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AG_STYLESHEET(3) Library Functions Manual AG_STYLESHEET(3) NAME AG_StyleSheet -- agar cascading style sheets SYNOPSIS #include <agar/core.h> #include <agar/gui.h> DESCRIPTION The graphical appearance of Agar widgets (including typography, colors, paddings, spacings and decorations) is determined by the stylesheet of their parent AG_Window(3). An AG_StyleSheet defines a set of attribute blocks. Each block has a selector associated with it. Selectors allow widgets to be targeted based on their class (E), the class of their parent (E > F) or their instance names in relation to the class of their parent (E > "F"). Selector conditions allow widgets to be styled based on their current geom- etry ("width", "height") or the zoom level of their windows ("zoom"). Attributes defined by a stylesheet can be overridden on a per widget in- stance basis with the AG_SetStyle(3) family of functions. Agar stylesheets allow C-style comments. TYPOGRAPHY Style attributes are case-insensitive. The following are available: font-family The name of the font face or the exact filename of a font (e.g., "DejaVu Sans", "agar-ideograms.agbf", "foo.woff2"). font-size The font size (e.g., "80%", "10pts", "10.5pts", "12px"). Fonts of GUI elements are normally expressed in "%". font-weight The font weight ("Thin", "ExtraLight", "Light", "Regular", "SemiBold", "Bold", "ExtraBold", "Black" or "!parent"). font-style The font style ("Normal", "Italic", "Oblique" or "!parent"). font-stretch Width variant ("Normal", "UltraCondensed", "Condensed", "SemiCondensed", "SemiExpanded", "Expanded", "UltraExpanded" or "!parent"). The font-family attribute selects the type face. Agar will look up system fonts (via fontconfig), Core Fonts as well as user-installed fonts (under AG_Config(3) AG_CONFIG_PATH_FONTS). Matching is case-insensitive except for fonts which are referenced by filename. The font-size attribute sets the font size either in points ("10pts", "10.5pts") for vector fonts, pixels ("12px") for bitmap fonts, or in per- centage of the parent widget font's size ("80%"). Generally, the font sizes of GUI elements should be given in "%" so that the zoom function may work as expected (the AG_ZoomIn(3) and AG_ZoomOut(3) functions work by sim- ply increasing or decreasing the target window's "font-size"). The font-weight attribute sets the weight of the font: Thin Wt#100 Thin ExtraLight Wt#200 Extra Light / Ultra Light Light Wt#300 Light Regular Wt#400 Regular / Normal SemiBold Wt#600 Semi Bold / Demi Bold Bold Wt#700 Bold ExtraBold Wt#800 Extra Bold Black Wt#900 Black / Heavy !Parent (opposite of parent) The font-style attribute selects the style of the font: Italic Italic style (with Oblique fallback) Oblique Oblique style (with Italic fallback) !Parent (opposite of parent) The font-stretch attribute selects the width variant: UltraCondensed 50.0% - Ultra Condensed Condensed 75.0% - Condensed SemiCondensed 87.5% - Semi Condensed / Demi Condensed SemiExpanded 112.5% - Semi Expanded / Demi Expanded Expanded 125.0% - Expanded UltraExpanded 200.0% - Ultra Expanded !Parent (opposite of parent) COLORS Color-defining style attributes include: color Foreground primary background-color Background primary text-color Text and vector icons line-color Lines and filled shapes high-color Shading (top and left) low-color Shading (bottom and right) selection-color Selection primary Colors allow an optional state selector (e.g., "color#focused"). If no se- lector is given then the given color is assigned to all states. #unfocused Widget is not focused (default state). #focused Widget is focused (see AG_WidgetFocus(3)). #disabled Widget is disabled (see AG_WidgetDisable(3)). #hover Cursor is over the widget (MOUSEOVER is set). Color values can be specified using any one of the representations below. See AG_ColorFromString(3) for details. 