I'm rendering some text using pangomm, but the font that I am using doesn't have glyphs for parts of the text (in this case, there is some Japanese mixed in with English). Pango seems to render the text correctly using a fallback font.
How can I determine which font is being used as the fallback?
Actually the font selection is based on the selected Pango font backend. Mostly used (I think) is Fontconfig.
You fonts are basically always chosen by looking at the fonts Unicode coverage, meaning that Fontconfig tries to choose the font that covers the letters in the text you want to render best.
Not knowing if your problem applies to Fontconfig, I won't go into to much detail. But if so, have a look at http://www.freedesktop.org/software/fontconfig/fontconfig-user.html, especially the section on 'font matching'.
Feel free to ask again.
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Suppose I wanted to create a text editor from scratch.
I searched around and everyone suggested using OS-specific native 2D APIs (e.g. GDI+ in Windows or XLib in Linux), especially for font rendering.
My question is: why is it that openGL isn't suited for such a task? Why is it so hard to render antialiased text and controls as in a text editor with openGL and why should I prefer the non-portable way of native 2D OS APIs?
Part of the difficulty is that OpenGL doesn't provide a font engine or any capabilities specifically for rendering text. In other words, it's not a matter of OpenGL being poorly suited to the rendering part of the task, just that OpenGL is missing a lot of pieces necessary to the task.
To render text under OpenGL, you'd typically start with some font engine to take (for example) a TrueType or OpenType font, and render a glyph from its info (e.g., FreeType). Then you need a text display engine to figure out how to render characters to display your strings decently. In a simple case like English, it has to handle things like kerning and leading. In a complex case like some Arabic scripts, you basically need kind of a feedback loop between the text rendering and the font rendering, because a glyph can take a different form depending on its context in the string.
In short, writing a text editor that renders its text via OpenGL means re-building a lot of a text rendering stack from the ground up.
If you don't care a lot about rendering quality, you might be able to get by with just rendering a few fonts to bitmaps, and displaying your text using them. This can simplify the code quite a bit, but a simple implementation will mean producing output that looks something like an MS-DOS command line. Even matching the output quality of, say, Windows 3.0 will take a fair amount of work. That's not to say it can't be done--but it could dwarf the difficulty of writing the editing part of the text editor.
I want to add an Unicode Symbol as a list widget item in QT. (Particularly this item : http://www.fileformat.info/info/unicode/char/25B6/index.htm )
I'm using following method for this :
this->addItem( new QListWidgetItem( QString::fromUtf8("\u25B6")) ) ;
But when I open the widget I see only a blank rectangle in place of this unicode symbol. I even tried other unicode symbols too, but they too are showing only blank rectangle.
What's wrong in this method?
EDIT: After following the answer, I changed the font of QListWidgetItem to Serif and it worked.
There are several possibilities, but the most probable one is that the font you are using doesn't implement the glyph at all. Can you see the triangle in eg. an editor when using the same font as your Qt font?
Edit: The fonts (which are stored in the system's font files) are the commands to draw the images of each character on the screen). Many (if not all) fonts are incomplete, which means they are not able to represent all 2,000,000,000+ codes which are possible in the unicode (the numbers which represent the characters). The files would just be to large to be practical.
The triangles you want printed are fairly basic, and should be available in many font sets. Liberation Sans and Liberation Serif are two I just checked.
I suspect Qt uses the font set of the system, which can probably be changed in the System Settings somewhere. If you tell us which distribution you are using (i.e. Ubuntu, Debian, ...), maybe we can help.
I use cocos2d:::Label and I need to control the spacing of adjustment characters in the text. I use cocos2d-x 3.0 and the font of the label is TTF. Is it possible to achieve, or I should use another thing instead of cocos2d:::Label?
I figured out that bitmap fonts can be created with appropriate inter-character spacing. There is a good online tool for that. And it can customize even more settings, and it is very handy.
I am developing User Interface software using X11 programming.(I am not used QT, Widget, GTk).In that i want to increase font size using font property function. How can i use XFontProp function? Is there any other method to increase font size using X windows? If is it possible give me a sample?
If you want to use the old-fashioned now-deprecated server-side font rendering method, you cannot change the font size, you need to load the correctly-sized fond. Use XLoadFont and/or XLoadQueryFont for this. Use the Font you get in your GC.
To see what the string parameter looks like, type xlsfonts on your computer, or use xfontsel GUI utility.
Note that any given X server may lack fonts you want to use. There are only few mandatory fonts including fixed and I forgot what else.
If you want to use the fashionable modern client-side font rendering (what most programss written today are using) you have to use one of the toolkits, or Xft2 or Cairo libraries.
I am working on an embedded platform (STM32F407) with a TFT LCD as a display (480x800px) and would like to make my user interface somewhat customizable to the end user. I figured the best source of fonts would be windows compatible as their the most common.
My current implementation uses my own custom drawn font in a binary format and a descriptor table giving the character width and ascii value but having to draw my own font bit by bit is tedious.
I would like to read in a True Type Font file from an SD card and be able to use the different sized glyphs inside it but I have not seen a strait forward implementation on how to actually achieve this magic. Can somebody point me to a good c/c++ example of what I am looking for?
Even better as a way to iron out the kinks I would like to make a simple gcc command line program that will print out my input with a selected font using '#' as pixels. That way I can just worry about implementation and not any other random bugs that might pop up.
Can anybody help me out?
Perhaps you can use the Freetype library.
As duskwuff says: TTF is primarily a vector format, would need to write a renderer. Better off using an image file to define the font, or using a bitmap font format like FNT (Windows) or BDF (UNIX).
Here is my answer to my own question: AngelCode's BMFont & Useage. This makes choosing selective characters from the installed char set, mix in a font and exports an image with a map file to each character. Simple to use.