dispose the ShaderWarmUp picture/image (#85465)

packages/flutter/lib/src/painting/debug.dart

@@ -4,7 +4,7 @@
 
 
 import 'dart:io';
-import 'dart:ui' show Size, hashValues;
+import 'dart:ui' show Size, hashValues, Picture, Image;
 
 import 'package:flutter/foundation.dart';
 
@@ -195,3 +195,29 @@ bool debugAssertAllPaintingVarsUnset(String reason, { bool debugDisableShadowsOv
   }());
   return true;
 }
+
+/// The signature of [debugCaptureShaderWarmUpPicture].
+///
+/// Used by tests to run assertions on the [Picture] created by
+/// [ShaderWarmUp.execute]. The return value indicates whether the assertions
+/// pass or not.
+typedef ShaderWarmUpPictureCallback = bool Function(Picture);
+
+/// The signature of [debugCaptureShaderWarmUpImage].
+///
+/// Used by tests to run assertions on the [Image] created by
+/// [ShaderWarmUp.execute]. The return value indicates whether the assertions
+/// pass or not.
+typedef ShaderWarmUpImageCallback = bool Function(Image);
+
+/// Called by [ShaderWarmUp.execute] immediately after it creates a [Picture].
+///
+/// Tests may use this to capture the picture and run assertions on it.
+ShaderWarmUpPictureCallback debugCaptureShaderWarmUpPicture = _defaultPictureCapture;
+bool _defaultPictureCapture(Picture picture) => true;
+
+/// Called by [ShaderWarmUp.execute] immediately after it creates an [Image].
+///
+/// Tests may use this to capture the picture and run assertions on it.
+ShaderWarmUpImageCallback debugCaptureShaderWarmUpImage = _defaultImageCapture;
+bool _defaultImageCapture(Image image) => true;

packages/flutter/lib/src/painting/shader_warm_up.dart

@@ -7,6 +7,8 @@ import 'dart:ui' as ui;
 
 import 'package:flutter/foundation.dart';
 
+import 'debug.dart';
+
 /// Interface for drawing an image to warm up Skia shader compilations.
 ///
 /// When Skia first sees a certain type of draw operation on the GPU, it needs
@@ -85,15 +87,19 @@ abstract class ShaderWarmUp {
     final ui.Canvas canvas = ui.Canvas(recorder);
     await warmUpOnCanvas(canvas);
     final ui.Picture picture = recorder.endRecording();
+    assert(debugCaptureShaderWarmUpPicture(picture));
     if (!kIsWeb) { // Picture.toImage is not yet implemented on the web.
       final TimelineTask shaderWarmUpTask = TimelineTask();
       shaderWarmUpTask.start('Warm-up shader');
       try {
-        await picture.toImage(size.width.ceil(), size.height.ceil());
+        final ui.Image image = await picture.toImage(size.width.ceil(), size.height.ceil());
+        assert(debugCaptureShaderWarmUpImage(image));
+        image.dispose();
       } finally {
         shaderWarmUpTask.finish();
       }
     }
+    picture.dispose();
   }
 }
 

packages/flutter/test/painting/shader_warm_up_test.dart

@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:ui' as ui;
+
+import 'package:flutter/foundation.dart';
 import 'package:flutter/painting.dart';
 import 'package:flutter_test/flutter_test.dart';
 
@@ -32,4 +35,27 @@ void main() {
 
     expect(hasDrawRectAfterClipRRect, true);
   });
+
+  test('ShaderWarmUp.execute disposes the image and picture', () async {
+    const DefaultShaderWarmUp shaderWarmUp = DefaultShaderWarmUp();
+    late ui.Picture capturedPicture;
+    late ui.Image capturedImage;
+    debugCaptureShaderWarmUpPicture = (ui.Picture picture) {
+      capturedPicture = picture;
+      expect(picture.approximateBytesUsed, greaterThan(0));
+      return true;
+    };
+    debugCaptureShaderWarmUpImage = (ui.Image image) {
+      capturedImage = image;
+      expect(image.width, 100);
+      expect(image.height, 100);
+      return true;
+    };
+    await shaderWarmUp.execute();
+    expect(
+      () => capturedPicture.approximateBytesUsed,
+      throwsA(isA<String>().having((String message) => message, 'message', 'Object has been disposed.')),
+    );
+    expect(capturedImage.debugDisposed, true);
+  }, skip: kIsWeb); // Browser doesn't support approximateBytesUsed and doesn't rasterize the picture at this time.
 }