Implement native Bitmap::peekPixels, add test (#306)

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

@@ -975,17 +975,21 @@ class Bitmap internal constructor(ptr: NativePointer) : Managed(ptr, _FinalizerH
     }
 
     /**
-     * If pixel address is available, return ByteBuffer wrapping it.
-     * If pixel address is not available, return null.
+     * Create a pixmap and copy buffer contents into it
      *
-     * @return  ByteBuffer with direct access to pixels, or null
+     * @return Pixamp with copied pixels, or null
      *
      * @see [https://fiddle.skia.org/c/@Bitmap_peekPixels](https://fiddle.skia.org/c/@Bitmap_peekPixels)
      */
-    fun peekPixels(): ByteBuffer? {
+    fun peekPixels(): Pixmap? {
         return try {
             Stats.onNativeCall()
-            _nPeekPixels(_ptr)
+            val res = _nPeekPixels(_ptr)
+            if (res == NullPointer) {
+                null
+            } else {
+                Pixmap(res, true)
+            }
         } finally {
             reachabilityBarrier(this)
         }
@@ -1189,7 +1193,7 @@ private external fun _nReadPixels(
 private external fun _nExtractAlpha(ptr: NativePointer, dstPtr: NativePointer, paintPtr: NativePointer, iPointResultIntArray: InteropPointer): Boolean
 
 @ExternalSymbolName("org_jetbrains_skia_Bitmap__1nPeekPixels")
-private external fun _nPeekPixels(ptr: NativePointer): ByteBuffer?
+private external fun _nPeekPixels(ptr: NativePointer): NativePointer
 
 @ExternalSymbolName("org_jetbrains_skia_Bitmap__1nMakeShader")
 private external fun _nMakeShader(ptr: NativePointer, tmx: Int, tmy: Int, samplingMode: Long, localMatrix: InteropPointer): NativePointer

skiko/src/commonTest/kotlin/org/jetbrains/skia/BitmapTest.kt

 package org.jetbrains.skia
 
+import org.jetbrains.skiko.KotlinBackend
+import org.jetbrains.skiko.kotlinBackend
 import org.jetbrains.skiko.tests.runTest
 import kotlin.test.*
 
@@ -68,6 +70,18 @@ class BitmapTest {
         assertTrue(bitmap.rowBytes > 0)
         assertEquals(5 * bitmap.rowBytes, result.size)
     }
+    @Test
+    fun canPeekPixels() = runTest {
+        val bitmap = Bitmap()
+        bitmap.allocPixels(ImageInfo.makeS32(10, 10, ColorAlphaType.OPAQUE))
+        val result = bitmap.peekPixels()!!
+
+        assertEquals(10 * 4, result.rowBytes)
+        assertEquals(10 * 10 * 4, result.computeByteSize())
+        if (kotlinBackend == KotlinBackend.JVM) {
+            assertEquals(bitmap.imageInfo, result.info)
+        }
+    }
 
     @Test //fixed bug https://github.com/JetBrains/skiko/pull/266
     fun canReadPixelsWithGivenRowBytes() = runTest {

skiko/src/jvmMain/cpp/common/Bitmap.cc

@@ -259,14 +259,16 @@ extern "C" JNIEXPORT jboolean JNICALL Java_org_jetbrains_skia_BitmapKt__1nExtrac
     return result;
 }
 
-extern "C" JNIEXPORT jobject JNICALL Java_org_jetbrains_skia_BitmapKt__1nPeekPixels
+extern "C" JNIEXPORT jlong JNICALL Java_org_jetbrains_skia_BitmapKt__1nPeekPixels
   (JNIEnv* env, jclass jclass, jlong ptr) {
     SkBitmap* instance = reinterpret_cast<SkBitmap*>(static_cast<uintptr_t>(ptr));
-    SkPixmap pixmap;
-    if (instance->peekPixels(&pixmap))
-        return env->NewDirectByteBuffer(pixmap.writable_addr(), pixmap.rowBytes() * pixmap.height());
-    else
-        return nullptr;
+    SkPixmap* pixmap = new SkPixmap();
+    if (instance->peekPixels(pixmap))
+        return ptrToJlong(pixmap);
+    else {
+        delete pixmap;
+        return 0;
+    }
 }
 
 extern "C" JNIEXPORT jlong JNICALL Java_org_jetbrains_skia_BitmapKt__1nMakeShader

skiko/src/jvmMain/kotlin/org/jetbrains/skiko/Convertors.kt

@@ -19,31 +19,6 @@ private class DirectDataBuffer(val backing: ByteBuffer): DataBuffer(TYPE_BYTE, b
     }
 }
 
-fun Bitmap.toBufferedImage(): BufferedImage {
-    val pixels = this.peekPixels()
-    val order = when (this.colorInfo.colorType) {
-        ColorType.RGB_888X -> intArrayOf(0, 1, 2, 3)
-        ColorType.BGRA_8888 -> intArrayOf(2, 1, 0, 3)
-        else -> throw UnsupportedOperationException("unsupported color type ${this.colorInfo.colorType}")
-    }
-    val raster = Raster.createInterleavedRaster(
-        DirectDataBuffer(pixels!!),
-        this.width,
-        this.height,
-        this.width * 4,
-        4,
-        order,
-        null
-    )
-    val colorModel = ComponentColorModel(
-        ColorSpace.getInstance(ColorSpace.CS_sRGB),
-        true,
-        false,
-        Transparency.TRANSLUCENT,
-        DataBuffer.TYPE_BYTE
-    )
-   return BufferedImage(colorModel, raster!!, false, null)
-}
 
 fun BufferedImage.toBitmap(): Bitmap {
     val bytesPerPixel = 4

skiko/src/nativeJsMain/cpp/Bitmap.cc

@@ -279,7 +279,14 @@ SKIKO_EXPORT KBoolean org_jetbrains_skia_Bitmap__1nExtractAlpha
 
 SKIKO_EXPORT KInteropPointer org_jetbrains_skia_Bitmap__1nPeekPixels
   (KNativePointer ptr) {
-    TODO("implement org_jetbrains_skia_Bitmap__1nPeekPixels");
+    SkBitmap* instance = reinterpret_cast<SkBitmap*>(ptr);
+    SkPixmap* pixmap = new SkPixmap();
+    if (instance->peekPixels(pixmap)) {
+        return reinterpret_cast<KNativePointer>(pixmap);
+    } else {
+        delete pixmap;
+        return nullptr;
+    }
 }
 
 SKIKO_EXPORT KNativePointer org_jetbrains_skia_Bitmap__1nMakeShader