ladybird/Libraries/LibGfx/BitmapSequence.cpp
Andreas Kling 4f684bb4c9 LibGfx: Don't create AnonymousBuffer for each bitmap in BitmapSequence
When decoding a BitmapSequence received over IPC, we were creating an
AnonymousBuffer for each bitmap and then making a Gfx::Bitmap wrapper
around it.

This was unnecessarily using up one file descriptor per bitmap, and also
wasting a lot of memory for small bitmaps since we always allocated at
least one VM page.

This patch changes the BitmapSequence decoder to use malloc memory
instead, saving file descriptors and using less memory overall.
2025-10-24 08:52:53 +02:00

143 lines
4.4 KiB
C++

/*
* Copyright (c) 2024, Zachary Huang <zack466@gmail.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Checked.h>
#include <LibCore/AnonymousBuffer.h>
#include <LibGfx/Bitmap.h>
#include <LibGfx/BitmapSequence.h>
#include <LibGfx/Size.h>
#include <LibIPC/Decoder.h>
#include <LibIPC/Encoder.h>
namespace Gfx {
static BitmapMetadata get_metadata(Bitmap const& bitmap)
{
return BitmapMetadata { .format = bitmap.format(), .alpha_type = bitmap.alpha_type(), .size = bitmap.size(), .size_in_bytes = bitmap.size_in_bytes() };
}
}
namespace IPC {
template<>
ErrorOr<void> encode(Encoder& encoder, Gfx::BitmapMetadata const& metadata)
{
TRY(encoder.encode(static_cast<u32>(metadata.format)));
TRY(encoder.encode(static_cast<u32>(metadata.alpha_type)));
TRY(encoder.encode(metadata.size_in_bytes));
TRY(encoder.encode(metadata.size));
return {};
}
template<>
ErrorOr<Gfx::BitmapMetadata> decode(Decoder& decoder)
{
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::BitmapSequence format");
auto format = static_cast<Gfx::BitmapFormat>(raw_bitmap_format);
auto raw_alpha_type = TRY(decoder.decode<u32>());
if (!Gfx::is_valid_alpha_type(raw_alpha_type))
return Error::from_string_literal("IPC: Invalid Gfx::BitmapSequence alpha type");
auto alpha_type = static_cast<Gfx::AlphaType>(raw_alpha_type);
auto size_in_bytes = TRY(decoder.decode<size_t>());
auto size = TRY(decoder.decode<Gfx::IntSize>());
return Gfx::BitmapMetadata { format, alpha_type, size, size_in_bytes };
}
template<>
ErrorOr<void> encode(Encoder& encoder, Gfx::BitmapSequence const& bitmap_sequence)
{
auto const& bitmaps = bitmap_sequence.bitmaps;
Vector<Optional<Gfx::BitmapMetadata>> metadata;
metadata.ensure_capacity(bitmaps.size());
size_t total_buffer_size = 0;
for (auto const& bitmap_option : bitmaps) {
Optional<Gfx::BitmapMetadata> data = {};
if (bitmap_option) {
data = get_metadata(*bitmap_option);
total_buffer_size += data->size_in_bytes;
}
metadata.unchecked_append(data);
}
TRY(encoder.encode(metadata));
TRY(encoder.encode(total_buffer_size));
if (total_buffer_size > 0) {
// collate all of the bitmap data into one contiguous buffer
auto collated_buffer = TRY(Core::AnonymousBuffer::create_with_size(total_buffer_size));
Bytes buffer_bytes = { collated_buffer.data<u8>(), collated_buffer.size() };
size_t write_offset = 0;
for (auto const& bitmap : bitmaps) {
if (bitmap) {
buffer_bytes.overwrite(write_offset, bitmap->scanline(0), bitmap->size_in_bytes());
write_offset += bitmap->size_in_bytes();
}
}
TRY(encoder.encode(collated_buffer));
}
return {};
}
template<>
ErrorOr<Gfx::BitmapSequence> decode(Decoder& decoder)
{
auto metadata_list = TRY(decoder.decode<Vector<Optional<Gfx::BitmapMetadata>>>());
auto total_buffer_size = TRY(decoder.decode<size_t>());
Core::AnonymousBuffer collated_buffer;
if (total_buffer_size > 0)
collated_buffer = TRY(decoder.decode<Core::AnonymousBuffer>());
Gfx::BitmapSequence result = {};
auto& bitmaps = result.bitmaps;
TRY(bitmaps.try_ensure_capacity(metadata_list.size()));
ReadonlyBytes bytes = ReadonlyBytes(collated_buffer.data<u8>(), collated_buffer.size());
size_t bytes_read = 0;
// sequentially read each valid bitmap's data from the collated buffer
for (auto const& metadata_option : metadata_list) {
RefPtr<Gfx::Bitmap> bitmap;
if (metadata_option.has_value()) {
auto metadata = metadata_option.value();
size_t size_in_bytes = metadata.size_in_bytes;
Checked<size_t> size_check = bytes_read;
size_check += size_in_bytes;
if (size_check.has_overflow() || size_check.value() > bytes.size())
return Error::from_string_literal("IPC: Invalid Gfx::BitmapSequence buffer data");
auto slice = bytes.slice(bytes_read, size_in_bytes);
bytes_read += size_in_bytes;
bitmap = TRY(Gfx::Bitmap::create_with_raw_data(metadata.format, metadata.alpha_type, slice, metadata.size));
}
bitmaps.append(bitmap);
}
return result;
}
}