Three years ago I played a bit with bar charts.
I started a YouTube channel and I like to create some bar charts.
An example is:
#!/usr/bin/env tclsh


package require Tk
package require BLT

package require sqlite3


set viewsArr {}
set weekArr {}

sqlite3 db ~/Databases/youtube.sqlite
db eval {
SELECT strftime('%W', dayDate, '+1 day') AS WeekNo
, SUM(dayViews) AS WeekTotals
FROM dayViews
WHERE WeekNo > '37'
GROUP BY WeekNo
ORDER BY WeekNo
} {
lappend viewsArr ${WeekTotals}
lappend weekArr ${WeekNo}
}
db close

blt::barchart .bc -plotbackground black
.bc axis configure y -stepsize 100
.bc element create best -xdata ${weekArr} -ydata ${viewsArr} -label {}
pack .bc -side top -expand yes -fill both

This gives a window with the bar chart. I can make a screen dump
of-course, but is there a way to also write the bar chart to a PNG
file?


What is a good resource for learning to work with Tk, (bar) charts and
the like?

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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Try something like:

package require img::window
image create photo bc -data .bc
bc write bar.png

Dave B

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Look for pdf4tcl: https://sourceforge.net/projects/pdf4tcl/

You can either recode the drawing code to create a PDF bargraph, or just convert the canvas to PDF.

Note: natively, Tcl can export a canvas to a PostScript file ($canvas postscript ...). There are utilities to convert PostScript to PDF or PNG (GhostScript can do that).

And I believe the TkImg package can convert a canvas to an image, which could then be saved as a PNG file.


At Sat, 21 Oct 2023 14:30:10 +0200 Cecil Westerhof <[email protected]> wrote:

Three years ago I played a bit with bar charts.
I started a YouTube channel and I like to create some bar charts.
An example is:
#!/usr/bin/env tclsh

package require Tk
package require BLT

package require sqlite3

set viewsArr {}
set weekArr {}

sqlite3 db ~/Databases/youtube.sqlite
db eval {
SELECT strftime('%W', dayDate, '+1 day') AS WeekNo
, SUM(dayViews) AS WeekTotals
FROM dayViews
WHERE WeekNo > '37'
GROUP BY WeekNo
ORDER BY WeekNo
} {
lappend viewsArr ${WeekTotals}
lappend weekArr ${WeekNo}
}
db close

blt::barchart .bc -plotbackground black
.bc axis configure y -stepsize 100
.bc element create best -xdata ${weekArr} -ydata ${viewsArr} -label {}
pack .bc -side top -expand yes -fill both

This gives a window with the bar chart. I can make a screen dump
of-course, but is there a way to also write the bar chart to a PNG
file?

What is a good resource for learning to work with Tk, (bar) charts and
the like?

--
Robert Heller -- Cell: 413-658-7953 GV: 978-633-5364
Deepwoods Software -- Custom Software Services
http://www.deepsoft.com/ -- Linux Administration Services
[email protected] -- Webhosting Services

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Cecil Westerhof schrieb am Samstag, 21. Oktober 2023 um 14:44:10 UTC+2:

Three years ago I played a bit with bar charts.
I started a YouTube channel and I like to create some bar charts.
An example is:
#!/usr/bin/env tclsh

package require Tk
package require BLT

package require sqlite3

set viewsArr {}
set weekArr {}

sqlite3 db ~/Databases/youtube.sqlite
db eval {
SELECT strftime('%W', dayDate, '+1 day') AS WeekNo
, SUM(dayViews) AS WeekTotals
FROM dayViews
WHERE WeekNo > '37'
GROUP BY WeekNo
ORDER BY WeekNo
} {
lappend viewsArr ${WeekTotals}
lappend weekArr ${WeekNo}
}
db close

blt::barchart .bc -plotbackground black
.bc axis configure y -stepsize 100
.bc element create best -xdata ${weekArr} -ydata ${viewsArr} -label {}
pack .bc -side top -expand yes -fill both

This gives a window with the bar chart. I can make a screen dump
of-course, but is there a way to also write the bar chart to a PNG
file?

What is a good resource for learning to work with Tk, (bar) charts and
the like?

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

slides.pdf
https://blt.sourceforge.net/

https://wiki.tcl-lang.org/page/BLT+%2D+graph+%2D+printing+postscript

and
https://wiki.tcl-lang.org/page/BLT


debian 12 with blt and blt-demo

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[email protected] writes:

Try something like:

package require img::window
image create photo bc -data .bc
bc write bar.png

Would be the best option, but I get:
can't find package img::window

Have to find out how to solve it, so at the moment I use another
option.

