QML/QtQuick2 Anchor Item to static location on a scaled image - image

Question

What I am attempting to do is anchor an Item over a particular place over an Image. The Image needs to use Image.PreserveAspectFit for the fillMode. The problem I am having is that the height/width/paintedWidth/paintedHeight of the Image are for the entire image "canvas" (I'm not sure what it's actually called), not the drawn part of the image itself. So I can't anchor to the actual image.
See code below for an example I tried with anchors (red rectangle) and with a child rectangle and x,y coordinates (green rectangle).
import QtQuick 2.3
import QtQuick.Window 2.2
Window {
visible: true
height: 400
width: 400
Image {
id: image
anchors.fill: parent
fillMode: Image.PreserveAspectFit
source: "image.jpg"
Rectangle {
id: bottomRight
width: 40
height: 40
color: "green"
x: parent.width * 0.75
y: parent.height * 0.75
}
}
Rectangle {
id: topLeft
width: 40
height: 40
color: "red"
anchors.top: image.top
anchors.left: image.left
anchors.topMargin: image.height * 0.25
anchors.leftMargin: image.width * 0.25
}
}
When you change the size of the window the placement of the rectangles is not in the same place over the image. I'd post some screenshots but I don't have enough reputation yet!
I poked around through the widget tree using the debugger but I can't seem to find any properties that provide the information about the scaling that I could use to calculate placement of the rectangles.
Update
I used the following functions to calculate the margins since I will be using potentially lots of these overlays.
function horMargin(val)
{
return ((image.width - image.paintedWidth)/2 + image.paintedWidth * val)
}
function verMargin(val)
{
return ((image.height - image.paintedHeight)/2 + image.paintedHeight * val)
}

Answer 1

Did you try to use paintedWidth and paintedHeight? :)
This will give you a rectangle that fills the painted image:
import QtQuick 2.3
import QtQuick.Window 2.2
Window {
visible: true
height: 400
width: 400
Image {
id: image
anchors.fill: parent
fillMode: Image.PreserveAspectFit
source: "image.jpg"
}
Rectangle {
x: (image.width - image.paintedWidth) / 2
y: (image.height - image.paintedHeight) / 2
width: image.paintedWidth
height: image.paintedHeight
color: "transparent"
border.color: "darkorange"
border.width: 2
}
}
From there, you can work out how to apply the margins that you need.