Added ImageAndIcon usage tutorial

tutorials/Image_And_Icons_Manipulations/main.md

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+# Image and in-app icons manipulations
+
+## What is covered
+
+In this tutorial we will show you how to work with images using Compose for Desktop.
+
+## Loading images from resources
+
+Using images from application resources is very simple. Suppose we have a PNG image that is placed in the `resources/images` directory in our project. For this tutorial we will use the image sample:
+
+<img src="sample.png" alt="Sample" width="256"/>
+
+```kotlin
+import androidx.compose.desktop.Window
+import androidx.compose.foundation.Image
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.imageResource
+
+fun main() {
+    Window {
+        Image(
+            asset = imageResource("images/sample.png"), // ImageAsset
+            modifier = Modifier.fillMaxSize()
+        )
+    }
+}
+```
+
+![Resources](image_from_resources.png)
+
+## Loading images from device storage
+
+To create `ImageAsset` from a loaded image stored in device memory you can use skija `Image`:
+
+```kotlin
+import androidx.compose.desktop.Window
+import androidx.compose.foundation.Image
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.ui.graphics.asImageAsset
+import androidx.compose.ui.graphics.ImageAsset
+import androidx.compose.ui.Modifier
+import java.awt.image.BufferedImage
+import java.io.ByteArrayOutputStream
+import java.io.File
+import javax.imageio.ImageIO
+import org.jetbrains.skija.Image
+
+fun main() {
+    Window {
+        val image = pathAsImageAsset("sample.png")
+        Image(
+            asset = image,
+            modifier = Modifier.fillMaxSize()
+        )
+    }
+}
+
+fun pathAsImageAsset(path: String): ImageAsset {
+    var image: BufferedImage? = null
+    try {
+        image = ImageIO.read(File(path))
+    } catch (e: Exception) {
+        // image file does not exist
+    }
+
+    if (image == null) {
+        image = BufferedImage(1, 1, BufferedImage.TYPE_INT_RGB)
+    }
+
+    val baos = ByteArrayOutputStream()
+    ImageIO.write(image, "png", baos)
+    
+    return Image.makeFromEncoded(baos.toByteArray()).asImageAsset()
+}
+```
+
+![Storage](image_from_resources.png)
+
+## Drawing raw images
+
+Sometimes you may want to draw raw image data, in which case you can use `Canvas` and` drawIntoCanvas`.
+
+```kotlin
+import androidx.compose.desktop.Window
+import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.ui.graphics.drawscope.drawIntoCanvas
+import androidx.compose.ui.graphics.nativeCanvas
+import androidx.compose.ui.Modifier
+import java.awt.image.BufferedImage
+import java.io.ByteArrayOutputStream
+import java.io.File
+import javax.imageio.ImageIO
+import org.jetbrains.skija.ColorAlphaType
+import org.jetbrains.skija.Bitmap
+import org.jetbrains.skija.ImageInfo
+import org.jetbrains.skija.IRect
+
+fun main() {
+    Window {
+        val bitmap = bitmapFromByteArray()
+        Canvas(
+            modifier = Modifier.fillMaxSize()
+        ) {
+            drawIntoCanvas { canvas ->
+                canvas.nativeCanvas.drawBitmapRect(
+                    bitmap,
+                    IRect(0, 0, bitmap.getWidth(), bitmap.getHeight()).toRect()
+                )
+            }
+        }
+    }
+}
+
+fun bitmapFromByteArray(): Bitmap {
+    var image: BufferedImage? = null
+    try {
+        image = ImageIO.read(File("sample.png"))
+    } catch (e: Exception) {
+        // image file does not exist
+    }
+
+    if (image == null) {
+        image = BufferedImage(1, 1, BufferedImage.TYPE_INT_RGB)
+    }
+    val pixels = getBytes(image) // assume we only have raw pixels
+
+    // allocate and fill skija Bitmap
+    val bitmap = Bitmap()
+    bitmap.allocPixels(ImageInfo.makeS32(image.width, image.height, ColorAlphaType.PREMUL))
+    bitmap.installPixels(bitmap.getImageInfo(), pixels, (image.width * 4).toLong())
+
+    return bitmap
+}
+
+// creating byte array from BufferedImage
+private fun getBytes(image: BufferedImage): ByteArray {
+    val width = image.width
+    val height = image.height
+
+    val buffer = IntArray(width * height)
+    image.getRGB(0, 0, width, height, buffer, 0, width)
+
+    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
+}
+```
+
+![Drawing raw images](draw_image_into_canvas.png)
+
+## Setting the application window icon
+
+You have 2 ways to set icon for window:
+1. Via parameter in `Window` function (or in `AppWindow` constructor)
+
+```kotlin
+import androidx.compose.desktop.Window
+import androidx.compose.foundation.Image
