {
            drawCircle(
                center = Offset(
                    x = center.x,
                    y = center.y
                ),
                radius = 350f,
                color = Color.Blue,
                style = Stroke(
                    width = 8f
                )
            )


            drawText(
                textMeasurer = textMeasurer,
                text = textToDraw,
                style = style,
                topLeft = Offset(
                    x = center.x - textLayoutResult.size.width / 2,
                    y = center.y - textLayoutResult.size.height / 2,
                )
            )
            drawPoints(
                points = listOf(Offset(center.x, center.y)),
                pointMode = PointMode.Points,
                cap = StrokeCap.Round,
                color = Color.Red,
                strokeWidth = 25f
            )
        }
    }
}