Expo matrix values (#914)

Author: wcandillon

example/src/Examples/API/Transform.tsx

@@ -126,19 +126,19 @@ export const Transform = () => {
         const pers0 = 0;
         const pers1 = 0;
         const pers2 = 1;
-        canvas.concat(
-          Skia.Matrix([
-            scaleX,
-            skewX,
-            transX,
-            skewY,
-            scaleY,
-            transY,
-            pers0,
-            pers1,
-            pers2,
-          ])
-        );
+        const m = Skia.Matrix([
+          scaleX,
+          skewX,
+          transX,
+          skewY,
+          scaleY,
+          transY,
+          pers0,
+          pers1,
+          pers2,
+        ]);
+        //console.log({ matrix: m.get() });
+        canvas.concat(m);
 
         canvas.drawImageRect(image, imgRect, rect, paint);
         canvas.restore();

package/cpp/api/JsiSkMatrix.h

@@ -88,6 +88,14 @@ class JsiSkMatrix : public JsiSkWrappingSharedPtrHostObject<SkMatrix> {
     return jsi::Value::undefined();
   }
 
+  JSI_HOST_FUNCTION(get) {
+    auto values = jsi::Array(runtime, 9);
+    for (auto i = 0; i < 9; i++) {
+      values.setValueAtIndex(runtime, i, getObject()->get(i));
+    }
+    return values;
+  }
+
   JSI_EXPORT_PROPERTY_GETTERS(JSI_EXPORT_PROP_GET(JsiSkMatrix, __typename__))
 
   JSI_EXPORT_FUNCTIONS(
@@ -97,6 +105,7 @@ class JsiSkMatrix : public JsiSkWrappingSharedPtrHostObject<SkMatrix> {
     JSI_EXPORT_FUNC(JsiSkMatrix, skew),
     JSI_EXPORT_FUNC(JsiSkMatrix, rotate),
     JSI_EXPORT_FUNC(JsiSkMatrix, identity),
+    JSI_EXPORT_FUNC(JsiSkMatrix, get),
   )
 
   /**

package/src/renderer/__tests__/Transform.spec.tsx

@@ -29,6 +29,7 @@ describe("Renderer", () => {
     matrix.translate(origin.x, origin.y);
     matrix.scale(0.5);
     matrix.translate(-origin.x, -origin.y);
+    expect(matrix.get()).toStrictEqual([0.5, 0, 192, 0, 0.5, 192, 0, 0, 1]);
     const surface = drawOnNode(
       <Group matrix={matrix}>
         <Rect x={0} y={0} width={size} height={size} color="lightblue" />

package/src/skia/types/Matrix.ts

@@ -22,6 +22,7 @@ export interface SkMatrix extends SkJSIInstance<"Matrix"> {
   skew: (x: number, y: number) => void;
   rotate: (theta: number) => void;
   identity: () => void;
+  get: () => number[];
 }
 
 type Transform2dName =

package/src/skia/web/JsiSkMatrix.ts

@@ -57,4 +57,8 @@ export class JsiSkMatrix
   identity() {
     this.ref.set(this.CanvasKit.Matrix.identity());
   }
+
+  get() {
+    return Array.from(this.ref);
+  }
 }