Drawing Lines

This topic provides examples that demonstrate how to draw lines of different widths and styles.

The examples assume common start and end points have been defined as follows:

...
// set up a pair of points for drawing diagonal lines
TPoint startPoint(50,50);
TPoint endPoint(590,190);
...

Drawing a line a single pixel wide

You can draw a thin line diagonally across the screen using DrawLine(). This illustrates how thin a single pixel width line is, and the visible stepping:

...
// draw a thin line from top left to bottom right 
gc.DrawLine(startPoint,endPoint);
...

Note: The line width is a single pixel by default.

Drawing a line three pixels wide

Use SetPenSize() to increase the pen size to three pixels.
Use DrawLine() to draw a wide line diagonally across the screen.

// Set up a "bold" size for the pen tip to (default is 1,1)
TSize penSizeBold(3,3);
...
// draw a line from top left to bottom right 
gc.SetPenSize(penSizeBold);
gc.DrawLine(startPoint,endPoint);
...

Drawing a line thirty pixels wide

Use SetPenWidth() to set the pen width to thirty pixels wide.
Use DrawLine() to draw a thirty pixel wide line, (x dimension), diagonally across the screen.

// Set up a "fat" size for the pen tip
TSize penSizeFat(30,30);
...
// draw a rather wide line from top left to bottom right,
// illustrating rounded ends and their clipping
gc.SetPenWidth(penSizeFat);
gc.DrawLine(startPoint,endPoint);
...

Notes

The ends of wide lines are rounded.
The effective width of the line depends on the size of the pen tip, which is elliptical.
The rounded end of a wide line may be clipped to the window, even though the end point is within the window.

Drawing a dotted line

Use SetPenStyle() to set the style of the pen to dotted.
Use DrawLine() to draw a thin dotted line diagonally across the screen.

...
// draw a dotted line from top left to bottom right 
gc.SetPenStyle(CGraphicsContext::EDottedPen);
gc.DrawLine(startPoint,endPoint);
...

Note: The pen style remains in effect until changed by another call to SetPenStyle() or the graphics context is reset to its default settings.

Drawing a dot-dashed line

Use SetPenStyle() to set the style of the pen to dot-dashed.
Use DrawLine() to draw a thin dot-dashed line diagonally across the screen.