From 5d2f14f37f3b12aebd438765abb083cf9f078552 Mon Sep 17 00:00:00 2001
From: Nick Badal <me@nbad.al>
Date: Sat, 21 May 2022 22:42:08 -0700
Subject: [PATCH] feat: add support for 'auto' values in clip property

---
 src/css/property-descriptors/clip.ts | 21 ++++++++++++---------
 src/css/syntax/parser.ts             |  2 ++
 src/css/syntax/tokenizer.ts          |  5 +++++
 src/render/bound-curves.ts           | 26 +++++++++++++++-----------
 tests/reftests/clip.html             |  8 ++++++++
 5 files changed, 42 insertions(+), 20 deletions(-)

diff --git a/src/css/property-descriptors/clip.ts b/src/css/property-descriptors/clip.ts
index 275ed88..03a370c 100644
--- a/src/css/property-descriptors/clip.ts
+++ b/src/css/property-descriptors/clip.ts
@@ -1,31 +1,34 @@
 import {IPropertyValueDescriptor, PropertyDescriptorParsingType} from '../IPropertyDescriptor';
-import {CSSValue, isDimensionToken, isIdentWithValue, nonFunctionArgSeparator} from '../syntax/parser';
+import {CSSValue, isAutoIdentToken, isDimensionToken} from '../syntax/parser';
 import {Context} from '../../core/context';
-import {DimensionToken, TokenType} from '../syntax/tokenizer';
+import {AutoIdentToken, DimensionToken, TokenType} from '../syntax/tokenizer';
 
 export interface RectClip {
-    top: DimensionToken;
-    right: DimensionToken;
-    bottom: DimensionToken;
-    left: DimensionToken;
+    top: DimensionToken | AutoIdentToken;
+    right: DimensionToken | AutoIdentToken;
+    bottom: DimensionToken | AutoIdentToken;
+    left: DimensionToken | AutoIdentToken;
 }
 
+const isDimensionOrAutoToken = (token: CSSValue): token is DimensionToken | AutoIdentToken =>
+    isDimensionToken(token) || isAutoIdentToken(token);
+
 export const clip: IPropertyValueDescriptor<RectClip | null> = {
     name: 'clip',
     initialValue: 'auto',
     type: PropertyDescriptorParsingType.VALUE,
     prefix: false,
     parse: (_context: Context, token: CSSValue) => {
-        if (isIdentWithValue(token, 'auto')) {
+        if (isAutoIdentToken(token)) {
             return null;
         }
         if (token.type !== TokenType.FUNCTION || token.name !== 'rect') {
             throw new Error('Clip value must be auto or a rect function');
         }
 
-        const rectArgs = token.values.filter(nonFunctionArgSeparator).filter(isDimensionToken);
+        const rectArgs = token.values.filter(isDimensionOrAutoToken);
         if (rectArgs.length !== 4) {
-            throw new Error('Rect clip must have 4 dimension elements');
+            throw new Error('Rect clip must have 4 elements that are either a dimension or "auto"');
         }
 
         return {
diff --git a/src/css/syntax/parser.ts b/src/css/syntax/parser.ts
index 7d65779..cf17016 100644
--- a/src/css/syntax/parser.ts
+++ b/src/css/syntax/parser.ts
@@ -1,4 +1,5 @@
 import {
+    AutoIdentToken,
     CSSToken,
     DimensionToken,
     EOF_TOKEN,
@@ -145,6 +146,7 @@ export const isDimensionToken = (token: CSSValue): token is DimensionToken => to
 export const isNumberToken = (token: CSSValue): token is NumberValueToken => token.type === TokenType.NUMBER_TOKEN;
 export const isIdentToken = (token: CSSValue): token is StringValueToken => token.type === TokenType.IDENT_TOKEN;
 export const isStringToken = (token: CSSValue): token is StringValueToken => token.type === TokenType.STRING_TOKEN;
+export const isAutoIdentToken = (token: CSSValue): token is AutoIdentToken => isIdentWithValue(token, 'auto');
 export const isIdentWithValue = (token: CSSValue, value: string): boolean =>
     isIdentToken(token) && token.value === value;
 
diff --git a/src/css/syntax/tokenizer.ts b/src/css/syntax/tokenizer.ts
index 11bbb03..b9b139d 100644
--- a/src/css/syntax/tokenizer.ts
+++ b/src/css/syntax/tokenizer.ts
@@ -97,6 +97,11 @@ export interface DimensionToken extends IToken {
     number: number;
 }
 
