I'm trying to load a png image in OCaml and make it into a matrix of color pixels. I'm using the OCaml Graphics module. I think I need to use the CamlImages module as well but I'm not quite sure how to.
First of all, let's make it clear. The OCaml graphics library doesn't provide any image decoders, so you have to use some other library to decode a file into the representation that the Graphics library understands, which is a matrix of colors.
I failed to find an online documentation for CamlImages, so I will teach you how to generate one using odig - the tool for querying and exporing OCaml universe. First of all you need to install it and odoc - a documentation generator, e.g., if you're using opam then do
opam install odig odoc
Now you can do
odig doc camlimages
and it will generate documentation and open it in your browser.
There you will find the Png.load function that will load a file encoded in the PNG format. It will return the image in the one of the CamlImages formats and you have to write a translation function from that format to the matrix of colors format.
Note, if in your course setup you doesn't have opam or odig or odoc, then ask your teachers for documentation. If they are nonresponsive, then you can read the mli files directly, the following command will show you all the interfaces available in the CamlImages library:
ls $(ocamlfind -query camlimages)/*/*.mli
Related
Since MonoD doesn't let me add use dub libraries natively I need to write dub.json myself. A good start would be to use an already existing template produced by e.g. dub init, but unfortunately this command produces a project that uses a competing dub.sdl and for some reason I cannot find any option to tell it to create a dub.json instead.
How do I convert a dub.sdl into dub.json so I can use it with MonoD?
As said by dub init --help, there is an option for generating JSON file instead of SDL:
-f --format=VALUE
Sets the format to use for the package description file. Possible values: sdl, json
So, try dub init --format=json.
DUB package of DUB is good for you.
It contains first hand library code it takes to
load,
manipulate and
save
packages (be it in SDL or JSON format).
Of course you've got to get your hand dirty to do the appropriate plumbing (writing a package converter command line utility in your case for instance).
I am using Fedora 18 on Virtual Box on my Windows XP desktop to learn Django. After going through the .txt documentation files, I discovered these files were written using restructuredText. I've been spending the last day or so trying to figure out how to convert the files into something readable (HTML, Latex, PDF, etc.). First thing I did, was install docutils (from source - download page) and used rst2html.py to convert the files to HTML to be readable.
When I used this tool, I was getting the Unknown interpreted text role "doc", Unknown interpreted text role "ref", Unknown interpreted text role "term" errors, and more when opening the docs/intro/index.txt, docs/intro/install.txt and docs/intro/tutorial01.txt files. I was able to find very little on Google describing the exact problem I was having so I tried to use a different option.
Naively thinking the errors were native to docutils I decided to search for another tool and found this page and installed restview. Well, I didn't realize restview used docutils so I ended up back at square one.
How do I get rid of these and other errors? Did I install docutils and restview correctly?
Please tell me if I need to add more info
You need to use Sphinx. This tool is used by the Django project and it defines additional reStructuredText constructs to complement those defined by docutils. Such as
http://sphinx-doc.org/markup/inline.html#role-doc
http://sphinx-doc.org/markup/inline.html#role-ref
http://sphinx-doc.org/markup/inline.html#role-term
LLVM can create graphs in Graphviz's "dot" format, and automatically invoke a viewer to display them. By default it uses dotty to display those graphs. I know that I can change it to use a different viewer, but I was not able to find precise instructions on how to do so.
How can I make it open the graphs with a different viewer?
I'm running on Linux but would be interested in an answer for Windows as well.
I found out I'm supposed to change the CMakeCache.txt file in my build folder. For instance, to use XDot instead of dotty, I edited the LLVM_PATH_XDOT_P property in that file to point to the full path of my xdot.py file.
It now opens the alternative viewer successfully, after rebuilding the project.
I just needed to do this.
I managed to do this with a workaround: made a backup of dotty (just in case) and created a link from dotty to XDot.
cp /usr/bin/dotty /usr/bin/dotty_copy
ln -s /usr/bin/dotty /usr/bin/xdot
I believe you could also set some variable during configuration step (possibly LLVM_PATH_DOTTY), but I never tried this as I didn't want to recompile LLVM.
You may try hacking the DisplayGraph function or fidging with the makefiles until you manage to enable one of the #ifdefs in DisplayGraph.
I've previously asked about the commands for converting R Markdown to HTML.
What is a good way to convert R Markdown files to PDF documents?
A good solution would preserve as much as possible of the content (e.g., images, equations, html tables, etc.). The solution needs to be able to be run from the command-line. A good solution would also be cross-platform, and ideally minimise dependencies to make it easier to share makefiles and so forth.
Specifically, there are a lot of options:
Whether to convert RMD to MD to HTML to PDF; or RMD to MD to PDF; or RMD to PDF
If using the markdown package in R, which options to specify
Whether to use pandoc, a package built into R, or something else
Here's an example rmd file that presumably provides a reasonable test of any proposed solution. It was used as the basis for this blog post.
