Add image render tests

Add tests that will match rendered words/paragraphs against reference
images.

Use env var `GENERATE_IMAGES` to write the initial reference images to
the repository.

.gitattributes

@@ -1 +1,2 @@
 *.png filter=lfs diff=lfs merge=lfs -text
+*.ttf filter=lfs diff=lfs merge=lfs -text

.gitignore

@@ -1,3 +1,4 @@
 Cargo.lock
 sample/udhr*
 target
+**/.DS_Store

Cargo.toml

@@ -53,6 +53,7 @@ harness = false
 members = ["examples/*"]
 
 [dev-dependencies]
+tiny-skia = "0.11"
 criterion = { version = "0.5.1", default-features = false, features = [
     "cargo_bench_support",
 ] }

fonts/NotoSans-LICENSE

@@ -0,0 +1,93 @@
+Copyright 2012 Google Inc. All Rights Reserved.
+
+This Font Software is licensed under the SIL Open Font License, Version 1.1.
+This license is copied below, and is also available with a FAQ at:
+http://scripts.sil.org/OFL
+
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font creation
+efforts of academic and linguistic communities, and to provide a free and
+open framework in which fonts may be shared and improved in partnership
+with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded, 
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply
+to any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software components as
+distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to, deleting,
+or substituting -- in part or in whole -- any of the components of the
+Original Version, by changing formats or by porting the Font Software to a
+new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed, modify,
+redistribute, and sell modified and unmodified copies of the Font
+Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components,
+in Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the corresponding
+Copyright Holder. This restriction only applies to the primary font name as
+presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created
+using the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.

fonts/NotoSans-Regular.ttf

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:2ec33f84606cbaa0a1a944488e14f97faf2f6a25ecdd8354f5358f06da13c7d9
+size 556216

fonts/NotoSansArabic.ttf

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:ee489b994b3e62def9874c918145e32b133b625abaf98cec60502bdb40102c56
+size 765740

fonts/NotoSansHebrew.ttf

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:3d4fef85b449ade4d165de982969374fa30b2a5fe7bc679f5a3f5bfc047fb703
+size 183688

tests/common/mod.rs

@@ -0,0 +1,144 @@
+use std::path::PathBuf;
+
+use cosmic_text::{
+    fontdb::Database, Attrs, AttrsOwned, Buffer, Color, Family, FontSystem, Metrics, Shaping,
+    SwashCache,
+};
+use tiny_skia::{Paint, Pixmap, Rect, Transform};
+
+/// The test configuration.
+/// The text in the test will be rendered as image using the one of the fonts found under the
+/// `fonts` directory in this repository.
+/// The image will then be compared to an image with the name `name` under the `tests/images`
+/// directory in this repository.
+/// If the images do not match the test will fail.
+/// NOTE: if an environment variable `GENERATE_IMAGES` is set, the test will create and save
+/// the images instead.
+#[derive(Debug)]
+pub struct DrawTestCfg {
+    /// The name of the test.
+    /// Will be used for the image name under the `tests/images` directory in this repository.
+    name: String,
+    /// The text to render to image
+    text: String,
+    /// The name, details of the font to be used.
+    /// Expected to be one of the fonts found under the `fonts` directory in this repository.
+    font: AttrsOwned,
+
+    font_size: f32,
+    line_height: f32,
+    canvas_width: u32,
+    canvas_height: u32,
+}
+
+impl Default for DrawTestCfg {
+    fn default() -> Self {
+        let font = Attrs::new().family(Family::Serif);
+        Self {
+            name: "default".into(),
+            font: AttrsOwned::new(font),
+            text: "".into(),
+            font_size: 16.0,
+            line_height: 20.0,
+            canvas_width: 300,
+            canvas_height: 300,
+        }
+    }
+}
+
+impl DrawTestCfg {
+    pub fn new(name: impl Into<String>) -> Self {
+        Self {
+            name: name.into(),
+            ..Default::default()
+        }
+    }
+
+    pub fn text(mut self, text: impl Into<String>) -> Self {
+        self.text = text.into();
+        self
+    }
+
+    pub fn font_attrs(mut self, attrs: Attrs) -> Self {
+        self.font = AttrsOwned::new(attrs);
+        self
+    }
+
+    pub fn font_size(mut self, font_size: f32, line_height: f32) -> Self {
+        self.font_size = font_size;
+        self.line_height = line_height;
+        self
+    }
+
+    pub fn canvas(mut self, width: u32, height: u32) -> Self {
+        self.canvas_width = width;
+        self.canvas_height = height;
+        self
+    }
+
+    pub fn validate_text_rendering(self) {
+        let repo_dir = std::env::var("CARGO_MANIFEST_DIR").unwrap();
+        // Create a db with just the fonts in our fonts dir to make sure we only test those
+        let fonts_path = PathBuf::from(&repo_dir).join("fonts");
+        let mut font_db = Database::new();
+        font_db.load_fonts_dir(fonts_path);
+        let mut font_system = FontSystem::new_with_locale_and_db("En-US".into(), font_db);
+        let mut swash_cache = SwashCache::new();
+        let metrics = Metrics::new(self.font_size, self.line_height);
+        let mut buffer = Buffer::new(&mut font_system, metrics);
+        let mut buffer = buffer.borrow_with(&mut font_system);
+        let margins = 5;
+        buffer.set_size(
+            (self.canvas_width - margins * 2) as f32,
+            (self.canvas_height - margins * 2) as f32,
+        );
+        buffer.set_text(&self.text, self.font.as_attrs(), Shaping::Advanced);
+        buffer.shape_until_scroll();
+
+        // Black
+        let text_color = Color::rgb(0x00, 0x00, 0x00);
+
+        let mut pixmap = Pixmap::new(self.canvas_width, self.canvas_height).unwrap();
+        pixmap.fill(tiny_skia::Color::WHITE);
+
+        buffer.draw(&mut swash_cache, text_color, |x, y, w, h, color| {
+            let mut paint = Paint {
+                anti_alias: true,
+                ..Paint::default()
+            };
+            paint.set_color_rgba8(color.r(), color.g(), color.b(), color.a());
+            let rect = Rect::from_xywh(
+                (x + margins as i32) as f32,
+                (y + margins as i32) as f32,
+                w as f32,
+                h as f32,
+            )
+            .unwrap();
+            pixmap.fill_rect(rect, &paint, Transform::identity(), None);
+        });
+
+        let image_name = format!("{}.png", self.name);
+        let reference_image_path = PathBuf::from(&repo_dir)
+            .join("tests")
+            .join("images")
+            .join(image_name);
+
+        let generate_images = std::env::var("GENERATE_IMAGES")
+            .map(|v| {
+                let val = v.trim().to_ascii_lowercase();
+                ["t", "true", "1"].iter().any(|&v| v == val)
+            })
+            .unwrap_or_default();
+
+        if generate_images {
+            pixmap.save_png(reference_image_path).unwrap();
+        } else {
+            let reference_image_data = std::fs::read(reference_image_path).unwrap();
+            let image_data = pixmap.encode_png().unwrap();
+            assert_eq!(
+                reference_image_data, image_data,
+                "rendering failed of {self:?}"
+            )
+        }
+    }
+}

