B2DLineJoin::Middle, drawPolyLine etc

classic Classic list List threaded Threaded
4 messages Options
Caolán McNamara Caolán McNamara
Reply | Threaded
Open this post in threaded view
|

B2DLineJoin::Middle, drawPolyLine etc

What is B2DLineJoin::Middle supposed to be ?

I see that the vcl pdf, windows and quartz backends treat ::Middle the
same as ::Mitre (so I made the cairo one do the same)

On the the other hand I see cppcanvas...setupStrokeAttributes and
filter...ImplWriteLineInfo would default ::Middle to the same as ::NONE

while

cui...SvxLineTabPage::Reset and
svx...LinePropertyPanelBase::updateLineJoint treat LineJoin_MIDDLE the
same as ROUND but
filter...EscherPropertyContainer::CreateLineProperties and
oox...DrawingML::WriteOutline the same as BEVEL

Is ::Middle a "mistake" and we should just treat it as ::Mitre
everywhere ? Especially as that's what it turns into for the windows
vcl drawPolyLine. Or is there some subtlety here ?

C.
_______________________________________________
LibreOffice mailing list
[hidden email]
http://lists.freedesktop.org/mailman/listinfo/libreoffice
Armin Le Grand-2 Armin Le Grand-2
Reply | Threaded
Open this post in threaded view
|

Re: B2DLineJoin::Middle, drawPolyLine etc

Hi Caolan,

no, not an error, another simple LineJoin method which just takes the
'middle' of the points to be joined. LineJoins are for fat lines, so you
have an inner and outer edge of the current and next segment. To join
the points of the inner edges, these are added and divided by two, same
for outer.
I do not remember where that came from, but it was used in some graphic
system and seemed a nice method for doing line joins. It should in
practise not be used much and did not make it into current/modern
systems, but is handled correctly e.g. in the primitive decomposition of
fat lines.
There are always exceptions in different systems, e.g. for DirectDraw on
Win there is no B2DLineJoin::NONE, so this has to be painted by painting
the single line segments.
For a primitive renderer this means if there is no support for that
style for the renderer you currently feed, use the decomposition :-)
In practise I know of no current usages - even on the UI that flag is
missing. If it can be removed (UNO API, ODF, ...), remove it.

HTH!

Am 02.02.2016 um 12:27 schrieb Caolán McNamara:

> What is B2DLineJoin::Middle supposed to be ?
>
> I see that the vcl pdf, windows and quartz backends treat ::Middle the
> same as ::Mitre (so I made the cairo one do the same)
>
> On the the other hand I see cppcanvas...setupStrokeAttributes and
> filter...ImplWriteLineInfo would default ::Middle to the same as ::NONE
>
> while
>
> cui...SvxLineTabPage::Reset and
> svx...LinePropertyPanelBase::updateLineJoint treat LineJoin_MIDDLE the
> same as ROUND but
> filter...EscherPropertyContainer::CreateLineProperties and
> oox...DrawingML::WriteOutline the same as BEVEL
>
> Is ::Middle a "mistake" and we should just treat it as ::Mitre
> everywhere ? Especially as that's what it turns into for the windows
> vcl drawPolyLine. Or is there some subtlety here ?
>
> C.

--
--
ALG (PGP Key: EE1C 4B3F E751 D8BC C485 DEC1 3C59 F953 D81C F4A2)

_______________________________________________
LibreOffice mailing list
[hidden email]
http://lists.freedesktop.org/mailman/listinfo/libreoffice
Armin Le Grand-2 Armin Le Grand-2
Reply | Threaded
Open this post in threaded view
|

Re: B2DLineJoin::Middle, drawPolyLine etc

Hi Caolan,

checked once again: B2DLineJoin::Middle is sometimes mapped to
B2DLineJoin::NONE, sometimes to B2DLineJoin::Miter, both are nearly
equally often used. This should be unified, I would prefer mapping to
B2DLineJoin::Miter due to being graphically 'closer' to
B2DLineJoin::Middle than B2DLineJoin::NONE.

Also checked: Canvas in HTML5 also e.g. knows no 'none' state. With
LineJoin probably all GraphicSystems are slightly different.

Am 02.02.2016 um 15:46 schrieb Armin Le Grand:

> Hi Caolan,
>
> no, not an error, another simple LineJoin method which just takes the
> 'middle' of the points to be joined. LineJoins are for fat lines, so
> you have an inner and outer edge of the current and next segment. To
> join the points of the inner edges, these are added and divided by
> two, same for outer.
> I do not remember where that came from, but it was used in some
> graphic system and seemed a nice method for doing line joins. It
> should in practise not be used much and did not make it into
> current/modern systems, but is handled correctly e.g. in the primitive
> decomposition of fat lines.
> There are always exceptions in different systems, e.g. for DirectDraw
> on Win there is no B2DLineJoin::NONE, so this has to be painted by
> painting the single line segments.
> For a primitive renderer this means if there is no support for that
> style for the renderer you currently feed, use the decomposition :-)
> In practise I know of no current usages - even on the UI that flag is
> missing. If it can be removed (UNO API, ODF, ...), remove it.
>
> HTH!
>
> Am 02.02.2016 um 12:27 schrieb Caolán McNamara:
>> What is B2DLineJoin::Middle supposed to be ?
>>
>> I see that the vcl pdf, windows and quartz backends treat ::Middle the
>> same as ::Mitre (so I made the cairo one do the same)
>>
>> On the the other hand I see cppcanvas...setupStrokeAttributes and
>> filter...ImplWriteLineInfo would default ::Middle to the same as ::NONE
>>
>> while
>>
>> cui...SvxLineTabPage::Reset and
>> svx...LinePropertyPanelBase::updateLineJoint treat LineJoin_MIDDLE the
>> same as ROUND but
>> filter...EscherPropertyContainer::CreateLineProperties and
>> oox...DrawingML::WriteOutline the same as BEVEL
>>
>> Is ::Middle a "mistake" and we should just treat it as ::Mitre
>> everywhere ? Especially as that's what it turns into for the windows
>> vcl drawPolyLine. Or is there some subtlety here ?
>>
>> C.
>

--
--
ALG (PGP Key: EE1C 4B3F E751 D8BC C485 DEC1 3C59 F953 D81C F4A2)

_______________________________________________
LibreOffice mailing list
[hidden email]
http://lists.freedesktop.org/mailman/listinfo/libreoffice
Caolán McNamara Caolán McNamara
Reply | Threaded
Open this post in threaded view
|

Re: B2DLineJoin::Middle, drawPolyLine etc

On Tue, 2016-02-02 at 16:04 +0100, Armin Le Grand wrote:
> Hi Caolan,
>
> In practise I know of no current usages - even on the UI that flag
> is missing. If it can be removed (UNO API, ODF, ...), remove it.

> checked once again: B2DLineJoin::Middle is sometimes mapped to
> B2DLineJoin::NONE, sometimes to B2DLineJoin::Miter, both are nearly
> equally often used. This should be unified, I would prefer mapping to
> B2DLineJoin::Miter due to being graphically 'closer' to
> B2DLineJoin::Middle than B2DLineJoin::NONE.

ok, I'll remove basegfx::B2DLineJoin::Middle and map all
css::drawing::LineJoin_MIDDLE to their css::drawing::LineJoin_MITRE
equivalents.

C.
_______________________________________________
LibreOffice mailing list
[hidden email]
http://lists.freedesktop.org/mailman/listinfo/libreoffice