Android Jetpack合成中的图像梯度
以下是我的组件：Android Jetpack合成中的图像梯度,android,gradient,android-jetpack-compose,Android,Gradient,Android Jetpack Compose,以下是我的组件： @Composable fun Cover( name: String, imageRes: Int, modifier: Modifier = Modifier.padding(16.dp, 8.dp) ) { Box(modifier) { Card( shape = RoundedCornerShape(4.dp), backgroundColor = MaterialThem
@Composable
fun Cover(
name: String,
imageRes: Int,
modifier: Modifier = Modifier.padding(16.dp, 8.dp)
) {
Box(modifier) {
Card(
shape = RoundedCornerShape(4.dp),
backgroundColor = MaterialTheme.colors.secondary,
elevation = 4.dp
) {
Stack {
Image(
imageResource(imageRes),
modifier = Modifier
.gravity(Alignment.Center)
.aspectRatio(2f),
contentScale = ContentScale.Crop,
)
Text(
text = name,
modifier = Modifier
.gravity(Alignment.BottomStart)
.padding(8.dp),
style = MaterialTheme.typography.h6
)
}
}
}
}
编辑：这是我正在尝试做的，但是用Jetpack撰写。哇，那一次花了几个小时 可以将Modifier.background与垂直渐变一起使用。我使用了一列来保存修改器，并进行了计算以获得图像大小，但您的解决方案可能不同，您可以以不同的方式计算或存储大小，然后将修改器放在其他地方。我在代码中留下了两个TODO，因此可以调整渐变
@Composable
fun Cover(
name: String,
imageRes: Int,
modifier: Modifier = Modifier.padding(16.dp, 8.dp)
) {
val density = DensityAmbient.current.density
val width = remember { mutableStateOf(0f) }
val height = remember { mutableStateOf(0f) }
Box(modifier) {
Card(
shape = RoundedCornerShape(4.dp),
backgroundColor = MaterialTheme.colors.secondary,
elevation = 4.dp
) {
Stack {
Image(
imageResource(imageRes),
modifier = Modifier
.gravity(Alignment.Center)
.aspectRatio(2f)
.onPositioned {
width.value = it.size.width / density
height.value = it.size.height / density
},
contentScale = ContentScale.Crop,
)
Column(
Modifier.size(width.value.dp, height.value.dp)
.background(
VerticalGradient(
listOf(Color.Transparent, Color.Black),
0f, // TODO: set start
500f, // TODO: set end
)
)
) {}
Text(
text = name,
modifier = Modifier.gravity(Alignment.BottomStart)
.padding(8.dp),
style = typography.h6,
)
}
}
}
}
哇，那一次花了几个小时 可以将Modifier.background与垂直渐变一起使用。我使用了一列来保存修改器，并进行了计算以获得图像大小，但您的解决方案可能不同，您可以以不同的方式计算或存储大小，然后将修改器放在其他地方。我在代码中留下了两个TODO，因此可以调整渐变
@Composable
fun Cover(
name: String,
imageRes: Int,
modifier: Modifier = Modifier.padding(16.dp, 8.dp)
) {
val density = DensityAmbient.current.density
val width = remember { mutableStateOf(0f) }
val height = remember { mutableStateOf(0f) }
Box(modifier) {
Card(
shape = RoundedCornerShape(4.dp),
backgroundColor = MaterialTheme.colors.secondary,
elevation = 4.dp
) {
Stack {
Image(
imageResource(imageRes),
modifier = Modifier
.gravity(Alignment.Center)
.aspectRatio(2f)
.onPositioned {
width.value = it.size.width / density
height.value = it.size.height / density
},
contentScale = ContentScale.Crop,
)
Column(
Modifier.size(width.value.dp, height.value.dp)
.background(
VerticalGradient(
listOf(Color.Transparent, Color.Black),
0f, // TODO: set start
500f, // TODO: set end
)
)
) {}
Text(
text = name,
modifier = Modifier.gravity(Alignment.BottomStart)
.padding(8.dp),
style = typography.h6,
)
}
}
}
}
var sizeImage by remember { mutableStateOf(IntSize.Zero) }
val gradient = Brush.verticalGradient(