8-bit Device RGB "r,g,b[,a]" or "rgb(r,g,b[,a])" 16-bit Device RGB "rgb16(r,g,b[,a])" Hue, Saturation and Value "hsv(h,s,v[,a])" 16-bit hex "#rgb[a]" 32-bit hex "#rrggbb[aa]" 64-bit hex "#rrrrggggbbbb[aaaa]" Color keyword "AliceBlue", "antiquewhite" RGBA and HSV components may be expressed in "%" (in relation to the same color entry in the parent widget's palette). Color keywords are matched case-insensitively. PADDING AND SPACING Paddings, margins and inner spacings are specified in pixels: padding "<Number>", "<T> <R> <B> <L>" or "inherit" margin "<Number>", "<T> <R> <B> <L>" or "inherit" spacing "<Number>", "<H> <V>" or "inherit" The padding attribute sets the inner padding amount in pixels. If given as a single "<Number>", the same amount is applied to all sides. Negative values are allowed, and may be used to condense content. The margin attribute sets the outer margin amount in pixels. If given as a single "<Number>", the same amount is applied to all sides. The margin amounts must be positive. The spacing attribute sets the horizontal and vertical spacings between in- ner elements of a widget. If given as a single "<Number>", the same amount is used for both horizontal and vertical spacings. Negative values are al- lowed, and may be used to condense content. Margin is handled generically by container widgts. Padding and inner spac- ings are implemented in a widget-specific way. Different widget classes will handle padding and spacing differently. C INTERFACE void AG_InitStyleSheet(AG_StyleSheet *ss) void AG_DestroyStyleSheet(AG_StyleSheet *css) AG_StyleSheet * AG_LoadStyleSheet(void *obj, const char *path) int AG_LookupStyleSheet(AG_StyleSheet *css, void *widget, const char *key, char **rv) The AG_InitStyleSheet() function initializes the given AG_StyleSheet as an empty style sheet. AG_DestroyStyleSheet() releases all resources allocated by a style sheet. The AG_LoadStyleSheet() function loads a style sheet from path. On suc- cess, a newly allocated AG_StyleSheet is returned. If path begins with a "_" character, AG_LoadStyleSheet() will search for a statically-compiled stylesheet (i.e., "_agStyleDefault" is always available). The AG_LookupStyleSheet() routine searches the style sheet for the speci- fied attribute (identified by key). If the style sheet defines an at- tribute applicable to the specified widget instance (the widget argument), its value is returned into rv. EXAMPLES Agar's default stylesheet is compiled from gui/style.css. It is a good starting point for writing new stylesheets. The following stylesheet fragment selects a condensed font, tweaks the color scheme and sets padding values for the AG_Button(3) class: AG_Button { font-family: league-gothic; font-stretch: condensed; font-size: 120%; color: AntiqueWhite; text-color: #000; color#disabled: rgb(200,200,200); text-color#disabled: rgb(125,125,125); high-color#hover: red; low-color#hover: darkred; padding: 5 4 5 4; /* TRBL */ } The following example uses an E > F (children of class) selector to set the color of all buttons embedded in the AG_Numerical(3) widget: AG_Numerical > AG_Button { color: blue; } The following example uses an E > "F" (children named) selector to set the color of specific button instances embedded in the AG_Numerical(3) widget: AG_Numerical > "increm" { color: red; } AG_Numerical > "decrem" { color: green; } The following example switches to a condensed font when the width of the widget is below a given threshold: AG_HSVPal { font-family: league-gothic; font-size: 140%; } AG_HSVPal (width < 90) { font-family: league-gothic-condensed; font-size: 120%; } By default, a widget instance inherits its style attributes from its par- ent. The syntax allows certain attributes, such as "font-size" and "color" to be specified in relation to the parent. For example: font-size: 50%; # Half of parent font size color: hsv(100%,50%,100%); # Half of parent saturation color: hsv(100%,100%,75%); # 3/4 of parent value SEE ALSO AG_Intro(3), AG_Widget(3), AG_Window(3) HISTORY A very basic AG_StyleSheet language first appeared in Agar 1.5.0. Agar 1.6.0 improved parsing and validation, introduced a new color scheme, added typography features as well as "padding" and "spacing". Agar 1.7.0 added "margin" and extended "font-weight" and "font-stretch" to include all stan- dard weights and width variants. The selectors E > F (children of class) and E > "F" (children named) appeared in Agar 1.7.0. Agar 1.7 February 18, 2023 AG_STYLESHEET(3)
NAME | SYNOPSIS | DESCRIPTION | TYPOGRAPHY | COLORS | PADDING AND SPACING | C INTERFACE | EXAMPLES | SEE ALSO | HISTORY
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