Canvas

Functions summary

Unit
@Composable
Canvas(modifier: Modifier, onDraw: DrawScope.() -> Unit)

Component that allow you to specify an area on the screen and perform canvas drawing on this area.
Cmn
Unit
@Composable
Canvas(modifier: Modifier, contentDescription: String, onDraw: DrawScope.() -> Unit)

Component that allow you to specify an area on the screen and perform canvas drawing on this area.
Cmn

Functions

Canvas

Cmn 
@Composable
fun Canvas(modifier: Modifier, onDraw: DrawScope.() -> Unit): Unit

Component that allow you to specify an area on the screen and perform canvas drawing on this area. You MUST specify size with modifier, whether with exact sizes via androidx.compose.foundation.layout.size modifier, or relative to parent, via androidx.compose.foundation.layout.fillMaxSize, ColumnScope.weight, etc. If parent wraps this child, only exact sizes must be specified.

import androidx.compose.foundation.Canvas
import androidx.compose.foundation.layout.size
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.drawscope.inset
import androidx.compose.ui.unit.dp

Canvas(modifier = Modifier.size(100.dp)) {
    drawRect(Color.Magenta)
    inset(10.0f) {
        drawLine(
            color = Color.Red,
            start = Offset.Zero,
            end = Offset(size.width, size.height),
            strokeWidth = 5.0f,
        )
    }
}
Parameters
modifier: Modifier

mandatory modifier to specify size strategy for this composable
onDraw: DrawScope.() -> Unit

lambda that will be called to perform drawing. Note that this lambda will be called during draw stage, you have no access to composition scope, meaning that Composable function invocation inside it will result to runtime exception

Canvas

Cmn 
@Composable
fun Canvas(modifier: Modifier, contentDescription: String, onDraw: DrawScope.() -> Unit): Unit

Component that allow you to specify an area on the screen and perform canvas drawing on this area. You MUST specify size with modifier, whether with exact sizes via androidx.compose.foundation.layout.size modifier, or relative to parent, via androidx.compose.foundation.layout.fillMaxSize, ColumnScope.weight, etc. If parent wraps this child, only exact sizes must be specified.

import androidx.compose.foundation.Canvas
import androidx.compose.foundation.layout.size
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.geometry.Size
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.unit.dp

Canvas(
    contentDescription = "Pie chart: 80% apples, 20% bananas (localized string)",
    modifier = Modifier.size(300.dp),
) {
    // Apples (80%)
    drawCircle(color = Color.Red, radius = size.width / 2)

    // Bananas (20%)
    drawArc(
        color = Color.Yellow,
        startAngle = 0f,
        sweepAngle = 360f * 0.20f,
        useCenter = true,
        topLeft = Offset(0f, (size.height - size.width) / 2f),
        size = Size(size.width, size.width),
    )
}
Parameters
modifier: Modifier

mandatory modifier to specify size strategy for this composable
contentDescription: String

text used by accessibility services to describe what this canvas represents. This should be provided unless the canvas is used for decorative purposes or as part of a larger entity already described in some other way. This text should be localized, such as by using androidx.compose.ui.res.stringResource
onDraw: DrawScope.() -> Unit

lambda that will be called to perform drawing. Note that this lambda will be called during draw stage, you have no access to composition scope, meaning that Composable function invocation inside it will result to runtime exception