CD_CGM

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/drv/cgm.html | 184 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 184 insertions(+) create mode 100644 html/en/drv/cgm.html (limited to 'html/en/drv/cgm.html') diff --git a/html/en/drv/cgm.html b/html/en/drv/cgm.html new file mode 100644 index 0000000..17ca141 --- /dev/null +++ b/html/en/drv/cgm.html @@ -0,0 +1,184 @@ + + + + + + +CD_CGM + + + + + +

CD_CGM - Computer Graphics Metafile Driver (cdcgm.h)

+ +

This driver allows generating a Computer Graphics Metafile, which is an ANSI standard for the persistent storage of + graphics primitives. The file usually has an extension .CGM.

+ +

Use

+ +

The file file is created by means of a call to the function + cdCreateCanvas(CD_CGM, + Data), which opens the file and writes its header. Then, other functions in the CD library can be called + as usual. The Data parameter string has the following format:

+ +

"filename [widthxheight] [resolution] [-t] -p[precision]" or in C style "%s %gx%g %g %s"

+ +

Only the parameter filename is required. The filename must be inside double quotes (") + if it has spaces. Width and height are provided in millimeters + (note the lowercase "x" between them), and their default value in pixels is INT_MAX for + both dimensions. When the canvas' size is not specified, the VDC Extension saved to the file is the image's bounding + rectangle. The resolution is the number of pixels per millimeter; its default value is "3.78 pixels/mm" (96 DPI). + Width, height and resolution are + real values. Width, height and resolution + are used only by cdGetCanvasSize and in pixel-millimeter conversion. + Parameter -t modifies the codification. Parameter -p specifies + the precision of integers, which can be 16 (default) or 32.

Any amount of such canvases may exist simultaneously. It is important to note that a call to function + + cdKillCanvas is required to close the file properly.

Coding - The CGM format supports binary and text coding. If you are not sure what to do, use + binary coding, which is the default. Should you prefer text coding, add a "-t" string to + the Data parameter.

Precision of Coordinates - The primitives can use coordinates in real numbers. However, for + compatibility reasons, we use coordinates in integers.

+ +

Behavior of Functions

Control

Clear: + does nothing.
Flush: + creates a new image, preserving the previous one. The CGM format supports multiple images in a file.
Play: + works with files created with text or binary coding. There are several callbacks for this driver. If one of the + callbacks returns a value different from zero, cdPlay's processing is interrupted. The + driver implements the callback CD_SIZECB and other callbacks + associated to CGM:
+ CD_COUNTERCB - int(*cdcgmcountercb)(cdContext *driver, double + percent) -Executed for each header of CGM commands; returns the percentage (0-100%) of headers read.
+ CD_SCLMDECB- int(*cdcgmsclmdecb)(cdContext + *driver, short scl_mde, short *drw_mode, double *factor) - Executed for the command + CGM SCALE MODE. Returns the current CGM scale mode and allows the callback to modify the scale mode used by the + cdPlay function (ABSTRACT=0, METRIC=1). Should you choose the + METRIC or ABSTRACT scale mode but the original scale mode is METRIC, you must provide the conversion factor in mm per + pixel.
+ CD_VDCEXTCB- int(*cdcgmvdcextcb)(cdContext + *driver, short type, void *xmn, void *ymn, void *xmx, void *ymx) - Executed for the + CGM command CGM VDC EXTENT, returns the VDC SPACE.
+ CD_BEGPICTCB- int(*cdcgmbegpictcb)(cdContext + *driver, char *pict) - Executed for the command BEGIN PICTURE, returns the string + that describes the image.
+ CD_BEGPICTBCB- int(*cdcgmbegpictbcb)(cdContext + *driver) - Executed for the command BEGIN PICTURE BODY.
+ CD_CGMBEGMTFCB - + int (*cdcgmbegmtfcb)(cdContext *driver, int *xmin, int *ymin, int *xmax, int *ymax) - Executed for the + command BEGIN METAFILE, provides the drawing limits of the image in the file.

Coordinate System and Clipping

+ UpdateYAxis: does nothing. The axis orientation is the same as the CD library.
Complex Regions: not supported.
Transformation Matrix: not supported.

Primitives

Begin: + if parameter CD_CLIP or CD_BEZIER are specified, does nothing.
Pixel: + does not exist in CGM, is simulated using a mark with size 1.
Chord: + does nothing.
Floating point primitives are supported.

Attributes

+ + WriteMode: does nothing, returns CD_REPLACE.
FontDim: + is simulated.
+ FillMode: does nothing.
+ LineCap: does nothing.
+ LineJoin: does nothing.
+ TextSize: is simulated.
+ + TextOrientation: does nothing.
Font: + see the table bellow for the generated font names. No other fonts are + supported.

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

Font Mapping
CD Fonts	Generated Font Names
CD Fonts	CD_PLAIN	CD_BOLD	CD_ITALIC	CD_BOLD\|CD_ITALIC
"System"	"SYSTEM"	"SYSTEM_BOLD"	"SYSTEM_ITALIC"	"SYSTEM_BOLDITALIC"
"Courier"	"COURIER"	"COURIER_BOLD"	"COURIER_ITALIC"	"COURIER_BOLDITALIC"
"Times"	"TIMES_ROMAN"	"TIMES_ROMAN_BOLD"	"TIMES_ROMAN_ITALIC"	"TIMES_ROMAN_BOLDITALIC"
"Helvetica"	"HELVETICA"	"HELVETICA_BOLD"	"HELVETICA_ITALIC"	"HELVETICA_BOLDITALIC"

+ +

Colors

+ + GetColorPlanes: returns 24.
Palette: + does nothing.

Client Images

+ GetImageRGB: does nothing.
+ PutImageRGBA: alpha is ignored.

Server Images

All functions do nothing.

+ + + + -- cgit v1.2.3