From bc7be68d0fb7cc3111f88f3cd07bfde5c3386b21 Mon Sep 17 00:00:00 2001
From: Christopher Gundler <christopher@gundler.de>
Date: Wed, 22 Dec 2021 10:48:52 +0100
Subject: [PATCH] Simplify tests

---
 tests/encode_images_with_compression.rs | 141 +++++++++++++-----------
 1 file changed, 78 insertions(+), 63 deletions(-)

diff --git a/tests/encode_images_with_compression.rs b/tests/encode_images_with_compression.rs
index c1aadc8..80f513a 100644
--- a/tests/encode_images_with_compression.rs
+++ b/tests/encode_images_with_compression.rs
@@ -1,88 +1,111 @@
 extern crate tiff;
 
-use std::io::Cursor;
+use std::io::{Cursor, Seek, Write};
 use tiff::{
     decoder::{Decoder, DecodingResult},
-    encoder::{colortype, compression::*, TiffEncoder},
-    tags::Tag,
+    encoder::{
+        colortype::{self, ColorType},
+        compression::*,
+        TiffEncoder, TiffValue,
+    },
 };
 
-trait TestImage {
+trait TestImage<const NUM_CHANNELS: usize>: From<Vec<<Self::Color as ColorType>::Inner>> {
     const WIDTH: u32;
     const HEIGHT: u32;
-    type PixelType;
+    type Color: ColorType;
 
-    fn generate() -> Vec<Self::PixelType>;
-}
+    fn reference_data(&self) -> &[<Self::Color as ColorType>::Inner];
+    fn generate_pixel(x: u32, y: u32) -> [<Self::Color as ColorType>::Inner; NUM_CHANNELS];
 
-struct TestImageColor;
-impl TestImage for TestImageColor {
-    const WIDTH: u32 = 1;
-    const HEIGHT: u32 = 7;
-    type PixelType = u16;
+    fn compress<C: Compression, W: Write + Seek>(
+        &self,
+        encoder: &mut TiffEncoder<W>,
+        compression: C,
+    ) where
+        [<Self::Color as ColorType>::Inner]: TiffValue,
+    {
+        let image = encoder
+            .new_image_with_compression::<Self::Color, C>(Self::WIDTH, Self::HEIGHT, compression)
+            .unwrap();
+        image.write_data(self.reference_data()).unwrap();
+    }
 
-    fn generate() -> Vec<Self::PixelType> {
-        let mut data: Vec<u16> = Vec::with_capacity((Self::WIDTH * Self::HEIGHT) as usize * 3);
+    fn generate() -> Self {
+        assert_eq!(
+            Self::Color::BITS_PER_SAMPLE.len(),
+            NUM_CHANNELS,
+            "Incompatible color type"
+        );
+
+        let mut data = Vec::with_capacity((Self::WIDTH * Self::HEIGHT) as usize * NUM_CHANNELS);
         for x in 0..Self::WIDTH {
             for y in 0..Self::HEIGHT {
-                let val = (x + y) % Self::PixelType::MAX as u32;
-                data.extend(std::iter::repeat(val as Self::PixelType).take(3));
+                data.extend(IntoIterator::into_iter(Self::generate_pixel(x, y)));
             }
         }
-        assert_eq!(data.len() as u32, Self::WIDTH * Self::HEIGHT * 3);
-        data
+        Self::from(data)
     }
 }
 
