Color Coding

From 7b52cc13af4e85f1ca2deb6b6c77de9c95ea0dcf Mon Sep 17 00:00:00 2001 From: scuri Date: Fri, 17 Oct 2008 06:10:33 +0000 Subject: First commit - moving from LuaForge to SourceForge --- html/en/func/color.html | 137 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 137 insertions(+) create mode 100644 html/en/func/color.html (limited to 'html/en/func/color.html') diff --git a/html/en/func/color.html b/html/en/func/color.html new file mode 100644 index 0000000..9ec9928 --- /dev/null +++ b/html/en/func/color.html @@ -0,0 +1,137 @@ + + + + Color Coding + + + + + +

Color Coding

The library's color system is RGB. In order to simplify some functions, a + compact representation was created for the 3 values. To make a conversion from + this representation to the 3 separate values and vice-versa, use functions + cdDecodeColor + and cdEncodeColor. +

When the canvas used does not support more than 8 bpp of color resolution, you + can use function Palette to give the driver an idea of which + colors to prioritize. Palette's behavior is driver dependent.

There are some predefined colors:

CD_RED          = (255,  0,  0)
+CD_DARK_RED     = (128,  0,  0)
+CD_GREEN        = (0  ,255,  0)
+CD_DARK_GREEN   = (  0,128,  0)
+CD_BLUE         = (  0,  0,255)
+CD_DARK_BLUE    = (  0,  0,128)
+CD_YELLOW       = (255,255,  0)
+CD_DARK_YELLOW  = (128,128,  0)
+CD_MAGENTA      = (255,  0,255)
+CD_DARK_MAGENTA = (128,  0,128)
+CD_CYAN         = (  0,255,255)
+CD_DARK_CYAN    = (  0,128,128)
+CD_WHITE        = (255,255,255)
+CD_BLACK        = (  0,  0 , 0)
+CD_DARK_GRAY    = (128,128,128)
+CD_GRAY         = (192,192,192)
+

long int cdEncodeColor(unsigned char red, unsigned char green, unsigned char blue) [in C]
+
+cd.EncodeColor(r, g, b: number) -> (old_color: lightuserdata) [in Lua]

Returns a codified triple (r,g,b) in a long integer such as 0x00RRGGBB, + where RR are the red components, GG are the + green ones and BB are the blue ones. The code is used in the CD + library to define colors. It can be used without an active canvas.

void cdDecodeColor(long int color, unsigned char *red, unsigned char *green, unsigned char *blue) [in C]
+
+cd.DecodeColor(color: lightuserdata) -> (r, g, b: number) [in Lua]

Returns the red, green and blue components of a color in the CD library. Can + be used without an active canvas.

long int cdEncodeAlpha(long int color, unsigned char alpha) [in C]
+
+cd.EncodeAlpha(color: lightuserdata, alpha: number) -> (color: lightuserdata) [in Lua]

Returns the given color coded with the alpha information. ATENTION: At the + moment only the Win32 with GDI+ and the IMAGERGB drivers support alpha + components in color coding. Se in Windows Using + GDI+ Base Driver and IMAGERGB driver. The + internal representation of the component is inverted, because the default value + must be 0 and opaque for backward compatibility, so you should use the cdDecodeAlpha + function ot the cdAlpha macro to retrieve the alpha component.

unsigned char cdDecodeAlpha(long int color) [in C]
+
+cd.DecodeAlpha(color: lightuserdata) -> (a: number) [in Lua]

Returns the alpha component of a color in the CD library. Can be used without + an active canvas. 0 is transparent, 255 is opaque.

unsigned char cdAlpha(long int color); [in C]
+
+cd.Alpha(color: lightuserdata) -> (r: number) [in Lua]

Macro that returns the alpha component of a color in the CD library. Can be + used without an active canvas.

unsigned char cdRed(long int color); [in C]
+
+cd.Red(color: lightuserdata) -> (r: number) [in Lua]

Macro that returns the red component of a color in the CD library. Can be used + without an active canvas.

unsigned char cdGreen(long int color); [in C]
+
+cd.Green(color: lightuserdata) -> (g: number) [in Lua]

Macro that returns the green component of a color in the CD library. Can be + used without an active canvas.

unsigned char cdBlue(long int color); [in C]
+
+cd.Blue(color: lightuserdata) -> (b: number) [in Lua]

Macro that returns the blue component of a color in the CD library. Can be + used without an active canvas.

int cdCanvasGetColorPlanes(cdCanvas* canvas); [in C]
+
+canvas:GetColorPlanes() -> (bpp: number) [in Lua]

Returns a given number, for instance p, which defines the number of + colors supported by the current device as 2^p, representing + the number of bits by pixel. +

void cdCanvasPalette(cdCanvas* canvas, int n, const long int *color, int mode); [in C]
+
+canvas:Palette(palette: cdPalette; mode: number) [in Lua]

In systems limited to 256 palette colors, this function aims at adding + n colors to the system's palette. In such systems, the colors + demanded forward or backward which are not in the palette are approximated to + the closest available color. The type can be CD_FORCE or CD_POLITE. + CD_FORCE ignores the system colors and interface elements, + since the menus and dialogues may be in illegible colors, but there will be + more colors available. CD_POLITE is the recommended type. It + must always be used before drawing. It cannot be queried.

+ +

Palette

+ +

cd.CreatePalette(size: number) -> (palette: cdPalette) [in Lua Only]

Creates a palette.

cd.KillPalette(palette: cdPalette) [in Lua Only]

Destroys the created palette and liberates allocated memory. If this + function is not called in Lua, the garbage collector will call it.

+ +

Palette Data Access

+ +

Data access in Lua is done directly using the array access operators. The + colors can have their values checked or changed directly as if they + were Lua tables:

+ +

palette[index] = cd.EncodeColor(r, g, b)
+count = #palette
+...
+color = palette[index]
+r, g, b = cd.DecodeColor(color)

+ +

Notice that the type of value returned or received by + palette[index] is a + lightuserdata, the same type used with functions + cdEncodeColor, + cdDecodeColor, + cdPixel, + cdForeground + and cdBackground.

+ + + + \ No newline at end of file -- cgit v1.2.3