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Class CL_Font

Draws text in bitmap and system fonts. More...

Derived from: none
Derived by: none
Group: Display (Fonts)

#include <ClanLib/display.h>

Construction:

CL_Font

Constructs a font.

Subclasses:

PrintInfo

The return type for draw(), draw_to_gb(), and test_draw().

Attributes:

get_width_offset	Returns width offset.
get_height_offset	Returns height offset.
get_baseline	Returns baseline.
get_scale	Returns current scale.
get_alpha	Returns current alpha.
get_color	Returns current color.
get_blend_func	Returns blending functions.
get_glyph_angle	Returns angle of glyph rotation.
get_glyph_rotation_hotspot	Returns glyph rotation hotspot.
get_angle	Returns angle in degrees of total rotation.
get_rotation_hotspot	Returns the rotation hotspot.
get_alignment	Returns translation hotspot.
get_height	Returns the drawn height of the entire font or a string.
get_width	Returns the drawn width of a character or string.
get_size	Returns the drawn size of a string.
get_glyphs	Returns the glyphs as a CL_Sprite.
get_glyph_index	Returns the glyph-index for a specific letter.
resource	Resource owning this sprite, if any.
test_draw	Gets the return value of a draw() without drawing anything.

Operations:

operator =	Copy assignment operator.
draw	Draws text to a graphic context.
draw_to_gb	Insert glyphs and the font into a CL_GlyphBuffer.
set_width_offset	Set width offset.
set_height_offset	Set height offset.
set_baseline	Set baseline.
set_scale	Set scale for x and y directions individually.
set_alpha	Sets transparency.
set_color	Sets the color.
set_blend_func	Sets blending functions.
set_glyph_angle	Sets absolute rotation angle for individual glyphs.
glyph_rotate	Adds angle to current angle for individual glyphs.
set_glyph_rotation_hotspot	Sets glyph rotation hotspot.
set_angle	Sets absolute total rotation angle in degrees.
rotate	Adds angle in degrees to current total angle.
set_rotation_hotspot	Sets total rotation hotspot.
set_alignment	Sets translation hotspot.

Detailed description:

A font can be either constructed from bitmap or from system font (or loaded from a resource as either).

A bitmap font uses a CL_Sprite as the source for the font glyphs (letters), where each frame frame in the sprite represents one glyph. A string (letter_chars) is then describing which character each glyph corresponds to. If the sprite contains the letters ABCZXY123 in that order, then the string should be "ABCZXY123".

To cut out letters for a bitmap font efficiently, have a look at the alpha clipper in CL_SpriteDescription.

A system font uses the underlaying windowing system to create the font glyphs. This means that in Windows you can choose any TTF font, and same applies to X11 if the font server supports it.

When a font is constructed based on an existing sprite, the sprite is copied into the font, and several properties are changed. Many properties of the font directly change the sprite's properties: the functions that do this are marked 'This property is set inside the glyphs sprite' in the documentation. In addition, when the sprite is immediately loaded, its translation and rotation hotspots are set to origin_top_left:0:0. The translation hotspot of the sprite is important to positioning in general, and cannot be changed within the font's internal sprite by the user. If you need to change it you can always do your own drawing by copying the sprite out using the get_glyphs() method. The rotation hotspot inside the font's internal sprite can be set directly using CL_Font::set_glyph_rotation_hotspot(), but at the cost of making total rotation (i.e. changes to the CL_Font's angle) produce illegible though still vaguely valid results.

Like CL_Surface and CL_Sprite, rotation does not affect the calcluation of any bounding rectangles (such as the result returned by draw() or bounding_rect(), or the rectangle calculated internally by draw() for alignment). However, the height and width offset properties still affect these calcluations, and so does the scale (since scaling the CL_Font is effectively just changing the point size of the glyphs, and that affects all sorts of things, such as word wrapping.)

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