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LibGfx: Re-structure the whole initialization pattern for image decoders

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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.
This commit is contained in:
Liav A 2023-01-20 10:13:14 +02:00 • committed by Linus Groh
parent 6e6999ce57
commit 57e19a7e56
33 changed files with 493 additions and 206 deletions
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44
Userland/Libraries/LibGfx/ICOLoader.cpp
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@ -136,7 +136,7 @@ static bool load_ico_directory(ICOLoadingContext& context)
return true;
}
static bool load_ico_bitmap(ICOLoadingContext& context, Optional<size_t> index)
bool ICOImageDecoderPlugin::load_ico_bitmap(ICOLoadingContext& context, Optional<size_t> index)
{
if (context.state < ICOLoadingContext::State::DirectoryDecoded) {
if (!load_ico_directory(context)) {
@ -153,20 +153,25 @@ static bool load_ico_bitmap(ICOLoadingContext& context, Optional<size_t> index)
}
ICOImageDescriptor& desc = context.images[real_index];
PNGImageDecoderPlugin png_decoder(context.data + desc.offset, desc.size);
if (png_decoder.sniff()) {
auto decoded_png_frame = png_decoder.frame(0);
if (decoded_png_frame.is_error() || !decoded_png_frame.value().image) {
dbgln_if(ICO_DEBUG, "load_ico_bitmap: failed to load PNG encoded image index: {}", real_index);
return false;
if (PNGImageDecoderPlugin::sniff({ context.data + desc.offset, desc.size }).release_value_but_fixme_should_propagate_errors()) {
auto png_decoder = PNGImageDecoderPlugin::create({ context.data + desc.offset, desc.size }).release_value_but_fixme_should_propagate_errors();
if (png_decoder->initialize()) {
auto decoded_png_frame = png_decoder->frame(0);
if (decoded_png_frame.is_error() || !decoded_png_frame.value().image) {
dbgln_if(ICO_DEBUG, "load_ico_bitmap: failed to load PNG encoded image index: {}", real_index);
return false;
}
desc.bitmap = decoded_png_frame.value().image;
return true;
}
desc.bitmap = decoded_png_frame.value().image;
return true;
return false;
} else {
BMPImageDecoderPlugin bmp_decoder(context.data + desc.offset, desc.size, true);
if (bmp_decoder.sniff_dib()) {
auto decoded_bmp_frame = bmp_decoder.frame(0);
auto bmp_decoder = BMPImageDecoderPlugin::create_as_included_in_ico({}, { context.data + desc.offset, desc.size }).release_value_but_fixme_should_propagate_errors();
// NOTE: We don't initialize a BMP decoder in the usual way, but rather
// we just create an object and try to sniff for a frame when it's included
// inside an ICO image.
if (bmp_decoder->sniff_dib()) {
auto decoded_bmp_frame = bmp_decoder->frame(0);
if (decoded_bmp_frame.is_error() || !decoded_bmp_frame.value().image) {
dbgln_if(ICO_DEBUG, "load_ico_bitmap: failed to load BMP encoded image index: {}", real_index);
return false;
@ -180,6 +185,17 @@ static bool load_ico_bitmap(ICOLoadingContext& context, Optional<size_t> index)
}
}
ErrorOr<bool> ICOImageDecoderPlugin::sniff(ReadonlyBytes data)
{
InputMemoryStream stream { { data.data(), data.size() } };
return decode_ico_header(stream).has_value();
}
ErrorOr<NonnullOwnPtr<ImageDecoderPlugin>> ICOImageDecoderPlugin::create(ReadonlyBytes data)
{
return adopt_nonnull_own_or_enomem(new (nothrow) ICOImageDecoderPlugin(data.data(), data.size()));
}
ICOImageDecoderPlugin::ICOImageDecoderPlugin(u8 const* data, size_t size)
{
m_context = make<ICOLoadingContext>();
@ -219,7 +235,7 @@ bool ICOImageDecoderPlugin::set_nonvolatile(bool& was_purged)
return m_context->images[0].bitmap->set_nonvolatile(was_purged);
}
bool ICOImageDecoderPlugin::sniff()
bool ICOImageDecoderPlugin::initialize()
{
InputMemoryStream stream { { m_context->data, m_context->data_size } };
return decode_ico_header(stream).has_value();