| // 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 struct decoder?( |
| width : base.u32, |
| height : base.u32, |
| ) |
| |
| pub func decoder.decode_image_config?(dst: nptr base.image_config, src: base.io_reader) { |
| var c : base.u8 |
| var i : base.u32 |
| var x32 : base.u32 |
| var x64 : base.u64 |
| |
| // TypeField, FixHeaderField. |
| i = 0 |
| while i < 2 { |
| c = args.src.read_u8?() |
| if c <> 0 { |
| return "#bad header" |
| } |
| i += 1 |
| } |
| |
| // Width, height. |
| i = 0 |
| while i < 2 { |
| x32 = 0 |
| |
| while true, |
| inv i < 2, |
| { |
| c = args.src.read_u8?() |
| x32 |= (c & 0x7F) as base.u32 |
| if (c >> 7) == 0 { |
| break |
| } |
| x64 = (x32 as base.u64) << 7 |
| if x64 > 0xFFFFFFFF { |
| return "#bad header" |
| } |
| x32 = x64 as base.u32 |
| } |
| |
| if i == 0 { |
| this.width = x32 |
| } else { |
| this.height = x32 |
| } |
| i += 1 |
| } |
| |
| if args.dst <> nullptr { |
| // TODO: a Wuffs (not just C) name for the |
| // WUFFS_BASE__PIXEL_FORMAT__INDEXED__BGRA_BINARY magic pixfmt constant. |
| args.dst.set!( |
| pixfmt: 0x47040008, |
| pixsub: 0, |
| width: this.width, |
| height: this.height, |
| first_frame_io_position: args.src.position(), |
| first_frame_is_opaque: true) |
| } |
| } |
| |
| pub func decoder.ack_metadata_chunk?(src: base.io_reader) { |
| // TODO: this final line shouldn't be necessary, here and in some other |
| // std/*/*.wuffs functions. |
| return ok |
| } |