Introduce hardware accelerated curve renderer for Shapes

This implements the Loop/Blinn algorithm for quadratic curves
as an optional backend for Qt Quick Shapes, basically distance
fields where the distance to curves are calculated in the
fragment shader.

This means cubic curves are approximated, which will give
varying results, but for many shapes (such as text) this is
efficient and means the shapes can be zoomed indefinitely
while still retaining curvature as well as anti-aliasing
working without MSAA.

Preliminary results give some frame rate improvements
compared to doing MSAA and GeometryRenderer, but the major
improvement is that you can get smooth curves at any zoom
level without re-triangulating the shape.

Note that the renderer currently does not do antialiasing
for straight lines. This would still require MSAA, but at
a lower cost than for GeometryRenderer since there are
much fewer triangles. Adding AA here as well is work in
progress.

Task-number: QTBUG-104122
Done-with: Paul Olav Tvete <paul.tvete@qt.io>
Done-with: Eirik Aavitsland <eirik.aavitsland@qt.io>
Done-with: Amr Elsayed <amr.elsayed@qt.io>
Change-Id: I6b4a1103546fbdfe760906f7a183101f8eedb9d3
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

1 files changed, 13 insertions, 1 deletions

diff --git a/src/quickshapes/qquickshape_p.h b/src/quickshapes/qquickshape_p.h
index f1e2eea546..a7c8611856 100644
--- a/src/quickshapes/qquickshape_p.h
+++ b/src/quickshapes/qquickshape_p.h
@@ -288,8 +288,12 @@ class Q_QUICKSHAPES_PRIVATE_EXPORT QQuickShape : public QQuickItem
     Q_PROPERTY(RendererType rendererType READ rendererType NOTIFY rendererChanged)
     Q_PROPERTY(bool asynchronous READ asynchronous WRITE setAsynchronous NOTIFY asynchronousChanged)
     Q_PROPERTY(bool vendorExtensionsEnabled READ vendorExtensionsEnabled WRITE setVendorExtensionsEnabled NOTIFY vendorExtensionsEnabledChanged)
+    Q_PROPERTY(RendererType preferredRendererType READ preferredRendererType
+               WRITE setPreferredRendererType NOTIFY preferredRendererTypeChanged REVISION(6, 6))
     Q_PROPERTY(Status status READ status NOTIFY statusChanged)
     Q_PROPERTY(ContainsMode containsMode READ containsMode WRITE setContainsMode NOTIFY containsModeChanged REVISION(1, 11))
+    Q_PROPERTY(QRectF boundingRect READ boundingRect NOTIFY boundingRectChanged REVISION(6, 6))
+
     Q_PROPERTY(QQmlListProperty<QObject> data READ data)
     Q_CLASSINFO("DefaultProperty", "data")
     QML_NAMED_ELEMENT(Shape)
@@ -300,7 +304,8 @@ public:
         UnknownRenderer,
         GeometryRenderer,
         NvprRenderer,
-        SoftwareRenderer
+        SoftwareRenderer,
+        CurveRenderer
     };
     Q_ENUM(RendererType)
 
@@ -325,6 +330,11 @@ public:
     bool asynchronous() const;
     void setAsynchronous(bool async);
 
+    Q_REVISION(6, 6) RendererType preferredRendererType() const;
+    Q_REVISION(6, 6) void setPreferredRendererType(RendererType preferredType);
+
+    Q_REVISION(6, 6) QRectF boundingRect() const override;
+
     bool vendorExtensionsEnabled() const;
     void setVendorExtensionsEnabled(bool enable);
 
@@ -349,6 +359,8 @@ Q_SIGNALS:
     void asynchronousChanged();
     void vendorExtensionsEnabledChanged();
     void statusChanged();
+    Q_REVISION(6, 6) void preferredRendererTypeChanged();
+    Q_REVISION(6, 6) void boundingRectChanged();
     Q_REVISION(1, 11) void containsModeChanged();
 
 private: