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  1. 78
      tutorials/Image_And_Icons_Manipulations/README.md

78
tutorials/Image_And_Icons_Manipulations/README.md

@ -19,7 +19,7 @@ import androidx.compose.ui.window.singleWindowApplication
fun main() = singleWindowApplication {
Image(
painter = painterResource("sample.png"), // ImageBitmap
painter = painterResource("sample.png"),
contentDescription = "Sample",
modifier = Modifier.fillMaxSize()
)
@ -135,70 +135,68 @@ fun loadXmlImageVector(file: File, density: Density): ImageVector =
[XML vector drawable](../../artwork/compose-logo.xml)
## Drawing raw image data using native canvas
You may want to draw raw image data, in which case you can use `Canvas` and` drawIntoCanvas`.
## Drawing images using Canvas
```kotlin
import androidx.compose.foundation.Canvas
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.graphics.ImageBitmap
import androidx.compose.ui.geometry.Size
import androidx.compose.ui.graphics.Paint
import androidx.compose.ui.graphics.asImageBitmap
import androidx.compose.ui.graphics.drawscope.drawIntoCanvas
import androidx.compose.ui.graphics.vector.rememberVectorPainter
import androidx.compose.ui.graphics.withSave
import androidx.compose.ui.platform.LocalDensity
import androidx.compose.ui.res.loadImageBitmap
import androidx.compose.ui.res.loadSvgPainter
import androidx.compose.ui.res.loadXmlImageVector
import androidx.compose.ui.res.useResource
import androidx.compose.ui.unit.dp
import androidx.compose.ui.window.WindowState
import androidx.compose.ui.window.singleWindowApplication
import org.jetbrains.skija.Bitmap
import org.jetbrains.skija.ColorAlphaType
import org.jetbrains.skija.ImageInfo
import org.xml.sax.InputSource
private val sample = useResource("sample.png", ::loadImageBitmap)
fun main() = singleWindowApplication(state = WindowState(width = 1024.dp, height = 768.dp)) {
val density = LocalDensity.current // to calculate the intrinsic size of vector images (SVG, XML)
val sample = remember {
useResource("sample.png", ::loadImageBitmap)
}
val ideaLogo = remember {
useResource("idea-logo.svg") { loadSvgPainter(it, density) }
}
val composeLogo = rememberVectorPainter(
remember {
useResource("compose-logo.xml") { loadXmlImageVector(InputSource(it), density) }
}
)
fun main() = singleWindowApplication {
val bitmap = remember { bitmapFromByteArray(sample.getBytes(), sample.width, sample.height) }
Canvas(
modifier = Modifier.fillMaxSize()
) {
drawIntoCanvas { canvas ->
canvas.drawImage(bitmap, Offset.Zero, Paint())
canvas.withSave {
canvas.drawImage(sample, Offset.Zero, Paint())
canvas.translate(sample.width.toFloat(), 0f)
with(ideaLogo) {
draw(ideaLogo.intrinsicSize)
}
canvas.translate(ideaLogo.intrinsicSize.width, 0f)
with(composeLogo) {
draw(Size(100f, 100f))
}
}
fun bitmapFromByteArray(pixels: ByteArray, width: Int, height: Int): ImageBitmap {
val bitmap = Bitmap()
bitmap.allocPixels(ImageInfo.makeS32(width, height, ColorAlphaType.PREMUL))
bitmap.installPixels(bitmap.imageInfo, pixels, (width * 4).toLong())
return bitmap.asImageBitmap()
}
// creating byte array from BufferedImage
private fun ImageBitmap.getBytes(): ByteArray {
val buffer = IntArray(width * height)
readPixels(buffer)
val pixels = ByteArray(width * height * 4)
var index = 0
for (y in 0 until height) {
for (x in 0 until width) {
val pixel = buffer[y * width + x]
pixels[index++] = ((pixel and 0xFF)).toByte() // Blue component
pixels[index++] = (((pixel shr 8) and 0xFF)).toByte() // Green component
pixels[index++] = (((pixel shr 16) and 0xFF)).toByte() // Red component
pixels[index++] = (((pixel shr 24) and 0xFF)).toByte() // Alpha component
}
}
return pixels
}
```
<img alt="Drawing raw images" src="draw_image_into_canvas.png" height="496" />
[PNG](sample.png)
[SVG](../../artwork/idea-logo.svg)
[XML vector drawable](../../artwork/compose-logo.xml)
## Setting the application window icon

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