Add zoom event handler that responds to mouse wheel events

[mro]

Originally reported on Google Code with ID 236

Feature request, add a zoom event handler that responds to mouse wheel events.

Reported by heuermh on 2012-01-25 22:35:37

[mro]

Patch to svn trunk attached.

Reported by heuermh on 2012-01-25 22:37:05

• Status changed: Started
• Labels added: Type-Enhancement, Priority-Medium, Effort-Low, OpSys-All, Toolkit-Piccolo2D.Java, Component-Core, Milestone-2.0

---

- _Attachment: [patch.txt](https://storage.googleapis.com/google-code-attachments/piccolo2d/issue-236/comment-1/patch.txt)_

[mro]

Looks good.

PZoomEventHandler uses a viewZoomPoint (where the user clicked) to anchor the zoom.
Consider anchoring zoom where the mouse is pointing when the wheel is rotated. (This
is how Google Maps works, for example.)

Something like:

...
final Point2D anchor = e.getCanvasPosition();
camera.localToView(anchor);
camera.scaleViewAboutPoint(scale, anchor.getX(), anchor.getY());
...

Reported by atdixon on 2012-02-12 00:06:26

[mro]

Thank you for the comments.

I was thinking of adding the viewZoomPoint feature, but I don't actually like that
behavior.  Would you be ok with making that configurable with a boolean bound property?
 The same might be added to PZoomEventHandler while I'm at it.

And one minor fix to the patch above,

-    PMouseWheelZoomEventHandler() {
+    public PMouseWheelZoomEventHandler() {

Reported by heuermh on 2012-02-12 02:18:22

[mro]

Yep, I like making it configurable with a boolean option.

Reported by atdixon on 2012-02-12 19:25:24

[mro]

Input event handlers don't have property change support, so I just went with a ZoomMode
enum instead.  Let me know what you think; updated patch attached.

Reported by heuermh on 2012-02-15 23:05:12

---

- _Attachment: [zoom-mode-patch.txt](https://storage.googleapis.com/google-code-attachments/piccolo2d/issue-236/comment-5/zoom-mode-patch.txt)_

[mro]

I like it.

Reported by atdixon on 2012-02-18 03:31:03

[mro]

Turns out another zoom mode was what I was actually after, zoom about canvas center.
 I added that and made it the default.

There is also a new MouseWheelZoomExample that demonstrates the different modes.

$ svn commit -m "Issue 236 ; adding zoom event handler that responds to mouse wheel
events" core/ examples/
Adding         core/src/main/java/org/piccolo2d/event/PMouseWheelZoomEventHandler.java
Adding         core/src/test/java/org/piccolo2d/event/PMouseWheelZoomEventHandlerTest.java
Sending        examples/src/main/java/org/piccolo2d/examples/ExampleRunner.java
Adding         examples/src/main/java/org/piccolo2d/examples/MouseWheelZoomExample.java
Transmitting file data ....
Committed revision 1163.

Reported by heuermh on 2012-02-23 22:05:40

• Status changed: Fixed

[mro]

Reported by atdixon on 2012-02-25 01:29:12

• Status changed: Verified