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CustomPainterSnippets.kt
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CustomPainterSnippets.kt
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/*
* Copyright 2022 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
*
* https://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 com.example.compose.snippets.images
import androidx.compose.foundation.Image
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.wrapContentSize
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.paint
import androidx.compose.ui.geometry.Size
import androidx.compose.ui.graphics.BlendMode
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.ImageBitmap
import androidx.compose.ui.graphics.drawscope.DrawScope
import androidx.compose.ui.graphics.painter.Painter
import androidx.compose.ui.layout.ContentScale
import androidx.compose.ui.res.imageResource
import androidx.compose.ui.res.stringResource
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.IntOffset
import androidx.compose.ui.unit.IntSize
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.toSize
import com.example.compose.snippets.R
import kotlin.math.roundToInt
/*
* Copyright 2022 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.
*/
@Preview
@Composable
fun CustomPainterUsage() {
// [START android_compose_images_custom_painter_usage]
val rainbowImage = ImageBitmap.imageResource(id = R.drawable.rainbow)
val dogImage = ImageBitmap.imageResource(id = R.drawable.dog)
val customPainter = remember {
OverlayImagePainter(dogImage, rainbowImage)
}
Image(
painter = customPainter,
contentDescription = stringResource(id = R.string.dog_content_description),
contentScale = ContentScale.Crop,
modifier = Modifier.wrapContentSize()
)
// [END android_compose_images_custom_painter_usage]
}
// [START android_compose_images_custom_painter]
class OverlayImagePainter constructor(
private val image: ImageBitmap,
private val imageOverlay: ImageBitmap,
private val srcOffset: IntOffset = IntOffset.Zero,
private val srcSize: IntSize = IntSize(image.width, image.height),
private val overlaySize: IntSize = IntSize(imageOverlay.width, imageOverlay.height)
) : Painter() {
private val size: IntSize = validateSize(srcOffset, srcSize)
override fun DrawScope.onDraw() {
// draw the first image without any blend mode
drawImage(
image,
srcOffset,
srcSize,
dstSize = IntSize(
this@onDraw.size.width.roundToInt(),
this@onDraw.size.height.roundToInt()
)
)
// draw the second image with an Overlay blend mode to blend the two together
drawImage(
imageOverlay,
srcOffset,
overlaySize,
dstSize = IntSize(
this@onDraw.size.width.roundToInt(),
this@onDraw.size.height.roundToInt()
),
blendMode = BlendMode.Overlay
)
}
/**
* Return the dimension of the underlying [ImageBitmap] as it's intrinsic width and height
*/
override val intrinsicSize: Size get() = size.toSize()
private fun validateSize(srcOffset: IntOffset, srcSize: IntSize): IntSize {
require(
srcOffset.x >= 0 &&
srcOffset.y >= 0 &&
srcSize.width >= 0 &&
srcSize.height >= 0 &&
srcSize.width <= image.width &&
srcSize.height <= image.height
)
return srcSize
}
}
// [END android_compose_images_custom_painter]
@Preview
@Composable
fun CustomPainterModifier() {
// [START android_compose_custom_painter_modifier]
val rainbowImage = ImageBitmap.imageResource(id = R.drawable.rainbow)
val dogImage = ImageBitmap.imageResource(id = R.drawable.dog)
val customPainter = remember {
OverlayImagePainter(dogImage, rainbowImage)
}
Box(
modifier =
Modifier.background(color = Color.Gray)
.padding(30.dp)
.background(color = Color.Yellow)
.paint(customPainter)
) { /** intentionally empty **/ }
// [END android_compose_custom_painter_modifier]
}