Re: [Interest] QML Image size vs sourceSize strange things

[Tor Arne Vestbø]

The icons provided from the system also go through a similar process of 
choosing the right size for what you request. If you request something specific 
by setting the sourceSize you will affect this, so please just set 
widht/heigth, as that should work. (If it doesn’t please file a bug with a 
small test case, thanks!)

Cheers,
Tor Arne

On 27 Mar 2021, at 08:57, Alexander Dyagilev 
mailto:alervd...@gmail.com>> wrote:


OK, thank you. We do use SVGs (but sometimes also PNGs).

However, these PNGs I was talking about in the original posting are files icons 
from system. I can't replace them with SVGs. :)


On 3/27/2021 9:51 AM, Nuno Santos wrote:
I had the same problem with blurry images on retina displays. I ended up 
creating a image component that inside was by default setting source size for 
twice the width and height of the item size to have good results on iOS screens.

However..

I have recently found that replacing the pngs for svgs has accelerated the UI 
loading time from seconds to a snap!!!

I have found this because I was not finding acceptable the time it took to 
resize a window.

I had to replace years of pngs into svgs but in the end it payed off.

You should definitely consider moving to svgs.

Best,

--
Nuno Santos

No dia 27/03/2021, às 03:17, Alexander Dyagilev 
 escreveu:



This all is not about my question in any matter. I do not care about SVG at 
all. And SVG are not used in this example.

Please learn to read question before answering

On 3/23/2021 4:16 PM, Jérôme Godbout wrote:
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 
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.



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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godbo...@amotus.ca




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Re: [Interest] QML Image size vs sourceSize strange things

[Alexander Dyagilev]

OK, thank you. We do use SVGs (but sometimes also PNGs).

However, these PNGs I was talking about in the original posting are 
files icons from system. I can't replace them with SVGs. :)



On 3/27/2021 9:51 AM, Nuno Santos wrote:
I had the same problem with blurry images on retina displays. I ended 
up creating a image component that inside was by default setting 
source size for twice the width and height of the item size to have 
good results on iOS screens.


However..

I have recently found that replacing the pngs for svgs has accelerated 
the UI loading time from seconds to a snap!!!


I have found this because I was not finding acceptable the time it 
took to resize a window.


I had to replace years of pngs into svgs but in the end it payed off.

You should definitely consider moving to svgs.

Best,

--
Nuno Santos

No dia 27/03/2021, às 03:17, Alexander Dyagilev  
escreveu:




This all is not about my question in any matter. I do not care about 
SVG at all. And SVG are not used in this example.


Please learn to read question before answering

On 3/23/2021 4:16 PM, Jérôme Godbout wrote:
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 
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.




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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Jerome Godbout
Software/Firmare Lead Amotus

C: (581) 777-0050
O: (418) 800-1073 ext.: 114
godbo...@amotus.ca 




dimonoff.com   | amotus.ca 

We have moved!
1015 Avenue Wilfrid-Pelletier, Québec, QC G1W 0C4, 4e étage


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Re: [Interest] QML Image size vs sourceSize strange things

[Nuno Santos]

I had the same problem with blurry images on retina displays. I ended up 
creating a image component that inside was by default setting source size for 
twice the width and height of the item size to have good results on iOS screens.

However..

I have recently found that replacing the pngs for svgs has accelerated the UI 
loading time from seconds to a snap!!! 

I have found this because I was not finding acceptable the time it took to 
resize a window.

I had to replace years of pngs into svgs but in the end it payed off.

You should definitely consider moving to svgs.

