TechDraw: new center/section draw style

using custom QT pen styles, the center and section lines look much
better.
With some math we are also able to control the middle position, thus
the centerlines will always look good, regardless of the size of an
object.

Also getting the section label size from the settings, so the font
size is controllable and not hardcoded.

Bonus: adding blank templates for the common paper sizes (as the
        Drawing WB has them)

src/Mod/TechDraw/App/CMakeLists.txt

@@ -158,6 +158,12 @@ SET(TechDraw_Templates
     Templates/A4_LandscapeTD.svg
     Templates/A4_Landscape_ISO7200TD.svg
     Templates/A4_Portrait_ISO7200TD.svg
+    Templates/A0_Landscape_blank.svg
+    Templates/A1_Landscape_blank.svg
+    Templates/A2_Landscape_blank.svg
+    Templates/A3_Landscape_blank.svg
+    Templates/A4_Landscape_blank.svg
+    Templates/A4_Portrait_blank.svg
 )
 
 SET(TechDraw_PATFile

src/Mod/TechDraw/Gui/QGICenterLine.cpp

@@ -26,6 +26,8 @@
 #include <QStyleOptionGraphicsItem>
 #endif
 
+#include <cmath>
+
 #include <App/Application.h>
 #include <App/Material.h>
 #include <Base/Console.h>
@@ -70,15 +72,15 @@ QColor QGICenterLine::getCenterColor()
 {
     Base::Reference<ParameterGrp> hGrp = App::GetApplication().GetUserParameter()
         .GetGroup("BaseApp")->GetGroup("Preferences")->GetGroup("Mod/TechDraw/Decorations");
-    App::Color fcColor = App::Color((uint32_t) hGrp->GetUnsigned("CenterColor", 0x08080800));
+    App::Color fcColor = App::Color((uint32_t) hGrp->GetUnsigned("CenterColor", 0x00000000));
     return fcColor.asValue<QColor>();
 }
 
 Qt::PenStyle QGICenterLine::getCenterStyle()
 {
     Base::Reference<ParameterGrp> hGrp = App::GetApplication().GetUserParameter().GetGroup("BaseApp")->
                                          GetGroup("Preferences")->GetGroup("Mod/TechDraw/Decorations");
-    Qt::PenStyle centerStyle = static_cast<Qt::PenStyle> (hGrp->GetInt("CenterLine",3));
+    Qt::PenStyle centerStyle = static_cast<Qt::PenStyle> (hGrp->GetInt("CenterLine", 4));
     return centerStyle;
 }
 
@@ -90,10 +92,48 @@ void QGICenterLine::paint ( QPainter * painter, const QStyleOptionGraphicsItem *
     QGIDecoration::paint (painter, &myOption, widget);
 }
 
+void QGICenterLine::setIntersection(bool isIntersecting) {
+    /**
+     * Set the intersection style for the centerline.
+     * If isIntersecting is set to true, the middle of the centerline
+     * will be the middle of a dash - therefore if two lines intersect, they
+     * will form a cross.
+     * If isIntersecting is set to false, the middle of the centerline will be a
+     * dot.
+     */
+    m_isintersection = isIntersecting;
+}
+
 void QGICenterLine::setTools()
 {
+    if (m_styleCurrent == Qt::DashDotLine) {
+        QVector<qreal> dashes;
+        qreal space = 4;  // in unit width
+        qreal dash = 16;
+        // dot must be really small when using CapStyle RoundCap but > 0
+        // for CapStyle FlatCap you would need to set it to 1
+        qreal dot = 0.000001;
+
+        dashes << dot << space << dash << space;
+        qreal dashlen = dot + 2 * space + dash;
+        qreal l_len = sqrt(pow(m_start.x() - m_end.x(), 2) + pow(m_start.y() - m_end.y(), 2)) / 2.0;
+        // convert from pixelunits to width units
+        l_len = l_len / m_width;
+        // note that the additional length using RoundCap or SquareCap does not
+        // count here!
+        if (m_isintersection) {
+            m_pen.setDashOffset(dashlen - fmod(l_len, dashlen) + space + dash / 2);
+        } else {
+            m_pen.setDashOffset(dashlen - fmod(l_len, dashlen));
+        }
+
+        m_pen.setDashPattern(dashes);
+    }
+    else {
+        m_pen.setStyle(m_styleCurrent);
+    }
+    m_pen.setCapStyle(Qt::RoundCap);
     m_pen.setWidthF(m_width);
     m_pen.setColor(m_colCurrent);
-    m_pen.setStyle(m_styleCurrent);
     m_line->setPen(m_pen);
 }

