1 files changed, 24 insertions, 19 deletions
diff --git a/src/modules/zoom.js b/src/modules/zoom.js
index fc0540b..834602b 100644
--- a/src/modules/zoom.js
+++ b/src/modules/zoom.js
@@ -5,14 +5,17 @@ function zoomIn(deltaY) {
 }
 
 function getScale(e, factor) {
-  return zoomIn(e.deltaY) ? 1 + factor : 1 - factor;
+  const outMult = 1 - factor;
+  const inMult = 1 + factor / outMult
+
+  return zoomIn(e.deltaY) ? inMult : outMult;
 }
 
 function getFocalPointBeforeTransform(el, e, inverseScreenCTM) {
-  const { x, y, width, height } = el.getBoundingClientRect(),
-    pointer = (new DOMPoint(e.clientX, e.clientY)).matrixTransform(inverseScreenCTM),
-    origin = (new DOMPoint(x, y)).matrixTransform(inverseScreenCTM),
-    terminus = (new DOMPoint(x + width, y + height)).matrixTransform(inverseScreenCTM);
+  const { x, y, width, height } = el.getBoundingClientRect();
+  const pointer = (new DOMPoint(e.clientX, e.clientY)).matrixTransform(inverseScreenCTM);
+  const origin = (new DOMPoint(x, y)).matrixTransform(inverseScreenCTM);
+  const terminus = (new DOMPoint(x + width, y + height)).matrixTransform(inverseScreenCTM);
 
   return {
     x: pointer.x,
@@ -25,10 +28,10 @@ function getFocalPointBeforeTransform(el, e, inverseScreenCTM) {
 }
 
 function getFocalPointAfterTransform(el, fpBeforeTrans, inverseScreenCTM) {
-  const { x, y, width, height } = el.getBoundingClientRect(),
-    origin = (new DOMPoint(x, y)).matrixTransform(inverseScreenCTM),
-    terminus = (new DOMPoint(x + width, y + height)).matrixTransform(inverseScreenCTM),
-    relativeFocalPoint = fpBeforeTrans.relativeToImageSize;
+  const { x, y, width, height } = el.getBoundingClientRect();
+  const origin = (new DOMPoint(x, y)).matrixTransform(inverseScreenCTM);
+  const terminus = (new DOMPoint(x + width, y + height)).matrixTransform(inverseScreenCTM);
+  const relativeFocalPoint = fpBeforeTrans.relativeToImageSize;
 
   return {
     x: origin.x + (terminus.x - origin.x) * relativeFocalPoint.x,
@@ -37,13 +40,13 @@ function getFocalPointAfterTransform(el, fpBeforeTrans, inverseScreenCTM) {
 }
 
 function getTranslateMatrix(el, e, scaleMatrix) {
-  const inverseScreenCTM = el.getScreenCTM().inverse(),
-    fpBeforeTrans = getFocalPointBeforeTransform(el, e, inverseScreenCTM);
+  const inverseScreenCTM = el.getScreenCTM().inverse();
+  const fpBeforeTrans = getFocalPointBeforeTransform(el, e, inverseScreenCTM);
 
   el.style.transform = scaleMatrix;
 
-  const fpAfterTrans = getFocalPointAfterTransform(el, fpBeforeTrans, inverseScreenCTM),
-    translateMatrix = new DOMMatrix();
+  const fpAfterTrans = getFocalPointAfterTransform(el, fpBeforeTrans, inverseScreenCTM);
+  const translateMatrix = new DOMMatrix();
 
   return translateMatrix.translate(
     fpBeforeTrans.x - fpAfterTrans.x,
@@ -51,12 +54,14 @@ function getTranslateMatrix(el, e, scaleMatrix) {
   );
 }
 
-export default function (el, e, factor = 0.1) {
-  e.preventDefault();
+export default function (el, factor = 0.1) {
+  return e => {
+    e.preventDefault();
 
-  const mtx = getComputedTransformMatrix(el),
-    scale = getScale(e, factor),
-    transMtx = getTranslateMatrix(el, e, mtx.scale(scale));
+    const mtx = getComputedTransformMatrix(el);
+    const scale = getScale(e, factor);
+    const transMtx = getTranslateMatrix(el, e, mtx.scale(scale));
 
-  el.style.transform = mtx.multiply(transMtx).scale(scale);
+    el.style.transform = mtx.multiply(transMtx).scale(scale);
+  }
 }