Hide Metal drawables from Kotlin runtime

compose/mpp/demo/src/uikitMain/kotlin/androidx/compose/mpp/demo/bugs/IosBugs.kt

@@ -38,5 +38,6 @@ val IosBugs = Screen.Selection(
     MeasureAndLayoutCrash,
     AnimationFreezeBug,
     ModalMemoryLeak,
-    ModalCrash
+    ModalCrash,
+    PopupStretching
 )

compose/mpp/demo/src/uikitMain/kotlin/androidx/compose/mpp/demo/bugs/PopupStretching.kt

@@ -0,0 +1,96 @@
+/*
+ * Copyright 2024 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.compose.mpp.demo.bugs
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.horizontalScroll
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material.Text
+import androidx.compose.material3.Button
+import androidx.compose.mpp.demo.Screen
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.interop.LocalUIViewController
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.window.ComposeUIViewController
+import platform.UIKit.UIModalPresentationFormSheet
+import platform.UIKit.UISheetPresentationControllerDetent
+import platform.UIKit.sheetPresentationController
+
+val PopupStretching = Screen.Example("Popup stretching") {
+    val viewController = LocalUIViewController.current
+
+    Button(onClick = {
+        val bottomSheetController = ComposeUIViewController {
+            VerticalScrollWithIndependentHorizontalRows()
+        }
+
+        bottomSheetController.modalPresentationStyle = UIModalPresentationFormSheet
+        bottomSheetController.sheetPresentationController?.setDetents(
+            listOf(
+                UISheetPresentationControllerDetent.mediumDetent(),
+                UISheetPresentationControllerDetent.largeDetent(),
+            )
+        )
+
+        viewController.presentViewController(bottomSheetController, animated = true, completion = {})
+    }) {
+        Text("Show popup")
+    }
+}
+
+
+@Composable
+fun VerticalScrollWithIndependentHorizontalRows() {
+    Column(
+        modifier =
+        Modifier.fillMaxSize().verticalScroll(rememberScrollState(), enabled = true),
+    ) {
+        repeat(10) { rowIndex ->
+            val horizontalScrollState = rememberScrollState()
+
+            Spacer(Modifier.height(30.dp).background(Color.DarkGray))
+            Row(
+                modifier =
+                Modifier
+                    .padding(start = 16.dp, end = 16.dp)
+                    .horizontalScroll(horizontalScrollState),
+            ) {
+                repeat(5) {
+                    Box(
+                        modifier =
+                        Modifier
+                            .size(100.dp)
+                            .background(Color.Gray),
+                    ) {
+                        Text("Item $it in row $rowIndex")
+                    }
+                }
+            }
+        }
+    }
+}

compose/ui/ui-uikit/src/uikitMain/objc/CMPUIKitUtils/CMPUIKitUtils.xcodeproj/project.pbxproj

