[GRASS-dev] [GRASS GIS] #1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't

GDAL · February 23, 2011, 7:13am

#1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't
---------------------+------------------------------------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.1
Component: Display | Version: svn-develbranch6
Keywords: | Platform: Linux
Cpu: x86-64 |
---------------------+------------------------------------------------------
Hi,

in GRASS 6.x the PNG driver and Cairo driver badly mangle large ring
symbols, while the XDRIVER doesn't. This makes the creation of
automated PNG plots on a headless server somewhat problematic,
unless the more tortuous ps.map + pstoimg method is used.

(note even though it's headless it still needs X.org installed, as a
dependency of the Cairo driver's X11-output option)

The PNG driver has an uneven inner/outer radius and gouges out of it; the
Cairo driver does not path the line segments together at all.

examples images attached.

{{{
cat << EOF > test.grf
width 30
symbol basic/circle 500 50 50 red none
EOF

d.mon x4
d.resize w=825 h=650
d.graph test.grf

xwd | xwdtopnm | pnmtopng > xdriver_ring.png
d.out.file png_driver_ring
d.out.file -c cairo_driver_ring
}}}

In GRASS 7 the situation is a bit better, the PS and one of the PNG|cairo*
drivers(?) makes nice looking output, only complaint is that the closed
ring has a sliver where it isn't closed. could a special beginning==end
test be added to have it code the path?

Also, is it possible to double or quadruple the number of vertices in the
ring? At the current number it is very obviously a polygon and not a
circle.

{{{
cat << EOF > test.grf
width 30
symbol basic/circle 500 50 50 red none
EOF

export GRASS_WIDTH=825
export GRASS_HEIGHT=650

export GRASS_RENDER_IMMEDIATE=PNG
export GRASS_PNGFILE=png_driver7_ring.png
d.graph test.grf

export GRASS_RENDER_IMMEDIATE=CAIRO
export GRASS_PNGFILE=cairo_driver7_ring.png
d.graph test.grf

export GRASS_RENDER_IMMEDIATE=PS
export GRASS_PNGFILE=cairo_driver7_ring.ps
d.graph test.grf
}}}

[*] I'm not sure which driver it's using actually, I get an identical
output file for both. -- that is when setting 7's
GRASS_RENDER_IMMEDIATE=PNG doesn't make d.graph SegFault, while the cairo
driver doesn't. then I can tell.

[**] should "GRASS_RENDER_IMMEDIATE=cairo" be uppercase or not? the man
page shows both ways.

thanks,
Hamish

--
Ticket URL: <http://trac.osgeo.org/grass/ticket/1283>
GRASS GIS <http://grass.osgeo.org>

GDAL · February 23, 2011, 7:21am

#1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't
---------------------+------------------------------------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.1
Component: Display | Version: svn-develbranch6
Keywords: | Platform: Linux
Cpu: x86-64 |
---------------------+------------------------------------------------------

Comment(by hamish):

> (note even though it's headless it still needs X.org installed,
> as a dependency of the Cairo driver's X11-output option)

make that: as a dependency of the OS's Cairo package; not our Cairo
driver.

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/1283#comment:1>
GRASS GIS <http://grass.osgeo.org>

GDAL · February 24, 2011, 6:16am

#1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't
---------------------+------------------------------------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.1
Component: Display | Version: svn-develbranch6
Keywords: | Platform: Linux
Cpu: x86-64 |
---------------------+------------------------------------------------------

Comment(by glynn):

Replying to [ticket:1283 hamish]:

> (note even though it's headless it still needs X.org installed, as a
dependency of the Cairo driver's X11-output option)

This depends upon whether GRASS was built --with-x. If USE_X11 is defined
in the Makefiles, libcairodriver will end up with Xlib as a dependency.

> In GRASS 7 the situation is a bit better, the PS and one of the
PNG|cairo* drivers(?) makes nice looking output, only complaint is that
the closed ring has a sliver where it isn't closed. could a special
beginning==end test be added to have it code the path?