Best,

--
Nuno Santos

> No dia 27/03/2021, às 03:17, Alexander Dyagilev  
> escreveu:
> 
> 
> This all is not about my question in any matter. I do not care about SVG at 
> all. And SVG are not used in this example.
> 
> Please learn to read question before answering
> 
> On 3/23/2021 4:16 PM, Jérôme Godbout wrote:
>> 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  wrote:
>>> 
>>> Hello,
>>> 
>>> We had a strange problem with blurred images under Retina displays. Left 
>>> part of the image - before, right one - after the fix.
>>> 
>>> 
>>> 
>>> 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.
>>> 
>>> ___
>>> Interest mailing list
>>> Interest@qt-project.org
>>> https://lists.qt-project.org/listinfo/interest
>> 
>> Jerome Godbout
>> Software/Firmare Lead Amotus
>> 
>> C: (581) 777-0050 
>> O: (418) 800-1073 ext.: 114   
>> godbo...@amotus.ca
>> 
>> 
>> 
>> 
>> dimonoff.com   |amotus.ca
>>  
>> We have moved!
>> 1015 Avenue Wilfrid-Pelletier, Québec, QC G1W 0C4, 4e étage
>> 
> ___
> Interest mailing list
> Interest@qt-project.org
> https://lists.qt-project.org/listinfo/interest
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Re: [Interest] QML Image size vs sourceSize strange things

[Alexander Dyagilev]

This all is not about my question in any matter. I do not care about SVG 
at all. And SVG are not used in this example.


Please learn to read question before answering

On 3/23/2021 4:16 PM, Jérôme Godbout wrote:
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 > wrote:


Hello,

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




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.


___
Interest mailing list
Interest@qt-project.org 
https://lists.qt-project.org/listinfo/interest


Jerome Godbout
Software/Firmare Lead Amotus

C: (581) 777-0050
O: (418) 800-1073 ext.: 114
godbo...@amotus.ca 



dimonoff.com   | amotus.ca 

We have moved!
1015 Avenue Wilfrid-Pelletier, Québec, QC G1W 0C4, 4e étage

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Re: [Interest] QML Image size vs sourceSize strange things

[Jérôme Godbout]

Yes good point, take care those built-in size attributes are optional, might 
not be there into an SVG, you might not want to count on it.

From: Interest  on behalf of Giuseppe D'Angelo 
via Interest 
Date: Tuesday, March 23, 2021 at 10:53 AM
To: interest@qt-project.org 
Subject: Re: [Interest] QML Image size vs sourceSize strange things
Il 23/03/21 14:16, Jérôme Godbout ha scritto:
> 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.

This isn't accurate. SVG files have a builtin "wanted" size, which is
IIRC what Qt would use by default:

> https://www.w3.org/TR/SVG11/struct.html#SVGElementWidthAttribute

By explictly setting `sourceSize` you're asking Qt to rasterize the SVG
at a different resolution rather than the wanted one (and downscaling
when rendering).


My 2 c,
--
Giuseppe D'Angelo | giuseppe.dang...@kdab.com | Senior Software Engineer
KDAB (France) S.A.S., a KDAB Group company
Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com
KDAB - The Qt, C++ and OpenGL Experts
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Re: [Interest] QML Image size vs sourceSize strange things

[Giuseppe D'Angelo via Interest]

Il 23/03/21 14:16, Jérôme Godbout ha scritto:
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.


This isn't accurate. SVG files have a builtin "wanted" size, which is 
IIRC what Qt would use by default:



https://www.w3.org/TR/SVG11/struct.html#SVGElementWidthAttribute


By explictly setting `sourceSize` you're asking Qt to rasterize the SVG 
at a different resolution rather than the wanted one (and downscaling 
when rendering).



My 2 c,
--
Giuseppe D'Angelo | giuseppe.dang...@kdab.com | Senior Software Engineer
KDAB (France) S.A.S., a KDAB Group company
Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com
KDAB - The Qt, C++ and OpenGL Experts



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Description: Firma crittografica S/MIME
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Re: [Interest] QML Image size vs sourceSize strange things

[Jérôme Godbout]

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 
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.



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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Jerome Godbout
Software/Firmare Lead Amotus

C: (581) 777-0050
O: (418) 800-1073 ext.: 114
godbo...@amotus.ca

[cid:image007.png@01D70B66.39FB01C0]

dimonoff.com   |amotus.ca

We have moved!
1015 Avenue Wilfrid-Pelletier, Québec, QC G1W 0C4, 4e étage

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