Do you really need to same memory by reducing the source size? I think you 
should left the source size alone and sample the image from the full source. 
Source size for SVG doesn’t make any sense, it’s vectoriel, doesn’t have any 
size, it can scale to any dimension. When playing with the image size (not the 
source) it will sample the source for each pixel, not sure about the algorithm 
but you might need an higher source resolution to get a proper image without 
artifact. I would at least take the Screen.devicePixelRatio into the source 
size into account and even add a x2 to ensure proper sampling, but I don’t see 
any real advantage to play with the source size unless you really are consuming 
way too much memory.

This might slow you down if the same image is using different sourceSize:

Note: Changing this property dynamically causes the image source to be 
reloaded, potentially even from the network, if it is not in the disk cache.


On Mar 23, 2021, at 3:31 AM, Alexander Dyagilev 
<alervd...@gmail.com<mailto:alervd...@gmail.com>> wrote:


Hello,

We had a strange problem with blurred images under Retina displays. Left part 
of the image - before, right one - after the fix.

<pjcgokflkeakcklh.png>

Our QML code was using with to show images:

Image {

        anchors.verticalCenter: parent.verticalCenter

        sourceSize.width: 25

        sourceSize.height: 25

        source: preview.url

    }



I've tried to multiply sourceSize by Screen.devicePixelRatio - images became 
bigger so they did not fit their places.

Then I've replaced sourceSize.width with just width and the same for height. 
And it works fine now.

My questions is:

1) Is it required to multiply sourceSize by devicePixelRatio? Or is it managed 
automatically? It seems that it is managed automatically for PNG and NOT 
managed for SVG.

2) If it is already managed automatically for PNG (these images preview.url are 
PNGs) then why was it blurred? The original PNG image is of size 64x64 pixels 
under Retina displays.

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