Optimize Matrix2d and fix skew spec conformance

ruslanaplid · Jan 9, 2019 · 88adb2a · 88adb2a
1 parent ca611a4
commit 88adb2a
Showing 1 changed file with 21 additions and 28 deletions.
diff --git a/lib/Matrix2D.js b/lib/Matrix2D.js
@@ -74,6 +74,7 @@ export default class Matrix2D {
     reset = function() {
         this.a = this.d = 1;
         this.b = this.c = this.tx = this.ty = 0;
+        this.hasInitialState = true;
         return this;
     };
 
@@ -99,6 +100,16 @@ export default class Matrix2D {
      * @return {Matrix2D} This matrix. Useful for chaining method calls.
      **/
     append = function(a, b, c, d, tx, ty) {
+        if (this.hasInitialState) {
+            this.hasInitialState = false;
+            this.a = a;
+            this.b = b;
+            this.c = c;
+            this.d = d;
+            this.tx = tx;
+            this.ty = ty;
+            return this;
+        }
         const a1 = this.a;
         const b1 = this.b;
         const c1 = this.c;
@@ -141,7 +152,7 @@ export default class Matrix2D {
         skewX,
         skewY,
         regX,
-        regY
+        regY,
     ) {
         let cos, sin;
         if (rotation % 360) {
@@ -153,35 +164,17 @@ export default class Matrix2D {
             sin = 0;
         }
 
+        const a = cos * scaleX;
+        const b = sin * scaleX;
+        const c = -sin * scaleY;
+        const d = cos * scaleY;
+
         if (skewX || skewY) {
-            // TODO: can this be combined into a single append operation?
-            skewX *= DEG_TO_RAD;
-            skewY *= DEG_TO_RAD;
-            this.append(
-                Math.cos(skewY),
-                Math.sin(skewY),
-                Math.sin(skewX),
-                Math.cos(skewX),
-                x,
-                y
-            );
-            this.append(
-                cos * scaleX,
-                sin * scaleX,
-                -sin * scaleY,
-                cos * scaleY,
-                0,
-                0
-            );
+            const b1 = Math.tan(skewY * DEG_TO_RAD);
+            const c1 = Math.tan(skewX * DEG_TO_RAD);
+            this.append(a + c1 * b, b1 * a + b, c + c1 * d, b1 * c + d, x, y);
         } else {
-            this.append(
-                cos * scaleX,
-                sin * scaleX,
-                -sin * scaleY,
-                cos * scaleY,
-                x,
-                y
-            );
+            this.append(a, b, c, d, x, y);
         }
 
         if (regX || regY) {