React-ing to the need for a modern MapGuide viewer (Part 19): Highlighting selected features

When I was implementing the Selection Panel for mapguide-react-layout, this super-ancient Fusion ticket was on the back of my mind as being able to highlight selected features is a very useful feature to have.

Whereas I didn't really have an idea how this would be done in Fusion, for mapguide-react-layout I had an idea how this would be done.

The trick is to use the v2.6 QUERYMAPFEATURES operation with the following parameters:

• REQUESTDATA=2 (asking for inline selection image only)
• LAYERATTRIBUTEFILTER=0 (so that selection is not constrained by layer selectability and our current view)
• FEATUREFILTER=(the selection XML sub-fragment that represents the selected feature)
• PERSIST=0 (the most important parameter. We want this operation to not alter the selection set)

Once the QUERYMAPFEATURES operation is sent and we get a response, the key is to be able to line up the inline selection image (data URI) with the current map. To handle this part, we use an OL static image source to store the inline selection image.

When all the pieces are brought together, we finally have the ability to highlight selected features.

This will be in the next release of mapguide-react-layout.

React-ing to the need for a modern MapGuide viewer (Part 18): Restoring the Quick Plot capture box

If you've been playing with mapguide-react-layout, you'll no doubt have noticed a glaring omission in the ported Quick Plot component.

The interactive map capture box.

Porting across the capture box sounded mostly simple:

• Manage the temporary OL vector layer containing the capture box.
• Attach an OL translate interaction so the capture box feature can be easily moved around by dragging the box around.
• Auto-update box geometry based on change in paper size / orientation / scale

There was just one technical hurdle: Rotating the box.

For the longest time, I was wracking my brain figuring out how to replace the rotation "grip handle" using the new OpenLayers APIs and I couldn't figure it out. The APIs were there to rotate feature geometry. I heard about ol-rotate-feature and gave it a try, but I couldn't grasp how that interaction actually rotates features.

So I went back to the mental drawing board. OpenLayers has APIs to rotate features, so what we really just need was an intuitive UI input to enter the box rotation. If I couldn't figure out how to replicate the rotation "grip handle", then the next best thing was ... a numerical slider.

And with that, the missing piece was found and I was finally able to port over the final piece of functionality of the original Fusion QuickPlot widget.

In the above GIF, you might have noticed a message flash by.

This is merely a simple countermeasure against the fact that with current OpenLayers, you can rotate the map as well. So rather than deal with number crunching 2 sets of rotations, it is easier to just reset the rotation on the map and prevent the ability to rotate the map while the map capture box is active.

And with that, our Quick Plot component has reached feature parity with the original Fusion widget.

This (newly feature parity) Quick Plot will be available in the next release of mapguide-react-layout, whenever I decide that will be.

Announcing: mapguide-react-layout 0.9.6

This is a quick release to make the awesome new layer transparency sliders in the previous release not break down when used on a map that doesn't actually have external base layers (OSM, Bing, etc)

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