PFD: split the compass band to parts to fit the texture limit

On older graphics cards the texture size limit
may be smaller than the compass band width,
QML downscales the element to fit the texture.

To avoid this, split compass band to tiles.

Added parameter like hslice=2:8 to svg image provider
and SvgElementImage.

ground/openpilotgcs/share/openpilotgcs/pfd/default/Compass.qml

@@ -0,0 +1,37 @@
+import Qt 4.7
+import "."
+
+Item {
+    id: sceneItem
+    property variant sceneSize
+
+    SvgElementImage {
+        id: compass
+        elementName: "compass"
+        sceneSize: sceneItem.sceneSize
+
+        clip: true
+
+        x: scaledBounds.x * sceneItem.width
+        y: scaledBounds.y * sceneItem.height
+        //anchors.horizontalCenter: parent.horizontalCenter
+
+        //split compass band to 8 parts to ensure it doesn't exceed the max texture size
+        Row {
+            anchors.centerIn: parent
+            //the band is 540 degrees wide, AttitudeActual.Yaw is converted to -180..180 range
+            anchors.horizontalCenterOffset: -1*((AttitudeActual.Yaw+180+720) % 360 - 180)/540*width
+
+            Repeater {
+                model: 5
+                SvgElementImage {
+                    id: compass_band
+                    elementName: "compass-band"
+                    sceneSize: background.sceneSize
+                    hSliceCount: 5
+                    hSlice: index
+                }
+            }
+        }
+    }
+}

ground/openpilotgcs/share/openpilotgcs/pfd/default/Pfd.qml

@@ -48,25 +48,9 @@ Rectangle {
                 anchors.centerIn: parent
             }
 
-            SvgElementImage {
-                id: compass
-                elementName: "compass"
+            Compass {
+                anchors.fill: parent
                 sceneSize: background.sceneSize
-
-                clip: true
-
-                y: 12
-                anchors.horizontalCenter: parent.horizontalCenter
-
-                SvgElementImage {
-                    id: compass_band
-                    elementName: "compass-band"
-                    sceneSize: background.sceneSize
-
-                    anchors.centerIn: parent
-                    //the band is 540 degrees wide, AttitudeActual.Yaw is converted to -180..180 range
-                    anchors.horizontalCenterOffset: -1*((AttitudeActual.Yaw+180+720) % 360 - 180)/540*width
-                }
             }
 
             SpeedScale {

ground/openpilotgcs/share/openpilotgcs/pfd/default/SvgElementImage.qml

@@ -4,11 +4,26 @@ Image {
     id: sceneItem
     property variant sceneSize
     property string elementName
-    property string svgFileName : "pfd.svg"
+    property string svgFileName: "pfd.svg"
+    property int vSlice: 0
+    property int vSliceCount: 0
+    property int hSlice: 0
+    property int hSliceCount: 0
     property variant scaledBounds: svgRenderer.scaledElementBounds(svgFileName, elementName)
 
     sourceSize.width: Math.round(sceneSize.width*scaledBounds.width)
     sourceSize.height: Math.round(sceneSize.height*scaledBounds.height)
 
-    Component.onCompleted: source = "image://svg/"+svgFileName+"!"+elementName
+    Component.onCompleted: {
+        var params = ""
+        if (hSliceCount > 1)
+            params += "hslice="+hSlice+":"+hSliceCount
+        if (vSliceCount > 1)
+            params += "vslice="+vSlice+":"+vSliceCount
+
+        if (params != "")
+            params = "?" + params
+
+        source = "image://svg/"+svgFileName+"!"+elementName+params
+    }
 }

ground/openpilotgcs/src/libs/utils/svgimageprovider.cpp

@@ -67,12 +67,23 @@ QSvgRenderer *SvgImageProvider::loadRenderer(const QString &svgFile)
 }
 
 /**
-  requestedSize is realted to the whole svg file, not to specific element
-  */
+   Supported id format: fileName[!elementName[?parameters]]
+   where parameters may be:
+   vslice=1:2;hslice=2:4 - use the 3rd horizontal slice of total 4 slices, slice numbering starts from 0
+
+   requestedSize is related to the whole element size, even if slice is requested.
+
+   usage:
+
+   Image {
+       source: "image://svg/pfd.svg!world"
+   }
+*/
 QImage SvgImageProvider::requestImage(const QString &id, QSize *size, const QSize &requestedSize)
 {
     QString svgFile = id;
     QString element;
+    QString parameters;
 
     int separatorPos = id.indexOf('!');
     if (separatorPos != -1) {
@@ -80,6 +91,29 @@ QImage SvgImageProvider::requestImage(const QString &id, QSize *size, const QSiz
         element = id.mid(separatorPos+1);
     }
 
+    int parametersPos = element.indexOf('?');
+    if (parametersPos != -1) {
+        parameters = element.mid(parametersPos+1);
+        element = element.left(parametersPos);
+    }
+
+    int hSlicesCount = 0;
+    int hSlice = 0;
+    int vSlicesCount = 0;
+    int vSlice = 0;
+    if (!parameters.isEmpty()) {
+        QRegExp hSliceRx("hslice=(\\d+):(\\d+)");
+        if (hSliceRx.indexIn(parameters) != -1) {
+            hSlice = hSliceRx.cap(1).toInt();
+            hSlicesCount = hSliceRx.cap(2).toInt();
+        }
+        QRegExp vSliceRx("vslice=(\\d+):(\\d+)");
+        if (vSliceRx.indexIn(parameters) != -1) {
+            vSlice = vSliceRx.cap(1).toInt();
+            vSlicesCount = vSliceRx.cap(2).toInt();
+        }
+    }
+
     if (size)
         *size = QSize();
 
@@ -114,8 +148,22 @@ QImage SvgImageProvider::requestImage(const QString &id, QSize *size, const QSiz
         }
 
         QRectF elementBounds = renderer->boundsOnElement(element);
-        int w = qRound(elementBounds.width() * xScale);
-        int h = qRound(elementBounds.height() * yScale);
+        int elementWidth = qRound(elementBounds.width() * xScale);
+        int elementHeigh = qRound(elementBounds.height() * yScale);
+        int w = elementWidth;
+        int h = elementHeigh;
+        int x = 0;
+        int y = 0;
+
+        if (hSlicesCount > 1) {
+            x = (w*hSlice)/hSlicesCount;
+            w = (w*(hSlice+1))/hSlicesCount - x;
+        }
+
+        if (vSlicesCount > 1) {
+            y = (h*(vSlice))/vSlicesCount;
+            h = (h*(vSlice+1))/vSlicesCount - y;
+        }
 
         QImage img(w, h, QImage::Format_ARGB32_Premultiplied);
         img.fill(0);
@@ -124,12 +172,13 @@ QImage SvgImageProvider::requestImage(const QString &id, QSize *size, const QSiz
                          QPainter::Antialiasing |
                          QPainter::SmoothPixmapTransform);
 
-        renderer->render(&p, element, QRectF(0, 0, w, h));
+        p.translate(-x,-y);
+        renderer->render(&p, element, QRectF(0, 0, elementWidth, elementHeigh));
 
         if (size)
             *size = QSize(w, h);
 
-        //img.save(element+".png");
+        //img.save(element+parameters+".png");
         return img;
     } else {
         //render the whole svg file