Doc: Add an overview of data visualization

Move some information from the front page and the known issues
to the overview. Add some information to the interacting with data
topic.

Change-Id: Ia63e1d46ec48861a144c51f0d8796809ea771ea4
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>

1 files changed, 21 insertions, 9 deletions

diff --git a/src/datavisualization/doc/src/qtdatavisualization.qdoc b/src/datavisualization/doc/src/qtdatavisualization.qdoc
index 551281d8..72f2302c 100644
--- a/src/datavisualization/doc/src/qtdatavisualization.qdoc
+++ b/src/datavisualization/doc/src/qtdatavisualization.qdoc
@@ -181,9 +181,27 @@
 
     \section1 Interacting with Data
 
-    You can interact with the rendered graph with either mouse or touch to rotate, zoom, or select
-    data. For the default mouse controls, see Q3DInputHandler documentation, and for the default
-    touch controls, see QTouch3DInputHandler documentation.
+    End users can interact with the rendered graph by using either the mouse or
+    touch to rotate, zoom, or select data. Graphs can be rotated freely by
+    holding down the right mouse button and moving the mouse. Zooming is done by
+    rolling the mouse wheel. Selecting, if enabled, is done by pressing the left
+    mouse button. The scene can be reset to the default camera view by clicking
+    the mouse wheel. In touch devices, rotation is done by tap-and-move,
+    selection by tap-and-hold, and zoom by pinch.
+
+    Qt Data Visualization has default handlers for mouse actions and touch
+    gestures. For the default mouse controls, see Q3DInputHandler, and for
+    the default touch controls, see QTouch3DInputHandler. The default handlers
+    must be disabled when using customized input handlers.
+
+    The \l{Custom Input Example} illustrates how to use a custom input handler
+    to select items upon mouseover instead of mouse click. The information
+    below the mouse cursor is displayed as a popup.
+
+    In addition to perspective projection, orthographic projection can be used
+    to create 2D graphs by replacing the default input handler with one that
+    does not allow rotating the graph and setting the camera to view the graph
+    directly from the side or from the top.
 
     \section1 Data Selection Modes
 
@@ -211,10 +229,6 @@
     \list
         \li Some platforms like Android and WinRT cannot handle multiple native windows properly,
             so only the Qt Quick 2 graphs are available in practice for those platforms.
-        \li Shadows are not supported with OpenGL ES2 (including Angle builds in Windows).
-        \li Anti-aliasing doesn't work with OpenGL ES2 (including Angle builds in Windows).
-        \li QCustom3DVolume items are not supported with OpenGL ES2 (including Angle builds in
-            Windows).
         \li Surfaces with non-straight rows and columns do not always render properly.
         \li Q3DLight class (and Light3D QML item) are currently not usable for anything.
         \li Changing most of Q3DScene properties affecting subviewports currently has no effect.
@@ -224,8 +238,6 @@
             "QT += datavisualization" in the pro file. This is because Qt Data Visualization
             QML plugin has a dependency to Qt Data Visualization C++ library, which Qt Creator
             doesn't automatically add to the deployment package.
-        \li Only OpenGL ES2 emulation is available for software renderer (that is, when using
-            QCoreApplication::setAttribute(Qt::AA_UseSoftwareOpenGL))
     \endlist
 */