src/Mod/TechDraw/Gui/QGICenterLine.h

@@ -48,6 +48,8 @@ class TechDrawGuiExport QGICenterLine : public QGIDecoration
     void setBounds(double x1,double y1,double x2,double y2);
     virtual void draw();
 
+    void setIntersection(bool isIntersecting);
+
 protected:
     QColor getCenterColor();
     Qt::PenStyle getCenterStyle();
@@ -58,6 +60,7 @@ class TechDrawGuiExport QGICenterLine : public QGIDecoration
     QGraphicsPathItem* m_line;           //primpath?
     QPointF            m_start;
     QPointF            m_end;
+    bool               m_isintersection;
 };
 
 }

src/Mod/TechDraw/Gui/QGISectionLine.cpp

@@ -119,7 +119,7 @@ void QGISectionLine::makeSymbols()
 {
     QPointF extLineStart,extLineEnd;
     QPointF offset(m_arrowDir.x,-m_arrowDir.y);
-    offset = 2.0 * m_extLen * offset;
+    offset = 1.5 * m_extLen * offset;
     extLineStart = m_start + offset;
     extLineEnd = m_end + offset;
 
@@ -173,15 +173,15 @@ QColor QGISectionLine::getSectionColor()
 {
     Base::Reference<ParameterGrp> hGrp = App::GetApplication().GetUserParameter()
         .GetGroup("BaseApp")->GetGroup("Preferences")->GetGroup("Mod/TechDraw/Colors");
-    App::Color fcColor = App::Color((uint32_t) hGrp->GetUnsigned("SectionColor", 0x08080800));
+    App::Color fcColor = App::Color((uint32_t) hGrp->GetUnsigned("SectionColor", 0x00000000));
     return fcColor.asValue<QColor>();
 }
 
 Qt::PenStyle QGISectionLine::getSectionStyle()
 {
     Base::Reference<ParameterGrp> hGrp = App::GetApplication().GetUserParameter().GetGroup("BaseApp")->
                                          GetGroup("Preferences")->GetGroup("Mod/TechDraw");
-    Qt::PenStyle sectStyle = static_cast<Qt::PenStyle> (hGrp->GetInt("SectionLine",2));
+    Qt::PenStyle sectStyle = static_cast<Qt::PenStyle> (hGrp->GetInt("SectionLine", 4));
     return sectStyle;
 }
 
@@ -195,9 +195,32 @@ void QGISectionLine::paint ( QPainter * painter, const QStyleOptionGraphicsItem
 
 void QGISectionLine::setTools()
 {
+    // Use our own style
+    if (m_styleCurrent == Qt::DashDotLine) {
+        QVector<qreal> dashes;
+        // the stroke width is double the one of center lines, but we like to
+        // have the same spacing. thus these values must be half as large
+        qreal space = 2;  // in unit r_width
+        qreal dash = 8;
+        // dot must be really small when using CapStyle RoundCap but > 0
+        // for CapStyle FlatCap you would need to set it to 1
+        qreal dot = 0.000001;
+
+        dashes << dot << space << dash << space;
+
+        // TODO for fancyness: calculate the offset so both arrows start with a
+        // dash!
+
+        m_pen.setDashPattern(dashes);
+
+        m_pen.setDashOffset(2);
+    }
+    else {
+        m_pen.setStyle(m_styleCurrent);
+    }
     m_pen.setWidthF(m_width);
     m_pen.setColor(m_colCurrent);
-    m_pen.setStyle(m_styleCurrent);
+    m_pen.setCapStyle(Qt::RoundCap);
     m_brush.setStyle(m_brushCurrent);
     m_brush.setColor(m_colCurrent);
 

