ladybird/Userland/Libraries/LibGfx/ImageDecoder.h
Liav A 57e19a7e56 LibGfx: Re-structure the whole initialization pattern for image decoders
When trying to figure out the correct implementation, we now have a very
strong distinction on plugins that are well suited for sniffing, and
plugins that need a MIME type to be chosen.

Instead of having multiple calls to non-static virtual sniff methods for
each Image decoding plugin, we have 2 static methods for each
implementation:
1. The sniff method, which in contrast to the old method, gets a
    ReadonlyBytes parameter and ensures we can figure out the result
    with zero heap allocations for most implementations.
2. The create method, which just creates a new instance so we don't
    expose the constructor to everyone anymore.

In addition to that, we have a new virtual method called initialize,
which has a per-implementation initialization pattern to actually ensure
each implementation can construct a decoder object, and then have a
correct context being applied to it for the actual decoding.
2023-01-20 15:13:31 +00:00

69 lines
1.9 KiB
C++

/*
* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/ByteBuffer.h>
#include <AK/OwnPtr.h>
#include <AK/RefCounted.h>
#include <AK/RefPtr.h>
#include <LibGfx/Bitmap.h>
#include <LibGfx/Size.h>
namespace Gfx {
class Bitmap;
static constexpr size_t maximum_width_for_decoded_images = 16384;
static constexpr size_t maximum_height_for_decoded_images = 16384;
struct ImageFrameDescriptor {
RefPtr<Bitmap> image;
int duration { 0 };
};
class ImageDecoderPlugin {
public:
virtual ~ImageDecoderPlugin() = default;
virtual IntSize size() = 0;
virtual void set_volatile() = 0;
[[nodiscard]] virtual bool set_nonvolatile(bool& was_purged) = 0;
virtual bool initialize() = 0;
virtual bool is_animated() = 0;
virtual size_t loop_count() = 0;
virtual size_t frame_count() = 0;
virtual ErrorOr<ImageFrameDescriptor> frame(size_t index) = 0;
protected:
ImageDecoderPlugin() = default;
};
class ImageDecoder : public RefCounted<ImageDecoder> {
public:
static RefPtr<ImageDecoder> try_create_for_raw_bytes(ReadonlyBytes, Optional<DeprecatedString> mime_type = {});
~ImageDecoder() = default;
IntSize size() const { return m_plugin->size(); }
int width() const { return size().width(); }
int height() const { return size().height(); }
void set_volatile() { m_plugin->set_volatile(); }
[[nodiscard]] bool set_nonvolatile(bool& was_purged) { return m_plugin->set_nonvolatile(was_purged); }
bool is_animated() const { return m_plugin->is_animated(); }
size_t loop_count() const { return m_plugin->loop_count(); }
size_t frame_count() const { return m_plugin->frame_count(); }
ErrorOr<ImageFrameDescriptor> frame(size_t index) const { return m_plugin->frame(index); }
private:
explicit ImageDecoder(NonnullOwnPtr<ImageDecoderPlugin>);
NonnullOwnPtr<ImageDecoderPlugin> mutable m_plugin;
};
}