Add fun Image.Companion.makeFromEncoded(nsData: NSData): Image (#873)

skiko/src/commonMain/kotlin/org/jetbrains/skia/Image.kt

@@ -428,7 +428,7 @@ private external fun _nMakeFromPixmap(pixmapPtr: NativePointer): NativePointer
 
 @ExternalSymbolName("org_jetbrains_skia_Image__1nMakeFromEncoded")
 @ModuleImport("./skiko.mjs", "org_jetbrains_skia_Image__1nMakeFromEncoded")
-private external fun _nMakeFromEncoded(bytes: InteropPointer, encodedLength: Int): NativePointer
+internal external fun _nMakeFromEncoded(bytes: InteropPointer, encodedLength: Int): NativePointer
 
 @ExternalSymbolName("org_jetbrains_skia_Image__1nEncodeToData")
 @ModuleImport("./skiko.mjs", "org_jetbrains_skia_Image__1nEncodeToData")

skiko/src/darwinMain/kotlin/org/jetbrains/skia/Image.darwin.kt

@@ -0,0 +1,14 @@
+package org.jetbrains.skia
+
+import platform.Foundation.NSData
+import kotlin.native.internal.NativePtr
+
+fun Image.Companion.makeFromEncoded(nsData: NSData): Image {
+    val ptr = nsData.bytes?.rawValue ?: NativePtr.NULL
+    require(ptr != NativePtr.NULL) { "Failed to Image::makeFromEncoded" }
+
+    // skia makes an internal copy of the nsData bytes
+    val imgPtr = _nMakeFromEncoded(ptr, nsData.length.toInt())
+    require(imgPtr != NativePtr.NULL) { "Failed to Image::makeFromEncoded" }
+    return Image(imgPtr)
+}

skiko/src/darwinTest/kotlin/org/jetbrains/skia/ImageTest.darwin.kt

@@ -0,0 +1,54 @@
+package org.jetbrains.skia
+
+import kotlinx.cinterop.ExperimentalForeignApi
+import kotlinx.cinterop.addressOf
+import kotlinx.cinterop.pin
+import platform.Foundation.NSData
+import platform.Foundation.dataWithBytes
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class ImageTestDarwin {
+
+    @Test
+    fun canCreateFromEncodedNsData() {
+
+        val bytes = intArrayOf(
+            0xCA, 0xDA, 0xCA, 0xC9, 0xA3,
+            0xAC, 0xA8, 0x89, 0xA7, 0x87,
+            0x9B, 0xB5, 0xE5, 0x95, 0x46,
+            0x90, 0x81, 0xC5, 0x71, 0x33,
+            0x75, 0x55, 0x44, 0x40, 0x30
+        ).map { it.toByte() }.toByteArray()
+
+        val imageInfo = ImageInfo(
+            width = 5, height = 5,
+            colorType = ColorType.GRAY_8,
+            alphaType = ColorAlphaType.OPAQUE
+        )
+
+        val image = Image.makeRaster(imageInfo, bytes, 5)
+        val data = image.encodeToData()!!
+        val originalBitmap = Bitmap.makeFromImage(image)
+
+        val nsData = createNSDataFromByteArray(data.bytes)
+        val imageFromNsData = Image.makeFromEncoded(nsData)
+        val bitmapFromNsData = Bitmap.makeFromImage(imageFromNsData)
+
+        assertEquals(imageInfo.height, imageFromNsData.imageInfo.height)
+        assertEquals(imageInfo.width, imageFromNsData.imageInfo.width)
+        assertEquals(imageInfo.colorAlphaType, imageFromNsData.imageInfo.colorAlphaType)
+        assertEquals(imageInfo.colorType, imageFromNsData.imageInfo.colorType)
+
+        repeat(5) { x ->
+            repeat(5) { y ->
+                assertEquals(originalBitmap.getColor(x, y), bitmapFromNsData.getColor(x, y))
+            }
+        }
+    }
+}
+
+@OptIn(ExperimentalForeignApi::class)
+fun createNSDataFromByteArray(bytes: ByteArray): NSData {
+    return NSData.dataWithBytes(bytes.pin().addressOf(0), bytes.size.toULong())
+}