Updated Answer (10 Feb 2013)
rmarkdown package:
There is now an rmarkdown package available on github that interfaces with Pandoc.
It includes a render function. The documentation makes it pretty clear how to convert rmarkdown to pdf among a range of other formats. This includes including output formats in the rmarkdown file or running supplying an output format to the rend function. E.g.,
render("input.Rmd", "pdf_document")
Command-line:
When I run render from the command-line (e.g., using a makefile), I sometimes have issues with pandoc not being found. Presumably, it is not on the search path.
The following answer explains how to add pandoc to the R environment.
So for example, on my computer running OSX, where I have a copy of pandoc through RStudio, I can use the following:
Rscript -e "Sys.setenv(RSTUDIO_PANDOC='/Applications/RStudio.app/Contents/MacOS/pandoc');library(rmarkdown); library(utils); render('input.Rmd', 'pdf_document')"
Old Answer (circa 2012)
So, a number of people have suggested that Pandoc is the way to go. See notes below about the importance of having an up-to-date version of Pandoc.
Using Pandoc
I used the following command to convert R Markdown to HTML (i.e., a variant of this makefile), where RMDFILE is the name of the R Markdown file without the .rmd component (it also assumes that the extension is .rmd and not .Rmd).
RMDFILE=example-r-markdown
Rscript -e "require(knitr); require(markdown); knit('$RMDFILE.rmd', '$RMDFILE.md'); markdownToHTML('$RMDFILE.md', '$RMDFILE.html', options=c('use_xhml'))"
and then this command to convert to pdf
Pandoc -s example-r-markdown.html -o example-r-markdown.pdf
A few notes about this:
I removed the reference in the example file which exports plots to imgur to host images.
I removed a reference to an image that was hosted on imgur. Figures appear to need to be local.
The options in the markdownToHTML function meant that image references are to files and not to data stored in the HTML file (i.e., I removed 'base64_images' from the option list).
The resulting output looked like this. It has clearly made a very LaTeX style document in contrast to what I get if I print the HTML file to pdf from a browser.
Getting up-to-date version of Pandoc
As mentioned by #daroczig, it's important to have an up-to-date version of Pandoc in order to output pdfs. On Ubuntu as of 15th June 2012, I was stuck with version 1.8.1 of Pandoc in the package manager, but it seems from the change log that for pdf support you need at least version 1.9+ of Pandoc.
Thus, I installed caball-install.
And then ran:
cabal update
cabal install pandoc
Pandoc was installed in ~/.cabal/bin/pandoc
Thus, when I ran pandoc it was still seeing the old version.
See here for adding to the path.
I think you really need pandoc, which great software was designed and built just for this task :) Besides pdf, you could convert your md file to e.g. docx or odt among others.
Well, installing an up-to-date version of Pandoc might be challanging on Linux (as you would need the entire haskell-platform˙to build from the sources), but really easy on Windows/Mac with only a few megabytes of download.
If you have the brewed/knitted markdown file you can just call pandoc in e.g bash or with the system function within R. A POC demo of that latter is implemented in the Ṗandoc.convert function of my little package (which you must be terribly bored of as I try to point your attention there at every opportunity).
Right now (August 2014) You could use RStudio for converting R Markdown to PDF.
Basically, RStudio use pandoc to convert Rmd to PDF.
You could change metadata to:
Add table of contents
Change figure options
Change syntax highlighting style
Add LaTeX options
And many more...
For more details - http://rmarkdown.rstudio.com/pdf_document_format.html
For an option that looks more like what you get when you print from a browser, wkhtmltopdf provides one option.
On Ubuntu
sudo apt-get install wkhtmltopdf
And then the same command as for the pandoc example to get to the HTML:
RMDFILE=example-r-markdown
Rscript -e "require(knitr); require(markdown); knit('$RMDFILE.rmd', '$RMDFILE.md'); markdownToHTML('$RMDFILE.md', '$RMDFILE.html', options=c('use_xhml'))"
and then
wkhtmltopdf example-r-markdown.html example-r-markdown.pdf
The resulting file looked like this. It did not seem to handle the MathJax (this issue is discussed here), and the page breaks are ugly. However, in some cases, such a style might be preferred over a more LaTeX style presentation.
Only two steps:
Install the latest release "pandoc" from here:
https://github.com/jgm/pandoc/releases
Call the function pandoc in the library(knitr)
library(knitr)
pandoc('input.md', format = 'latex')
Thus, you can convert your "input.md" into "input.pdf".