colors = listOf(Color.Transparent, Color.Black),
startY = sizeImage.height.toFloat()/3, // 1/3
endY = sizeImage.height.toFloat()
)
Box(){
Image(painter = painterResource(id = R.drawable.banner),
contentDescription = "",
modifier = Modifier.onGloballyPositioned {
sizeImage = it.size
})
Box(modifier = Modifier.matchParentSize().background(gradient))
}
Image(painter = painterResource(id = R.drawable.conero),
contentDescription = "",
modifier = Modifier.drawWithCache {
val gradient = Brush.verticalGradient(
colors = listOf(Color.Transparent, Color.Black),
startY = size.height/3,
endY = size.height
)
onDrawWithContent {
drawContent()
drawRect(gradient,blendMode = BlendMode.Multiply)
}
}
)
var sizeImage by remember { mutableStateOf(IntSize.Zero) }
val gradient = Brush.verticalGradient(
colors = listOf(Color.Transparent, Color.Black),
startY = sizeImage.height.toFloat()/3, // 1/3
endY = sizeImage.height.toFloat()
)
Box(){
Image(painter = painterResource(id = R.drawable.banner),
contentDescription = "",
modifier = Modifier.onGloballyPositioned {
sizeImage = it.size
})
Box(modifier = Modifier.matchParentSize().background(gradient))
}
Image(painter = painterResource(id = R.drawable.conero),
contentDescription = "",
modifier = Modifier.drawWithCache {
val gradient = Brush.verticalGradient(
colors = listOf(Color.Transparent, Color.Black),
startY = size.height/3,
endY = size.height
)
onDrawWithContent {
drawContent()
drawRect(gradient,blendMode = BlendMode.Multiply)
}
}
)
Card(shape = RoundedCornerShape(8.dp)) {
Box {
Image(...)
Text(
text = "title",
modifier = Modifier
.align(Alignment.BottomCenter)
.fillMaxWidth()
.background(Brush.verticalGradient(0F to Color.Transparent, .5F to Color.Red, 1F to Color.Red))
.padding(start = 8.dp, end = 8.dp, bottom = 8.dp, top = 16.dp),
color = Color.White,
style = MaterialTheme.typography.body1,
textAlign = TextAlign.Start
)
}
}
Card(shape = RoundedCornerShape(8.dp)) {
Box {
Image(...)
Text(
text = "title",
modifier = Modifier
.align(Alignment.BottomCenter)
.fillMaxWidth()
.background(Brush.verticalGradient(0F to Color.Transparent, .5F to Color.Red, 1F to Color.Red))
.padding(start = 8.dp, end = 8.dp, bottom = 8.dp, top = 16.dp),
color = Color.White,
style = MaterialTheme.typography.body1,
textAlign = TextAlign.Start
)
}
}
使用Modifier.DruckGround传递LinearGradient或RadialGradient@MohammadSianaki该函数现在称为just Modifier.background使用Modifier.trackground传递LinearGradient或RadialGradient@MohammadSianaki该函数现在称为just Modifier.background看起来很棒！但是为什么要用500f呢？我试了几个值，注意到不同的情况会有所不同，所以我只留下了500，在样本中看起来不错。我相信数字和颜色都会根据图像的大小和种类而变化，看起来很棒！但是为什么要用500f呢？我试了几个值，注意到不同的情况会有所不同，所以我只留下了500，在样本中看起来不错。我相信数字值和颜色都会根据图像的大小和类型而变化，但实际效果并不理想。这只会使图像更暗。也许我也做错了什么，我不明白startX，startY，endX，endY参数期望什么。为什么endY有size.width？“它不应该是尺寸。高度吗？”阿沙尔7回答正确。它应该是size.height我的错，尝试了一个正方形的代码。startX、startY、endX、endY是渐变的坐标。在上面的代码中，它们是通过size=this.size构建的。您也可以使用不同的BlendMode，但实际效果并不理想。这只会使图像更暗。也许我也做错了什么，我不明白startX，startY，endX，endY参数期望什么。为什么endY有size.width？“它不应该是尺寸。高度吗？”阿沙尔7回答正确。它应该是size.height我的错，尝试了一个正方形的代码。startX、startY、endX、endY是渐变的坐标。在上面的代码中，它们是通过size=this.size构建的。也可以使用不同的blendMode