LibGfx: Add ability to pass NonnullRefPtr<Gfx::Bitmap> over IPC

Author: https://github.com/awesomekling
Commit: https://github.com/LadybirdBrowser/ladybird/commit/9f1a853cc83
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/688
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/tcl3

Userland/Libraries/LibGfx/Bitmap.cpp

@@ -17,6 +17,9 @@
 #include <LibGfx/Bitmap.h>
 #include <LibGfx/ImageFormats/ImageDecoder.h>
 #include <LibGfx/ShareableBitmap.h>
+#include <LibIPC/Decoder.h>
+#include <LibIPC/Encoder.h>
+#include <LibIPC/File.h>
 #include <errno.h>
 
 namespace Gfx {
@@ -435,3 +438,42 @@ bool Bitmap::visually_equals(Bitmap const& other) const
 }
 
 }
+
+namespace IPC {
+
+template<>
+ErrorOr<void> encode(Encoder& encoder, AK::NonnullRefPtr<Gfx::Bitmap> const& bitmap)
+{
+    Core::AnonymousBuffer buffer;
+    if (bitmap->anonymous_buffer().is_valid()) {
+        buffer = bitmap->anonymous_buffer();
+    } else {
+        buffer = MUST(Core::AnonymousBuffer::create_with_size(bitmap->size_in_bytes()));
+        memcpy(buffer.data<void>(), bitmap->scanline(0), bitmap->size_in_bytes());
+    }
+    TRY(encoder.encode(TRY(IPC::File::clone_fd(buffer.fd()))));
+    TRY(encoder.encode(static_cast<u32>(bitmap->format())));
+    TRY(encoder.encode(bitmap->size_in_bytes()));
+    TRY(encoder.encode(bitmap->pitch()));
+    TRY(encoder.encode(bitmap->size()));
+    return {};
+}
+
+template<>
+ErrorOr<AK::NonnullRefPtr<Gfx::Bitmap>> decode(Decoder& decoder)
+{
+    auto anon_file = TRY(decoder.decode<IPC::File>());
+    auto raw_bitmap_format = TRY(decoder.decode<u32>());
+    if (!Gfx::is_valid_bitmap_format(raw_bitmap_format))
+        return Error::from_string_literal("IPC: Invalid Gfx::ShareableBitmap format");
+    auto bitmap_format = static_cast<Gfx::BitmapFormat>(raw_bitmap_format);
+    auto size_in_bytes = TRY(decoder.decode<size_t>());
+    auto pitch = TRY(decoder.decode<size_t>());
+    auto size = TRY(decoder.decode<Gfx::IntSize>());
+    auto* data = TRY(Core::System::mmap(nullptr, round_up_to_power_of_two(size_in_bytes, PAGE_SIZE), PROT_READ | PROT_WRITE, MAP_SHARED, anon_file.fd(), 0));
+    return Gfx::Bitmap::create_wrapper(bitmap_format, size, pitch, data, [data, size_in_bytes] {
+        MUST(Core::System::munmap(data, size_in_bytes));
+    });
+}
+
+}

Userland/Libraries/LibGfx/Bitmap.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2023, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2018-2024, Andreas Kling <kling@serenityos.org>
  * Copyright (c) 2022, Timothy Slater <tslater2006@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
@@ -15,6 +15,7 @@
 #include <LibGfx/Color.h>
 #include <LibGfx/Forward.h>
 #include <LibGfx/Rect.h>
+#include <LibIPC/Forward.h>
 
 namespace Gfx {
 
@@ -295,3 +296,13 @@ ALWAYS_INLINE void Bitmap::set_pixel(int x, int y, Color color)
 }
 
 }
+
+namespace IPC {
+
+template<>
+ErrorOr<void> encode(Encoder&, AK::NonnullRefPtr<Gfx::Bitmap> const&);
+
+template<>
+ErrorOr<AK::NonnullRefPtr<Gfx::Bitmap>> decode(Decoder&);
+
+}