I want to read a ttf and draw a text with that font on a buffer. Even though there are libraries such as freetype, gd to do this task, I want to write my own code. Can you advice me on how to accomplish this task?
Unless you're one of the world's top experts on fonts, typography, and writing systems, the answer is simple: DON'T. TrueType/OpenType has a lot of tables you need to support for correct rendering, and even when using FreeType (which is an extremely low-level library), most people get it wrong.
If you need to do low-level, deterministic-across-platforms font handling, then at the very least, you should be using FreeType and libotf. This will provide you with access to the glyphs and outlines which you can then render however you like. In most cases though using your GUI system's text rendering routines will be a lot easier and less error-prone.
Finally, if you insist on ignoring my advice, a good RTFS on FreeType and Microsoft's online resources explaining the tables in TrueType/OpenType fonts are probably the best place to get started.
I would suggest you
Read all the TTF docs you can find
Find all the open source TTF parsers + renderers you can find, in many different languages, such as Freetype (c/c++), Batik (java), and anything else you can google for. Also George Williams' fontforge will likely be very helpful to you on your journey.
Rip apart all the programs you collected in 1. and see how they work. See if you can make a tiny small example program to do something simple, like dump the list of points for the outline of the letter "I".
Work on your rasterization. Start with something very simple, like rasterizing the letter "l".
The problem with TTF is that there is not a simple file format, and freetype handles a lot of crazy details for you. However if you don't care about portability, and you already have a specific TTF file you want to render, and you only care about a small simple alphabet, like Latin or Cyrillic, you might be OK.
Also you might want to check out a list of TTF documentation I linked to from my little project https://github.com/donbright/font_to_svg/
Not impossible, for anyone else tempted to try. I was curious about doing it because I like the DIY graphics approach where I allocate some memory and write into it, then save as a jpg or png. I pirated a bitmap font from giflib but that's strictly 8x8 pixels.
A few links:
`http://stevehanov.ca/blog/index.php?id=143`
`https://www.google.com/search?q=ttf+parser+c&ie=utf-8&oe=utf-8`
as R.. wrote the same time as i did in my comment, i would not to suggest to build another TTF-parser by your own. If you are eager to learn this very "spannende" field of Computer Science I would recommend "The Art of Computer Programming" Vol 2 from Donald E. Knuth. (it is Metafont, not TTF, but proven to be correct:-)
Related
I have ahead of me a fairly specific task, and I was hoping someone on this site can give me the benefit of their experience
I have a text file somewhere with some 17000 lines of text. This text will need to be printed very specifically on around 80 double sided pages. These pages will then be cut into several pieces, and bound into small books (hey, it's a hobby!) This means I need to have text placed very specifically on the page. (I am also toying with the idea of having text cut off mid letter in one place and continued elsewhere)
Note that I have done this before, by manually placing text using a word processor. However, the sheer magnitude of this project really requires programming. I have thought about making some PNG files (which is easy enough to do), but I do not know how nicely they will look when printed. I have also briefly looked at some standard document file formats (like doc and pdf) and it looks like it'll take a long time before I can learn these last.
Does anyone happen to have any helpful tips, or at least know the best file format to use for such a project?
Thanks
The best recommendation I'd give is to use C to parse the input and generate a latex document, which is in turn used to generate a pdf for printing. Although it might seem more complicated, latex is much more flexible when it comes to typesetting placing manually the text in a bmp file for example (basically, latex is a language that consist of a set of rules to specify where and how a text should be printed).
Paul92 mentioned LaTex which is one option I'd consider. The learning curve can be quite steep but it will undoubtedly do a nice job with your text if you're willing to fuss with it.
If you're feeling a bit more 'rough and ready' you might consider markdown. It will keep the source text a bit more readable, and there are some reasonable options for getting from markdown to a nice print out.
Since there is this: http://en.wikipedia.org/wiki/Code_page_437 For MSDOS, is there something similar for Linux systems? Is it possible to access that font data via userland program? I would actually just need an access to the actual bit patterns which define the font, and I would do the rendering myself. I'm fairly sure that something like this exists, but I haven't been able to find what exactly is it and how to access it. After all, e.g. text mode console font has to reside somewhere, and I really do hope it is "rawly" accessible somehow for a userland program.
Before I forget, I'm programming my program in C, and have access only to the "standard" linux/posix development headers. The only thing I could came up with myself is to use the fonts in /usr/share/fonts, but having to write my own implementations to extract the data from there doesn't sound really an option; I would really want to achieve this with the least amount of bytes possible, so I feel I'm left with finding a standard way of doing this.
