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EvansJahjaEvansJahja
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Ignore compressed data length on RGB compression mehod (#47)
* Add image * add failing tests * Handle potentially incorrect compressed data len on compression type RGB * rustfmt * use old method for calculating uncompressed rgb size * replace unwrap to match in const fn * Simplify RawBmp::from_slice data_length calculation * bump changelog * Rearrange comments * cargo fmt
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‎CHANGELOG.md‎

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- [#46](https://github.com/embedded-graphics/tinybmp/pull/46) `Bmp::from_slice` is now `const`, so BMPs can be put in `const`s and `static`s.
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- [#47](https://github.com/embedded-graphics/tinybmp/pull/47) Ignore compressed data length on RGB compression mehod
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## [0.6.0] - 2024-06-11
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‎src/header/mod.rs‎

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@@ -161,8 +161,8 @@ impl Header {
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/// Returns the row length in bytes.
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///
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/// Each row in a BMP file is a multiple of 4 bytes long.
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pub(crate) fn bytes_per_row(&self) -> usize {
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let bits_per_row = self.image_size.width as usize * usize::from(self.bpp.bits());
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pub(crate) const fn bytes_per_row(&self) -> usize {
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let bits_per_row = self.image_size.width as usize * self.bpp.bits() as usize;
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(bits_per_row + 31) / 32 * (32 / 8)
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}

‎src/raw_bmp.rs‎

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@@ -44,18 +44,32 @@ impl<'a> RawBmp<'a> {
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let color_type = try_const!(ColorType::from_header(&header));
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// Believe what the bitmap tells us rather than multiplying width by
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// height by bits-per-pixel, because the image data might be compressed.
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let compressed_data_length = header.image_data_len as usize;
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if bytes.len() < header.image_data_start {
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return Err(ParseError::UnexpectedEndOfFile);
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}
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let (_, image_data) = bytes.split_at(header.image_data_start);
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if image_data.len() < compressed_data_length {
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let data_length = if let crate::header::CompressionMethod::Rgb = header.compression_method {
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// `Header::image_data_len` may be zero or bogus when compression mode is RGB
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// see `biSizeImage` on https://learn.microsoft.com/en-us/previous-versions/dd183376(v=vs.85)
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// so we should calculate width x height instead.
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let height = header.image_size.height as usize;
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let Some(data_length) = header.bytes_per_row().checked_mul(height) else {
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return Err(ParseError::UnexpectedEndOfFile);
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};
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data_length
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} else {
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// Believe what the bitmap tells us rather than multiplying width by
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// height by bits-per-pixel, because the image data might be compressed.
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header.image_data_len as usize
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};
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if image_data.len() < data_length {
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return Err(ParseError::UnexpectedEndOfFile);
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}
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let (image_data, _) = image_data.split_at(compressed_data_length);
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let (image_data, _) = image_data.split_at(data_length);
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Ok(Self {
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header,

‎tests/chessboard-16px-1bit.bmp‎

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‎tests/chessboard-16px-1bit.rs‎

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use embedded_graphics::{
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pixelcolor::{BinaryColor, Rgb888},
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prelude::*,
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};
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use tinybmp::{Bmp, Bpp, CompressionMethod, Header, RawBmp, RowOrder};
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#[test]
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fn chessboard_16px_1bit() {
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let bmp =
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RawBmp::from_slice(include_bytes!("./chessboard-16px-1bit.bmp")).expect("Failed to parse");
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assert_eq!(
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bmp.header(),
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&Header {
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file_size: 94,
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image_data_start: 62,
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bpp: Bpp::Bits1,
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image_size: Size::new(16, 16),
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image_data_len: 32,
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channel_masks: None,
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row_order: RowOrder::BottomUp,
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compression_method: CompressionMethod::Rgb,
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}
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);
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let color_table = bmp.color_table().unwrap();
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assert_eq!(color_table.len(), 2);
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assert_eq!(color_table.get(0), Some(Rgb888::BLACK));
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assert_eq!(color_table.get(1), Some(Rgb888::WHITE));
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assert_eq!(color_table.get(2), None);
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assert_eq!(bmp.image_data().len(), 64);
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}
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#[test]
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fn chessboard_16px_1bit_iter_raw() {
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let bmp =
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RawBmp::from_slice(include_bytes!("./chessboard-16px-1bit.bmp")).expect("Failed to parse");
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let pixels: Vec<u32> = bmp.pixels().map(|pixel| pixel.color).collect();
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// 16px x 16px image. Check that iterator returns all pixels in it
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assert_eq!(pixels.len(), 16 * 16);
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let w = 1u32;
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let b = 0u32;
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let expected = vec![
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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];
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assert_eq!(pixels, expected);
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}
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#[test]
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fn chessboard_16px_1bit_iter() {
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let bmp = Bmp::<'_, Rgb888>::from_slice(include_bytes!("./chessboard-16px-1bit.bmp"))
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.expect("Failed to parse");
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let pixels: Vec<u32> = bmp
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.pixels()
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.map(|Pixel(_pos, color)| color.into_storage().into())
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.collect();
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// 16px x 16px image. Check that iterator returns all pixels in it
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assert_eq!(pixels.len(), 16 * 16);
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// Imagemagick inverts using a color mapping table which maps a 0 to [255, 255, 255, 0], hence
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// this instead of a simple `1` value.
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let w = Rgb888::WHITE.into_storage();
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let b = Rgb888::BLACK.into_storage();
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let expected = vec![
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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w, w, b, b, w, w, b, b, w, w, b, b, w, w, b, b, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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b, b, w, w, b, b, w, w, b, b, w, w, b, b, w, w, //
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];
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assert_eq!(pixels, expected);
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}

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