XDrawLine



XDrawLine

NAME
SYNTAX
ARGUMENTS
DESCRIPTION
STRUCTURES
DIAGNOSTICS
SEE ALSO

NAME

XDrawLine, XDrawLines, XDrawSegments, XSegment − draw lines, polygons, and line structure

SYNTAX

int XDrawLine(Display *display, Drawable d, GC gc, int x1, int y1, int x2, int y2);

int XDrawLines(Display *display, Drawable d, GC gc, XPoint *points, int npoints, int mode);

int XDrawSegments(Display *display, Drawable d, GC gc, XSegment *segments, int nsegments);

ARGUMENTS

d

Specifies the drawable.

display

Specifies the connection to the X server.

gc

Specifies the GC.

mode

Specifies the coordinate mode. You can pass CoordModeOrigin or CoordModePrevious.

npoints

Specifies the number of points in the array.

nsegments

Specifies the number of segments in the array.

points

Specifies an array of points.

segments

Specifies an array of segments.

x1

y1

x2

y2

Specify the points (x1, y1) and (x2, y2) to be connected.

DESCRIPTION

The XDrawLine function uses the components of the specified GC to draw a line between the specified set of points (x1, y1) and (x2, y2). It does not perform joining at coincident endpoints. For any given line, XDrawLine does not draw a pixel more than once. If lines intersect, the intersecting pixels are drawn multiple times.

The XDrawLines function uses the components of the specified GC to draw npoints−1 lines between each pair of points (point[i], point[i+1]) in the array of XPoint structures. It draws the lines in the order listed in the array. The lines join correctly at all intermediate points, and if the first and last points coincide, the first and last lines also join correctly. For any given line, XDrawLines does not draw a pixel more than once. If thin (zero line-width) lines intersect, the intersecting pixels are drawn multiple times. If wide lines intersect, the intersecting pixels are drawn only once, as though the entire PolyLine protocol request were a single, filled shape. CoordModeOrigin treats all coordinates as relative to the origin, and CoordModePrevious treats all coordinates after the first as relative to the previous point.

The XDrawSegments function draws multiple, unconnected lines. For each segment, XDrawSegments draws a line between (x1, y1) and (x2, y2). It draws the lines in the order listed in the array of XSegment structures and does not perform joining at coincident endpoints. For any given line, XDrawSegments does not draw a pixel more than once. If lines intersect, the intersecting pixels are drawn multiple times.

All three functions use these GC components: function, plane-mask, line-width, line-style, cap-style, fill-style, subwindow-mode, clip-x-origin, clip-y-origin, and clip-mask. The XDrawLines function also uses the join-style GC component. All three functions also use these GC mode-dependent components: foreground, background, tile, stipple, tile-stipple-x-origin, tile-stipple-y-origin, dash-offset, and dash-list.

XDrawLine, XDrawLines, and XDrawSegments can generate BadDrawable, BadGC, and BadMatch errors. XDrawLines can also generate a BadValue error.

STRUCTURES

The XSegment structure contains:

typedef struct {

short x1, y1, x2, y2;

} XSegment;

All x and y members are signed integers. The width and height members are 16-bit unsigned integers. You should be careful not to generate coordinates and sizes out of the 16-bit ranges, because the protocol only has 16-bit fields for these values.

DIAGNOSTICS

BadDrawable

A value for a Drawable argument does not name a defined Window or Pixmap.

BadGC

A value for a GContext argument does not name a defined GContext.

BadMatch

An InputOnly window is used as a Drawable.

BadMatch

Some argument or pair of arguments has the correct type and range but fails to match in some other way required by the request.

BadValue

Some numeric value falls outside the range of values accepted by the request. Unless a specific range is specified for an argument, the full range defined by the argument’s type is accepted. Any argument defined as a set of alternatives can generate this error.

SEE ALSO

XDrawArc(3), XDrawPoint(3), XDrawRectangle(3)
Xlib − C Language X Interface






Opportunity


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.





Free Software


Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.


Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.





Free Books


The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.


Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.





Education


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.


Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.