IMPROVED: JKQTMathText: rendering of sqrt

doc/dox/whatsnew.dox

@@ -38,6 +38,7 @@ Changes, compared to  \ref page_whatsnew_V4_0_0 "v4.0.0" include:
     <li>MODIFIED: brace node  now calculates the extension of the child height above or below the strikeoutPos, in order to center braces around the strikeoutPos</li>
     <li>IMPROVED: improved drawing of parantheses, square brackets ... , underbrace/overbrace</li>
     <li>IMPROVED: added x-correction for sub/superscript above/below/besides integrals</li>
+    <li>IMPROVED: rendering of sqrt</li>
     <li>remove/breaking: \v[a-zA-Z] and shorthand for \vec{a-zA-Z} was removed, implementation of \bbR,\bbC,... changed</li>
     <li>NEW: now supports new decoration instructions: \cancel, \xcancel, \bcancel, \sout, \ocirc, \widetilde, \widehat, \breve</li>
     <li>NEW: reworked drawing of decorations: improved appearance and positioning!</li>

examples/jkqtmathtext_test/mathtest.tex

@@ -89,7 +89,12 @@
     \item\textbf{math 1:} \[f(x)=\int_{-\infty}^xe^{-t^2}\;\mathrm{d}t \]
     \item\textbf{math 2:} \[\sum_{i=1}^\infty\frac{-e^{i\pi}}{2^n} \]
     \item\textbf{math 3:} \[\mbox{det} \begin{pmatrix} 1 & x_1 & \ldots & x_1^{n-1} \\ 1 & x_2 & \ldots & x_2^{n-1} \\ \vdots & \vdots & \ddots & \vdots \\ 1 & x_n & \ldots & x_n^{n-1} \end{pmatrix} = \prod_{1 \leq i < j \leq n} (x_j - x_i)  \]
-    \item\textbf{math 4:} \[\sqrt{1+\sqrt{1+\sqrt{1+\sqrt{1+\sqrt{1+\sqrt{1+x}}}}}} \]
+    \item\textbf{math 4:} \[M\sqrt{1+\sqrt{1+\sqrt{1+\sqrt{1+\sqrt{1+\sqrt{1+x}}}}}} \]
+    \item\textbf{math 4:} \[M\sqrt[3]{1+\sqrt[3]{1+\sqrt[3]{1+\sqrt[3]{1+\sqrt[3]{1+\sqrt[3]{1+x}}}}}} \]
+    \item\textbf{math 4:} \[M\sqrt{1+X}\sqrt[3]{1+X}\sqrt[3.14156]{1+X} \]
+    \item\textbf{math 4:} \[M\sqrt{1+X}\sqrt[\frac{1}{2}]{1+X}\sqrt[3.14156\cdot\frac{1}{2}]{1+X} \]
+    \item\textbf{math 4:} \[M\sqrt{\frac{1}{2}+\sqrt{\frac{1}{2}+\sqrt{\frac{1}{2}+\sqrt{\frac{1}{2}+\sqrt{\frac{1}{2}+\sqrt{1+x}}}}}} \]
+    \item\textbf{math 4:} \[M\sqrt{a}\frac{\sqrt{a}}{\sqrt{a}}\sqrt{\frac{1}{a}} \]
     \item\textbf{math 5:} \[\left(\stackrel{p}{2}\right)=x^2y^{p-2}-\frac{1}{1-x}\frac{1}{1-x^2} \]
     \item\textbf{math 6:} \[a_0+\frac{1}{a_1+\frac{1}{a_2+\frac{1}{a_3+\frac{1}{a_4}}}} \]
     \item\textbf{math 7:} \[\left(\frac{\partial^2}{\partial x^2}+\frac{\partial^2}{\partial y^2}\right)\left|\varphi(x+\mathrm{i}y)\right|^2=0 \]