src/Mod/TechDraw/Gui/QGIViewPart.cpp

@@ -654,6 +654,7 @@ void QGIViewPart::drawSectionLine(TechDraw::DrawViewSection* viewSection, bool b
         double sectionSpan;
         double sectionFudge = Rez::guiX(10.0);
         double xVal, yVal;
+        double fontSize = getPrefFontSize();
         if (horiz)  {
             sectionSpan = m_border->rect().width() + sectionFudge;
             xVal = sectionSpan / 2.0;
@@ -664,8 +665,8 @@ void QGIViewPart::drawSectionLine(TechDraw::DrawViewSection* viewSection, bool b
             yVal = sectionSpan / 2.0;
         }
         sectionLine->setBounds(-xVal,-yVal,xVal,yVal);
-        sectionLine->setWidth(Rez::guiX(vp->IsoWidth.getValue()));
-        sectionLine->setFont(m_font,Rez::guiX(6.0));
+        sectionLine->setWidth(Rez::guiX(vp->LineWidth.getValue()));
+        sectionLine->setFont(m_font, fontSize);
         sectionLine->setZValue(ZVALUE::SECTIONLINE);
         sectionLine->setRotation(viewPart->Rotation.getValue());
         sectionLine->draw();
@@ -690,7 +691,7 @@ void QGIViewPart::drawCenterLines(bool b)
 
         QGICenterLine* centerLine;
         double sectionSpan;
-        double sectionFudge = 10.0;
+        double sectionFudge = Rez::guiX(10.0);
         double xVal, yVal;
         if (horiz)  {
             centerLine = new QGICenterLine();
@@ -699,8 +700,9 @@ void QGIViewPart::drawCenterLines(bool b)
             sectionSpan = m_border->rect().width() + sectionFudge;
             xVal = sectionSpan / 2.0;
             yVal = 0.0;
+            centerLine->setIntersection(horiz && vert);
             centerLine->setBounds(-xVal,-yVal,xVal,yVal);
-            centerLine->setWidth(Rez::guiX(vp->IsoWidth.getValue()));
+            centerLine->setWidth(Rez::guiX(vp->HiddenWidth.getValue()));
             centerLine->setZValue(ZVALUE::SECTIONLINE);
             centerLine->setRotation(viewPart->Rotation.getValue());
             centerLine->draw();
@@ -712,8 +714,9 @@ void QGIViewPart::drawCenterLines(bool b)
             sectionSpan = (m_border->rect().height() - m_label->boundingRect().height()) + sectionFudge;
             xVal = 0.0;
             yVal = sectionSpan / 2.0;
+            centerLine->setIntersection(horiz && vert);
             centerLine->setBounds(-xVal,-yVal,xVal,yVal);
-            centerLine->setWidth(Rez::guiX(vp->IsoWidth.getValue()));
+            centerLine->setWidth(Rez::guiX(vp->HiddenWidth.getValue()));
             centerLine->setZValue(ZVALUE::SECTIONLINE);
             centerLine->setRotation(viewPart->Rotation.getValue());
             centerLine->draw();
@@ -1001,3 +1004,11 @@ bool QGIViewPart::getFaceEdgesPref(void)
     result = hGrp->GetBool("DrawFaceEdges", 0l);
     return result;
 }
+
+double QGIViewPart::getPrefFontSize()
+{
+    Base::Reference<ParameterGrp> hGrp = App::GetApplication().GetUserParameter().
+                                         GetGroup("BaseApp")->GetGroup("Preferences")->GetGroup("Mod/TechDraw/Labels");
+    double fontSize = hGrp->GetFloat("LabelSize", 5.0);
+    return Rez::guiX(fontSize);
+}

src/Mod/TechDraw/Gui/QGIViewPart.h

@@ -100,6 +100,7 @@ class TechDrawGuiExport QGIViewPart : public QGIView
     void removePrimitives(void);
     void removeDecorations(void);
     bool getFaceEdgesPref(void);
+    double getPrefFontSize(void);
 
 private:
     QList<QGraphicsItem*> deleteItems;