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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Cecil Westerhof schrieb am Samstag, 21. Oktober 2023 um 22:28:25 UTC+2:

greg writes:

Cecil Westerhof schrieb am Samstag, 21. Oktober 2023 um 14:44:10 UTC+2:

Three years ago I played a bit with bar charts.
I started a YouTube channel and I like to create some bar charts.
An example is:
#!/usr/bin/env tclsh


package require Tk
package require BLT

package require sqlite3


set viewsArr {}
set weekArr {}

sqlite3 db ~/Databases/youtube.sqlite
db eval {
SELECT strftime('%W', dayDate, '+1 day') AS WeekNo
, SUM(dayViews) AS WeekTotals
FROM dayViews
WHERE WeekNo > '37'
GROUP BY WeekNo
ORDER BY WeekNo
} {
lappend viewsArr ${WeekTotals}
lappend weekArr ${WeekNo}
}
db close

blt::barchart .bc -plotbackground black
.bc axis configure y -stepsize 100
.bc element create best -xdata ${weekArr} -ydata ${viewsArr} -label {}
pack .bc -side top -expand yes -fill both

This gives a window with the bar chart. I can make a screen dump
of-course, but is there a way to also write the bar chart to a PNG
file?


What is a good resource for learning to work with Tk, (bar) charts and
the like?

slides.pdf
https://blt.sourceforge.net/

https://wiki.tcl-lang.org/page/BLT+%2D+graph+%2D+printing+postscript

and
https://wiki.tcl-lang.org/page/BLT

At the moment I use:
.bc postscript configure -landscape yes -maxpect yes
.bc postscript output ytWeek.ps

And I convert it to png with:
gs -dSAFER -o ytWeek.png ytWeek.ps

Works reasonable, but there is a problem: left and right there is a transparency area of 135 pixels and above and under of 95 pixels.
How do I get rid of this area?
--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

https://manpages.debian.org/testing/blt-dev/blt::graph.3tcl.en.html

Finally, to get hardcopy of the graph, use the postscript component.
# Print the graph into file "file.ps"

.g postscript output file.ps -maxpect yes -decorations no

This generates a file file.ps containing the encapsulated PostScript of the graph. The option -maxpect says to scale the plot to the size of the page. Turning off the -decorations option denotes that no borders or color backgrounds should be drawn (i.e.
the background of the margins, legend, and plotting area will be white).

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greg <[email protected]> writes:

Cecil Westerhof schrieb am Samstag, 21. Oktober 2023 um 14:44:10 UTC+2:

Three years ago I played a bit with bar charts.
I started a YouTube channel and I like to create some bar charts.
An example is:
#!/usr/bin/env tclsh


package require Tk
package require BLT

package require sqlite3


set viewsArr {}
set weekArr {}

sqlite3 db ~/Databases/youtube.sqlite
db eval {
SELECT strftime('%W', dayDate, '+1 day') AS WeekNo
, SUM(dayViews) AS WeekTotals
FROM dayViews
WHERE WeekNo > '37'
GROUP BY WeekNo
ORDER BY WeekNo
} {
lappend viewsArr ${WeekTotals}
lappend weekArr ${WeekNo}
}
db close

blt::barchart .bc -plotbackground black
.bc axis configure y -stepsize 100
.bc element create best -xdata ${weekArr} -ydata ${viewsArr} -label {}
pack .bc -side top -expand yes -fill both

This gives a window with the bar chart. I can make a screen dump
of-course, but is there a way to also write the bar chart to a PNG
file?


What is a good resource for learning to work with Tk, (bar) charts and
the like?

slides.pdf
https://blt.sourceforge.net/

https://wiki.tcl-lang.org/page/BLT+%2D+graph+%2D+printing+postscript

and
https://wiki.tcl-lang.org/page/BLT

At the moment I use:
.bc postscript configure -landscape yes -maxpect yes
.bc postscript output ytWeek.ps

And I convert it to png with:
gs -dSAFER -o ytWeek.png ytWeek.ps

Works reasonable, but there is a problem: left and right there is a transparency area of 135 pixels and above and under of 95 pixels.
How do I get rid of this area?