+export interface AutoIdentToken extends IToken {
+    type: TokenType.IDENT_TOKEN;
+    value: 'auto';
+}
+
 export interface UnicodeRangeToken extends IToken {
     type: TokenType.UNICODE_RANGE_TOKEN;
     start: number;
diff --git a/src/render/bound-curves.ts b/src/render/bound-curves.ts
index 6a7b30c..ca2577b 100644
--- a/src/render/bound-curves.ts
+++ b/src/render/bound-curves.ts
@@ -1,8 +1,9 @@
 import {ElementContainer} from '../dom/element-container';
-import {getAbsoluteValue, getAbsoluteValueForTuple, getAbsoluteValueForDimension} from '../css/types/length-percentage';
+import {getAbsoluteValue, getAbsoluteValueForDimension, getAbsoluteValueForTuple} from '../css/types/length-percentage';
 import {Vector} from './vector';
 import {BezierCurve} from './bezier-curve';
 import {Path} from './path';
+import {TokenType} from '../css/syntax/tokenizer';
 
 export class BoundCurves {
     readonly topLeftBorderDoubleOuterBox: Path;
@@ -76,16 +77,19 @@ export class BoundCurves {
         const paddingBottom = getAbsoluteValue(styles.paddingBottom, element.bounds.width);
         const paddingLeft = getAbsoluteValue(styles.paddingLeft, element.bounds.width);
 
-        let rectClipTop = 0;
-        let rectClipRight = 0;
-        let rectClipBottom = 0;
-        let rectClipLeft = 0;
-        if (styles.clip) {
-            rectClipTop = getAbsoluteValueForDimension(styles.clip.top);
-            rectClipRight = getAbsoluteValueForDimension(styles.clip.right);
-            rectClipBottom = getAbsoluteValueForDimension(styles.clip.bottom);
-            rectClipLeft = getAbsoluteValueForDimension(styles.clip.left);
-        }
+        const rectClipTop =
+            styles.clip?.top.type == TokenType.DIMENSION_TOKEN ? getAbsoluteValueForDimension(styles.clip.top) : 0;
+        const rectClipLeft =
+            styles.clip?.left.type == TokenType.DIMENSION_TOKEN ? getAbsoluteValueForDimension(styles.clip.left) : 0;
+
+        const rectClipBottom =
+            styles.clip?.bottom.type == TokenType.DIMENSION_TOKEN
+                ? getAbsoluteValueForDimension(styles.clip.bottom)
+                : bounds.height;
+        const rectClipRight =
+            styles.clip?.right.type == TokenType.DIMENSION_TOKEN
+                ? getAbsoluteValueForDimension(styles.clip.right)
+                : bounds.width;
 
         this.topLeftBorderDoubleOuterBox =
             tlh > 0 || tlv > 0
diff --git a/tests/reftests/clip.html b/tests/reftests/clip.html
index 88f4cae..4166f75 100644
--- a/tests/reftests/clip.html
+++ b/tests/reftests/clip.html
@@ -45,5 +45,13 @@
 <div style="clip: rect(0px, 400px, 50px, 200px); position: absolute; top: 500px; left: 500px; border-radius: 100%; overflow: hidden;">Some inline text <span> followed by text in span </span> followed by more inline text.
     <p>Then a block level element.</p>
     Then more inline text.</div>
+
+<div style="clip: rect(auto, auto, auto, 30px); position: absolute; top: 750px;">Some inline text <span> followed by text in span </span> followed by more inline text.
+    <p>Then a block level element.</p>
+    Then more inline text.</div>
+
+<div style="clip: auto; position: absolute; top: 750px; left: 500px;">Some inline text <span> followed by text in span </span> followed by more inline text.
+    <p>Then a block level element.</p>
+    Then more inline text.</div>
 </body>
 </html>