Add an empty bitmap pool implementation.

coil-base/src/main/java/coil/bitmap/BitmapPool.kt

@@ -18,7 +18,9 @@ interface BitmapPool {
          */
         @JvmStatic
         @JvmName("create")
-        operator fun invoke(maxSize: Int): BitmapPool = RealBitmapPool(maxSize)
+        operator fun invoke(maxSize: Int): BitmapPool {
+            return if (maxSize == 0) EmptyBitmapPool() else RealBitmapPool(maxSize)
+        }
     }
 
     /**

coil-base/src/main/java/coil/bitmap/EmptyBitmapPool.kt

@@ -0,0 +1,35 @@
+package coil.bitmap
+
+import android.graphics.Bitmap
+import androidx.core.graphics.createBitmap
+import coil.util.isHardware
+
+/** A lock-free [BitmapPool] implementation that recycles any [Bitmap]s that are added to it. */
+internal class EmptyBitmapPool : BitmapPool {
+
+    override fun put(bitmap: Bitmap) {
+        bitmap.recycle()
+    }
+
+    override fun get(width: Int, height: Int, config: Bitmap.Config) = getDirty(width, height, config)
+
+    override fun getOrNull(width: Int, height: Int, config: Bitmap.Config) = getDirtyOrNull(width, height, config)
+
+    override fun getDirty(width: Int, height: Int, config: Bitmap.Config): Bitmap {
+        assertNotHardware(config)
+        return createBitmap(width, height, config)
+    }
+
+    override fun getDirtyOrNull(width: Int, height: Int, config: Bitmap.Config): Bitmap? {
+        assertNotHardware(config)
+        return null
+    }
+
+    override fun trimMemory(level: Int) {}
+
+    override fun clear() {}
+
+    private fun assertNotHardware(config: Bitmap.Config) {
+        require(!config.isHardware) { "Cannot create a mutable hardware bitmap." }
+    }
+}

coil-base/src/test/java/coil/bitmap/RealBitmapPoolTest.kt

@@ -7,13 +7,16 @@ import android.content.ComponentCallbacks2.TRIM_MEMORY_RUNNING_CRITICAL
 import android.content.ComponentCallbacks2.TRIM_MEMORY_RUNNING_LOW
 import android.content.ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN
 import android.graphics.Bitmap
+import android.os.Build.VERSION.SDK_INT
 import coil.util.DEFAULT_BITMAP_SIZE
 import coil.util.createBitmap
+import org.junit.Assume.assumeTrue
 import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.robolectric.RobolectricTestRunner
 import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
 import kotlin.test.assertTrue
 
 @RunWith(RobolectricTestRunner::class)
@@ -55,7 +58,7 @@ class RealBitmapPoolTest {
     @Test
     fun `clear memory removes all bitmaps`() {
         pool.fill(MAX_BITMAPS)
-        pool.clearMemory()
+        pool.clear()
 
         assertEquals(MAX_BITMAPS, strategy.numRemoves)
     }
@@ -64,7 +67,7 @@ class RealBitmapPoolTest {
     fun `evicted bitmaps are recycled`() {
         pool.fill(MAX_BITMAPS)
         val bitmaps = strategy.bitmaps.toList()
-        pool.clearMemory()
+        pool.clear()
 
         bitmaps.forEach { assertTrue(it.isRecycled) }
     }
@@ -152,7 +155,32 @@ class RealBitmapPoolTest {
         assertEquals(1, strategy.numPuts)
     }
 
-    private fun RealBitmapPool.fill(fillCount: Int) {
+    @Test
+    fun `real - getting a hardware bitmap throws`() {
+        assumeTrue(SDK_INT >= 26)
+
+        val bitmap = createBitmap(config = Bitmap.Config.HARDWARE)
+
+        pool.put(bitmap)
+
+        assertFailsWith<IllegalArgumentException> { pool.get(bitmap.width, bitmap.height, bitmap.config) }
+        assertFailsWith<IllegalArgumentException> { pool.getOrNull(bitmap.width, bitmap.height, bitmap.config) }
+    }
+
+    @Test
+    fun `empty - getting a hardware bitmap throws`() {
+        assumeTrue(SDK_INT >= 26)
+
+        val pool = EmptyBitmapPool()
+        val bitmap = createBitmap(config = Bitmap.Config.HARDWARE)
+
+        pool.put(bitmap)
+
+        assertFailsWith<IllegalArgumentException> { pool.get(bitmap.width, bitmap.height, bitmap.config) }
+        assertFailsWith<IllegalArgumentException> { pool.getOrNull(bitmap.width, bitmap.height, bitmap.config) }
+    }
+
+    private fun BitmapPool.fill(fillCount: Int) {
         repeat(fillCount) { put(createBitmap()) }
     }
 

coil-base/src/test/java/coil/util/TestFunctions.kt

@@ -3,6 +3,7 @@
 package coil.util
 
 import android.graphics.Bitmap
+import android.os.Build.VERSION.SDK_INT
 import android.os.Looper
 import androidx.core.graphics.createBitmap
 import org.robolectric.Shadows
@@ -13,7 +14,7 @@ fun createBitmap(
     width: Int = 100,
     height: Int = 100,
     config: Bitmap.Config = Bitmap.Config.ARGB_8888,
-    isMutable: Boolean = true
+    isMutable: Boolean = SDK_INT < 26 || config != Bitmap.Config.HARDWARE
 ): Bitmap {
     val bitmap = createBitmap(width, height, config)
     Shadows.shadowOf(bitmap).setMutable(isMutable)

coil-gif/api/coil-gif.api

@@ -23,6 +23,7 @@ public final class coil/decode/ImageDecoderDecoder$Companion {
 public final class coil/drawable/MovieDrawable : android/graphics/drawable/Drawable, androidx/vectordrawable/graphics/drawable/Animatable2Compat {
 	public static final field Companion Lcoil/drawable/MovieDrawable$Companion;
 	public static final field REPEAT_INFINITE I
+	public fun <init> (Landroid/graphics/Movie;)V
 	public fun <init> (Landroid/graphics/Movie;Lcoil/bitmap/BitmapPool;)V
 	public fun <init> (Landroid/graphics/Movie;Lcoil/bitmap/BitmapPool;Landroid/graphics/Bitmap$Config;)V
 	public fun <init> (Landroid/graphics/Movie;Lcoil/bitmap/BitmapPool;Landroid/graphics/Bitmap$Config;Lcoil/size/Scale;)V

coil-gif/src/main/java/coil/drawable/MovieDrawable.kt

@@ -29,7 +29,7 @@ import coil.size.Scale
  */
 class MovieDrawable @JvmOverloads constructor(
     private val movie: Movie,
-    private val pool: BitmapPool,
+    private val pool: BitmapPool = BitmapPool(0),
     val config: Bitmap.Config = Bitmap.Config.ARGB_8888,
     val scale: Scale = Scale.FIT
 ) : Drawable(), Animatable2Compat {