LibGfx: Improve ImageDecoder construction

Previously, ImageDecoder::create() would return a NonnullRefPtr and
could not "fail", although the returned decoder may be "invalid" which
you then had to check anyway.

The new interface looks like this:

    static RefPtr<Gfx::ImageDecoder> try_create(ReadonlyBytes);

This simplifies ImageDecoder since it no longer has to worry about its
validity. Client code gets slightly clearer as well.

1 files changed, 8 insertions, 2 deletions

diff --git a/Userland/Libraries/LibWeb/Loader/FrameLoader.cpp b/Userland/Libraries/LibWeb/Loader/FrameLoader.cpp
index 6db5f9b13c..1fc5755223 100644
--- a/Userland/Libraries/LibWeb/Loader/FrameLoader.cpp
+++ b/Userland/Libraries/LibWeb/Loader/FrameLoader.cpp
@@ -68,7 +68,9 @@ static bool build_text_document(DOM::Document& document, const ByteBuffer& data)
 
 static bool build_image_document(DOM::Document& document, const ByteBuffer& data)
 {
-    auto image_decoder = Gfx::ImageDecoder::create(data.data(), data.size());
+    auto image_decoder = Gfx::ImageDecoder::try_create(data.bytes());
+    if (!image_decoder)
+        return false;
     auto bitmap = image_decoder->bitmap();
     if (!bitmap)
         return false;
@@ -164,7 +166,11 @@ bool FrameLoader::load(const LoadRequest& request, Type type)
             favicon_url,
             [this, favicon_url](auto data, auto&, auto) {
                 dbgln("Favicon downloaded, {} bytes from {}", data.size(), favicon_url);
-                auto decoder = Gfx::ImageDecoder::create(data.data(), data.size());
+                auto decoder = Gfx::ImageDecoder::try_create(data);
+                if (!decoder) {
+                    dbgln("No image decoder plugin for favicon {}", favicon_url);
+                    return;
+                }
                 auto bitmap = decoder->bitmap();
                 if (!bitmap) {
                     dbgln("Could not decode favicon {}", favicon_url);