From 8e1702b29c8ab76d85eaa5ca784c89720ef2e0f0 Mon Sep 17 00:00:00 2001
From: jonahwilliams <jonahwilliams@google.com>
Date: Mon, 11 Nov 2024 19:17:13 -0800
Subject: [PATCH] [Impeller] prevent no-op backend from throwing exceptions
 during image decoding.

---
 lib/ui/painting/image_decoder_impeller.cc |  7 +++++++
 lib/ui/painting/multi_frame_codec.cc      | 11 +++++++++++
 2 files changed, 18 insertions(+)

diff --git a/lib/ui/painting/image_decoder_impeller.cc b/lib/ui/painting/image_decoder_impeller.cc
index 6a1118954a9be..a73310c492b2e 100644
--- a/lib/ui/painting/image_decoder_impeller.cc
+++ b/lib/ui/painting/image_decoder_impeller.cc
@@ -519,6 +519,13 @@ void ImageDecoderImpeller::Decode(fml::RefPtr<ImageDescriptor> descriptor,
        result,
        supports_wide_gamut = supports_wide_gamut_,  //
        gpu_disabled_switch = gpu_disabled_switch_]() {
+#if FML_OS_IOS_SIMULATOR
+        // No-op backend.
+        if (!context) {
+          return;
+        }
+#endif  // FML_OS_IOS_SIMULATOR
+
         if (!context) {
           result(nullptr, "No Impeller context is available");
           return;
diff --git a/lib/ui/painting/multi_frame_codec.cc b/lib/ui/painting/multi_frame_codec.cc
index 1521c535fd97c..f05ff111236ce 100644
--- a/lib/ui/painting/multi_frame_codec.cc
+++ b/lib/ui/painting/multi_frame_codec.cc
@@ -190,6 +190,17 @@ void MultiFrameCodec::State::GetNextFrameAndInvokeCallback(
     const std::shared_ptr<const fml::SyncSwitch>& gpu_disable_sync_switch,
     size_t trace_id,
     const std::shared_ptr<impeller::Context>& impeller_context) {
+#if FML_OS_IOS_SIMULATOR
+  // Noop backend.
+  if (!resourceContext && !impeller_context) {
+    ui_task_runner->PostTask(
+        fml::MakeCopyable([callback = std::move(callback)]() {
+          // must be destroyed on UI thread.
+        }));
+    return;
+  }
+#endif  // FML_OS_IOS_SIMULATOR
+
   fml::RefPtr<CanvasImage> image = nullptr;
   int duration = 0;
   sk_sp<DlImage> dlImage;