Chris, thanks for the information.
Antialiasing is switched off, and the lines are one pixel wide and
horizontal. But my app is not running slow at all, and I was only
wondering why about 50% of the time was spent on line drawing. Since
drawing the text only seems to be an issue of drawing some bitmaps, this
probably explains why.
Regarding more performance improvements I was wondering if a new
interface Shape2 could help in some cases. The interface could look like
this:
public interface Shape2 extends Shape {
public Shape getTransformedInstance(AffineTransform at);
public Shape intersection(Shape s);
// maybe more methods
}
If a shape implemented Shape2, in the clip() and setClip() methods of
Graphics2D you would not have to create a GeneralPath to get the
transformed shape, which currently seems to happen for all shapes except
rectangles. Instead the shape would be responsible of creating a
transformed instance, which in case of a Trapezoid and a
identity/translate/scale transform this could be a translated instance
of Trapezoid. The contains()/intersects() methods of these instances can
be much, much faster that the methods of a GeneralPath instance.
If this really helps improving performance, introducing the interface
should not be too difficult and backward compatible. Standard
implementations of the methods can always use the good old GeneralPath
to create transformed intances and intersections, but it would also be
possible to have optimized implementations. And shapes that do not
implement Shape2 will be treated as before.
Not sure if this idea is really worth thinking about, but I had the
feeling that I needed to share it ;-)
Cheers
Jan
Chris Campbell schrieb:
Hi Jan,
On Nov 10, 2006, at 3:17 AM, Jan Bösenberg (INCORS GmbH) wrote:
In one application I do a lot of text rendering and some line drawing.
Much to my surprise, my profiler says that the app spends much more time
on line drawing than on the text rendering. OK, I am using ready made
GlyphVectors for the text rendering, which should make text rendering
quite fast, but I still would not expect the app to spend that much time
on line drawing.
Complex (wide, antialiased, etc) line drawing can be quite time
consuming, and you're right that it's not exactly a fair comparison.
In the text case, we can convert glyphs into bitmaps which are much
faster to render than say, on-the-fly rasterized wide lines.
One important thing to note is that I am using a non-rectangular shape
for clipping when drawing lines (I am using a trapezoid shaped
GeneralPath). The rest is simply done by creating a Line2D object,
setting a BasicStroke (with CAP_BUTT and JOIN_BEVEL) and calling the
draw(Shape s) method on the Graphics object.
Any ideas where the time is spent? Is it the non-rectangular clipping
shape?
I assume you have antialiasing enabled? For things like antialiasing,
non-rectangular clip, wide BasicStroke... any of these things can
cause us to fall back on a different renderer, so it's not just one
thing that's causing the slowdown. The OpenGL-based pipeline can
accelerate things like antialiased rendering as well as complex
clipping, so that might help improve performance in your case. Short
of that, we'll just need to continue improving performance of our
rasterizing code.
Thanks,
Chris
Cheers
Jan
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