Expose SVG elements geometry to QML side

This allows to reuse the existing svg file like pfd.svg
without manually positioning individual svg element.

ground/openpilotgcs/src/plugins/qmlview/qmlviewgadgetwidget.cpp

@@ -31,15 +31,11 @@
 #include "uavobjectmanager.h"
 #include "uavobject.h"
 
-#include <utils/stylehelper.h>
-#include <utils/cachedsvgitem.h>
-#include <iostream>
 #include <QDebug>
-#include <QPainter>
+#include <QSvgRenderer>
 #include <QtOpenGL/QGLWidget>
 #include <QtCore/qfileinfo.h>
 #include <QtCore/qdir.h>
-#include <cmath>
 
 #include <QtDeclarative/qdeclarativeengine.h>
 #include <QtDeclarative/qdeclarativecontext.h>
@@ -69,6 +65,8 @@ QmlViewGadgetWidget::QmlViewGadgetWidget(QWidget *parent) :
         else
             qWarning() << "Failed to load object" << objectName;
     }
+
+    engine()->rootContext()->setContextProperty("qmlWidget", this);
 }
 
 QmlViewGadgetWidget::~QmlViewGadgetWidget()
@@ -80,8 +78,12 @@ void QmlViewGadgetWidget::setQmlFile(QString fn)
     m_fn = fn;
 
     engine()->removeImageProvider("svg");
-    engine()->addImageProvider("svg",
-              new SvgImageProvider(fn));
+    SvgImageProvider *svgProvider = new SvgImageProvider(fn);
+    engine()->addImageProvider("svg", svgProvider);
+
+    //it's necessary to allow qml side to query svg element position
+    engine()->rootContext()->setContextProperty("svgRenderer", svgProvider);
+    engine()->setBaseUrl(QUrl::fromLocalFile(fn));
 
     qDebug() << Q_FUNC_INFO << fn;
     setSource(QUrl::fromLocalFile(fn));

ground/openpilotgcs/src/plugins/qmlview/svgimageprovider.cpp

@@ -31,6 +31,7 @@
 #include <QUrl>
 
 SvgImageProvider::SvgImageProvider(const QString &basePath):
+    QObject(),
     QDeclarativeImageProvider(QDeclarativeImageProvider::Image),
     m_basePath(basePath)
 {
@@ -41,6 +42,30 @@ SvgImageProvider::~SvgImageProvider()
     qDeleteAll(m_renderers);
 }
 
+QSvgRenderer *SvgImageProvider::loadRenderer(const QString &svgFile)
+{
+    QSvgRenderer *renderer = m_renderers.value(svgFile);
+    if (!renderer) {
+        renderer = new QSvgRenderer(svgFile);
+
+        QString fn = QUrl::fromLocalFile(m_basePath).resolved(svgFile).toLocalFile();
+
+        //convert path to be relative to base
+        if (!renderer->isValid())
+            renderer->load(fn);
+
+        if (!renderer->isValid()) {
+            qWarning() << "Failed to load svg file:" << svgFile << fn;
+            delete renderer;
+            return 0;
+        }
+
+        m_renderers.insert(svgFile, renderer);
+    }
+
+    return renderer;
+}
+
 /**
   requestedSize is realted to the whole svg file, not to specific element
   */
@@ -58,23 +83,9 @@ QImage SvgImageProvider::requestImage(const QString &id, QSize *size, const QSiz
     if (size)
         *size = QSize();
 
-    QSvgRenderer *renderer = m_renderers.value(svgFile);
-    if (!renderer) {
-        renderer = new QSvgRenderer(svgFile);
-
-        QString fn = QUrl::fromLocalFile(m_basePath).resolved(svgFile).toLocalFile();
-
-        //convert path to be relative to base
-        if (!renderer->isValid())
-            renderer->load(fn);
-
-        if (!renderer->isValid()) {
-            qWarning() << "Failed to load svg file:" << svgFile << fn;
-            return QImage();
-        }
-
-        m_renderers.insert(svgFile, renderer);
-    }
+    QSvgRenderer *renderer = loadRenderer(svgFile);
+    if (!renderer)
+        return QImage();
 
     qreal xScale = 1.0;
     qreal yScale = 1.0;
@@ -128,3 +139,32 @@ QPixmap SvgImageProvider::requestPixmap(const QString &id, QSize *size, const QS
 {
     return QPixmap::fromImage(requestImage(id, size, requestedSize));
 }
+
+/*!
+  \fn SvgImageProvider::scaledElementBounds(const QString &svgFile, const QString &element)
+
+  Returns the bound of \a element in logical coordinates,
+  scalled to the default size of svg document (so the bounds of whole doc would be (0,0,1,1) ).
+*/
+QRectF SvgImageProvider::scaledElementBounds(const QString &svgFile, const QString &elementName)
+{
+    QSvgRenderer *renderer = loadRenderer(svgFile);
+
+    if (!renderer)
+        return QRectF();
+
+    if (!renderer->elementExists(elementName)) {
+        qWarning() << "invalid element:" << elementName << "of" << svgFile;
+        return QRectF();
+    }
+
+    QRectF elementBounds = renderer->boundsOnElement(elementName);
+    QMatrix matrix = renderer->matrixForElement(elementName);
+    elementBounds = matrix.mapRect(elementBounds);
+
+    QSize docSize = renderer->defaultSize();
+    return QRectF(elementBounds.x()/docSize.width(),
+                  elementBounds.y()/docSize.height(),
+                  elementBounds.width()/docSize.width(),
+                  elementBounds.height()/docSize.height());
+}

ground/openpilotgcs/src/plugins/qmlview/svgimageprovider.h

@@ -28,19 +28,25 @@
 #ifndef SVGIMAGEPROVIDER_H_
 #define SVGIMAGEPROVIDER_H_
 
+#include <QObject>
 #include <QtDeclarative/qdeclarativeimageprovider.h>
 #include <QSvgRenderer>
 #include <QMap>
 
-class SvgImageProvider : public QDeclarativeImageProvider
+class SvgImageProvider : public QObject, public QDeclarativeImageProvider
 {
+    Q_OBJECT
 public:
     SvgImageProvider(const QString &basePath);
    ~SvgImageProvider();
 
+    QSvgRenderer *loadRenderer(const QString &svgFile);
+
     QImage requestImage(const QString &id, QSize *size, const QSize& requestedSize);
     QPixmap requestPixmap(const QString &id, QSize *size, const QSize& requestedSize);
 
+    Q_INVOKABLE QRectF scaledElementBounds(const QString &svgFile, const QString &elementName);
+
 private:
     QMap<QString, QSvgRenderer*> m_renderers;
     QString m_basePath;