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.ui.graphics.asImageAsset
+import androidx.compose.ui.graphics.ImageAsset
+import androidx.compose.ui.Modifier
+import java.awt.image.BufferedImage
+import java.io.ByteArrayOutputStream
+import java.io.File
+import javax.imageio.ImageIO
+import org.jetbrains.skija.Image
+
+fun main() {
+    val image = getWindowIcon()
+    Window(
+        icon = image
+    ) {
+        val imageAsset = asImageAsset(image)
+        Image(
+            asset = imageAsset,
+            modifier = Modifier.fillMaxSize()
+        )
+    }
+}
+
+fun getWindowIcon(): BufferedImage {
+    var image: BufferedImage? = null
+    try {
+        image = ImageIO.read(File("sample.png"))
+    } catch (e: Exception) {
+        // image file does not exist
+    }
+
+    if (image == null) {
+        image = BufferedImage(1, 1, BufferedImage.TYPE_INT_RGB)
+    }
+
+    return image
+}
+
+fun asImageAsset(image: BufferedImage): ImageAsset {
+    val baos = ByteArrayOutputStream()
+    ImageIO.write(image, "png", baos)
+    
+    return Image.makeFromEncoded(baos.toByteArray()).asImageAsset()
+}
+```
+
+2. Using `setIcon()` method
+
+```kotlin
+import androidx.compose.desktop.AppManager
+import androidx.compose.desktop.Window
+import androidx.compose.foundation.Image
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.ui.graphics.asImageAsset
+import androidx.compose.ui.graphics.ImageAsset
+import androidx.compose.ui.Modifier
+import java.awt.image.BufferedImage
+import java.io.ByteArrayOutputStream
+import java.io.File
+import javax.imageio.ImageIO
+import org.jetbrains.skija.Image
+
+fun main() {
+    val image = getWindowIcon()
+    Window {
+        val imageAsset = asImageAsset(image)
+        Image(
+            asset = imageAsset,
+            modifier = Modifier.fillMaxSize()
+        )
+    }
+
+    val current = AppManager.focusedWindow
+    if (current != null) {
+        current.setIcon(image)
+    }
+}
+
+fun getWindowIcon(): BufferedImage {
+    var image: BufferedImage? = null
+    try {
+        image = ImageIO.read(File("sample.png"))
+    } catch (e: Exception) {
+        // image file does not exist
+    }
+
+    if (image == null) {
+        image = BufferedImage(1, 1, BufferedImage.TYPE_INT_RGB)
+    }
+
+    return image
+}
+
+fun asImageAsset(image: BufferedImage): ImageAsset {
+    val baos = ByteArrayOutputStream()
+    ImageIO.write(image, "png", baos)
+    
+    return Image.makeFromEncoded(baos.toByteArray()).asImageAsset()
+}
+```
+
+![Window icon](window_icon.png)
+
+## Setting the application tray icon
+
+You can create tray icon for your application:
+
+```kotlin
+import androidx.compose.desktop.AppManager
+import androidx.compose.desktop.Window
+import androidx.compose.foundation.Image
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.runtime.onActive
+import androidx.compose.runtime.onDispose
+import androidx.compose.ui.graphics.asImageAsset
+import androidx.compose.ui.graphics.ImageAsset
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.window.Tray
+import androidx.compose.ui.window.MenuItem
+import java.awt.image.BufferedImage
+import java.io.ByteArrayOutputStream
+import java.io.File
+import javax.imageio.ImageIO
+import org.jetbrains.skija.Image
+
+fun main() {
+    val image = getWindowIcon()
+    Window {
+        onActive {
+            val tray = Tray().apply {
+                icon(getWindowIcon())
+                menu(
+                    MenuItem(
+                        name = "Quit App",
+                        onClick = { AppManager.exit() }
+                    )
+                )
+            }
+            onDispose {
+                tray.remove()
+            }
+        }
+
+        val imageAsset = asImageAsset(image)
+        Image(
+            asset = imageAsset,
+            modifier = Modifier.fillMaxSize()
+        )
+    }
+
+    val current = AppManager.focusedWindow
+    if (current != null) {
+        current.setIcon(image)
+    }
+}
+
+fun getWindowIcon(): BufferedImage {
+    var image: BufferedImage? = null
+    try {
+        image = ImageIO.read(File("sample.png"))
+    } catch (e: Exception) {
+        // image file does not exist
+    }
+
+    if (image == null) {
+        image = BufferedImage(1, 1, BufferedImage.TYPE_INT_RGB)
+    }
+
+    return image
+}
+
+fun asImageAsset(image: BufferedImage): ImageAsset {
+    val baos = ByteArrayOutputStream()
+    ImageIO.write(image, "png", baos)
+    
+    return Image.makeFromEncoded(baos.toByteArray()).asImageAsset()
+}
+```
+
+![Tray icon](tray_icon.png)