examples/jkqtmathtext_test/testform.cpp

@@ -149,12 +149,14 @@ TestForm::TestForm(QWidget *parent) :
     ui->cmbTestset->addItem("math 1", "$f(x)=\\int_{-\\infty}^xe^{-t^2}\\;\\mathrm{d}t$");
     ui->cmbTestset->addItem("math 2", "$\\sum_{i=1}^\\infty\\frac{-e^{i\\pi}}{2^n}$");
     ui->cmbTestset->addItem("math 3", "$\\mbox{det} \\begin{pmatrix} 1 & x_1 & \\ldots & x_1^{n-1} \\\\ 1 & x_2 & \\ldots & x_2^{n-1} \\\\ \\vdots & \\vdots & \\ddots & \\vdots \\\\ 1 & x_n & \\ldots & x_n^{n-1} \\end{pmatrix} = \\prod_{1 \\leq i < j \\leq n} (x_j - x_i) $");
-    ui->cmbTestset->addItem("math 4", "$\\sqrt{1+\\sqrt{1+\\sqrt{1+\\sqrt{1+\\sqrt{1+\\sqrt{1+x}}}}}}$");
-    ui->cmbTestset->addItem("math 5", "$\\left(\\stackrel{p}{2}\\right)=x^2y^{p-2}-\\frac{1}{1-x}\\frac{1}{1-x^2}$");
-    ui->cmbTestset->addItem("math 6", "$a_0+\\frac{1}{a_1+\\frac{1}{a_2+\\frac{1}{a_3+\\frac{1}{a_4}}}}$");
-    ui->cmbTestset->addItem("math 7", "$\\left(\\frac{\\partial^2}{\\partial x^2}+\\frac{\\partial^2}{\\partial y^2}\\right)\\left|\\varphi(x+\\mathrm{i}y)\\right|^2=0$");
-    ui->cmbTestset->addItem("math 8", "$2^{2^{2^{x}}}$");
-    ui->cmbTestset->addItem("math 9", "$\\iint_Df(x,y)\\;\\mathrm{d}x\\;\\mathrm{d}y$");
+    ui->cmbTestset->addItem("math: nestes sqrt", "$\\sqrt{1+\\sqrt{1+\\sqrt{1+\\sqrt{1+\\sqrt{1+\\sqrt{1+x}}}}}}$");
+    ui->cmbTestset->addItem("math: nestes cbrt", "$\\sqrt[3]{1+\\sqrt[3]{1+\\sqrt[3]{1+\\sqrt[3]{1+\\sqrt[3]{1+\\sqrt[3]{1+x}}}}}}$");
+    ui->cmbTestset->addItem("math: nestes sqrt, high contents", "$\\sqrt{\\frac{1}{2}+\\sqrt{\\frac{1}{2}+\\sqrt{\\frac{1}{2}+\\sqrt{\\frac{1}{2}+\\sqrt{\\frac{1}{2}+\\sqrt{\\frac{1}{2}+x}}}}}}$");
+    ui->cmbTestset->addItem("math 5 (frac+stackrel)", "$\\left(\\stackrel{p}{2}\\right)=x^2y^{p-2}-\\frac{1}{1-x}\\frac{1}{1-x^2}$");
+    ui->cmbTestset->addItem("math 6 (nested frac)", "$a_0+\\frac{1}{a_1+\\frac{1}{a_2+\\frac{1}{a_3+\\frac{1}{a_4}}}}$");
+    ui->cmbTestset->addItem("math 7 (partial derivatives)", "$\\left(\\frac{\\partial^2}{\\partial x^2}+\\frac{\\partial^2}{\\partial y^2}\\right)\\left|\\varphi(x+\\mathrm{i}y)\\right|^2=0$");
+    ui->cmbTestset->addItem("math 8 (powers of powers)", "$2^{2^{2^{x}}}$");
+    ui->cmbTestset->addItem("math 9 (integral)", "$\\iint_Df(x,y)\\;\\mathrm{d}x\\;\\mathrm{d}y$");
     ui->cmbTestset->addItem("math 10 (overbrace+overbracket)", "$\\overbrace{x+x+...+x}{k\\ \\mathrm{times}}\\ \\ \\ \\overbracket{x+x+...+x}{k\\ \\mathrm{times}}$");
     ui->cmbTestset->addItem("math 11 (underbrace+underbracket)", "$\\underbrace{x+x+...+x}{k\\ \\mathrm{times}}\\ \\ \\ \\underbracket{x+x+...+x}{k\\ \\mathrm{times}}$");
     ui->cmbTestset->addItem("math 12 (under/overbrace+under/overbracket)", "$\\underbrace{\\overbrace{x+x+...+x}{k\\ \\mathrm{times}} \\overbrace{x+x+...+x}{k\\ \\mathrm{times}}}{2k\\ \\mathrm{times}}\\ \\ \\ \\underbracket{\\overbracket{x+x+...+x}{k\\ \\mathrm{times}} \\overbracket{x+x+...+x}{k\\ \\mathrm{times}}}{2k\\ \\mathrm{times}}$");

lib/jkqtmathtext/jkqtmathtext.cpp

@@ -92,6 +92,10 @@ JKQTMathText::JKQTMathText(QObject* parent):
     mathoperator_width_factor=1.5;
     bigmathoperator_font_factor=1.8;
 
+    sqrt_width_Xfactor=0.8;
+    sqrt_height_factor=1.2;
+    sqrt_smallfont_factor=0.57;
+
     blackboardSimulated=true;
 