tests/images/a_hebrew_paragraph.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:e0350ffaa09ac5b9976b0441cfb0fab0db0b13e3a2d33260592e113c347bedfe
+size 23202

tests/images/a_hebrew_word.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:95bbe8f4db74914f6a124547f024463a3e434b3c7be3f86c1464af71ed39bba0
+size 3512

tests/images/an_arabic_paragraph.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:eb6966eec660c39584f11d353940f6a274eb90125c8b58fabf3c3e5066a5e1e4
+size 24322

tests/images/an_arabic_word.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:ba0219c8e226f4bd79e0681a3189013ed035459fd3ed90405ec53d595e70ab81
+size 3851

tests/images/some_english_mixed_with_arabic.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:ffbac330d91e73d8e28a2a83010e7f231bff6abfc9d9eda8720cb339c587084e
+size 23093

tests/images/some_english_mixed_with_hebrew.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:29fa23360829f2c11b960343b716eda01a069f6256a09b4eeb30d010abf7977f
+size 57340

tests/shaping_and_rendering.rs

@@ -0,0 +1,75 @@
+use common::DrawTestCfg;
+use cosmic_text::Attrs;
+use fontdb::Family;
+
+mod common;
+
+#[test]
+fn test_hebrew_word_rendering() {
+    let attrs = Attrs::new().family(Family::Name("Noto Sans"));
+    DrawTestCfg::new("a_hebrew_word")
+        .font_size(36., 40.)
+        .font_attrs(attrs)
+        .text("בדיקה")
+        .canvas(100, 60)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_hebrew_paragraph_rendering() {
+    let paragraph = "השועל החום המהיר קופץ מעל הכלב העצלן";
+    let attrs = Attrs::new().family(Family::Name("Noto Sans"));
+    DrawTestCfg::new("a_hebrew_paragraph")
+        .font_size(36., 40.)
+        .font_attrs(attrs)
+        .text(paragraph)
+        .canvas(400, 110)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_english_mixed_with_hebrew_paragraph_rendering() {
+    let paragraph = "Many computer programs fail to display bidirectional text correctly. For example, this page is mostly LTR English script, and here is the RTL Hebrew name Sarah: שרה, spelled sin (ש) on the right, resh (ר) in the middle, and heh (ה) on the left.";
+    let attrs = Attrs::new().family(Family::Name("Noto Sans"));
+    DrawTestCfg::new("some_english_mixed_with_hebrew")
+        .font_size(16., 20.)
+        .font_attrs(attrs)
+        .text(paragraph)
+        .canvas(400, 120)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_arabic_word_rendering() {
+    let attrs = Attrs::new().family(Family::Name("Noto Sans"));
+    DrawTestCfg::new("an_arabic_word")
+        .font_size(36., 40.)
+        .font_attrs(attrs)
+        .text("خالصة")
+        .canvas(100, 60)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_arabic_paragraph_rendering() {
+    let paragraph = "الثعلب البني السريع يقفز فوق الكلب الكسول";
+    let attrs = Attrs::new().family(Family::Name("Noto Sans"));
+    DrawTestCfg::new("an_arabic_paragraph")
+        .font_size(36., 40.)
+        .font_attrs(attrs)
+        .text(paragraph)
+        .canvas(400, 110)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_english_mixed_with_arabic_paragraph_rendering() {
+    let paragraph = "I like to render اللغة العربية in Rust!";
+    let attrs = Attrs::new().family(Family::Name("Noto Sans"));
+    DrawTestCfg::new("some_english_mixed_with_arabic")
+        .font_size(36., 40.)
+        .font_attrs(attrs)
+        .text(paragraph)
+        .canvas(400, 110)
+        .validate_text_rendering();
+}