It's not really feasible for me to store my own 8x8 ASCII-compatible font with the program either(it takes some 1024 bytes(128 chars * 8x8 bits) just to store the font, which is definitely unacceptable for the strict size limits(some < 1024 bytes for code+data) which I am working with), so being able to use the font data stored at the system itself would greatly simplify my task.
I had a look at consolechars sources and it looks like there is a whole library for this kind of stuff. On Ubuntu it's named libconsole and header files (like lct/font.h) are in the console-tools-dev package. There are functions to find and load fonts which seems to be exactly what you need. And consolechars source is a nice example of how to use them.
You should use freetype , its commonly installed in all the Linuxes.
How would I change a pixel on a display, in C?
Assume NOTHING: I am using a linux machine from console to do this. I do not want to use GUI toolkits or frameworks to draw the pixel. I do not want to draw the pixel in a window. I want to draw the pixel directly to the screen.
EDIT: I have a screen. I'm on a laptop running linux from console. I'd prefer a solution not using X as I'd rather learn how X works than how to use X.
If theres more information, ask, but don't assume. I'm not trying to build a GUI, and that was the main purpose of blocking assumptions as I don't want people to assume I'm doing things the long way when in reality I'm just tinkering.
EDIT 2: You may use any X11 related libraries provided that you can explain how they work.
If we really assume nothing, can we even assume that X is running? For that matter, can we even assume that there is a video card? Perhaps Linux is running headless and we're accessing it over a serial console.
If we are allowed to assume a few things, let's assume that Linux has booted with framebuffer support. (It's been a couple years since I worked with Linux framebuffers, I may get some of the details wrong.) There will be a device created, probably /dev/fb or /dev/fb0. Open that file and start writing RGB values at an offset, and the screen will change, pretty much regardless of anything: text console, graphical console, full-fledged desktop envrionment, etc. If you want to see if framebuffer support is working, do dd if=/dev/zero of=/dev/fb on the command line, and the display should go all black.
C doesnt have any graphics capabilities - you'd need to use a third party library for this.
You cannot assume a display in C. There is literally no way to do what you ask.
Edit: Okay, you have a display, but again, there's not a whole lot you can get from there. The point is that there are a TON of competing standards for graphics displays, and while some of them (VGA interfaces, for example) are standardized, a lot of the others (display driver interfaces, for example) are NOT. Much of what X (and other display device drivers, such as Windows or the like) do, is have specific interface code for how to talk to the display drivers; they abstract out the complexity of dealing with the display drivers. The windowing systems, though, have HUGE libraries of complicated and specific code for dealing with the display drivers; the fact that these things are relatively transparent is an indication of just how much work they've put into these things over time.
Very primitive and making a lot of assumptions:
fd = open("/dev/fb0", O_RDWR);
lseek(fd, 640*y+x, SEEK_SET);
write(fd, "\377\377\377\377", 4);
In reality, you would use mmap rather than write, and use the appropriate ioctl to query the screen mode rather than assuming 640xHHH 32bpp. There are also endian issues, etc.
So in real reality, you might use some sort of library code that handles this kind of thing for you.
I suppose you could paint to the terminal program that you are using as your console. All you have to do is figure out which one that is and look it up.
Whoops I assumed a terminal. :P
I think what you are looking for is information on how to write to the frame buffer. The easiest way would be to use SDL and render to the frame buffer, or else use GTK+ with DirectFB, although that goes against your edict on not using toolkits or frameworks.
Consider the following file:
-rw-r--r-- 1 user user 470886479 2009-12-15 08:26 the_known_universe.png
How would you scale the image down to a reasonable resolution, using no more than 4GB of RAM?
For example:
$ convert -scale 7666x3833 the_known_universe.png
What C library would handle it?
Thank you!
I believe libpng has a stream interface. I think this can be used to read parts of the image at a time; depending on the image file you might be able to get the lines in order. You could then shrink each line (e.g. for 50% shrinking, shrink the line horizontally and discard every second line) and write to an output file.
Using libpng in C can take a fair amount of code, but the documentation guides you through it pretty well.
http://www.libpng.org/pub/png/libpng-1.2.5-manual.html#section-3.8
You could try making a 64 bit build of ImageMagick or seeing if there is one. My colleague wrote a blog with a super-simple png decoder (assumes you have zlib or equivalent) so you can kind of see the code you'd need to roll your own.
http://www.atalasoft.com/cs/blogs/stevehawley/archive/2010/02/23/libpng-you-re-doing-it-wrong.aspx
You would need to do the resample as you're reading it in.
