Adding extensions for ImageDecoder (#540)

* Adding extensions for decoding ImageDecoder.Source instances to Bitmaps and Drawables

* Renaming ImageDecoder extensions to highlight decoding

* Fixing tests to avoid relying on the file system

Author: RamV13

api/current.txt

@@ -153,6 +153,12 @@ package androidx.core.graphics {
     method @RequiresApi(26) @ColorLong public static long toColorLong(int);
   }
 
+  public final class ImageDecoderKt {
+    ctor public ImageDecoderKt();
+    method @RequiresApi(28) public static android.graphics.Bitmap decodeBitmap(android.graphics.ImageDecoder.Source, kotlin.jvm.functions.Function3<? super android.graphics.ImageDecoder,? super android.graphics.ImageDecoder.ImageInfo,? super android.graphics.ImageDecoder.Source,kotlin.Unit> action);
+    method @RequiresApi(28) public static android.graphics.drawable.Drawable decodeDrawable(android.graphics.ImageDecoder.Source, kotlin.jvm.functions.Function3<? super android.graphics.ImageDecoder,? super android.graphics.ImageDecoder.ImageInfo,? super android.graphics.ImageDecoder.Source,kotlin.Unit> action);
+  }
+
   public final class MatrixKt {
     ctor public MatrixKt();
     method public static android.graphics.Matrix rotationMatrix(float degrees, float px = "0.0f", float py = "0.0f");

src/androidTest/java/androidx/core/graphics/ImageDecoderTest.kt

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2018 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.
+ */
+
+package androidx.core.graphics
+
+import android.graphics.Bitmap
+import android.graphics.ImageDecoder
+import org.junit.Assert.assertEquals
+import org.junit.BeforeClass
+import org.junit.Test
+import java.io.ByteArrayOutputStream
+import java.nio.ByteBuffer
+
+class ImageDecoderTest {
+
+    @Test fun decodeBitmap() {
+        val src = ImageDecoder.createSource(buffer)
+        val decodedBitmap = src.decodeBitmap { _, _ -> setTargetSize(10, 10) }
+        assertEquals(10, decodedBitmap.width)
+        assertEquals(10, decodedBitmap.height)
+    }
+
+    @Test fun decodeDrawable() {
+        val src = ImageDecoder.createSource(buffer)
+        val decodedDrawable = src.decodeDrawable { _, _ -> setTargetSize(10, 10) }
+        assertEquals(10, decodedDrawable.intrinsicWidth)
+        assertEquals(10, decodedDrawable.intrinsicHeight)
+    }
+
+    companion object {
+        private lateinit var buffer: ByteBuffer
+
+        @BeforeClass
+        @JvmStatic
+        fun beforeClass() {
+            val stream = ByteArrayOutputStream().apply {
+                Bitmap
+                    .createBitmap(1, 1, Bitmap.Config.ARGB_8888)
+                    .compress(Bitmap.CompressFormat.JPEG, 100, this)
+            }
+
+            buffer = ByteBuffer.wrap(stream.toByteArray())
+        }
+    }
+}

src/main/java/androidx/core/graphics/ImageDecoder.kt

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2018 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.
+ */
+
+package androidx.core.graphics
+
+import android.graphics.Bitmap
+import android.graphics.ImageDecoder
+import android.graphics.ImageDecoder.ImageInfo
+import android.graphics.ImageDecoder.Source
+import android.graphics.drawable.Drawable
+import androidx.annotation.RequiresApi
+
+/**
+ * Create a Bitmap from a Source
+ *
+ * @see ImageDecoder.decodeBitmap
+ */
+@RequiresApi(28)
+inline fun ImageDecoder.Source.decodeBitmap(
+    crossinline action: ImageDecoder.(info: ImageInfo, source: Source) -> Unit
+): Bitmap {
+    return ImageDecoder.decodeBitmap(this) { decoder, info, source ->
+        decoder.action(info, source)
+    }
+}
+
+/**
+ * Create a Drawable from a Source
+ *
+ * @see ImageDecoder.decodeDrawable
+ */
+@RequiresApi(28)
+inline fun ImageDecoder.Source.decodeDrawable(
+    crossinline action: ImageDecoder.(info: ImageInfo, source: Source) -> Unit
+): Drawable {
+    return ImageDecoder.decodeDrawable(this) { decoder, info, source ->
+        decoder.action(info, source)
+    }
+}