How to get current widget relative mouse pos on hover ?

[manuel-koch]

I can attach an hover event handler to my widget, but how do I get the widget relative mouse position ?
The onHovered callback has no additional arguments ?

giu.Image(texture).Size(100, 100),
giu.Event().OnHover(func() {
    // how to get image relative mouse position that triggered the hover event ?
})

[gucio321]

math 😄

// save this somewhere before rendering your widget
x, y := giu.GetCursorPos()
// and in event handler:
mouse := giu.GetMousePos()
relativeposInsideWidget := mouse.Sub(image.Pt(x, y))
// do your stuff...

[manuel-koch]

I tried to adapt your example to my use case, but the printed results are not relative to the image ?

giu.Custom(func() {
	pt := giu.GetCursorPos()
	giu.Image(diffTexture).BorderCol(imageBorderFg).Size(renderWidth, renderHeight).Build()
	giu.Event().OnHover(func() {
		mouse := giu.GetMousePos()
		relativeposInsideWidget := mouse.Sub(pt)
		fmt.Printf("Hover on image %v\n", relativeposInsideWidget)
	}).Build()
}),

I.e. I have 3 of those customs in a row and the printed coords never start a zero, actually just look like the global window mouse position.

What am I doing wrong ?

[gucio321]

ok, yah, sorry, I was testing in single window and everything worked fine, but as long as you need multiple windows, use GetCursorScreenPos instead of GetCursorPos

[manuel-koch]

The following seems to work, but I have to substract (1,1) to get good relative points matching the actual image area. Is this maybe due to the border around the image ? How can image border be disabled - i.e. not just selecting transparent color ?

giu.Custom(func() {
    imageBorderSize := float32(1)
    cursorPt := giu.GetCursorScreenPos()
    giu.Layout{
	    giu.Image(texture).BorderCol(color.RGBA{R: 128, G: 128, B: 128, A: 255}).Size(width, height),
	    giu.Event().OnHover(func() {
		    relPt := giu.GetMousePos().Sub(cursorPt)
		    // need to account for image border !?
		    if relPt.X > 0 && relPt.Y > 0 && relPt.X < int(width+2*imageBorderSize) && relPt.Y < int(height+2*imageBorderSize) {
			    onHover(relPt.Sub(image.Pt(int(imageBorderSize), int(imageBorderSize))))
		    }
	    }),
    }.Build()
    })