On Tue, January 15, 2013 08:47:33 Samuel Rødal wrote:
> On 01/14/2013 06:04 PM, Thomas Senyk wrote:
> > On Mon, January 14, 2013 12:54:56 Samuel Rødal wrote:
> >> On 01/11/2013 04:59 PM, Thomas Senyk wrote:
> >>> Hi,
> >>>
> >>> as with Quick2.0 we got the very nice DistanceField-font-rendering.
> >>> So in theory animations on Text{ font.pixelSize } should be fairly
> >>> cheap,
> >>> right?
> >>>
> >>> With the following code snipped I got performance problems never the
> >>> less:
> >>>
> >>> import QtQuick 2.0
> >>> Text {
> >>>
> >>> id: text
> >>> width: 500
> >>> height: 100
> >>> text: "Test font.pixelSize animation"
> >>> NumberAnimation {
> >>>
> >>> running: true
> >>> loops: Animation.Infinite
> >>> duration: 2000
> >>> target: text
> >>> property: "font.pixelSize"
> >>> from: 10
> >>> to: 90
> >>>
> >>> }
> >>>
> >>> }
> >>>
> >>>
> >>> The strange thing is, on my desktop he has 100% cpu load for the first
> >>> 2-4
> >>> loops.
> >>> ... I wild guess: It looks like it needs to render the font-glyphs for
> >>> each(?) size and after a few cycles it got all of them rendered and
> >>> cached...? (it can't render all of them in the first loop as he jumps
> >>> due
> >>> to bad performance)
> >>>
> >>> On embedded (raspberry pi) I get <20% load all the time.
> >>>
> >>> On desktop I got:
> >>> - intel xeon 3ghz
> >>> - nvidia 8600gts
> >>> - Qt5 checkout from this week, branch: stable
> >>> - xcb as platform backend (using freetype and fontconfig)
> >>>
> >>> On the raspberry I got:
> >>> - BCM 2835 (slow ARM11 cpu, fast VideoCore IV GPU)
> >>> - eglfs as platform backend
> >>> - no fontconfig -> QBasicFontDatabase
> >>>
> >>> (If it helps I can do a fontconfig build)
> >>>
> >>> Is this know? Can anyone verify?
> >>> And possible explanation? .. maybe my Qt5 build on desktop is flawed?
> >>
> >> Try adding "renderType: Text.QtRendering" in the Text element. On
> >> desktop it might be that Text.NativeRendering is the default (which does
> >> not use distance field glyphs but texture glyphs cached based on the
> >> pixel size, maybe even on the scale?).
> >
> > No the default was already "renderType: Text.QtRendering"
> >
> > Changing the property does work, as the font is rendered differently with
> > "renderType: Text.NativeRendering"
> > (Especially during the animation one can see how the font is changing with
> > renderType: Text.NativeRendering, e.g. line-width/boldness is jumping)
> >
> >
> > The performance behavior seams to be the same.
> > First 2-4 cycles it's 100% cpu then is drops to <5%
> >
> >
> > Again from the other side of this thread:
> > I'm not searching for a quick work-around (e.g. scale), I rather want to
> > understand why this is happening, why it's different on my rpi and if this
> > is a bug or a wanted/accepted behavior.
>
> I don't understand it, the distance field text should not be
> re-generated based on pixelSize. Maybe there's something else going on,
> since it's on desktop you could run it through callgrind perhaps :)
K! This is the answer I was seeking for, now I can invest time with the
guarantee that I'm not wasting it ;)
I might not have the time this week, hopefully next week.
(If somebody else got the same problem, send me an mail with your
configuration so I can take it in consideration.)
>
> > Greets
> > Thomas
> >
> > p.s.: (a bit off-topic)
> > @ "cached based even on scale"
> > Scale with "renderType: Text.NativeRendering" is similar as with
> > Qt4/Quick1: He renders with the specified font size and scales it during
> > gl-painting>
> > -> "font.pixelSize: 1; scale: 30" looks extremely unreadable.
> >
> > Where "renderType: Text.QtRendering" produces the same output with
> > "font.pixelSize: 1; scale: 30;" and "font.pixelSize: 30; scale: 1;"
> > (not counting the 'Text' elements geometry properties)
>
> Good to know :)
>
> --
> Samuel
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