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

At Sat, 21 Oct 2023 22:17:34 +0200 Cecil Westerhof <[email protected]> wrote:

greg <[email protected]> writes:

Cecil Westerhof schrieb am Samstag, 21. Oktober 2023 um 14:44:10 UTC+2:

Three years ago I played a bit with bar charts.
I started a YouTube channel and I like to create some bar charts.
An example is:
#!/usr/bin/env tclsh


package require Tk
package require BLT

package require sqlite3


set viewsArr {}
set weekArr {}

sqlite3 db ~/Databases/youtube.sqlite
db eval {
SELECT strftime('%W', dayDate, '+1 day') AS WeekNo
, SUM(dayViews) AS WeekTotals
FROM dayViews
WHERE WeekNo > '37'
GROUP BY WeekNo
ORDER BY WeekNo
} {
lappend viewsArr ${WeekTotals}
lappend weekArr ${WeekNo}
}
db close

blt::barchart .bc -plotbackground black
.bc axis configure y -stepsize 100
.bc element create best -xdata ${weekArr} -ydata ${viewsArr} -label {}
pack .bc -side top -expand yes -fill both

This gives a window with the bar chart. I can make a screen dump
of-course, but is there a way to also write the bar chart to a PNG
file?


What is a good resource for learning to work with Tk, (bar) charts and
the like?

slides.pdf
https://blt.sourceforge.net/

https://wiki.tcl-lang.org/page/BLT+%2D+graph+%2D+printing+postscript

and
https://wiki.tcl-lang.org/page/BLT

At the moment I use:
.bc postscript configure -landscape yes -maxpect yes
.bc postscript output ytWeek.ps

And I convert it to png with:
gs -dSAFER -o ytWeek.png ytWeek.ps

Works reasonable, but there is a problem: left and right there is a transparency area of 135 pixels and above and under of 95 pixels.
How do I get rid of this area?

GhostScript is probably creating a "page" (eg 8.5" x 11") and is filling out the "empty" "paper". You probably need to set the paper size to match the image (or something like that). I wonder if ImageMagick will take care of that...

sudo apt install imagemagick



--
Robert Heller -- Cell: 413-658-7953 GV: 978-633-5364
Deepwoods Software -- Custom Software Services
http://www.deepsoft.com/ -- Linux Administration Services
[email protected] -- Webhosting Services

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Cecil Westerhof <[email protected]> writes:

greg <[email protected]> writes:

Cecil Westerhof schrieb am Samstag, 21. Oktober 2023 um 14:44:10 UTC+2:

Three years ago I played a bit with bar charts.
I started a YouTube channel and I like to create some bar charts.
An example is:
#!/usr/bin/env tclsh


package require Tk
package require BLT

package require sqlite3


set viewsArr {}
set weekArr {}

sqlite3 db ~/Databases/youtube.sqlite
db eval {
SELECT strftime('%W', dayDate, '+1 day') AS WeekNo
, SUM(dayViews) AS WeekTotals
FROM dayViews
WHERE WeekNo > '37'
GROUP BY WeekNo
ORDER BY WeekNo
} {
lappend viewsArr ${WeekTotals}
lappend weekArr ${WeekNo}
}
db close

blt::barchart .bc -plotbackground black
.bc axis configure y -stepsize 100
.bc element create best -xdata ${weekArr} -ydata ${viewsArr} -label {}
pack .bc -side top -expand yes -fill both

This gives a window with the bar chart. I can make a screen dump
of-course, but is there a way to also write the bar chart to a PNG
file?


What is a good resource for learning to work with Tk, (bar) charts and
the like?

slides.pdf
https://blt.sourceforge.net/

https://wiki.tcl-lang.org/page/BLT+%2D+graph+%2D+printing+postscript

and
https://wiki.tcl-lang.org/page/BLT

At the moment I use:
.bc postscript configure -landscape yes -maxpect yes
.bc postscript output ytWeek.ps

And I convert it to png with:
gs -dSAFER -o ytWeek.png ytWeek.ps

Works reasonable, but there is a problem: left and right there is a transparency area of 135 pixels and above and under of 95 pixels.
How do I get rid of this area?

By using convert from Image Magick:
convert -trim -resize 800x ytWeek.ps ytWeek.png

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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* Origin: fsxNet Usenet Gateway (21:1/5)

On Sat, 21 Oct 2023 14:30:10 +0200
Cecil Westerhof <[email protected]> wrote:

Three years ago I played a bit with bar charts.
I started a YouTube channel and I like to create some bar charts.
An example is:
#!/usr/bin/env tclsh

package require Tk
package require BLT

package require sqlite3

set viewsArr {}
set weekArr {}

sqlite3 db ~/Databases/youtube.sqlite
db eval {
SELECT strftime('%W', dayDate, '+1 day') AS WeekNo
, SUM(dayViews) AS WeekTotals
FROM dayViews
WHERE WeekNo > '37'
GROUP BY WeekNo
ORDER BY WeekNo
} {
lappend viewsArr ${WeekTotals}
lappend weekArr ${WeekNo}
}
db close

blt::barchart .bc -plotbackground black
.bc axis configure y -stepsize 100
.bc element create best -xdata ${weekArr} -ydata ${viewsArr}
-label {} pack .bc -side top -expand yes -fill both

This gives a window with the bar chart. I can make a screen dump
of-course, but is there a way to also write the bar chart to a PNG
file?