I found using R studio the easiest way, but if wanting to control from the command line, then a simple R script can do the trick using rmarkdown render command (as mentioned above). Full script details here
#!/usr/bin/env R
# Render R markdown to PDF.
# Invoke with:
# > R -q -f make.R --args my_report.Rmd
# load packages
require(rmarkdown)
# require a parameter naming file to render
if (length(args) == 0) {
stop("Error: missing file operand", call. = TRUE)
} else {
# read report to render from command line
for (rmd in commandArgs(trailingOnly = TRUE)) {
# render Rmd to PDF
if ( grepl("\\.Rmd$", rmd) && file.exists(rmd)) {
render(rmd, pdf_document())
} else {
print(paste("Ignoring: ", rmd))
}
}
}
If you don't want to install anything you can output html. Then open the html file - it should open in a browser window, then right click to print. In the print window, select "save as pdf" in the bottom right hand corner if you're on a Mac. Voila!
Follow these simple steps :
1: In the Rmarkdown script run Knit(Ctrl+Shift+K)
2: Then after the html markdown is opened click Open in Browser(top left side) and
the html is opened in your web browser
3: Then use Ctrl+P and save as PDF .
I've downloaded Chromium Embedded Framework r306 for Windows and built it. Unfortunately, it shows, that it doesn't support mp3:
<script>
var a = document.createElement("audio");
document.write(a.canPlayType('audio/mpeg'));
</script>
Output is empty and when I try to open an mp3 file, it can't be played (ogg is playable).
The same time Google Chrome writes "maybe" (and it actually plays).
How can I add support for MP3 in CEF?
Marshall Greenblatt (the maintainer of the Chromium Embedded Framework) addresses the lack of support for MP3 (and AAC) in Chromium and CEF in this bug report (see comment #7, copied below):
Codecs like MP3 and AAC are included in Google Chrome releases but not Chromium builds. This is because these formats are not open and require licensing. Distributing these codecs with your application without a licensing agreement may violate the law in certain countries. You should discuss with a lawyer if appropriate.
NOTE: PLEASE CONSIDER LEGAL ISSUES BEFORE PROCEEDING
There is a way to enable MP3 support in CEF, but you'll have to modify the cef.gypi in the source distribution, regenerate the visual studio projects and rebuild.
Step by step instructions:
a
a
There is a way to enable MP3 support in CEF, but you'll have to modify the cef.gypi in the source distribution, regenerate the visual studio projects and rebuild.
Detailed build instructions:
https://bitbucket.org/chromiumembedded/cef/wiki/BranchesAndBuilding
Enabling proprietary codecs support:
http://code.google.com/p/chromiumembedded/issues/detail?id=371
Add 'proprietary_codecs': 1 to your cef.gypi configuration so that USE_PROPRIETARY_CODECS will be defined as required by net/base/mime_util.cc.
You'll also need proper builds of the avcodec, avformat and avutil DLLs. Luckily, you can just get these from the installation directory of Google Chrome itself ($User/AppData/Local/Google/Chrome/$Version).
the options to enable proprietary codecs (i.e. H.264 and MP3) have been moved since the last answer.
you can read my answer with all the details on how to compile CEF with enabled proprietary codecs
the magic now happens here:
set GN_DEFINES=is_official_build=true proprietary_codecs=true ffmpeg_branding=Chrome
there is 2 batch files that you should update/create (as found here):
c:\code\chromium_git\update.bat:
set CEF_USE_GN=1
set GN_DEFINES=is_official_build=true proprietary_codecs=true ffmpeg_branding=Chrome
set GN_ARGUMENTS=--ide=vs2015 --sln=cef --filters=//cef/*
python ..\automate\automate-git.py --download-dir=C:\code\chromium_git --depot-tools-dir=C:\code\depot_tools --no-distrib --no-build
c:\code\chromium_git\chromium\src\cef\create.bat:
set CEF_USE_GN=1
set GN_DEFINES=is_win_fastlink=true proprietary_codecs=true ffmpeg_branding=Chrome
set GN_ARGUMENTS=--ide=vs2015 --sln=cef --filters=//cef/*
call cef_create_projects.bat
There is 2 wiki articles that explain how to build CEF/Chromium:
https://bitbucket.org/chromiumembedded/cef/wiki/MasterBuildQuickStart.md
and BranchesAndBuilding in the same wiki
MP3 codec only be supported When build to Google Chrome, check chromium's Codec Support.
On client side, the compatible way may be Flash, check google translate's code.
I followed the steps in null1941's answer and they worked great save a few caveats having to do with modifying the build.ps1 script
step 16 e. search for any instances of 3.y.z and replace them with the current version you are building (from the folder name containing the builds ex. 3.2272.32.gbda8dc7).
in function DownloadNuget it is trying to see if you have nuget in a specific place and if it isn't there it tries to go get it. Problem is DownloadFile would fail if the save directory didn't already exist. so you can manualy create or add this to the function:
$Nuget_dir = Join-Path $env:LOCALAPPDATA .\nuget
if(-not (Test-Path $Nuget_dir))
{
mkdir $Nuget_dir
}
change line: "Copy-Item $Cef64\include $CefInclude -Recurse | Out-Null" to use $Cef32 if you don't have 64bit cef folders