This might be an artifact of an attempt at simplifying paths. One of the
complaints with making d.vect use the driver's polygon filling (instead of
pre-rasterising paths with G_plot_polygon()) was that rasterising complex
areas was slow. Some code was added to lib/display in 7.0 (reduce_path(),
in draw2.c) to merge small, adjacent segments (effectively filtering the
path), but it can cause problems if you create complex paths (with islands
/cut-outs) using "cont" instead of "move".

Or it might be something else entirely. 7.0's lib/display has a specific
D_close() function for closing paths; writing coincident vertices won't
cause a path to be closed.

> [**] should "GRASS_RENDER_IMMEDIATE=cairo" be uppercase or not? the man
page shows both ways.

It doesn't matter; the value is compared using G_strcasecmp(). To the
extent that it matters, the canonical form should be "cairo".

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/1283#comment:2>
GRASS GIS <http://grass.osgeo.org>

GDAL · March 12, 2011, 5:13am

#1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't
---------------------+------------------------------------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.1
Component: Display | Version: svn-develbranch6
Keywords: symbols | Platform: Linux
Cpu: x86-64 |
---------------------+------------------------------------------------------
Changes (by hamish):

* keywords: => symbols

Comment:

Hi,

in an effort to relieve the symptoms I've modified lib/symbol/stroke.c in
trunk (r45639) and devbr65 to draw every 1 degree around the arc instead
of every 10 degrees when the symbol size is larger than 50. This in no way
fixes the underlying problem though, and other stuttering artifacts are
now seen in the gr6.5 PNG driver where before there were missing notches.

Hamish

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/1283#comment:3>
GRASS GIS <http://grass.osgeo.org>

GDAL · August 20, 2012, 7:33am

#1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't
---------------------+------------------------------------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.4
Component: Display | Version: svn-develbranch6
Keywords: symbols | Platform: Linux
Cpu: x86-64 |
---------------------+------------------------------------------------------
Changes (by neteler):

* milestone: 6.4.1 => 6.4.4

Comment:

On the real-time earthquake mapper it looks ok (is that GRASS 7 based?):

http://adhoc.osgeo.osuosl.org/grass/alternate_projections/earthquakes_wintri.png

--
Ticket URL: <http://trac.osgeo.org/grass/ticket/1283#comment:4>
GRASS GIS <http://grass.osgeo.org>

GDAL · May 8, 2013, 9:16am

#1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't
---------------------+------------------------------------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.4
Component: Display | Version: svn-develbranch6
Keywords: symbols | Platform: Linux
Cpu: x86-64 |
---------------------+------------------------------------------------------

Comment(by hamish):

Replying to [comment:4 neteler]:
> On the real-time earthquake mapper it looks ok (is that GRASS 7 based?):
>
>
http://adhoc.osgeo.osuosl.org/grass/alternate_projections/earthquakes_wintri.png

it looks a little better there because I manually patched the build, but
it's still an issue. (wait for a M7.5+ to see it, last week it was visible
there)

for the record, the cron job is currently running 6.4.2rc2.

Hamish

--
Ticket URL: <http://trac.osgeo.org/grass/ticket/1283#comment:5>
GRASS GIS <http://grass.osgeo.org>

GDAL · April 2, 2014, 4:03am

#1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't
----------------------------------------------+-----------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.4
Component: Display | Version: svn-develbranch6
Keywords: symbols, png driver, Draw_line.c | Platform: Linux
Cpu: x86-64 |
----------------------------------------------+-----------------------------
Changes (by hamish):

* keywords: symbols => symbols, png driver, Draw_line.c

Comment:

PNG driver line width rendering now working in trunk r59549, which shows
that this bug exists in GRASS 7 too.

cairo driver seems to be working ok in trunk now, but not in 6.x.

