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LibGfx: Saner memory usage of indexed bitmaps

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Indexed bitmaps used to allocate four times the required amount of memory.

Also, we should acknowledge that the underlying data is not always RGBA32,
and instead cast it only when the true type is known.
This commit is contained in:
Ben Wiederhake 2020-09-06 23:59:20 +02:00 • committed by Andreas Kling
parent d6673b384e
commit 9c3a33762b
5 changed files with 89 additions and 86 deletions
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43
Libraries/LibGfx/Bitmap.cpp
View file

@ -44,16 +44,34 @@
namespace Gfx {
static bool size_would_overflow(BitmapFormat, const IntSize& size)
size_t Bitmap::minimum_pitch(size_t width, BitmapFormat format)
{
size_t element_size;
switch (determine_storage_format(format)) {
case StorageFormat::Indexed8:
element_size = 1;
break;
case StorageFormat::RGB32:
case StorageFormat::RGBA32:
element_size = 4;
break;
default:
ASSERT_NOT_REACHED();
}
return width * element_size;
}
static bool size_would_overflow(BitmapFormat format, const IntSize& size)
{
if (size.width() < 0 || size.height() < 0)
return true;
// This check is a bit arbitrary, but should protect us from most shenanigans:
if (size.width() >= 32768 || size.height() >= 32768)
return true;
// This check is absolutely necessary. Note that Bitmap::Bitmap always stores
// data as RGBA32 internally, so currently we ignore the indicated format.
return Checked<size_t>::multiplication_would_overflow(size.width(), size.height(), sizeof(RGBA32));
// In contrast, this check is absolutely necessary:
size_t pitch = Bitmap::minimum_pitch(size.width(), format);
return Checked<size_t>::multiplication_would_overflow(pitch, size.height());
}
RefPtr<Bitmap> Bitmap::create(BitmapFormat format, const IntSize& size)
@ -72,7 +90,7 @@ RefPtr<Bitmap> Bitmap::create_purgeable(BitmapFormat format, const IntSize& size
Bitmap::Bitmap(BitmapFormat format, const IntSize& size, Purgeable purgeable)
: m_size(size)
, m_pitch(round_up_to_power_of_two(size.width() * sizeof(RGBA32), 16))
, m_pitch(minimum_pitch(size.width(), format))
, m_format(format)
, m_purgeable(purgeable == Purgeable::Yes)
{
@ -81,10 +99,10 @@ Bitmap::Bitmap(BitmapFormat format, const IntSize& size, Purgeable purgeable)
allocate_palette_from_format(format, {});
#ifdef __serenity__
int map_flags = purgeable == Purgeable::Yes ? (MAP_PURGEABLE | MAP_PRIVATE) : (MAP_ANONYMOUS | MAP_PRIVATE);
m_data = (RGBA32*)mmap_with_name(nullptr, size_in_bytes(), PROT_READ | PROT_WRITE, map_flags, 0, 0, String::format("GraphicsBitmap [%dx%d]", width(), height()).characters());
m_data = mmap_with_name(nullptr, size_in_bytes(), PROT_READ | PROT_WRITE, map_flags, 0, 0, String::format("GraphicsBitmap [%dx%d]", width(), height()).characters());
#else
int map_flags = (MAP_ANONYMOUS | MAP_PRIVATE);
m_data = (RGBA32*)mmap(nullptr, size_in_bytes(), PROT_READ | PROT_WRITE, map_flags, 0, 0);
m_data = mmap(nullptr, size_in_bytes(), PROT_READ | PROT_WRITE, map_flags, 0, 0);
#endif
if (m_data == MAP_FAILED) {
perror("mmap");
@ -94,7 +112,7 @@ Bitmap::Bitmap(BitmapFormat format, const IntSize& size, Purgeable purgeable)
m_needs_munmap = true;
}
RefPtr<Bitmap> Bitmap::create_wrapper(BitmapFormat format, const IntSize& size, size_t pitch, RGBA32* data)
RefPtr<Bitmap> Bitmap::create_wrapper(BitmapFormat format, const IntSize& size, size_t pitch, void* data)
{
if (size_would_overflow(format, size))
return nullptr;
@ -112,13 +130,16 @@ RefPtr<Bitmap> Bitmap::load_from_file(const StringView& path)
return nullptr;
}
Bitmap::Bitmap(BitmapFormat format, const IntSize& size, size_t pitch, RGBA32* data)
Bitmap::Bitmap(BitmapFormat format, const IntSize& size, size_t pitch, void* data)
: m_size(size)
, m_data(data)
, m_pitch(pitch)
, m_format(format)
{
ASSERT(pitch >= minimum_pitch(size.width(), format));
ASSERT(!size_would_overflow(format, size));
// FIXME: assert that `data` is actually long enough!
allocate_palette_from_format(format, {});
}
@ -138,8 +159,8 @@ RefPtr<Bitmap> Bitmap::create_with_shared_buffer(BitmapFormat format, NonnullRef
Bitmap::Bitmap(BitmapFormat format, NonnullRefPtr<SharedBuffer>&& shared_buffer, const IntSize& size, const Vector<RGBA32>& palette)
: m_size(size)
, m_data((RGBA32*)shared_buffer->data())
, m_pitch(round_up_to_power_of_two(size.width() * sizeof(RGBA32), 16))
, m_data(shared_buffer->data())
, m_pitch(minimum_pitch(size.width(), format))
, m_format(format)
, m_shared_buffer(move(shared_buffer))
{