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LibGfx: Add some tile math from the spec to JPEG2000Loader.cpp

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Not used for anything yet, but will be used to figure out number of
codeblocks (and hence, size of tag trees) in a packet.
This commit is contained in:
Nico Weber 2025-01-03 10:10:02 -05:00
parent 1d6b0ebd18
commit e99fe94cfb
1 changed files with 88 additions and 0 deletions
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88
Userland/Libraries/LibGfx/ImageFormats/JPEG2000Loader.cpp
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@ -156,6 +156,13 @@ static ErrorOr<StartOfTilePart> read_start_of_tile_part(ReadonlyBytes data)
return sot; return sot;
} }
enum class SubBand {
HorizontalLowpassVerticalLowpass, // "LL" in spec
HorizontalHighpassVerticalLowpass, // "HL" in spec
HorizontalLowpassVerticalHighpass, // "LH" in spec
HorizontalHighpassVerticalHighpass, // "HH" in spec
};
// A.5.1 Image and tile size (SIZ) // A.5.1 Image and tile size (SIZ)
struct ImageAndTileSize { struct ImageAndTileSize {
// "Denotes capabilities that a decoder needs to properly decode the codestream." // "Denotes capabilities that a decoder needs to properly decode the codestream."
@ -202,6 +209,87 @@ struct ImageAndTileSize {
u8 vertical_separation { 0 }; // "YRsiz" in spec. u8 vertical_separation { 0 }; // "YRsiz" in spec.
}; };
Vector<ComponentInformation> components; Vector<ComponentInformation> components;
// (B-5)
u32 number_of_x_tiles() const { return ceil_div(width - x_offset, tile_width); }
u32 number_of_y_tiles() const { return ceil_div(height - y_offset, tile_height); }
IntPoint tile_2d_index_from_1d_index(u32 tile_index) const
{
// (B-6)
return { tile_index % number_of_x_tiles(), tile_index / number_of_x_tiles() };
}
IntRect reference_grid_coordinates_for_tile(IntPoint tile_2d_index) const
{
int p = tile_2d_index.x();
int q = tile_2d_index.y();
int tx0 = max(tile_x_offset + p * tile_width, x_offset); // (B-7)
int ty0 = max(tile_y_offset + q * tile_height, y_offset); // (B-8)
int tx1 = min(tile_x_offset + (p + 1) * tile_width, width); // (B-9)
int ty1 = min(tile_y_offset + (q + 1) * tile_height, height); // (B-10)
return { tx0, ty0, tx1 - tx0, ty1 - ty0 }; // (B-11)
}
IntRect reference_grid_coordinates_for_tile_component(IntRect tile_rect, int component_index) const
{
// (B-12)
int tcx0 = ceil_div(tile_rect.left(), static_cast<int>(components[component_index].horizontal_separation));
int tcx1 = ceil_div(tile_rect.right(), static_cast<int>(components[component_index].horizontal_separation));
int tcy0 = ceil_div(tile_rect.top(), static_cast<int>(components[component_index].vertical_separation));
int tcy1 = ceil_div(tile_rect.bottom(), static_cast<int>(components[component_index].vertical_separation));
return { tcx0, tcy0, tcx1 - tcx0, tcy1 - tcy0 }; // (B-13)
}
IntRect reference_grid_coordinates_for_tile_component(IntPoint tile_2d_index, int component_index) const
{
auto tile_rect = reference_grid_coordinates_for_tile(tile_2d_index);
return reference_grid_coordinates_for_tile_component(tile_rect, component_index);
}
IntRect reference_grid_coordinates_for_ll_band(IntRect tile_rect, int component_index, int r, int N_L) const
{
// B.5
// (B-14)
auto component_rect = reference_grid_coordinates_for_tile_component(tile_rect, component_index);
int denominator = 1 << (N_L - r);
int trx0 = ceil_div(component_rect.left(), denominator);
int try0 = ceil_div(component_rect.top(), denominator);
int trx1 = ceil_div(component_rect.right(), denominator);
int try1 = ceil_div(component_rect.bottom(), denominator);
return { trx0, try0, trx1 - trx0, try1 - try0 };
}
IntRect reference_grid_coordinates_for_sub_band(IntRect tile_rect, int component_index, int n_b, SubBand sub_band) const
{
// B.5
// Table B.1 – Quantities (xob, yob) for sub-band b
int xob = 0;
int yob = 0;
if (sub_band == SubBand::HorizontalHighpassVerticalLowpass || sub_band == SubBand::HorizontalHighpassVerticalHighpass)
xob = 1;
if (sub_band == SubBand::HorizontalLowpassVerticalHighpass || sub_band == SubBand::HorizontalHighpassVerticalHighpass)
yob = 1;
VERIFY(n_b >= 1 || (n_b == 0 && sub_band == SubBand::HorizontalLowpassVerticalLowpass));
int o_scale = 1 << (n_b - 1);
// (B-15)
auto component_rect = reference_grid_coordinates_for_tile_component(tile_rect, component_index);
int denominator = 1 << n_b;
int tbx0 = ceil_div(component_rect.left() - o_scale * xob, denominator);
int tby0 = ceil_div(component_rect.top() - o_scale * yob, denominator);
int tbx1 = ceil_div(component_rect.right() - o_scale * xob, denominator);
int tby1 = ceil_div(component_rect.bottom() - o_scale * yob, denominator);
return { tbx0, tby0, tbx1 - tbx0, tby1 - tby0 };
}
IntRect reference_grid_coordinates_for_sub_band(IntPoint tile_2d_index, int component_index, int n_b, SubBand sub_band) const
{
auto tile_rect = reference_grid_coordinates_for_tile(tile_2d_index);
return reference_grid_coordinates_for_sub_band(tile_rect, component_index, n_b, sub_band);
}
}; };
static ErrorOr<ImageAndTileSize> read_image_and_tile_size(ReadonlyBytes data) static ErrorOr<ImageAndTileSize> read_image_and_tile_size(ReadonlyBytes data)