| // Copyright 2020 The Wuffs Authors. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| pub status "#bad header" |
| pub status "#unsupported PNG file" |
| |
| pub const DECODER_WORKBUF_LEN_MAX_INCL_WORST_CASE : base.u64 = 0 |
| |
| pub struct decoder? implements base.image_decoder( |
| // The 0x00FF_FFFF limit is arbitrary (the PNG spec says 0x7FFF_FFFF) but |
| // it means that (width * height * bytes_per_pixel) doesn't overflow. |
| width : base.u32[..= 0x00FF_FFFF], |
| height : base.u32[..= 0x00FF_FFFF], |
| |
| // bytes_per_row doesn't include the 1 byte for the per-row filter. |
| bytes_per_row : base.u64[..= 0x07FF_FFF8], |
| |
| workbuf_length : base.u64[..= 0x0007_FFFF_F100_0007], |
| |
| // Call sequence states: |
| // - 0x00: initial state. |
| // - 0x03: image config decoded. |
| // - 0x04: frame config decoded. |
| // - 0xFF: end-of-data, usually after (the non-animated) frame decoded. |
| // |
| // State transitions: |
| // |
| // - 0x00 -> 0x03: via DIC |
| // - 0x00 -> 0x04: via DFC with implicit DIC |
| // - 0x00 -> 0xFF: via DF with implicit DIC and DFC |
| // |
| // - 0x03 -> 0x04: via DFC |
| // - 0x03 -> 0xFF: via DF with implicit DFC |
| // |
| // - 0x04 -> 0xFF: via DFC |
| // - 0x04 -> 0xFF: via DF |
| // |
| // - ???? -> 0x03: via RF for ???? > 0x00 |
| // |
| // Where: |
| // - DF is decode_frame |
| // - DFC is decode_frame_config, implicit means nullptr args.dst |
| // - DIC is decode_image_config, implicit means nullptr args.dst |
| // - RF is restart_frame |
| call_sequence : base.u8, |
| |
| depth : base.u8[..= 16], |
| |
| src_pixfmt : base.u32, |
| |
| chunk_length : base.u32, |
| chunk_type : base.u32, |
| |
| frame_config_io_position : base.u64, |
| |
| swizzler : base.pixel_swizzler, |
| util : base.utility, |
| )( |
| ) |
| |
| pub func decoder.set_quirk_enabled!(quirk: base.u32, enabled: base.bool) { |
| } |
| |
| pub func decoder.decode_image_config?(dst: nptr base.image_config, src: base.io_reader) { |
| var magic : base.u64 |
| var a32 : base.u32 |
| var a8 : base.u8 |
| var dst_pixfmt : base.u32 |
| |
| if this.call_sequence <> 0 { |
| return base."#bad call sequence" |
| } |
| |
| magic = args.src.read_u64le?() |
| if magic <> '\x89PNG\x0D\x0A\x1A\x0A'le { |
| return "#bad header" |
| } |
| |
| magic = args.src.read_u64le?() |
| if magic <> '\x00\x00\x00\x0DIHDR'le { |
| return "#bad header" |
| } |
| |
| a32 = args.src.read_u32be?() |
| if a32 >= 0x8000_0000 { |
| return "#bad header" |
| } else if a32 >= 0x0100_0000 { |
| return "#unsupported PNG file" |
| } |
| this.width = a32 |
| |
| a32 = args.src.read_u32be?() |
| if a32 >= 0x8000_0000 { |
| return "#bad header" |
| } else if a32 >= 0x0100_0000 { |
| return "#unsupported PNG file" |
| } |
| this.height = a32 |
| |
| // Depth. |
| a8 = args.src.read_u8?() |
| if a8 > 16 { |
| return "#bad header" |
| } |
| this.depth = a8 |
| |
| // Color. |
| a8 = args.src.read_u8?() |
| if a8 == 0 { |
| dst_pixfmt = base.PIXEL_FORMAT__Y |
| this.src_pixfmt = base.PIXEL_FORMAT__Y |
| if this.depth == 8 { |
| this.bytes_per_row = (this.width as base.u64) * 1 |
| } else { |
| return "#unsupported PNG file" |
| } |
| } else if a8 == 2 { |
| dst_pixfmt = base.PIXEL_FORMAT__BGR |
| this.src_pixfmt = base.PIXEL_FORMAT__RGB |
| if this.depth == 8 { |
| this.bytes_per_row = (this.width as base.u64) * 3 |
| } else { |
| return "#unsupported PNG file" |
| } |
| } else { |
| return "#unsupported PNG file" |
| } |
| this.workbuf_length = (this.height as base.u64) * (1 + this.bytes_per_row) |
| |
| // Compression. |
| a8 = args.src.read_u8?() |
| if a8 <> 0 { |
| return "#bad header" |
| } |
| |
| // Filter. |
| a8 = args.src.read_u8?() |
| if a8 <> 0 { |
