Drawing a line with RGA

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Article Metadata
Tested with
Devices(s): Nokia N93, Nokia N95
Platform(s): S60 3rd Edition
Created: stolik (26 Sep 2008)
Last edited: lpvalente (18 Sep 2012)



This snippet shows how to draw a line using the RGA API. RGA does not have a function for drawing lines.

Note: In order to use this code, you need to install the Open C plug-in.


This example relies on the RGA API ngi framework to draw a pixel (IGraphicsContext:: SetPixel()).

To run this snippet you need to create a project according to Using RGA with Carbide.c++ and create a simple application like this Simple RGA application. You can also modify the existing examples provided with Open C/C++ Plug-ins for S60 3rd Edition.

MMP file

The following capabilities and libraries are required:

LIBRARY euser.lib
LIBRARY runtime.lib
LIBRARY libc.lib
LIBRARY libm.lib
LIBRARY libpthread.lib

Note: The snippet itself does not require any special capabilities, but due to the use of RGA API ngi framework, the resulting application requires SwEvent capability. (See also Open C/C++ DLL.)

Source file

#include <graphicscontext.h>    // ngi
#include "helper.h" //examplefw
#include <math.h>
int CExamplePage::sgn (long a)
if (a > 0)
return +1;
if (a < 0)
return -1;
return 0;
void CExamplePage::Line(IGraphicsContext& aGraphicsContext,
int aX1, int aY1, int aX2, int aY2, int aColor)
long u,s,v,d1x,d1y,d2x,d2y,m,n;
int i;
u = aX2-aX1;
v = aY2-aY1;
d1x = sgn(u);
d1y = sgn(v);
d2x = sgn(u);
d2y = 0;
m = abs(u);
n = abs(v);
if (m<=n)
d2x = 0;
d2y = sgn(v);
m = abs(v);
n = abs(u);
s = (int)(m / 2);
for (i=0;i<round(m);i++)
aGraphicsContext.SetPixel(aColor, CPoint(aX1,aY1));
s += n;
if (s >= m)
s -= m;
aX1 += d1x;
aY1 += d1y;
aX1 += d2x;
aY1 += d2y;


The function will draw a line from a start point to the end point with the provided color.

See also

This page was last modified on 18 September 2012, at 21:09.
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