@@ -20,6 +20,7 @@
 		EA70A7EC2B27106100300068 /* CMPAccessibilityContainer.m in Sources */ = {isa = PBXBuildFile; fileRef = EA70A7E92B27106100300068 /* CMPAccessibilityContainer.m */; };
 		EA82F4F92B86144E00465418 /* CMPOSLogger.m in Sources */ = {isa = PBXBuildFile; fileRef = EA82F4F82B86144E00465418 /* CMPOSLogger.m */; };
 		EA82F4FC2B86184F00465418 /* CMPOSLoggerInterval.m in Sources */ = {isa = PBXBuildFile; fileRef = EA82F4FB2B86184F00465418 /* CMPOSLoggerInterval.m */; };
+		EAB33E182C12E746002CFF44 /* CMPMetalDrawablesHandler.m in Sources */ = {isa = PBXBuildFile; fileRef = EAB33E172C12E746002CFF44 /* CMPMetalDrawablesHandler.m */; };
 		EABD912B2BC02B5F00455279 /* CMPInteropWrappingView.m in Sources */ = {isa = PBXBuildFile; fileRef = EABD912A2BC02B5F00455279 /* CMPInteropWrappingView.m */; };
 		EAC703E32B8C826E001ECDA6 /* CMPAccessibilityElement.m in Sources */ = {isa = PBXBuildFile; fileRef = EA70A7E82B27106100300068 /* CMPAccessibilityElement.m */; };
 		EAC703E42B8C826E001ECDA6 /* CMPViewController.m in Sources */ = {isa = PBXBuildFile; fileRef = 997DFCDD2B18D135000B56B5 /* CMPViewController.m */; };
@@ -82,6 +83,8 @@
 		EA82F4F82B86144E00465418 /* CMPOSLogger.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = CMPOSLogger.m; sourceTree = "<group>"; };
 		EA82F4FA2B86184F00465418 /* CMPOSLoggerInterval.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = CMPOSLoggerInterval.h; sourceTree = "<group>"; };
 		EA82F4FB2B86184F00465418 /* CMPOSLoggerInterval.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = CMPOSLoggerInterval.m; sourceTree = "<group>"; };
+		EAB33E162C12E746002CFF44 /* CMPMetalDrawablesHandler.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = CMPMetalDrawablesHandler.h; sourceTree = "<group>"; };
+		EAB33E172C12E746002CFF44 /* CMPMetalDrawablesHandler.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = CMPMetalDrawablesHandler.m; sourceTree = "<group>"; };
 		EABD91292BC02B5F00455279 /* CMPInteropWrappingView.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = CMPInteropWrappingView.h; sourceTree = "<group>"; };
 		EABD912A2BC02B5F00455279 /* CMPInteropWrappingView.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = CMPInteropWrappingView.m; sourceTree = "<group>"; };
 		EAC703DF2B8C8154001ECDA6 /* CMPUIKitUtilsTestApp-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "CMPUIKitUtilsTestApp-Bridging-Header.h"; sourceTree = "<group>"; };
@@ -134,6 +137,8 @@
 				99DCAB0D2BD00F5C002E6AC7 /* CMPTextLoupeSession.m */,
 				99D97A862BF73A9B0035552B /* CMPEditMenuView.h */,
 				99D97A872BF73A9B0035552B /* CMPEditMenuView.m */,
+				EAB33E162C12E746002CFF44 /* CMPMetalDrawablesHandler.h */,
+				EAB33E172C12E746002CFF44 /* CMPMetalDrawablesHandler.m */,
 			);
 			path = CMPUIKitUtils;
 			sourceTree = "<group>";
@@ -308,6 +313,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				997DFCDE2B18D135000B56B5 /* CMPViewController.m in Sources */,
+				EAB33E182C12E746002CFF44 /* CMPMetalDrawablesHandler.m in Sources */,
 				99D97A882BF73A9B0035552B /* CMPEditMenuView.m in Sources */,
 				EABD912B2BC02B5F00455279 /* CMPInteropWrappingView.m in Sources */,
 				EA70A7EC2B27106100300068 /* CMPAccessibilityContainer.m in Sources */,

compose/ui/ui-uikit/src/uikitMain/objc/CMPUIKitUtils/CMPUIKitUtils/CMPMacros.h

@@ -18,3 +18,12 @@
 
 #define CMP_MUST_BE_OVERRIDED
 #define CMP_MUST_BE_OVERRIDED_INVARIANT_VIOLATION assert(false && "MUST_OVERRIDE");
+
+// Marker for indicating that raw pointer returned from a function is owned by the caller
+#define CMP_OWNED
+
+// Marker for indicating that raw pointer is consumed when passed as an argument
+#define CMP_CONSUMED
+
+// Marker for indicating that raw pointer is implied as borrowed when returned from a function or passed as an argument
+#define CMP_BORROWED

compose/ui/ui-uikit/src/uikitMain/objc/CMPUIKitUtils/CMPUIKitUtils/CMPMetalDrawablesHandler.h

