displayOutput hover/click coordinates

[markgrujic]

Hi,
Just wondering if there is the capability in the shiny binding to get the location of the cursor as with plotOutput:

plotOutput("plot1", click = "plot_click", dblclick = "plot_dblclick", hover = "plot_hover", brush = "plot_brush" ),

Which are then available via input$plot_click etc. I can't see anything in the docs, so maybe this is a feature request?

[markgrujic]

Adding to this, being able to extract the coordinates of the extent of the current viewed area (after zooming) would be very useful.

[jkh1]

For on hover events, one needs to modify the function updatePixelPosition() in EBImage/htmlwidgets/lib/viewer/viewer.js by adding the line
Shiny.setInputValue("pixelPosition", pixelPos);
at the end of the function. This will make the mouse pixel coordinates available in the variable input$pixelPosition. Similarly, one can get the current frame by adding
Shiny.setInputValue("currentFrame", currentFrame);
to setFrame() and the image dimensions with:

Shiny.setInputValue("imgWidth", originalWidth);
Shiny.setInputValue("imgHeight", originalHeight);

in reset().
The mouse click function is already used for panning so to get the mouse position in pixel coordinates, one needs to add
Shiny.setInputValue("pixelPosition", viewer.getPixelPosition(event));
to the function grabImage().