-struct TestImageGrayscale;
-impl TestImage for TestImageGrayscale {
+struct TestImageColor(Vec<u16>);
+
+impl From<Vec<u16>> for TestImageColor {
+    fn from(value: Vec<u16>) -> Self {
+        Self(value)
+    }
+}
+
+impl TestImage<3> for TestImageColor {
+    const WIDTH: u32 = 1;
+    const HEIGHT: u32 = 7;
+    type Color = colortype::RGB16;
+
+    fn reference_data(&self) -> &[u16] {
+        &self.0
+    }
+
+    fn generate_pixel(x: u32, y: u32) -> [<Self::Color as ColorType>::Inner; 3] {
+        let val = (x + y) % <Self::Color as ColorType>::Inner::MAX as u32;
+        [val as <Self::Color as ColorType>::Inner; 3]
+    }
+}
+
+struct TestImageGrayscale(Vec<u8>);
+
+impl From<Vec<u8>> for TestImageGrayscale {
+    fn from(value: Vec<u8>) -> Self {
+        Self(value)
+    }
+}
+
+impl TestImage<1> for TestImageGrayscale {
     const WIDTH: u32 = 21;
     const HEIGHT: u32 = 10;
-    type PixelType = u8;
+    type Color = colortype::Gray8;
 
-    fn generate() -> Vec<Self::PixelType> {
-        let mut data: Vec<u8> = Vec::with_capacity((Self::WIDTH * Self::HEIGHT) as usize);
-        for x in 0..Self::WIDTH {
-            for y in 0..Self::HEIGHT {
-                let val = (x + y) % Self::PixelType::MAX as u32;
-                data.push(val as Self::PixelType);
-            }
-        }
-        assert_eq!(data.len() as u32, Self::WIDTH * Self::HEIGHT);
-        data
+    fn reference_data(&self) -> &[u8] {
+        &self.0
+    }
+
+    fn generate_pixel(x: u32, y: u32) -> [<Self::Color as ColorType>::Inner; 1] {
+        let val = (x + y) % <Self::Color as ColorType>::Inner::MAX as u32;
+        [val as <Self::Color as ColorType>::Inner]
     }
 }
 
 fn encode_decode_with_compression<C: Compression + Clone>(compression: C) {
     let mut data = Cursor::new(Vec::new());
 
-    let image_data_rgb = TestImageColor::generate();
-    let image_data_gray = TestImageGrayscale::generate();
+    let image_rgb = TestImageColor::generate();
+    let image_grayscale = TestImageGrayscale::generate();
 
     // Encode tiff with compression
     {
         // Create a multipage image with 2 images
         let mut encoder = TiffEncoder::new(&mut data).unwrap();
-
-        // Write first colored image
-        let image_rgb = encoder
-            .new_image_with_compression::<colortype::RGB16, C>(
-                TestImageColor::WIDTH,
-                TestImageColor::HEIGHT,
-                compression.clone(),
-            )
-            .unwrap();
-        image_rgb.write_data(&image_data_rgb).unwrap();
-
-        // Write second grayscale image
-        let image_gray = encoder
-            .new_image_with_compression::<colortype::Gray8, C>(
-                TestImageGrayscale::WIDTH,
-                TestImageGrayscale::HEIGHT,
-                compression,
-            )
-            .unwrap();
-        image_gray.write_data(&image_data_gray).unwrap();
+        image_rgb.compress(&mut encoder, compression.clone());
+        image_grayscale.compress(&mut encoder, compression);
     }
 
     // Decode tiff
@@ -91,20 +114,12 @@ fn encode_decode_with_compression<C: Compression + Clone>(compression: C) {
         let mut decoder = Decoder::new(data).unwrap();
 
         // Check the RGB image
-        assert_eq!(
-            decoder
-                .get_tag(Tag::ImageWidth)
-                .unwrap()
-                .into_u32()
-                .unwrap(),
-            TestImageColor::WIDTH
-        );
         assert_eq!(
             match decoder.read_image() {
                 Ok(DecodingResult::U16(image_data)) => image_data,
                 unexpected => panic!("Descoding RGB failed: {:?}", unexpected),
             },
-            image_data_rgb
+            image_rgb.reference_data()
         );
 
         // Check the grayscale image
@@ -114,7 +129,7 @@ fn encode_decode_with_compression<C: Compression + Clone>(compression: C) {
                 Ok(DecodingResult::U8(image_data)) => image_data,
                 unexpected => panic!("Decoding grayscale failed: {:?}", unexpected),
             },
-            image_data_gray
+            image_grayscale.reference_data()
         );
     }
 }