 
@@ -234,6 +238,9 @@ void JKQTMathText::loadSettings(const QSettings& settings, const QString& group)
     mathoperator_width_factor=settings.value(group+"mathoperator_width_factor", mathoperator_width_factor).toDouble();
     intsubsuper_xcorrection_factor=settings.value(group+"intsubsuper_xcorrection_factor", intsubsuper_xcorrection_factor).toDouble();
     intsubbesides_xcorrection_xfactor=settings.value(group+"intsubbesides_xcorrection_xfactor", intsubbesides_xcorrection_xfactor).toDouble();
+    sqrt_width_Xfactor=settings.value(group+"sqrt_width_Xfactor", sqrt_width_Xfactor).toDouble();
+    sqrt_height_factor=settings.value(group+"sqrt_height_factor", sqrt_height_factor).toDouble();
+    sqrt_smallfont_factor=settings.value(group+"sqrt_smallfont_factor", sqrt_smallfont_factor).toDouble();
 
 
     if (settings.value(group+"use_stix_fonts", false).toBool()) useSTIX();
@@ -269,6 +276,9 @@ void JKQTMathText::saveSettings(QSettings& settings, const QString& group) const
     settings.setValue(group+ "brace_y_shift_factor", brace_y_shift_factor);
     settings.setValue(group+ "decoration_height_factor", decoration_height_factor);
     settings.setValue(group+ "decoration_width_reduction_xfactor", decoration_width_reduction_Xfactor);
+    settings.setValue(group+ "sqrt_width_Xfactor", sqrt_width_Xfactor);
+    settings.setValue(group+ "sqrt_height_factor", sqrt_height_factor);
+    settings.setValue(group+ "sqrt_smallfont_factor", sqrt_smallfont_factor);
 }
 
 bool JKQTMathText::useSTIX(bool mathModeOnly) {
@@ -908,6 +918,36 @@ double JKQTMathText::getDecorationWidthReductionXFactor() const
     return decoration_width_reduction_Xfactor;
 }
 
+void JKQTMathText::setSqrtWidthXFactor(double __value)
+{
+    sqrt_width_Xfactor=__value;
+}
+
+double JKQTMathText::getSqrtWidthXFactor() const
+{
+    return sqrt_width_Xfactor;
+}
+
+void JKQTMathText::setSqrtHeightFactor(double __value)
+{
+    sqrt_height_factor=__value;
+}
+
+double JKQTMathText::getSqrtHeightFactor() const
+{
+    return sqrt_height_factor;
+}
+
+void JKQTMathText::setSqrtSmallFontFactor(double __value)
+{
+    sqrt_smallfont_factor=__value;
+}
+
+double JKQTMathText::getSqrtSmallFontFactor() const
+{
+    return sqrt_smallfont_factor;
+}
+
 void JKQTMathText::setUseUnparsed(bool __value)
 {
     this->useUnparsed = __value;

lib/jkqtmathtext/jkqtmathtext.h

@@ -152,6 +152,12 @@ class JKQTMathTextNode; // forward
       - You can use \c \\left. or \c \\right. to have only right or only left brace
     .
 
+    \subsection JKQTMathTextSuppoertedLaTeXRoots Roots
+    There are also instructions that allow to write roots:
+      - <code>$\\sqrt{1+\\sqrt{1+x}}$</code> \image html jkqtmathtext/jkqtmathtext_sqrt.png
+      - <code>$\\sqrt[3]{1+\\sqrt[3]{1+x}}$</code> \image html jkqtmathtext/jkqtmathtext_cbrt.png
+    .
+
     \subsection JKQTMathTextSuppoertedLaTeXUnderOver Undersetting, Oversetting, Underbraces, Overbraces ...
     There are also instructions that allow to under/overset braces, arrows, ...:
       - <code>$\\underbrace{x+x+...+x}{k\\ \\mathrm{times}}$</code> \image html jkqtmathtext/jkqtmathtext_brace_underbrace.png
@@ -535,6 +541,23 @@ class JKQTMATHTEXT_LIB_EXPORT JKQTMathText : public QObject {
         void setDecorationWidthReductionXFactor(double __value);
         /** \copydoc decoration_width_reduction_Xfactor */
         double getDecorationWidthReductionXFactor() const;
+
+
+        /** \copydoc sqrt_width_Xfactor */
+        void setSqrtWidthXFactor(double __value);
+        /** \copydoc sqrt_width_Xfactor */
+        double getSqrtWidthXFactor() const;
+        /** \copydoc sqrt_height_factor */
+        void setSqrtHeightFactor(double __value);
+        /** \copydoc sqrt_height_factor */
+        double getSqrtHeightFactor() const;
+        /** \copydoc sqrt_smallfont_factor */
+        void setSqrtSmallFontFactor(double __value);
+        /** \copydoc sqrt_smallfont_factor */
+        double getSqrtSmallFontFactor() const;
+
+
+
         /** \copydoc useUnparsed */ 
         void setUseUnparsed(bool __value);
         /** \copydoc useUnparsed */ 
@@ -692,6 +715,12 @@ class JKQTMATHTEXT_LIB_EXPORT JKQTMathText : public QObject {
          *  \image html jkqtmathtext/decoration_sizing.png
          */
         double decoration_width_reduction_Xfactor;
+        /** \brief scaling factor for the small font used to indicate the degree of the sqrt */
+        double sqrt_smallfont_factor;
+        /** \brief width of the sqrt-symbol, as factor to width("X") */
+        double sqrt_width_Xfactor;
+        /** \brief height-increase of the sqrt-symbol, as factor of the child's height */
+        double sqrt_height_factor;
         /** \brief a list that will be filled with error messages while parsing, if any error occur */
         QStringList error_list;
 