I used cximage a few years ago. I think the latest version is at
http://www.xdp.it/cximage.htm
after moving off of CodeProject.
Edit: sorry, it's C++ not C.
You could use an image processing library that is intended to do complex operations on large (and small) images. One example is the IM imaging toolkit. It links well with C (but is implemented at least partly in C++) and has a good binding to Lua. From the Lua binding it should be easy to experiment.
libvips is comfortable with huge images. It's a streaming image processing library, so it can read from the source, process, and write to the destination simultaneously and in parallel. It's typically 3x to 5x faster than imagemagick and needs very little memory.
For example, with the largest PNG I have on my laptop (1.8gb), I can downsize 10x with:
$ vipsheader huge.png
huge.png: 72000x72000 uchar, 3 bands, srgb, pngload
$ ls -l huge.png
-rw-r--r-- 1 john john 1785845477 Feb 19 09:39 huge.png
$ time vips resize huge.png x.png 0.1
real 1m35.279s
user 1m49.178s
sys 0m1.208s
peak RES 230mb
Not fast, but not too shabby either. PNG is rather a slow format, it would be much quicker with TIFF.
libvips is installable by most package managers (eg. homebrew on macOS, apt on Debian), there's a Windows binary, and it's free (LGPL). As well as the command-line, there are bindings for C, C++, Python, Ruby, Lua, node, PHP, and others.
Have you considered exploring pyramid based images? Imagine a pyramid where the image is divided up in multiple layers, each layer with a different resolution. Each layer is split up into tiles.
This way you can display a zoomed out version of the image, and also a zoomed in partial view of the image, without having to re-scale.
See the Wikipedia entry.
One of the original formats was FlashPix, which I wrote a renderer for.
I've also created a new format of a pyramid converter and renderer, which was used for a medical application. An actual scanner would produce 90GB+ scans of a slice of an organ for cancer research.
The algorithm of the converter was actually pretty tricky to get efficient, to produce the pyramid images efficienty. Believe it or not, it was actually Java based, and it performed much better than you'd think. It used multithreading. Benchmarking showed it was unlikely that a C version would do a whole lot better. This was 6ish years ago. The original renderer I did over 10 years ago.
You don't hear anything about pyramid based images anymore these days. But it's really the only efficient way to produce scaled images on demand without having to generate cached scaled versions.
Jpeg2000 may or may not have an optional pyramid feature as well.
I recall that ImageMagick's supporter formats and conversions perhaps, include FlashPix.
Googling for "image pyramid" reveals some interesting results. Bring back some memories ;-)
If you can move it to a 64-bit OS you can open it as a memory mapped file or equivalent and use pretty much any library you want. It won't be fast, and may need the increase of the page/swap file (depending on the OS and what else you want to do with it) but in return you won't be limited to streaming libraries so you'll be able to do more operation before going into resolution reduction or slicing.
Does anybody know a good C sample that loads bitmaps and handles all the cases: rle, b/w bitmaps, so on?
Code should be cross-platform.
Thanks.
I would suggest using a library like SDL image
If you are looking for a minimal bmp loader this link will give you all you need to know about the BMP format, data structures and sample code without any library dependency to load:
http://paulbourke.net/dataformats/bmp/.
It also contains code to see the loaded BMP in a open gl texture, so pretty much all you need...
Chris Backhouse made a functional little BMP loader (with an eye to using them as OpenGL textures). It's C++, not C, and he admits it's not cross platform. However, it's small and easy to understand, so I thought I'd add the link here:
http://users.ox.ac.uk/~orie1330/bmploader.html
You need some external library to do this (I recommend ImageMagick). The ImageMagick web site also includes documentation and examples.
Check out for OpenCV Library developed by Intel .
If you are tied to the BMP file format, it's pretty simple to look at the header yourself and get the pixels. See this google search. One of the more interesting matches is here. The most counter-intuitive part is that every line of pixels is 4-byte aligned. Also, watch out for compressed BMPs... (My experience is that many third-party tools have trouble with compressed BMPs, so maybe some libraries you encounter will also..)
If you aren't tied to the BMP file format, I recommend libpng. The manual provides some sample code which is pretty clear.
As others suggested you might want to use an external library like SDL. If you want to learn something and do it yourself, see my answer to this very similar question: Getting RGB values for each pixel from a 24bpp Bitmap for conversion to GBA format in C where you'll find C code which prints out each pixel, and have a look at the wikipedia page about bmp files, because it's very good.