223 lines
6.9 KiB
Rust
223 lines
6.9 KiB
Rust
//! Render a QR code into image.
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#![cfg(feature="image")]
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use image::{Pixel, Rgb, Rgba, Luma, LumaA, Primitive, ImageBuffer};
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/// A pixel which can support black and white colors.
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pub trait BlankAndWhitePixel: Pixel {
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fn black_color() -> Self;
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fn white_color() -> Self;
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}
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impl<S: Primitive + 'static> BlankAndWhitePixel for Rgb<S> {
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fn black_color() -> Self {
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Rgb { data: [S::zero(); 3] }
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}
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fn white_color() -> Self {
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Rgb { data: [S::max_value(); 3] }
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}
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}
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impl<S: Primitive + 'static> BlankAndWhitePixel for Rgba<S> {
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fn black_color() -> Self {
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Rgba { data: [S::zero(), S::zero(), S::zero(), S::max_value()] }
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}
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fn white_color() -> Self {
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Rgba { data: [S::max_value(); 4] }
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}
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}
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impl<S: Primitive + 'static> BlankAndWhitePixel for Luma<S> {
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fn black_color() -> Self {
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Luma { data: [S::zero()] }
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}
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fn white_color() -> Self {
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Luma { data: [S::max_value()] }
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}
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}
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impl<S: Primitive + 'static> BlankAndWhitePixel for LumaA<S> {
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fn black_color() -> Self {
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LumaA { data: [S::zero(), S::max_value()] }
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}
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fn white_color() -> Self {
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LumaA { data: [S::max_value(); 2] }
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}
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}
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/// A QR code renderer. This is a builder type which converts a bool-vector into
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/// an image.
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pub struct Renderer<'a, P: BlankAndWhitePixel> {
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content: &'a [bool],
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modules_count: u32, // <- we call it `modules_count` here to avoid ambiguity of `width`.
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quiet_zone: u32,
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module_size: u32,
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dark_color: P,
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light_color: P,
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has_quiet_zone: bool,
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}
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impl<'a, P: BlankAndWhitePixel + 'static> Renderer<'a, P> {
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/// Creates a new renderer.
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pub fn new(content: &'a [bool], modules_count: usize, quiet_zone: u32) -> Renderer<'a, P> {
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assert!(modules_count * modules_count == content.len());
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Renderer {
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content: content,
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modules_count: modules_count as u32,
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quiet_zone: quiet_zone,
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module_size: 8,
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dark_color: P::black_color(),
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light_color: P::white_color(),
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has_quiet_zone: true,
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}
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}
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/// Sets color of a dark module. Default is opaque black.
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pub fn dark_color(&mut self, color: P) -> &mut Self {
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self.dark_color = color;
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self
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}
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/// Sets color of a light module. Default is opaque white.
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pub fn light_color(&mut self, color: P) -> &mut Self {
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self.light_color = color;
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self
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}
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/// Whether to include the quiet zone in the generated image.
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pub fn quiet_zone(&mut self, has_quiet_zone: bool) -> &mut Self {
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self.has_quiet_zone = has_quiet_zone;
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self
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}
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/// Sets the size of each module in pixels. Default is 8px.
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pub fn module_size(&mut self, size: u32) -> &mut Self {
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self.module_size = size;
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self
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}
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/// Sets the minimal total image width (and thus height) in pixels,
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/// including the quiet zone if applicable. The renderer will try to find
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/// the dimension as small as possible, such that each module in the QR code
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/// has uniform size (no distortion).
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///
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/// For instance, a version 1 QR code has 19 modules across including the
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/// quiet zone. If we request an image of width ≥200px, we get that each
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/// module's size should be 11px, so the actual image size will be 209px.
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pub fn min_width(&mut self, width: u32) -> &mut Self {
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let quiet_zone = if self.has_quiet_zone { 2 } else { 0 } * self.quiet_zone;
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let width_in_modules = self.modules_count + quiet_zone;
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let module_size = (width + width_in_modules - 1) / width_in_modules;
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self.module_size(module_size)
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}
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/// Renders the QR code into an image.
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pub fn to_image(&self) -> ImageBuffer<P, Vec<P::Subpixel>> {
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let w = self.modules_count;
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let qz = if self.has_quiet_zone { self.quiet_zone } else { 0 };
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let width = w + 2 * qz;
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let ms = self.module_size;
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let real_width = width * ms;
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let mut image = ImageBuffer::new(real_width, real_width);
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let mut i = 0;
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for y in 0 .. width {
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for x in 0 .. width {
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let color = if qz <= x && x < w + qz && qz <= y && y < w + qz {
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let c = if self.content[i] { self.dark_color } else { self.light_color };
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i += 1;
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c
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} else {
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self.light_color
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};
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for yy in y * ms .. (y + 1) * ms {
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for xx in x * ms .. (x + 1) * ms {
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image.put_pixel(xx, yy, color);
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}
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}
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}
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}
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image
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}
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}
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#[cfg(test)]
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mod render_tests {
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use render::Renderer;
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use image::{Luma, Rgba};
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#[test]
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fn test_render_luma8_unsized() {
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let image = Renderer::<Luma<u8>>::new(&[
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false, true, true,
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true, false, false,
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false, true, false,
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], 3, 1).module_size(1).to_image();
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let expected = [
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255, 255, 255, 255, 255,
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255, 255, 0, 0, 255,
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255, 0, 255, 255, 255,
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255, 255, 0, 255, 255,
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255, 255, 255, 255, 255,
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];
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assert_eq!(image.into_raw(), expected);
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}
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#[test]
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fn test_render_rgba_unsized() {
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let image = Renderer::<Rgba<u8>>::new(&[
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false, true,
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true, true,
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], 2, 1).module_size(1).to_image();
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let expected: &[u8] = &[
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255,255,255,255, 255,255,255,255, 255,255,255,255, 255,255,255,255,
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255,255,255,255, 255,255,255,255, 0, 0, 0,255, 255,255,255,255,
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255,255,255,255, 0, 0, 0,255, 0, 0, 0,255, 255,255,255,255,
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255,255,255,255, 255,255,255,255, 255,255,255,255, 255,255,255,255,
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];
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assert_eq!(image.into_raw(), expected);
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}
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#[test]
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fn test_render_resized() {
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let image = Renderer::<Luma<u8>>::new(&[
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true, false,
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false, true,
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], 2, 1).min_width(10).to_image();
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let expected: &[u8] = &[
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255,255,255, 255,255,255, 255,255,255, 255,255,255,
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255,255,255, 255,255,255, 255,255,255, 255,255,255,
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255,255,255, 255,255,255, 255,255,255, 255,255,255,
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255,255,255, 0, 0, 0, 255,255,255, 255,255,255,
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255,255,255, 0, 0, 0, 255,255,255, 255,255,255,
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255,255,255, 0, 0, 0, 255,255,255, 255,255,255,
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255,255,255, 255,255,255, 0, 0, 0, 255,255,255,
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255,255,255, 255,255,255, 0, 0, 0, 255,255,255,
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255,255,255, 255,255,255, 0, 0, 0, 255,255,255,
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255,255,255, 255,255,255, 255,255,255, 255,255,255,
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255,255,255, 255,255,255, 255,255,255, 255,255,255,
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255,255,255, 255,255,255, 255,255,255, 255,255,255,
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];
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assert_eq!(image.dimensions(), (12, 12));
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assert_eq!(image.into_raw(), expected);
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}
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}
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