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2023 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.
+ */
+
+#import <Foundation/Foundation.h>
+#import <QuartzCore/QuartzCore.h>
+#import <Metal/Metal.h>
+
+#import "CMPMacros.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ A handler class for managing Metal drawables explicitly using raw pointers.
+ This class encapsulates the lifecycle management of drawable objects,
+ facilitating the use in environments where automatic reference counting (ARC)
+ mixed with Kotlin/Native memory model that  leads to violation of practices enstated by Apple (namely, not releasing drawables as soon as possible), which lead to inadequate memory spikes during drawable size updates across consequent frames.
+ @see https://developer.apple.com/library/archive/documentation/3DDrawing/Conceptual/MTLBestPracticesGuide/Drawables.html
+
+ The class methods handle the acquisition, release, and presentation of
+ drawable objects associated with a given CAMetalLayer. Usage of raw pointers
+ helps in explicitly controlling the drawable lifecycle, preventing application from keeping drawables and their pools alive longer, than needed, due to awaiting deallocation by GC.
+ */
+@interface CMPMetalDrawablesHandler : NSObject
+
+/// Initializes the handler with a given Metal layer.
+/// @param metalLayer The CAMetalLayer instance to be associated with this handler.
+- (instancetype)initWithMetalLayer:(CAMetalLayer *)metalLayer;
+
+/// Retrieves the next drawable object from the associated Metal layer.
+/// @return A raw pointer to the next drawable object, ownership is transferred to the caller.
+- (void * CMP_OWNED)nextDrawable;
+
+/// Releases a drawable object, indicating that it is no longer in use by the caller.
+/// @param drawablePtr A raw pointer to the drawable to be released, indicating transfer of ownership back to the handler.
+- (void)releaseDrawable:(void * CMP_CONSUMED)drawablePtr;
+
+/// Retrieves the texture of a drawable without transferring ownership.
+/// @param drawablePtr A raw pointer to the drawable from which to get the texture.
+/// @return A raw pointer to the texture of the drawable, ownership is not transferred.
+- (void * CMP_BORROWED)drawableTexture:(void * CMP_BORROWED)drawablePtr;
+
+/// Presents a drawable to the screen immediately.
+/// @param drawablePtr A raw pointer to the drawable to be presented, indicating transfer of ownership.
+- (void)presentDrawable:(void * CMP_CONSUMED)drawablePtr;
+
+/// Schedules the presentation of a drawable on a specific command buffer.
+/// @param drawablePtr A raw pointer to the drawable to be presented, indicating transfer of ownership.
+/// @param commandBuffer The command buffer on which the drawable will be scheduled for presentation.
+- (void)scheduleDrawablePresentation:(void * CMP_CONSUMED)drawablePtr onCommandBuffer:(id <MTLCommandBuffer>)commandBuffer;
+
+@end
+
+NS_ASSUME_NONNULL_END

compose/ui/ui-uikit/src/uikitMain/objc/CMPUIKitUtils/CMPUIKitUtils/CMPMetalDrawablesHandler.m

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2023 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.
+ */
+
+#import "CMPMetalDrawablesHandler.h"
+
+@implementation CMPMetalDrawablesHandler {
+    CAMetalLayer *_metalLayer;
+}
+
+- (instancetype)initWithMetalLayer:(CAMetalLayer *)metalLayer {
+    self = [super init];
+    if (self) {
+        _metalLayer = metalLayer;
+    }
+    return self;
+}
+
+- (void * CMP_OWNED)nextDrawable {
+    id <CAMetalDrawable> drawable = [_metalLayer nextDrawable];
+
+    if (drawable) {
+        void *ptr = (__bridge_retained void *)drawable;
+        return ptr;
+    } else {
+        return NULL;
+    }
+}
+
+- (void)releaseDrawable:(void * CMP_CONSUMED)drawablePtr {
+    assert(drawablePtr != NULL);
+
+    id <CAMetalDrawable> drawable __unused = (__bridge_transfer id <CAMetalDrawable>)drawablePtr;
+    // drawable will be released by ARC
+}
+
+- (void * CMP_BORROWED)drawableTexture:(void * CMP_BORROWED)drawablePtr {
+    assert(drawablePtr != NULL);
+
+    id <CAMetalDrawable> drawable = (__bridge id <CAMetalDrawable>)drawablePtr;
+    id <MTLTexture> texture = drawable.texture;    
+    void *texturePtr = (__bridge void *)texture;
+    return texturePtr;
+}
+
+- (void)presentDrawable:(void * CMP_CONSUMED)drawablePtr {
+    assert(drawablePtr != NULL);
+
+    id <CAMetalDrawable> drawable = (__bridge_transfer id <CAMetalDrawable>)drawablePtr;
+    [drawable present];
+}
+
+- (void)scheduleDrawablePresentation:(void * CMP_CONSUMED)drawablePtr onCommandBuffer:(id <MTLCommandBuffer>)commandBuffer {
+    assert(drawablePtr != NULL);
+
+    id <CAMetalDrawable> drawable = (__bridge_transfer id <CAMetalDrawable>)drawablePtr;
+    [commandBuffer presentDrawable:drawable];
+}
+
+@end

compose/ui/ui-uikit/src/uikitMain/objc/CMPUIKitUtils/CMPUIKitUtils/CMPUIKitUtils.h

