Hi,
I was testing the three zoom tools we have now (basic zoom, continuos zoom and
the new Super Zoom) with a few different computerers (desktop/laptop, 2-button
mouse/3-button mouse/laptop mouse systems).
The old zoom tool behaves in a way that is more or less standard in GIS
programs. What happens with left click, right click and left-drag (zoom to a
box) are rather much what I think that new users believe them to do. Mouse
wheel works fine too and rescaling the map view gives an immediate feedback
about what is going to happen. Main thing that is missing in this tool is the
easy way for swithing to pan mode. It requires either pressing the Shift-Alt
keyboard shortcuts or selecting the pan tool from the tool bar.
The new Super Zoom combines zoom and pan tools. Zoom in and zoom our by a mouse
click are obvious and Click and drag too, because the cursor is changing and
the moving map image gives immediate feed back. It is OpenLayers-like too.
Next thing taht OpenLayers users will try is to do Shift-Drag for zoom to box
but. However, in OpenJUMP this has always been done by Alt-drag. Because Shift
key alone is not used as a keyboard shortcut it might be an alternative to make
it do the same thing as Alt is doing now. I am so used to work with the
existing shortcuts that personally I would not like to see Alt shortcut to be
moved to Shift.
Super zoom tool has some caveats. Without a mouse wheel user must use keyboard
Alt for zooming to an accurate box. Even with mouse wheel it is not very
accurate because of the zoom steps but it is acceptable. What would be good to
improve is to give some visual hint about what happens when zooming out.
Zooming in with mouse wheel shows the wireframe but user does not see anything
when zooming out because the wireframe is outside the image. Scaling the
mapimage like the old zoom tool and continuous zoom tool are doing would be
good.
I am not sure if the two phase zoom (draw and place the box and click) is
needed with Super Zoom mouse wheel because panning is always available. Perhaps
it could just zoom around the pointed place and final tuning could be done by
dragging.
I would suggest to consider enhancing the existing zoom tool with a few
features from the Super zoom tool.
- Left click and Left click - drag would do what they do now (zoom in and zoom
to box) because they are common and intuitive.
- Right click would continue to zoom out.
- Right click - drag does not do anything at the moment. It could start to do
panning. It would be good for laptop users and those with just two mouse
buttons. The somehow natural alternative is "Zoom out to box" but myself I have
always felt it is not as intuitive as the "Zoom in to box" is.
- Middle button/Press the mouse wheel would always pan.
- Mouse wheel would zoom in/out similarly than the standard zoom tool does by
rescaling the map image
- Status line usage hints and scale would be added from the Super Zoom.
I must admit that Left click - drag is also rather standard
Middle click/Right click and drag for panning would be a great addition for the
digitizing mode. Now it is impossible to digitize roads or large polygons
without using keyboard shortcuts. But perhaps it is not possible with right
click because it is already reserved from context menu.
With these changes OpenJUMP user could do all the general zoom and pan tasks
with one zoom tool and without touching the keyboard. Only two-button mouse
would be needed but three button mouse and mouse wheel would give even better
options.
The Continuos zoom tool is one of the kind and I personally use it a lot
because of the nice visual feeling it gives be rescaling the map when planning
the zoom in / zoom out operation. Panning is bit odd, though, because for
panning east-west or north-south one must use left/right mouse button,
respectively. It would be great if the tool would do just panning to all
directions by pressing the middle button/mouse wheel. Anyway, continuos zoom
tool probabably cannot be integrated with other zoom tools.
-Jukka Rahkonen-
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