Attributes of drawing elements

1
Attributes of drawing elements

• All drawn objects have attributes
• Color
• Line widths
• Fill
• These are often specified in a structure
• Windows Device Context (DC)
• X Graphics Context (GC)
• Abstracted in Qt by a QPainter Object
• See http//doc.trolltech.com/3.0/qpainter.html
• Abstracted in Javas Swing classes by the
  Graphics object

2
Colorsee http//doc.trolltech.com/3.0/qcolor.htm
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• Specified by Red, Green, and Blue (usually 0-255)
• Great for hardware, poor for the user?
• Predefined color names (known by Qt)
• Predefined names for standard colors
• Mapped to RGB values (Papaya whip, Peru,)

3
Line Attributessee http//doc.trolltech.com/3.0/
qpen.html

• Width
• How many pixels wide is a line
• Draws rectangle or lines parallel to ideal line
• Style
• Solid, Dashed, etc.
• Line cap
• Line end

4
Line Cap Styles http//doc.trolltech.com/3.0/qt.h
tmlPenCapStyle-enum
Not last
Line endpoint
Butt
Not all styles are supported by Qt.
Round
Projecting
5
Line Join Styleshttp//doc.trolltech.com/qt.html
PenJoinStyle-enum
Bevel
Round
Miter
Qt 3 supports all 3 styles.
6
Polygon Attributessee http//doc.trolltech.com/3
.0/qbrush.html

• Filling
• Inside-Outside Rule
• Even-Odd
• Non-Zero Winding Number
• Solid
• Pattern