49 lines
1.9 KiB
Plaintext
49 lines
1.9 KiB
Plaintext
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INTERFACE
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CLASS: QskGraphic
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BASE: QPaintDevice
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HEADER: QskGraphic.h
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DESCRIPTION
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\brief A paint device for scalable graphics
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QskGraphic is the representation of a graphic that is tailored for
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scalability. Like QPicture it will be initialized by QPainter
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operations and can be replayed later to any target paint device.
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It can be stored and loaded from disk using the operators
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from QskGraphicIO. Together with QSvgRenderer it can be used to
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implement a simple SVG compiler.
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QskGraphic maps all scalable drawing primitives to a QPainterPath
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and stores them together with the painter state changes
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( pen, brush, transformation ... ) in a list of QskPainterCommand.
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For being a complete QPaintDevice it also stores pixmaps or images,
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what is somehow against the idea of the class, because these objects
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can't be scaled without a loss in quality.
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The main issue about scaling a QskGraphic object are the pens used for
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drawing the outlines of the painter paths. While non cosmetic pens
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( QPen::isCosmetic() ) are scaled with the same ratio as the path,
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cosmetic pens have a fixed width. A graphic might have paths with
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different pens - cosmetic and non-cosmetic.
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QskGraphic caches 2 different rectangles:
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- control point rectangle\n
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The control point rectangle is the bounding rectangle of all
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control point rectangles of the painter paths, or the target
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rectangle of the pixmaps/images.
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- bounding rectangle\n
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The bounding rectangle extends the control point rectangle by
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what is needed for rendering the outline with an unscaled pen.
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Because the offset for drawing the outline depends on the shape
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of the painter path ( the peak of a triangle is different than the flat side )
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scaling with a fixed aspect ratio always needs to be calculated from the
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control point rectangle.
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\sa QskGraphicIO, QskPainterCommand
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END
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END
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