feat(Circle): Add counterclockwise parameter to Circle class

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## [next]
 
+- feat(Circle): Add counterclockwise parameter to Circle class [#9670](https://github.com/fabricjs/fabric.js/pull/9670)
+
 ## [6.0.0-beta19]
 
 - feat(LayoutManager): Expose objects registration [#9661](https://github.com/fabricjs/fabric.js/pull/9661)

src/shapes/Circle.ts

@@ -19,20 +19,26 @@ interface UniqueCircleProps {
   radius: number;
 
   /**
-   * degrees of start of the circle.
-   * probably will change to degrees in next major version
-   * @type Number 0 - 359
+   * Angle for the start of the circle, in degrees.
+   * @type TDegree 0 - 359
    * @default 0
    */
   startAngle: number;
 
   /**
-   * End angle of the circle
-   * probably will change to degrees in next major version
-   * @type Number 1 - 360
+   * Angle for the end of the circle, in degrees
+   * @type TDegree 1 - 360
    * @default 360
    */
   endAngle: number;
+
+  /**
+   * Orientation for the direction of the circle.
+   * Setting to true will switch the arc of the circle to traverse from startAngle to endAngle in a counter-clockwise direction.
+   * Note: this will only change how the circle is drawn, and does not affect rotational transformation.
+   * @default false
+   */
+  counterClockwise: boolean;
 }
 
 export interface SerializedCircleProps
@@ -41,12 +47,18 @@ export interface SerializedCircleProps
 
 export interface CircleProps extends FabricObjectProps, UniqueCircleProps {}
 
-const CIRCLE_PROPS = ['radius', 'startAngle', 'endAngle'] as const;
+const CIRCLE_PROPS = [
+  'radius',
+  'startAngle',
+  'endAngle',
+  'counterClockwise',
+] as const;
 
 export const circleDefaultValues: UniqueCircleProps = {
   radius: 0,
   startAngle: 0,
   endAngle: 360,
+  counterClockwise: false,
 };
 
 export class Circle<
@@ -60,6 +72,7 @@ export class Circle<
   declare radius: number;
   declare startAngle: number;
   declare endAngle: number;
+  declare counterClockwise: boolean;
 
   static type = 'Circle';
 
@@ -101,7 +114,7 @@ export class Circle<
       this.radius,
       degreesToRadians(this.startAngle),
       degreesToRadians(this.endAngle),
-      false
+      this.counterClockwise
     );
     this._renderPaintInOrder(ctx);
   }
@@ -169,14 +182,10 @@ export class Circle<
         startY = sin(start) * radius,
         endX = cos(end) * radius,
         endY = sin(end) * radius,
-        largeFlag = angle > 180 ? '1' : '0';
+        largeFlag = angle > 180 ? 1 : 0,
+        sweepFlag = this.counterClockwise ? 0 : 1;
       return [
-        `<path d="M ${startX} ${startY}`,
-        ` A ${radius} ${radius}`,
-        ' 0 ',
-        `${largeFlag} 1`,
-        ` ${endX} ${endY}`,
-        '" ',
+        `<path d="M ${startX} ${startY} A ${radius} ${radius} 0 ${largeFlag} ${sweepFlag} ${endX} ${endY}" `,
         'COMMON_PARTS',
         ' />\n',
       ];

test/unit/circle.js

@@ -117,6 +117,7 @@
       radius:                   0,
       startAngle:               0,
       endAngle:                 360,
+      counterClockwise:         false,
       skewX:                    0,
       skewY:                    0,
       strokeUniform:            false
@@ -159,13 +160,21 @@
   });
 
   QUnit.test('toSVG with half circle', function(assert) {
-    var circle = new fabric.Circle({ width: 100, height: 100, radius: 10, endAngle: fabric.util.radiansToDegrees(Math.PI) });
+    var circle = new fabric.Circle({ width: 100, height: 100, radius: 10, endAngle: 180 });
     var svg = circle.toSVG();
     var svgClipPath = circle.toClipPathSVG();
     assert.equal(svg, '<g transform=\"matrix(1 0 0 1 10.5 10.5)\"  >\n<path d=\"M 10 0 A 10 10 0 0 1 -10 0\" style=\"stroke: none; stroke-width: 1; stroke-dasharray: none; stroke-linecap: butt; stroke-dashoffset: 0; stroke-linejoin: miter; stroke-miterlimit: 4; fill: rgb(0,0,0); fill-rule: nonzero; opacity: 1;\"   />\n</g>\n');
     assert.equal(svgClipPath, '\t<path d=\"M 10 0 A 10 10 0 0 1 -10 0\" transform=\"matrix(1 0 0 1 10.5 10.5)\"  />\n', 'half circle as clipPath');
   });
 
+  QUnit.test('toSVG with counterclockwise half circle', function (assert) {
+    var circle = new fabric.Circle({ width: 100, height: 100, radius: 10, endAngle: 180, counterClockwise: true });
+    var svg = circle.toSVG();
+    var svgClipPath = circle.toClipPathSVG();
+    assert.equal(svg, '<g transform=\"matrix(1 0 0 1 10.5 10.5)\"  >\n<path d=\"M 10 0 A 10 10 0 0 0 -10 0\" style=\"stroke: none; stroke-width: 1; stroke-dasharray: none; stroke-linecap: butt; stroke-dashoffset: 0; stroke-linejoin: miter; stroke-miterlimit: 4; fill: rgb(0,0,0); fill-rule: nonzero; opacity: 1;\"   />\n</g>\n');
+    assert.equal(svgClipPath, '\t<path d=\"M 10 0 A 10 10 0 0 0 -10 0\" transform=\"matrix(1 0 0 1 10.5 10.5)\"  />\n', 'half circle as clipPath');
+  });
+
   QUnit.test('fromElement', function(assert) {
     var done = assert.async();
     assert.ok(typeof fabric.Circle.fromElement === 'function');