Yes. I tested this on Ubuntu 18 with package tk8.6-blt2.5, which gives
BLT version 2.5.3.

# Create a image to hold the graph, use the "snap" subcommand and then
# write the image to a file.
image create photo snapshot
.bc snap snapshot
snapshot write snapshot.png -format png

What is a good resource for learning to work with Tk, (bar) charts and
the like?

Tcl.

I didn't have your database as a data set, so the expr function can
quickly generate data sets based upon any function you can imagine -

# Sample graph data generator.
proc grfunc {x} {
set xr [expr $x * 3.14159 / 180]
return [expr sin($xr) + 4 * cos($xr)]
}

set xseries ""
set yseries ""
set xstep 5

for {set x 0} {$x < 360} {incr x $xstep} {
lappend xseries $x
lappend yseries [grfunc $x]
}

blt::barchart .bc -plotbackground black
.bc axis configure y -stepsize 100
.bc element create best -xdata $xseries -ydata $yseries \
-label {} -barwidth $xstep
pack .bc -side top -expand yes -fill both


Kind regards,
Scott


--

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can't find package img::window

you need the Img package. It can be found on sourceforge.net as tkimg

package require Img loads all the additional image format handlers.

package require img::window just loads the handler for reading Tk windows

Note the capitalized "I" when loading the overall package.

The png handler is already part of Tk
I use the ...Linux64 version of the package, however the documentation appears to only be in the source package.

Dave B

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Scott Pitcher <[email protected]> writes:

On Sat, 21 Oct 2023 14:30:10 +0200
Cecil Westerhof <[email protected]> wrote:

Three years ago I played a bit with bar charts.
I started a YouTube channel and I like to create some bar charts.
An example is:
#!/usr/bin/env tclsh


package require Tk
package require BLT

package require sqlite3


set viewsArr {}
set weekArr {}

sqlite3 db ~/Databases/youtube.sqlite
db eval {
SELECT strftime('%W', dayDate, '+1 day') AS WeekNo
, SUM(dayViews) AS WeekTotals
FROM dayViews
WHERE WeekNo > '37'
GROUP BY WeekNo
ORDER BY WeekNo
} {
lappend viewsArr ${WeekTotals}
lappend weekArr ${WeekNo}
}
db close

blt::barchart .bc -plotbackground black
.bc axis configure y -stepsize 100
.bc element create best -xdata ${weekArr} -ydata ${viewsArr}
-label {} pack .bc -side top -expand yes -fill both

This gives a window with the bar chart. I can make a screen dump
of-course, but is there a way to also write the bar chart to a PNG
file?

Yes. I tested this on Ubuntu 18 with package tk8.6-blt2.5, which gives
BLT version 2.5.3.

# Create a image to hold the graph, use the "snap" subcommand and then
# write the image to a file.
image create photo snapshot
.bc snap snapshot
snapshot write snapshot.png -format png

Works likes a charm.
Thanks.

Now I have to learn to get the most out of it. ;-)

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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Robert Heller <[email protected]> writes:

At Sat, 21 Oct 2023 21:38:28 +0200 Cecil Westerhof <[email protected]> wrote:

[email protected] writes:

Try something like:

package require img::window
image create photo bc -data .bc
bc write bar.png

Would be the best option, but I get:
can't find package img::window

If you are on a Linux system, you need to do:

sudo apt install TkImg

to install the package.

On Debian it is:
libtk-img

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Cecil Westerhof <[email protected]> writes:

Yes. I tested this on Ubuntu 18 with package tk8.6-blt2.5, which gives
BLT version 2.5.3.

# Create a image to hold the graph, use the "snap" subcommand and then
# write the image to a file.
image create photo snapshot
.bc snap snapshot
snapshot write snapshot.png -format png

Works likes a charm.
Thanks.

Now I have to learn to get the most out of it. ;-)

By the way the generated PNG is a lot smaller as the one generated
with the postscript/ghostscript way and at the same time looks a lot
better.
It is also less steps, so a very BIG win.

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

[email protected] writes:

can't find package img::window

you need the Img package. It can be found on sourceforge.net as tkimg

package require Img loads all the additional image format handlers.

package require img::window just loads the handler for reading Tk windows

Note the capitalized "I" when loading the overall package.

The png handler is already part of Tk
I use the ...Linux64 version of the package, however the documentation appears to only be in the source package.

I already had solved it, but I also tried your approach. Works. (But
maybe because I solved the other one.) Funny: for me the two images
look exactly the same, but the one done with Img is about 25% bigger
as the one done with img::window.

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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