| return "#bad header" |
| } |
| |
| // Interlace. |
| a8 = args.src.read_u8?() |
| if a8 == 0 { |
| // No-op. |
| } else if a8 == 1 { |
| return "#unsupported PNG file" |
| } else { |
| return "#bad header" |
| } |
| |
| // TODO: verify CRC-32 checksum. |
| args.src.skip_u32?(n: 4) |
| |
| // Read up until an IDAT chunk. |
| while true { |
| this.chunk_length = args.src.read_u32be?() |
| this.chunk_type = args.src.read_u32le?() |
| if this.chunk_type == 'IDAT'le { |
| break |
| } |
| args.src.skip_u32?(n: this.chunk_length) |
| // TODO: verify CRC-32 checksum. |
| args.src.skip_u32?(n: 4) |
| } endwhile |
| |
| this.frame_config_io_position = args.src.position() |
| |
| if args.dst <> nullptr { |
| args.dst.set!( |
| pixfmt: dst_pixfmt, |
| pixsub: 0, |
| width: this.width, |
| height: this.height, |
| first_frame_io_position: this.frame_config_io_position, |
| first_frame_is_opaque: false) |
| } |
| |
| this.call_sequence = 3 |
| } |
| |
| pub func decoder.decode_frame_config?(dst: nptr base.frame_config, src: base.io_reader) { |
| if this.call_sequence < 3 { |
| this.decode_image_config?(dst: nullptr, src: args.src) |
| } else if this.call_sequence == 3 { |
| if this.frame_config_io_position <> args.src.position() { |
| return base."#bad restart" |
| } |
| } else if this.call_sequence == 4 { |
| this.call_sequence = 0xFF |
| return base."@end of data" |
| } else { |
| return base."@end of data" |
| } |
| |
| if args.dst <> nullptr { |
| args.dst.set!(bounds: this.util.make_rect_ie_u32( |
| min_incl_x: 0, |
| min_incl_y: 0, |
| max_excl_x: this.width, |
| max_excl_y: this.height), |
| duration: 0, |
| index: 0, |
| io_position: this.frame_config_io_position, |
| disposal: 0, |
| opaque_within_bounds: false, |
| overwrite_instead_of_blend: false, |
| background_color: 0x0000_0000) |
| } |
| |
| this.call_sequence = 4 |
| } |
| |
| pub func decoder.decode_frame?(dst: ptr base.pixel_buffer, src: base.io_reader, blend: base.pixel_blend, workbuf: slice base.u8, opts: nptr base.decode_frame_options) { |
| if this.call_sequence < 4 { |
| this.decode_frame_config?(dst: nullptr, src: args.src) |
| } else if this.call_sequence == 4 { |
| // No-op. |
| } else { |
| return base."@end of data" |
| } |
| |
| while true { |
| io_limit (io: args.src, limit: this.chunk_length as base.u64) { |
| } |
| break |
| } endwhile |
| |
| this.call_sequence = 0xFF |
| } |
| |
| pub func decoder.frame_dirty_rect() base.rect_ie_u32 { |
| return this.util.make_rect_ie_u32( |
| min_incl_x: 0, |
| min_incl_y: 0, |
| max_excl_x: this.width, |
| max_excl_y: this.height) |
| } |
| |
| pub func decoder.num_animation_loops() base.u32 { |
| return 0 |
| } |
| |
| pub func decoder.num_decoded_frame_configs() base.u64 { |
| if this.call_sequence > 3 { |
| return 1 |
| } |
| return 0 |
| } |
| |
| pub func decoder.num_decoded_frames() base.u64 { |
| if this.call_sequence > 4 { |
| return 1 |
| } |
| return 0 |
| } |
| |
| pub func decoder.restart_frame!(index: base.u64, io_position: base.u64) base.status { |
| if this.call_sequence < 3 { |
| return base."#bad call sequence" |
| } |
| if args.index <> 0 { |
| return base."#bad argument" |
| } |
| this.call_sequence = 3 |
| this.frame_config_io_position = args.io_position |
| return ok |
| } |
| |
| pub func decoder.set_report_metadata!(fourcc: base.u32, report: base.bool) { |
| // TODO. |
| } |
| |
| pub func decoder.tell_me_more?(dst: base.io_writer, minfo: nptr base.more_information, src: base.io_reader) { |
| return base."#no more information" |
| } |
| |
| pub func decoder.workbuf_len() base.range_ii_u64 { |
| return this.util.make_range_ii_u64( |
| min_incl: this.workbuf_length, |
| max_incl: this.workbuf_length) |
| } |