solvespace · phkahler · Feb 28, 2022 · Mar 31, 2021 · Apr 1, 2021 · Feb 5, 2022
diff --git a/src/graphicswin.cpp b/src/graphicswin.cpp
@@ -712,16 +712,47 @@ double GraphicsWindow::ZoomToFit(const Camera &camera,
     return scale;
 }
 
+
+void GraphicsWindow::ZoomToMouse(double zoomMultiplyer) {
+    double offsetRight = offset.Dot(projRight);
+    double offsetUp    = offset.Dot(projUp);
+
+    double width, height;
+    window->GetContentSize(&width, &height);
+
+    double righti = currentMousePosition.x / scale - offsetRight;
+    double upi    = currentMousePosition.y / scale - offsetUp;
+
+    // zoomMultiplyer of 1 gives a default zoom factor of 1.2x: zoomMultiplyer * 1.2
+    // zoom = adjusted zoom negative zoomMultiplyer will zoom out, positive will zoom in
+    //
+
+    scale *= exp(0.1823216 * zoomMultiplyer); // ln(1.2) = 0.1823216
+
+    double rightf = currentMousePosition.x / scale - offsetRight;
+    double upf    = currentMousePosition.y / scale - offsetUp;
+
+    offset = offset.Plus(projRight.ScaledBy(rightf - righti));
+    offset = offset.Plus(projUp.ScaledBy(upf - upi));
+
+    if(SS.TW.shown.screen == TextWindow::Screen::EDIT_VIEW) {
+        if(havePainted) {
+            SS.ScheduleShowTW();
+        }
+    }
+    havePainted = false;
+    Invalidate();
+}
+
+
 void GraphicsWindow::MenuView(Command id) {
     switch(id) {
         case Command::ZOOM_IN:
-            SS.GW.scale *= 1.2;
-            SS.ScheduleShowTW();
+            SS.GW.ZoomToMouse(1);
             break;
 
         case Command::ZOOM_OUT:
-            SS.GW.scale /= 1.2;
-            SS.ScheduleShowTW();
+            SS.GW.ZoomToMouse(-1);
             break;
 
         case Command::ZOOM_TO_FIT:

diff --git a/src/mouse.cpp b/src/mouse.cpp
@@ -914,7 +914,7 @@ bool GraphicsWindow::MouseEvent(Platform::MouseEvent event) {
             break;
 
         case MouseEvent::Type::SCROLL_VERT:
-            this->MouseScroll(event.x, event.y, event.shiftDown ? event.scrollDelta / 10 : event.scrollDelta);
+            this->MouseScroll(event.shiftDown ? event.scrollDelta / 10 : event.scrollDelta);
             break;
 
         case MouseEvent::Type::LEAVE:
@@ -1478,39 +1478,18 @@ void GraphicsWindow::EditControlDone(const std::string &s) {
     }
 }
 
-void GraphicsWindow::MouseScroll(double x, double y, double delta) {
-    double offsetRight = offset.Dot(projRight);
-    double offsetUp = offset.Dot(projUp);
-
-    double righti = x/scale - offsetRight;
-    double upi = y/scale - offsetUp;
-
-    // The default zoom factor is 1.2x for one scroll wheel click (delta==1).
+void GraphicsWindow::MouseScroll(double zoomMultiplyer) {
     // To support smooth scrolling where scroll wheel events come in increments
     // smaller (or larger) than 1 we do:
-    //     scale *= exp(ln(1.2) * delta);
+    //     scale *= exp(ln(1.2) * zoomMultiplyer);
     // to ensure that the same total scroll delta always results in the same
     // total zoom irrespective of in how many increments the zoom was applied.
     // For example if we scroll a total delta of a+b in two events vs. one then
     //     scale * e^a * e^b == scale * e^(a+b)
     // while
     //     scale * a * b != scale * (a+b)
     // So this constant is ln(1.2) = 0.1823216 to make the default zoom 1.2x
-    scale *= exp(0.1823216 * delta);
-
-    double rightf = x/scale - offsetRight;
-    double upf = y/scale - offsetUp;
-
-    offset = offset.Plus(projRight.ScaledBy(rightf - righti));
-    offset = offset.Plus(projUp.ScaledBy(upf - upi));
-
-    if(SS.TW.shown.screen == TextWindow::Screen::EDIT_VIEW) {
-        if(havePainted) {
-            SS.ScheduleShowTW();
-        }
-    }
-    havePainted = false;
-    Invalidate();
+    ZoomToMouse(zoomMultiplyer);
 }
 
 void GraphicsWindow::MouseLeave() {

diff --git a/src/ui.h b/src/ui.h
@@ -622,6 +622,7 @@ class GraphicsWindow {
     void HandlePointForZoomToFit(Vector p, Point2d *pmax, Point2d *pmin,
                                  double *wmin, bool usePerspective,
                                  const Camera &camera);
+    void ZoomToMouse(double delta);
     void LoopOverPoints(const std::vector<Entity *> &entities,
                         const std::vector<Constraint *> &constraints,
                         const std::vector<hEntity> &faces,
@@ -842,7 +843,7 @@ class GraphicsWindow {
     void MouseLeftDoubleClick(double x, double y);
     void MouseMiddleOrRightDown(double x, double y);
     void MouseRightUp(double x, double y);
-    void MouseScroll(double x, double y, double delta);
+    void MouseScroll(double delta);
     void MouseLeave();
     bool KeyboardEvent(Platform::KeyboardEvent event);
     void EditControlDone(const std::string &s);