Color padding in snapshot testing images (#275)

As discussed in #274.

Fixes #274.

Author: wfdewith

parley/src/tests/utils/cursor_test.rs

@@ -184,21 +184,25 @@ impl CursorTest {
         // without visual cursors and with a warning that the text may not be accurate.
 
         let bg_color_expected = Color::from_rgba8(255, 255, 255, 255);
+        let padding_color_expected = Color::from_rgba8(166, 200, 255, 255);
         let cursor_color_expected = Color::from_rgba8(0, 255, 0, 255);
         let selection_color_expected = Color::from_rgba8(0, 255, 0, 200);
         let bg_color_actual = Color::from_rgba8(230, 230, 230, 255);
+        let padding_color_actual = Color::from_rgba8(166, 255, 240, 255);
         let cursor_color_actual = Color::from_rgba8(255, 0, 0, 255);
         let selection_color_actual = Color::from_rgba8(255, 0, 0, 200);
 
         let rendering_config_expected = RenderingConfig {
             background_color: bg_color_expected,
+            padding_color: padding_color_expected,
             inline_box_color: bg_color_expected,
             cursor_color: cursor_color_expected,
             selection_color: selection_color_expected,
             size: None,
         };
         let rendering_config_actual = RenderingConfig {
             background_color: bg_color_actual,
+            padding_color: padding_color_actual,
             inline_box_color: bg_color_actual,
             cursor_color: cursor_color_actual,
             selection_color: selection_color_actual,
@@ -351,11 +355,13 @@ impl CursorTest {
     #[allow(dead_code)]
     pub(crate) fn render_cursor(&self, cursor: Cursor) {
         let bg_color_cursor = Color::from_rgba8(255, 255, 255, 255);
+        let padding_color_cursor = Color::from_rgba8(166, 200, 255, 255);
         let cursor_color_cursor = Color::from_rgba8(0, 255, 0, 255);
         let selection_color_cursor = Color::from_rgba8(0, 255, 0, 200);
 
         let rendering_config_cursor = RenderingConfig {
             background_color: bg_color_cursor,
+            padding_color: padding_color_cursor,
             inline_box_color: bg_color_cursor,
             cursor_color: cursor_color_cursor,
             selection_color: selection_color_cursor,

parley/src/tests/utils/env.rs

@@ -148,6 +148,7 @@ impl TestEnv {
             text_color: Color::BLACK,
             rendering_config: RenderingConfig {
                 background_color: Color::WHITE,
+                padding_color: Color::from_rgba8(166, 200, 255, 255),
                 cursor_color: Color::from_rgba8(255, 0, 0, 255),
                 selection_color: Color::from_rgba8(196, 196, 0, 255),
                 inline_box_color: Color::BLACK,

parley/src/tests/utils/renderer.rs

@@ -32,6 +32,7 @@ impl Default for ColorBrush {
 
 pub(crate) struct RenderingConfig {
     pub background_color: Color,
+    pub padding_color: Color,
     pub inline_box_color: Color,
     pub cursor_color: Color,
     pub selection_color: Color,
@@ -73,10 +74,19 @@ pub(crate) fn render_layout(
 
     let mut img = Pixmap::new(padded_width, padded_height).unwrap();
 
-    img.fill(config.background_color);
+    img.fill(config.padding_color);
 
     let mut pen = TinySkiaPen::new(img.as_mut());
 
+    draw_rect(
+        &mut pen,
+        fpadding,
+        fpadding,
+        width as f32,
+        height as f32,
+        config.background_color,
+    );
+
     for rect in selection_rects {
         draw_rect(
             &mut pen,