@@ -27,3 +27,4 @@ FOUNDATION_EXPORT const unsigned char CMPUIKitUtilsVersionString[];
 #import "CMPAccessibilityContainer.h"
 #import "CMPOSLogger.h"
 #import "CMPTextLoupeSession.h"
+#import "CMPMetalDrawablesHandler.h"

compose/ui/ui/src/uikitMain/kotlin/androidx/compose/ui/window/MetalRedrawer.uikit.kt

@@ -20,6 +20,7 @@ import androidx.compose.ui.interop.UIKitInteropState
 import androidx.compose.ui.interop.UIKitInteropTransaction
 import androidx.compose.ui.interop.doLocked
 import androidx.compose.ui.interop.isNotEmpty
+import androidx.compose.ui.uikit.utils.CMPMetalDrawablesHandler
 import androidx.compose.ui.util.fastForEach
 import androidx.compose.ui.util.trace
 import kotlin.math.roundToInt
@@ -145,6 +146,13 @@ internal class MetalRedrawer(
     private val metalLayer: CAMetalLayer,
     private val callbacks: MetalRedrawerCallbacks
 ) {
+    /**
+     * A wrapper around CAMetalLayer that allows to perform operations on its drawables without
+     * exposing the objects to Kotlin/Native runtime and thus allowing explicit lifetime control of them.
+     *
+     * See ObjC implementation of [CMPMetalDrawablesHandler] for more details.
+     */
+    private val metalDrawablesHandler = CMPMetalDrawablesHandler(metalLayer)
     // Workaround for KN compiler bug
     // Type mismatch: inferred type is objcnames.protocols.MTLDeviceProtocol but platform.Metal.MTLDeviceProtocol was expected
     @Suppress("USELESS_CAST")
@@ -316,7 +324,7 @@ internal class MetalRedrawer(
             }
 
             val metalDrawable = trace("MetalRedrawer:draw:nextDrawable") {
-                metalLayer.nextDrawable()
+                metalDrawablesHandler.nextDrawable()
             }
 
             if (metalDrawable == null) {
@@ -328,7 +336,7 @@ internal class MetalRedrawer(
             }
 
             val renderTarget =
-                BackendRenderTarget.makeMetal(width, height, metalDrawable.texture.objcPtr())
+                BackendRenderTarget.makeMetal(width, height, metalDrawablesHandler.drawableTexture(metalDrawable).rawValue)
 
             val surface = Surface.makeFromBackendRenderTarget(
                 context,
@@ -344,6 +352,7 @@ internal class MetalRedrawer(
                 // Logger.warn { "'Surface.makeFromBackendRenderTarget' returned null. Skipping the frame." }
                 picture.close()
                 renderTarget.close()
+                metalDrawablesHandler.releaseDrawable(metalDrawable)
                 dispatch_semaphore_signal(inflightSemaphore)
                 return@autoreleasepool
             }
@@ -372,7 +381,9 @@ internal class MetalRedrawer(
                     commandBuffer.label = "Present"
 
                     if (!presentsWithTransaction) {
-                        commandBuffer.presentDrawable(metalDrawable)
+                        // scheduleDrawablePresentation consumes metalDrawable
+                        // don't use metalDrawable after this call
+                        metalDrawablesHandler.scheduleDrawablePresentation(metalDrawable, commandBuffer)
                     }
 
                     commandBuffer.addCompletedHandler {
@@ -388,7 +399,9 @@ internal class MetalRedrawer(
                             commandBuffer.waitUntilScheduled()
                         }
 
-                        metalDrawable.present()
+                        // presentDrawable consumes metalDrawable
+                        // don't use metalDrawable after this call
+                        metalDrawablesHandler.presentDrawable(metalDrawable)
 
                         interopTransaction.actions.fastForEach {
                             it.invoke()