CanvasDrawTextCompose.kt

/**
 * - Requires two frames
 * - Need to hide BasicText from view
 * - Unnecessary extra composition, way too hacky
 * - Can do everything that a BasicText can do
 * - Constraints must be applied to BasicText
 */
@Composable
fun UsingBasicText() {
    Box(Modifier.fillMaxSize()) {
        var textLayoutResult by remember { mutableStateOf<TextLayoutResult?>(null) }
        BasicText(
            text = "Here is a text",
            style = TextStyle(Color.Red),
            modifier = Modifier.alpha(0f),
            onTextLayout = { textLayoutResult = it }
        )
        Canvas(modifier = Modifier.matchParentSize()) {
            translate(100f, 100f) {
                textLayoutResult?.let {
                    drawIntoCanvas { canvas ->
                        TextPainter.paint(canvas, it)
                    }
                }
            }
        }
    }
}

/**
 * - Does not support clipping out of the box.
 * - FontFamilyResolver must be passed via reading Local
 * - Must call resolveDefaults on TextStyle to have predictable outcome
 */
@Composable
fun UsingMultiParagraph() {
    val fontFamilyResolver = LocalFontFamilyResolver.current
    Box(modifier = Modifier.fillMaxSize().drawWithCache {
        val multiParagraph = MultiParagraph(
            annotatedString = AnnotatedString("Here is a text"),
            style = resolveDefaults(TextStyle(Color.Red), layoutDirection),
            constraints = Constraints(
                maxWidth = size.width.toInt(),
                maxHeight = size.height.toInt()
            ),
            density = this,
            fontFamilyResolver = fontFamilyResolver
        )
        onDrawBehind {
            translate(100f, 100f) {
                drawIntoCanvas { canvas ->
                    multiParagraph.paint(canvas)
                }
            }
        }
    })
}

/**
 * - No support for multi-styling
 * - Single ParagraphStyle
 * - Does not support clipping out of the box.
 * - FontFamilyResolver must be passed via reading Local
 * - Must call resolveDefaults on TextStyle to have predictable outcome
 */
@Composable
fun UsingParagraph() {
    val fontFamilyResolver = LocalFontFamilyResolver.current
    Box(modifier = Modifier.fillMaxSize().drawWithCache {
        val paragraph = Paragraph(
            text = "Here is a text",
            style = resolveDefaults(TextStyle(Color.Red), layoutDirection),
            constraints = Constraints(
                maxWidth = size.width.toInt(),
                maxHeight = size.height.toInt()
            ),
            density = this,
            fontFamilyResolver = fontFamilyResolver
        )
        onDrawBehind {
            translate(100f, 100f) {
                drawIntoCanvas { canvas ->
                    paragraph.paint(canvas)
                }
            }
        }
    })
}

/**
 * - Does not support async fonts
 * - Platform dependent
 * - Requires converting Compose concepts into platform APIs
 * - Measurement only returns width
 * - No support for softwrap, line breaks must be calculated manually via breakText
 */
@Composable
fun UsingNative() {
    Box(modifier = Modifier.fillMaxSize().drawWithCache {
        val paint = TextPaint()
        paint.color = android.graphics.Color.RED
        paint.textSize = 14.sp.toPx()
        val text = "Here is a text"
        onDrawBehind {
            drawIntoCanvas { canvas ->
                canvas.nativeCanvas.drawText(text, 100f, 100f, paint)
            }
        }
    })
}