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# Class CL_Font_Description

Font provider interface.
Contained in: global
Derived from: none
Derived by: none
Group: Display (Fonts)

#include <ClanLib/display.h>

### public function member index:
### Construction:
`` | `CL_Font_Description` | `(`CL_InputSource`* `input`)`;
`` | `CL_Font_Description` | `(`CL_SurfaceProvider`* `p`, `int` `x`, `int` `y`, `int`* `tcols`, `int` `num_tcols`, `int` `spacelen`, `int` `subtract_width`, `const` `std::string`& `letters`)`;
`` | `CL_Font_Description` | `(`CL_SurfaceProvider`* `source`, `float` `trans_limit`, `int` `space_len`, `int` `subtract_width`, `const` `std::string`& `letters`)`;
`` | `CL_Font_Description` | `(`std::vector`<`CL_SurfaceProvider`*> `letter_provider`, `int` `space_len`, `int` `subtract_width`, `std::string` `letters`)`;
`` | `~CL_Font_Description` | `()`;
### Operations:
``void`` | `lock` | `()`;
``void`` | `unlock` | `()`;

## Description:

The font description class is used by the CL_Font" font class to load the font.
Currently ClanLib support two types of fonts:
The old method.
You may find some 256 color indexed fonts with some of ClanLib's example applications. They use the three last colors in the palette to seperate the letters, break the line, and to determine the size of the font. The method is deprecated.
The new method.
The font description class constructs the font letters from an image with alpha values. Each letter is seperated with transparent lines and the font description class uses this information to determine where it so seperate the letters.
CL_Font_Description allows you to adjust how much transparent a line must be before it consideres it as a letter seperator line. The trans_limit parameter handles this.
If your font is italic you can use the subtract_width parameter to move the printed letters "closer to each other". This is, with a fine word, called the kerning of the font.

## Function Member Descriptions:

CL_Font_Description::CL_Font_Description - This constructor is used to load the font from an input source. Usually this from a resource datafile.
Normally you do not use this constructor directly. It is much easier to use CL_Font::load() when retrieving a font from a datafile.
`` `CL_Font_Description``(`CL_InputSource`* `input`)`;

CL_Font_Description::CL_Font_Description - This constructs a font description using the old font method. It is obsolete and only provided for backward compatibility. Please don't use it.
`` `CL_Font_Description``(`CL_SurfaceProvider`* `p`, `int` `x`, `int` `y`, `int`* `tcols`, `int` `num_tcols`, `int` `spacelen`, `int` `subtract_width`, `const` `std::string`& `letters`)`;

> p - Image which contain the font letters.
> x - Start x coordinate on top-left most font letter.
> y - Start y coordinate on top-left most font letter.
> tcols - Array of colors to be transparent.
> num_tcols - Number of elements in the tcols array.
> spacelen - Pixel width of the space character.
> subtract_width - Width to subtract from each letter when drawing the font (aka. font kerning).
> letters - String containing all the letters listed in the image file. Must be ordered in the same way as in the image file.

CL_Font_Description::CL_Font_Description - This constructs a font description using the new alpha cutter method.
Please have a look on the class overview reference page for more information.
`` `CL_Font_Description``(`CL_SurfaceProvider`* `source`, `float` `trans_limit`, `int` `space_len`, `int` `subtract_width`, `const` `std::string`& `letters`)`;

> source - Image which contain the font letters.
> trans_limit - The maximum amount of alpha allowed before a pixel is no longer considered transparent.
> space_len - Pixel width of the space character.
> subtract_width - Width to subtract from each letter when drawing the font (aka. font kerning).
> letters - String containing all the letters listed in the image file. Must be ordered in the same way as in the image file.

CL_Font_Description::CL_Font_Description - This is primarily used by the TTF resource loader to handle fonts
`` `CL_Font_Description``(`std::vector`<`CL_SurfaceProvider`*> `letter_provider`, `int` `space_len`, `int` `subtract_width`, `std::string` `letters`)`;

> letters - A vector array of pointers to the letters themselves
> space_len - Pixel width of the space character
> subtract_width - Width to subtract from each letter when drawing the font (aka. font kerning).
> letters - String containing all the letters listed in the image file. Must be ordered in the same way as in the image file.

CL_Font_Description::lock - Lock
``void`` `lock``()`;

CL_Font_Description::unlock - Unlock
``void`` `unlock``()`;

CL_Font_Description::~CL_Font_Description - Standard destructor for cleanup
`` `~CL_Font_Description``()`;

## Variable Member Descriptions:

CL_Font_Description::letter_providers - Letter Providers
``std::vector`<`CL_SurfaceProvider`*>` ``letter_providers`;`

CL_Font_Description::letters - Letters
``std::string`` ``letters`;`

CL_Font_Description::space_len - Space length
``int`` ``space_len`;`

CL_Font_Description::subtract_width - Subtract Width
``int`` ``subtract_width`;`