[Interest] Anti-Aliased line drawing.

Andy asmaloney at gmail.com
Fri Mar 24 14:39:12 CET 2017


Bill:

I really think it depends on your use-case.

In my application I need to draw a bunch of lines (on the order of
hundreds) in a viewer-like tool and I use a QGraphicsView with
anitaliasing. Works and looks great - even when zooming in and out
dramatically. I did spend some time profiling my custom items to make sure
they weren't doing anything unnecessary.

When I tried to use an OpenGL-backed QGraphicsView - which you can do with
setViewport( new QOpenGLWidget ) - I just couldn't get it to look as clean.
Granted I didn't spend too much time on that path because what I have works
for me.

Not sure if that helps, but it might give you some ideas.

---
Andy Maloney  //  https://asmaloney.com
twitter ~ @asmaloney <https://twitter.com/asmaloney>


On Fri, Mar 24, 2017 at 6:38 AM, william.crocker at analog.com <
william.crocker at analog.com> wrote:

> Hello:
>
> I am still hoping for some insight.
>
> What does it take to efficiently draw a good looking, anti-aliased line?
> Do I have to buy in to the use of OpenGL?
> I am just drawing lines.
>
> Thanks.
>
> Bill
> (The man who *is* who he appears to be.
>  Apparently that is not as easy as you might think.)
>
>
> On 03/16/2017 08:15 AM, william.crocker at analog.com wrote:
>
>> [This sender failed our fraud detection checks and may not be who they
>> appear to
>> be. Learn about spoofing at http://aka.ms/LearnAboutSpoofing]
>>
>> Hello:
>>
>> I am slowly porting my app forward from Qt 4.8.6
>>
>> With 4.8.6, it is my observation that simple line drawings,
>> as made by a QPainter and with Antialiasing enabled in render hints,
>> are implemented in software which makes them quite slow.
>>
>> What can I look forward to if I port my app to 5.X (5.7)
>> Is there an option for hardware acceleration
>> of AA line drawing and how would I enable it.
>>
>> I develop on RedHat Enterprise Linux 6.8
>>
>> Thanks.
>>
>> Bill
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