From 19fd8e6e26065665a85ca8030acf4d871fbea854 Mon Sep 17 00:00:00 2001
From: James Turner <zakalawe@mac.com>
Date: Mon, 24 Apr 2017 12:24:58 +0100
Subject: [PATCH] WIP on clipping working

---
 utils/fgqcanvas/canvasitem.cpp      | 32 +++++++++++++++++++++++++++++
 utils/fgqcanvas/canvasitem.h        |  7 +++++++
 utils/fgqcanvas/fgcanvaselement.cpp |  2 +-
 utils/fgqcanvas/fgcanvaspath.cpp    |  7 +++++++
 4 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/utils/fgqcanvas/canvasitem.cpp b/utils/fgqcanvas/canvasitem.cpp
index fdf6bdd25..8fc6a2aba 100644
--- a/utils/fgqcanvas/canvasitem.cpp
+++ b/utils/fgqcanvas/canvasitem.cpp
@@ -18,6 +18,7 @@
 #include "canvasitem.h"
 
 #include <QMatrix4x4>
+#include <QSGClipNode>
 
 class LocalTransform : public QQuickTransform
 {
@@ -48,4 +49,35 @@ void CanvasItem::setTransform(const QMatrix4x4 &mat)
     m_localTransform->setTransform(mat);
 }
 
+void CanvasItem::setGlobalClip(const QRectF &clip)
+{
+    m_hasClip = true;
+    update();
+}
+
+void CanvasItem::setScaleToFit(const QSizeF &windowSize)
+{
+    const double verticalScaling = windowSize.height() / implicitHeight();
+    const double horizontalScaling = windowSize.width() / implicitWidth();
+    const double usedScale = std::min(verticalScaling, horizontalScaling);
+    setScale(usedScale);
+}
+
+QSGClipNode *CanvasItem::getClipNode()
+{
+    if (!m_hasClip) {
+        return nullptr;
+    }
+
+    if (!m_clipNode) {
+        m_clipNode = new QSGClipNode();
+    }
+
+    // transform global rect to local
+    QRectF localRect(mapFromGlobal(m_globalClipRect.topLeft()),
+                     mapFromGlobal(m_globalClipRect.bottomRight()));
+    m_clipNode->setClipRect(localRect);
+    return m_clipNode;
+}
+
 #include "canvasitem.moc"
diff --git a/utils/fgqcanvas/canvasitem.h b/utils/fgqcanvas/canvasitem.h
index ebf46ae76..f232765cb 100644
--- a/utils/fgqcanvas/canvasitem.h
+++ b/utils/fgqcanvas/canvasitem.h
@@ -21,6 +21,7 @@
 #include <QQuickItem>
 
 class LocalTransform;
+class QSGClipNode;
 
 class CanvasItem : public QQuickItem
 {
@@ -33,8 +34,14 @@ signals:
 
 public slots:
 
+protected:
+    QSGClipNode* getClipNode();
+
 private:
     LocalTransform* m_localTransform;
+    QRectF m_globalClipRect;
+    bool m_hasClip = false;
+    QSGClipNode* m_clipNode = nullptr;
 };
 
 #endif // CANVASITEM_H
diff --git a/utils/fgqcanvas/fgcanvaselement.cpp b/utils/fgqcanvas/fgcanvaselement.cpp
index a120b8b8b..8c4520329 100644
--- a/utils/fgqcanvas/fgcanvaselement.cpp
+++ b/utils/fgqcanvas/fgcanvaselement.cpp
@@ -148,7 +148,7 @@ void FGCanvasElement::paint(FGCanvasPaintContext *context) const
 
     if (_hasClip)
     {
-        // clip is definef in the global coordinate system
+        // clip is defined in the global coordinate system
 #if 0
         p->save();
         p->setTransform(context->globalCoordinateTransform());
diff --git a/utils/fgqcanvas/fgcanvaspath.cpp b/utils/fgqcanvas/fgcanvaspath.cpp
index 1831ec143..dcdf90f21 100644
--- a/utils/fgqcanvas/fgcanvaspath.cpp
+++ b/utils/fgqcanvas/fgcanvaspath.cpp
@@ -168,6 +168,13 @@ public:
             strokeGeom->setFlag(QSGNode::OwnsMaterial);
         }
 
+        QSGClipNode* clip = getClipNode();
+        if (clip) {
+            if (fillGeom) clip->appendChildNode(fillGeom);
+            if (strokeGeom) clip->appendChildNode(strokeGeom);
+            return clip;
+        }
+
         if (fillGeom && strokeGeom) {
             QSGNode* groupNode = new QSGNode;
             groupNode->appendChildNode(fillGeom);