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authorJason Barron <jbarron@trolltech.com>2010-04-13 15:37:06 (GMT)
committerJason Barron <jbarron@trolltech.com>2010-04-14 07:32:22 (GMT)
commit779123b79cc27599f73a61b2f2055a32cc15230a (patch)
tree176d78d8c18308c57f4b8e20d968cf30f2e0fd85 /doc
parent67f6618f887b3c524f9da58de8136d474881d29f (diff)
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Implement OpenVG buffer scrolling and enable it on Symbian.
Add support for accelerated scrolling in the "direct" window surface implementation. Using vgCopyPixels(), the already rasterized content on the surface can be shifted to a new location such that only a portion of the suqsequent frame needs to be repainted instead of the entire frame. This only works when the "preserved" EGL swap behavior is enabled and the impact on performance is highly dependant on the specific hardware platform in use. Task-number: QT-2972 Reviewed-by: Rhys Weatherley
Diffstat (limited to 'doc')
-rw-r--r--doc/src/howtos/openvg.qdoc10
-rw-r--r--doc/src/platforms/emb-openvg.qdocinc6
2 files changed, 16 insertions, 0 deletions
diff --git a/doc/src/howtos/openvg.qdoc b/doc/src/howtos/openvg.qdoc
index 9c805bb..f70ed54 100644
--- a/doc/src/howtos/openvg.qdoc
+++ b/doc/src/howtos/openvg.qdoc
@@ -295,6 +295,16 @@
Convolution, colorize, drop shadow, and blur filters are accelerated
using OpenVG operations.
+ \section2 Scrolling
+
+ By default, accelerated scrolling is not enabled because the impact on
+ performance is very much tied to the hardware platform. To enable
+ accelerated scrolling, you should ensure that QVG_BUFFER_SCROLLING is
+ defined when compiling the QtOpenVG module.
+
+ You should only enable this feature if vgCopyPixels() is known to be
+ efficient on your hardware platform.
+
\section1 Known issues
Performance of copying the contents of an OpenVG-rendered window to the
diff --git a/doc/src/platforms/emb-openvg.qdocinc b/doc/src/platforms/emb-openvg.qdocinc
index 37ccb9c..2f9cc21 100644
--- a/doc/src/platforms/emb-openvg.qdocinc
+++ b/doc/src/platforms/emb-openvg.qdocinc
@@ -259,6 +259,12 @@ at present.
\o Convolution, colorize, drop shadow, and blur filters are
accelerated using OpenVG operations.
+ \row
+ \o Scrolling
+ \o Accelerated scrolling is implemented but disabled by default
+unless QVG_BUFFER_SCROLLING is defined. This should only be enabled on
+OpenVG engines where vgCopyPixels() is known to be efficient.
+
\endtable
\section2 Known issues