🐛 Fixes problems with gradients when rotation

common/app/common/geom/shapes.cljc

@@ -266,6 +266,7 @@
 (d/export gpr/points->selrect)
 (d/export gtr/transform-shape)
 (d/export gtr/transform-matrix)
+(d/export gtr/inverse-transform-matrix)
 (d/export gtr/transform-point-center)
 (d/export gtr/transform-rect)
 (d/export gtr/update-group-selrect)

common/app/common/geom/shapes/transforms.cljc

@@ -38,6 +38,18 @@
              (and (not no-flip) flip-y) (gmt/scale (gpt/point 1 -1)))
          (gmt/translate (gpt/negate shape-center))))))
 
+(defn inverse-transform-matrix
+  ([shape]
+   (let [shape-center (or (gco/center-shape shape)
+                          (gpt/point 0 0))]
+     (inverse-transform-matrix shape shape-center)))
+  ([shape center]
+   (let []
+     (-> (gmt/matrix)
+         (gmt/translate center)
+         (gmt/multiply (:transform-inverse shape (gmt/matrix)))
+         (gmt/translate (gpt/negate center))))))
+
 (defn transform-point-center
   "Transform a point around the shape center"
   [point center matrix]
@@ -257,6 +269,30 @@
           apply-transform-rect)]
     (apply-transform-fn shape transform)))
 
+(defn transform-gradients [shape modifiers]
+  (let [angle (d/check-num (get modifiers :rotation))
+        ;; Gradients are represented with unit vectors so its center is 0.5, 0.5
+        center (gpt/point 0.5 0.5)
+        transform (gmt/rotate-matrix angle center)
+        transform-gradient
+        (fn [{:keys [start-x start-y end-x end-y] :as gradient}]
+          (let [start-point (gpt/point start-x start-y)
+                end-point   (gpt/point end-x end-y)
+                {start-x :x start-y :y} (gpt/transform start-point transform)
+                {end-x :x end-y :y}     (gpt/transform end-point transform)]
+
+            (assoc gradient
+                   :start-x start-x
+                   :start-y start-y
+                   :end-x end-x
+                   :end-y end-y)))]
+    (cond-> shape
+      (:fill-color-gradient shape)
+      (update :fill-color-gradient transform-gradient)
+
+      (:stroke-color-gradient shape)
+      (update :stroke-color-gradient transform-gradient))))
+
 (defn set-flip [shape modifiers]
   (let [rx (get-in modifiers [:resize-vector :x])
         ry (get-in modifiers [:resize-vector :y])]
@@ -271,6 +307,7 @@
         (-> shape
             (set-flip (:modifiers shape))
             (apply-transform transform)
+            (transform-gradients (:modifiers shape))
             (dissoc :modifiers)))
       shape)))
 
@@ -296,3 +333,4 @@
         (assoc :selrect new-selrect)
         (assoc :points new-points)
         (apply-transform-rect (gmt/matrix)))))
+

frontend/src/app/main/ui/shapes/gradients.cljs

@@ -14,15 +14,21 @@
    [app.util.object :as obj]
    [app.common.uuid :as uuid]
    [app.main.ui.context :as muc]
-   [app.common.geom.point :as gpt]))
+   [app.common.geom.point :as gpt]
+   [app.common.geom.matrix :as gmt]
+   [app.common.geom.shapes :as gsh]))
 
 (mf/defc linear-gradient [{:keys [id gradient shape]}]
-  (let [{:keys [x y width height]} shape]
+  (let [{:keys [x y width height]} (:selrect shape)
+        transform (case (:type shape)
+                    :path (gmt/matrix)
+                    (gsh/inverse-transform-matrix shape (gpt/point 0.5 0.5)))]
     [:linearGradient {:id id
                       :x1 (:start-x gradient)
                       :y1 (:start-y gradient)
                       :x2 (:end-x gradient)
-                      :y2 (:end-y gradient)}
+                      :y2 (:end-y gradient)
+                      :gradient-transform transform}
      (for [{:keys [offset color opacity]} (:stops gradient)]
        [:stop {:key (str id "-stop-" offset)
                :offset (or offset 0)
@@ -30,7 +36,10 @@
                :stop-opacity opacity}])]))
 
 (mf/defc radial-gradient [{:keys [id gradient shape]}]
-  (let [{:keys [x y width height]} shape]
+  (let [{:keys [x y width height]} (:selrect shape)
+        transform (case (:type shape)
+                    :path (gmt/matrix)
+                    (gsh/inverse-transform-matrix shape))]
     (let [[x y] (if (= (:type shape) :frame) [0 0] [x y])
           translate-vec (gpt/point (+ x (* width (:start-x gradient)))
                                    (+ y (* height (:start-y gradient))))
@@ -51,10 +60,10 @@
           scale-vec (gpt/point (* scale-factor-y (/ height 2))
                                (* scale-factor-x (/ width 2)))
 
-          tr-translate (str/fmt "translate(%s, %s)" (:x translate-vec) (:y translate-vec))
-          tr-rotate (str/fmt "rotate(%s)" angle)
-          tr-scale (str/fmt "scale(%s, %s)" (:x scale-vec) (:y scale-vec))
-          transform (str/fmt "%s %s %s" tr-translate tr-rotate tr-scale)]
+          transform (gmt/multiply transform
+                                  (gmt/translate-matrix translate-vec)
+                                  (gmt/rotate-matrix angle)
+                                  (gmt/scale-matrix scale-vec))]
       [:radialGradient {:id id
                         :cx 0
                         :cy 0