I'll attach some more screenshots, made with the following command:
(d.mark from addons, same script works in both G6 and G7)

{{{
    export GRASS_WIDTH=800
    export GRASS_HEIGHT=606
    d.mon start=PNG
    d.mark symbol=ring at=50,50 size=500 width=30
    d.mon stop=PNG
}}}

Hamish

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/1283#comment:6>
GRASS GIS <http://grass.osgeo.org>

GDAL · April 2, 2014, 4:21am

#1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't
----------------------------------------------+-----------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.4
Component: Display | Version: svn-develbranch6
Keywords: symbols, png driver, Draw_line.c | Platform: Linux
Cpu: x86-64 |
----------------------------------------------+-----------------------------

Comment(by hamish):

note that between this lot and the last lot of screenshots I upped the
number of vertices used when rendering large circles. that solved (masks)
the missing sliver dur to the unjoined line beginning/end stroke, and by
comparing the before and after PNG driver images you can visualize the now
much shorter but same width lines that it draws.

summary for fat line width rendering:

working: G6 XDRIVER, G7 cairo

no good: all pngdriver, G6 cairo

Hamish

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/1283#comment:7>
GRASS GIS <http://grass.osgeo.org>

GDAL · August 26, 2014, 10:43pm

#1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't
---------------------------------------------+------------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.4
Component: Display | Version: svn-develbranch6
Keywords: symbols, pngdriver, Draw_line.c | Platform: Linux
Cpu: x86-64 |
---------------------------------------------+------------------------------
Changes (by neteler):

* keywords: symbols, png driver, Draw_line.c => symbols, pngdriver,
Draw_line.c

Comment:

I have backported fix r59547 in r61752.

But there are still differences between trunk and relbr7 in the PNG driver
in Draw_line.c. Backport, too?

--
Ticket URL: <http://trac.osgeo.org/grass/ticket/1283#comment:8>
GRASS GIS <http://grass.osgeo.org>

GDAL · August 27, 2014, 11:33am

#1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't
---------------------------------------------+------------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.5
Component: Display | Version: svn-develbranch6
Keywords: symbols, pngdriver, Draw_line.c | Platform: Linux
Cpu: x86-64 |
---------------------------------------------+------------------------------
Changes (by hamish):

* milestone: 6.4.4 => 6.4.5

Comment:

Replying to [comment:8 neteler]:
> I have backported fix r59547 in r61752.

Thanks, I don't remember the exact details of that change, but from the
look of it and comment:6 it's good & I should have backported it at the
time.

> But there are still differences between trunk and relbr7 in the PNG
driver
> in Draw_line.c. Backport, too?

I that's r59549? It is a bugfix and I believe that it should be backported
to relbr70.

AFAIK the fixme mentioned there still remains todo, although the png
driver situation is better than it is in G6 thanks to Glynn's rewrite.

(this ticket is mostly specific to the png driver rendering issues which
exist in G6, which I still hope to fix one day)

thanks,
Hamish

--
Ticket URL: <http://trac.osgeo.org/grass/ticket/1283#comment:9>
GRASS GIS <http://grass.osgeo.org>

GDAL · August 27, 2014, 11:55am

#1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't
---------------------------------------------+------------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.5
Component: Display | Version: svn-develbranch6
Keywords: symbols, pngdriver, Draw_line.c | Platform: Linux
Cpu: x86-64 |
---------------------------------------------+------------------------------

Comment(by neteler):

Replying to [comment:9 hamish]:
> I that's r59549? It is a bugfix and I believe that it should be
backported to relbr70.

Done so in relbr7.

--
Ticket URL: <http://trac.osgeo.org/grass/ticket/1283#comment:10>
GRASS GIS <http://grass.osgeo.org>

GDAL · August 27, 2014, 11:56am

#1283: PNG driver and Cairo driver mangle large symbols, XDRIVER doesn't
---------------------------------------------+------------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.5
Component: Display | Version: svn-develbranch6
Keywords: symbols, pngdriver, Draw_line.c | Platform: Linux
Cpu: x86-64 |
---------------------------------------------+------------------------------

Comment(by hamish):

thanks!

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/1283#comment:11>
GRASS GIS <http://grass.osgeo.org>