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LibGfx: Allow creating a Gfx::Bitmap backed by an anonymous file

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Gfx::Bitmap::create_with_anon_fd() creates such a Bitmap, and also
optionally takes ownership of the file, making sure to close() it
on destruction.
This commit is contained in:
Andreas Kling 2021-01-15 12:09:37 +01:00
parent fb4993f067
commit 4d97b955e6
2 changed files with 50 additions and 0 deletions
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40
Userland/Libraries/LibGfx/Bitmap.cpp
View file

@ -182,6 +182,29 @@ static bool check_size(const IntSize& size, BitmapFormat format, unsigned actual
return true;
}
RefPtr<Bitmap> Bitmap::create_with_anon_fd(BitmapFormat format, int anon_fd, const IntSize& size, ShouldCloseAnonymousFile should_close_anon_fd)
{
if (size_would_overflow(format, size))
return nullptr;
const auto pitch = minimum_pitch(size.width(), format);
const auto data_size_in_bytes = size_in_bytes(pitch, size.height());
auto* data = mmap(nullptr, round_up_to_power_of_two(data_size_in_bytes, PAGE_SIZE), PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, anon_fd, 0);
if (data == MAP_FAILED) {
perror("mmap");
return nullptr;
}
if (should_close_anon_fd == ShouldCloseAnonymousFile::Yes) {
int rc = close(anon_fd);
ASSERT(rc == 0);
anon_fd = -1;
}
return adopt(*new Bitmap(format, anon_fd, size, data));
}
RefPtr<Bitmap> Bitmap::create_with_shared_buffer(BitmapFormat format, NonnullRefPtr<SharedBuffer>&& shared_buffer, const IntSize& size, const Vector<RGBA32>& palette)
{
if (size_would_overflow(format, size))
@ -293,6 +316,19 @@ Bitmap::Bitmap(BitmapFormat format, NonnullRefPtr<SharedBuffer>&& shared_buffer,
allocate_palette_from_format(m_format, palette);
}
Bitmap::Bitmap(BitmapFormat format, int anon_fd, const IntSize& size, void* data)
: m_size(size)
, m_data(data)
, m_pitch(minimum_pitch(size.width(), format))
, m_format(format)
, m_needs_munmap(true)
, m_purgeable(true)
, m_anon_fd(anon_fd)
{
ASSERT(!is_indexed());
ASSERT(!size_would_overflow(format, size));
}
RefPtr<Gfx::Bitmap> Bitmap::clone() const
{
RefPtr<Gfx::Bitmap> new_bitmap {};
@ -378,6 +414,10 @@ Bitmap::~Bitmap()
int rc = munmap(m_data, size_in_bytes());
ASSERT(rc == 0);
}
if (m_anon_fd != -1) {
int rc = close(m_anon_fd);
ASSERT(rc == 0);
}
m_data = nullptr;
delete[] m_palette;
}

10
Userland/Libraries/LibGfx/Bitmap.h
View file

@ -88,11 +88,17 @@ enum RotationDirection {
class Bitmap : public RefCounted<Bitmap> {
public:
enum class ShouldCloseAnonymousFile {
No,
Yes,
};
static RefPtr<Bitmap> create(BitmapFormat, const IntSize&);
static RefPtr<Bitmap> create_shareable(BitmapFormat, const IntSize&);
static RefPtr<Bitmap> create_purgeable(BitmapFormat, const IntSize&);
static RefPtr<Bitmap> create_wrapper(BitmapFormat, const IntSize&, size_t pitch, void*);
static RefPtr<Bitmap> load_from_file(const StringView& path);
static RefPtr<Bitmap> create_with_anon_fd(BitmapFormat, int anon_fd, const IntSize&, ShouldCloseAnonymousFile);
static RefPtr<Bitmap> create_with_shared_buffer(BitmapFormat, NonnullRefPtr<SharedBuffer>&&, const IntSize&);
static RefPtr<Bitmap> create_with_shared_buffer(BitmapFormat, NonnullRefPtr<SharedBuffer>&&, const IntSize&, const Vector<RGBA32>& palette);
static RefPtr<Bitmap> create_from_serialized_byte_buffer(ByteBuffer&& buffer);
@ -224,6 +230,8 @@ public:
void set_volatile();
[[nodiscard]] bool set_nonvolatile();
int anon_fd() const { return m_anon_fd; }
private:
enum class Purgeable {
No,
@ -232,6 +240,7 @@ private:
Bitmap(BitmapFormat, const IntSize&, Purgeable, const BackingStore&);
Bitmap(BitmapFormat, const IntSize&, size_t pitch, void*);
Bitmap(BitmapFormat, NonnullRefPtr<SharedBuffer>&&, const IntSize&, const Vector<RGBA32>& palette);
Bitmap(BitmapFormat, int anon_fd, const IntSize&, void*);
static Optional<BackingStore> allocate_backing_store(BitmapFormat, const IntSize&, Purgeable);
@ -246,6 +255,7 @@ private:
bool m_purgeable { false };
bool m_volatile { false };
RefPtr<SharedBuffer> m_shared_buffer;
int m_anon_fd { -1 };
};
inline u8* Bitmap::scanline_u8(int y)