1 files changed, 252 insertions, 0 deletions
diff --git a/vendor/jpeg-decoder/src/upsampler.rs b/vendor/jpeg-decoder/src/upsampler.rs
new file mode 100644
index 0000000..a5c39d4
--- /dev/null
+++ b/vendor/jpeg-decoder/src/upsampler.rs
@@ -0,0 +1,252 @@
+use alloc::boxed::Box;
+use alloc::vec;
+use alloc::vec::Vec;
+use crate::error::{Error, Result, UnsupportedFeature};
+use crate::parser::Component;
+
+pub struct Upsampler {
+    components: Vec<UpsamplerComponent>,
+    line_buffer_size: usize
+}
+
+struct UpsamplerComponent {
+    upsampler: Box<dyn Upsample + Sync>,
+    width: usize,
+    height: usize,
+    row_stride: usize,
+}
+
+impl Upsampler {
+    pub fn new(components: &[Component], output_width: u16, output_height: u16) -> Result<Upsampler> {
+        let h_max = components.iter().map(|c| c.horizontal_sampling_factor).max().unwrap();
+        let v_max = components.iter().map(|c| c.vertical_sampling_factor).max().unwrap();
+        let mut upsampler_components = Vec::with_capacity(components.len());
+
+        for component in components {
+            let upsampler = choose_upsampler((component.horizontal_sampling_factor,
+                                              component.vertical_sampling_factor),
+                                             (h_max, v_max),
+                                             output_width,
+                                             output_height)?;
+            upsampler_components.push(UpsamplerComponent {
+                upsampler,
+                width: component.size.width as usize,
+                height: component.size.height as usize,
+                row_stride: component.block_size.width as usize * component.dct_scale,
+            });
+        }
+
+        let buffer_size = components.iter().map(|c| c.size.width).max().unwrap() as usize * h_max as usize;
+
+        Ok(Upsampler {
+            components: upsampler_components,
+            line_buffer_size: buffer_size
+        })
+    }
+
+    pub fn upsample_and_interleave_row(&self, component_data: &[Vec<u8>], row: usize, output_width: usize, output: &mut [u8], color_convert: fn(&[Vec<u8>], &mut [u8])) {
+        let component_count = component_data.len();
+        let mut line_buffers = vec![vec![0u8; self.line_buffer_size]; component_count];
+
+        debug_assert_eq!(component_count, self.components.len());
+
+        for (i, component) in self.components.iter().enumerate() {
+            component.upsampler.upsample_row(&component_data[i],
+                                             component.width,
+                                             component.height,
+                                             component.row_stride,
+                                             row,
+                                             output_width,
+                                             &mut line_buffers[i]);
+        }
+        color_convert(&line_buffers, output);
+    }
+}
+
+struct UpsamplerH1V1;
+struct UpsamplerH2V1;
+struct UpsamplerH1V2;
+struct UpsamplerH2V2;
+
+struct UpsamplerGeneric {
+    horizontal_scaling_factor: u8,
+    vertical_scaling_factor: u8
+}
+
+fn choose_upsampler(sampling_factors: (u8, u8),
+                    max_sampling_factors: (u8, u8),
+                    output_width: u16,
+                    output_height: u16) -> Result<Box<dyn Upsample + Sync>> {
+    let h1 = sampling_factors.0 == max_sampling_factors.0 || output_width == 1;
+    let v1 = sampling_factors.1 == max_sampling_factors.1 || output_height == 1;
+    let h2 = sampling_factors.0 * 2 == max_sampling_factors.0;
+    let v2 = sampling_factors.1 * 2 == max_sampling_factors.1;
+
+    if h1 && v1 {
+        Ok(Box::new(UpsamplerH1V1))
+    }
+    else if h2 && v1 {
+        Ok(Box::new(UpsamplerH2V1))
+    }
+    else if h1 && v2 {
+        Ok(Box::new(UpsamplerH1V2))
+    }
+    else if h2 && v2 {
+        Ok(Box::new(UpsamplerH2V2))
+    }
+    else {
+        if max_sampling_factors.0 % sampling_factors.0 != 0 || max_sampling_factors.1 % sampling_factors.1 != 0 {
+            Err(Error::Unsupported(UnsupportedFeature::NonIntegerSubsamplingRatio))
+        }
+        else {
+            Ok(Box::new(UpsamplerGeneric {
+                horizontal_scaling_factor: max_sampling_factors.0 / sampling_factors.0,
+                vertical_scaling_factor: max_sampling_factors.1 / sampling_factors.1
+            }))
+        }
+    }
+}
+
+trait Upsample {
+    fn upsample_row(&self,
+                    input: &[u8],
+                    input_width: usize,
+                    input_height: usize,
+                    row_stride: usize,
+                    row: usize,
+                    output_width: usize,
+                    output: &mut [u8]);
+}
+
+impl Upsample for UpsamplerH1V1 {
