CurvedText.kt
/*
* Copyright 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.wear.compose.material
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.takeOrElse
import androidx.compose.ui.text.TextStyle
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.TextUnit
import androidx.compose.ui.unit.dp
import androidx.wear.compose.foundation.ArcPaddingValues
import androidx.wear.compose.foundation.BasicCurvedText
import androidx.wear.compose.foundation.CurvedTextStyle
import androidx.wear.compose.foundation.CurvedRowScope
/**
* CurvedText is a component allowing developers to easily write curved text following
* the curvature a circle (usually at the edge of a circular screen).
* CurvedText can be only created within the CurvedRow to ensure the best experience, like being
* able to specify to positioning.
*
* The default [style] uses the [LocalTextStyle] provided by the [MaterialTheme] / components,
* converting it to a [CurvedTextStyle]. Note that not all parameters are used by [CurvedText].
*
* If you are setting your own style, you may want to consider first retrieving [LocalTextStyle],
* and using [TextStyle.copy] to keep any theme defined attributes, only modifying the specific
* attributes you want to override, then convert to [CurvedTextStyle]
*
* For ease of use, commonly used parameters from [CurvedTextStyle] are also present here. The
* order of precedence is as follows:
* - If a parameter is explicitly set here (i.e, it is _not_ `null` or [TextUnit.Unspecified]),
* then this parameter will always be used.
* - If a parameter is _not_ set, (`null` or [TextUnit.Unspecified]), then the corresponding value
* from [style] will be used instead.
*
* Additionally, for [color], if [color] is not set, and [style] does not have a color, then
* [LocalContentColor] will be used with an alpha of [LocalContentAlpha]- this allows this
* [CurvedText] or element containing this [CurvedText] to adapt to different background colors and
* still maintain contrast and accessibility.
*
* @sample androidx.wear.compose.material.samples.CurvedTextDemo
*
* For more information, see the
* [Curved Text](https://developer.android.com/training/wearables/components/curved-text)
* guide.
*
* @param text The text to display
* @param color [Color] to apply to the text. If [Color.Unspecified], and [style] has no color set,
* this will be [LocalContentColor].
* @param fontSize The size of glyphs to use when painting the text. See [TextStyle.fontSize].
* @param style Specified the style to use.
* @param background The background color for the text.
* @param clockwise The direction the text follows (default is true). Usually text at the top of the
* screen goes clockwise, and text at the bottom goes counterclockwise.
* @param contentArcPadding Allows to specify additional space along each "edge" of the content in
* [Dp] see [ArcPaddingValues]
*/
@Composable
fun CurvedRowScope.CurvedText(
text: String,
modifier: Modifier = Modifier,
color: Color = Color.Unspecified,
background: Color = Color.Unspecified,
fontSize: TextUnit = TextUnit.Unspecified,
style: CurvedTextStyle = CurvedTextStyle(LocalTextStyle.current),
clockwise: Boolean = true,
contentArcPadding: ArcPaddingValues = ArcPaddingValues(0.dp),
) {
val textColor = color.takeOrElse {
style.color.takeOrElse {
LocalContentColor.current.copy(alpha = LocalContentAlpha.current)
}
}
val mergedStyle = style.merge(
CurvedTextStyle(
color = textColor,
fontSize = fontSize,
background = background
)
)
BasicCurvedText(
text = text,
style = mergedStyle,
modifier = modifier,
clockwise = clockwise,
contentArcPadding = contentArcPadding
)
}