+    fn upsample_row(&self,
+                    input: &[u8],
+                    _input_width: usize,
+                    _input_height: usize,
+                    row_stride: usize,
+                    row: usize,
+                    output_width: usize,
+                    output: &mut [u8]) {
+        let input = &input[row * row_stride ..];
+
+        output[..output_width].copy_from_slice(&input[..output_width]);
+    }
+}
+
+impl Upsample for UpsamplerH2V1 {
+    fn upsample_row(&self,
+                    input: &[u8],
+                    input_width: usize,
+                    _input_height: usize,
+                    row_stride: usize,
+                    row: usize,
+                    _output_width: usize,
+                    output: &mut [u8]) {
+        let input = &input[row * row_stride ..];
+
+        if input_width == 1 {
+            output[0] = input[0];
+            output[1] = input[0];
+            return;
+        }
+
+        output[0] = input[0];
+        output[1] = ((input[0] as u32 * 3 + input[1] as u32 + 2) >> 2) as u8;
+
+        for i in 1 .. input_width - 1 {
+            let sample = 3 * input[i] as u32 + 2;
+            output[i * 2]     = ((sample + input[i - 1] as u32) >> 2) as u8;
+            output[i * 2 + 1] = ((sample + input[i + 1] as u32) >> 2) as u8;
+        }
+
+        output[(input_width - 1) * 2] = ((input[input_width - 1] as u32 * 3 + input[input_width - 2] as u32 + 2) >> 2) as u8;
+        output[(input_width - 1) * 2 + 1] = input[input_width - 1];
+    }
+}
+
+impl Upsample for UpsamplerH1V2 {
+    fn upsample_row(&self,
+                    input: &[u8],
+                    _input_width: usize,
+                    input_height: usize,
+                    row_stride: usize,
+                    row: usize,
+                    output_width: usize,
+                    output: &mut [u8]) {
+        let row_near = row as f32 / 2.0;
+        // If row_near's fractional is 0.0 we want row_far to be the previous row and if it's 0.5 we
+        // want it to be the next row.
+        let row_far = (row_near + row_near.fract() * 3.0 - 0.25).min((input_height - 1) as f32);
+
+        let input_near = &input[row_near as usize * row_stride ..];
+        let input_far = &input[row_far as usize * row_stride ..];
+
+        let output = &mut output[..output_width];
+        let input_near = &input_near[..output_width];
+        let input_far = &input_far[..output_width];
+        for i in 0..output_width {
+            output[i] = ((3 * input_near[i] as u32 + input_far[i] as u32 + 2) >> 2) as u8;
+        }
+    }
+}
+
+impl Upsample for UpsamplerH2V2 {
+    fn upsample_row(&self,
+                    input: &[u8],
+                    input_width: usize,
+                    input_height: usize,
+                    row_stride: usize,
+                    row: usize,
+                    _output_width: usize,
+                    output: &mut [u8]) {
+        let row_near = row as f32 / 2.0;
+        // If row_near's fractional is 0.0 we want row_far to be the previous row and if it's 0.5 we
+        // want it to be the next row.
+        let row_far = (row_near + row_near.fract() * 3.0 - 0.25).min((input_height - 1) as f32);
+
+        let input_near = &input[row_near as usize * row_stride ..];
+        let input_far = &input[row_far as usize * row_stride ..];
+
+        if input_width == 1 {
+            let value = ((3 * input_near[0] as u32 + input_far[0] as u32 + 2) >> 2) as u8;
+            output[0] = value;
+            output[1] = value;
+            return;
+        }
+
+        let mut t1 = 3 * input_near[0] as u32 + input_far[0] as u32;
+        output[0] = ((t1 + 2) >> 2) as u8;
+
+        for i in 1 .. input_width {
+            let t0 = t1;
+            t1 = 3 * input_near[i] as u32 + input_far[i] as u32;
+
+            output[i * 2 - 1] = ((3 * t0 + t1 + 8) >> 4) as u8;
+            output[i * 2]     = ((3 * t1 + t0 + 8) >> 4) as u8;
+        }
+
+        output[input_width * 2 - 1] = ((t1 + 2) >> 2) as u8;
+    }
+}
+
+impl Upsample for UpsamplerGeneric {
+    // Uses nearest neighbor sampling
+    fn upsample_row(&self,
+                    input: &[u8],
+                    input_width: usize,
+                    _input_height: usize,
+                    row_stride: usize,
+                    row: usize,
+                    _output_width: usize,
+                    output: &mut [u8]) {
+        let mut index = 0;
+        let start = (row / self.vertical_scaling_factor as usize) * row_stride;
+        let input = &input[start..(start + input_width)];
+        for val in input {
+            for _ in 0..self.horizontal_scaling_factor {
+                output[index] = *val;
+                index += 1;
+            }
+        }
+    }
+}