lib/jkqtmathtext/nodes/jkqtmathtextsqrtnode.cpp

@@ -45,54 +45,92 @@ JKQTMathTextSqrtNode::~JKQTMathTextSqrtNode() {
 }
 
 void JKQTMathTextSqrtNode::getSizeInternal(QPainter& painter, JKQTMathTextEnvironment currentEv, double& width, double& baselineHeight, double& overallHeight, double& strikeoutPos, const JKQTMathTextNodeSize* /*prevNodeSize*/) {
-    QFontMetricsF fm(currentEv.getFont(parentMathText), painter.device());
+    const QFontMetricsF fm(currentEv.getFont(parentMathText), painter.device());
+    QFont fsmall=currentEv.getFont(parentMathText);
+    fsmall.setPointSizeF(fsmall.pointSizeF()*parentMathText->getSqrtSmallFontFactor());
+    fsmall.setItalic(false);
+    const QFontMetricsF fmsmall(fsmall, painter.device());
 
     getChild()->getSize(painter, currentEv, width, baselineHeight, overallHeight, strikeoutPos);
+    const double descent=overallHeight-baselineHeight;
+    const double sqrtwidth=fm.boundingRect("X").width()*parentMathText->getSqrtWidthXFactor();
+    const double newAscent=qMax(baselineHeight*parentMathText->getSqrtHeightFactor(), fm.ascent());
+    const double newDescent=qMax(descent*parentMathText->getSqrtHeightFactor(), fm.descent());
 
-    overallHeight=overallHeight*1.2;//+fm.ascent()*0.1;
-    baselineHeight=baselineHeight*1.2;//+fm.ascent()*0.1;
-    width=width+fm.boundingRect("A").width()*2; // 1.53
+    overallHeight=newAscent+newDescent;;
+    baselineHeight=newAscent;
+    width=width+sqrtwidth;
+    if (degree!=2) {
+        const QString degreetext=QLocale::c().toString(degree);
+        const double degwidth=fmsmall.width(degreetext);
+        const double smalltextIndent=0.6*sqrtwidth;
+        if (degwidth>smalltextIndent) width=width+(degwidth-smalltextIndent);
+    }
 }
 
 double JKQTMathTextSqrtNode::draw(QPainter& painter, double x, double y, JKQTMathTextEnvironment currentEv, const JKQTMathTextNodeSize* /*prevNodeSize*/) {
     doDrawBoxes(painter, x, y, currentEv);
-    double width=0, baselineHeight=0, overallHeight=0, sp=0;
-    getChild()->getSize(painter, currentEv, width, baselineHeight, overallHeight, sp);
-    QFont f=currentEv.getFont(parentMathText);
+
+    const QFont f=currentEv.getFont(parentMathText);
     QFont fsmall=f;
-    QFontMetricsF fm(f, painter.device());
-    double w=fm.boundingRect("A").width();
-    double a=baselineHeight*1.15;
-    double d=overallHeight-baselineHeight;
+    const QFontMetricsF fm(f, painter.device());
+    fsmall.setPointSizeF(fsmall.pointSizeF()*parentMathText->getSqrtSmallFontFactor());
+    fsmall.setItalic(false);
+    const QFontMetricsF fmsmall(fsmall, painter.device());
+
+    double width=0, baselineHeight=0, overallHeight=0, strikeoutPos=0;
+    getChild()->getSize(painter, currentEv, width, baselineHeight, overallHeight, strikeoutPos);
+    const double descent=overallHeight-baselineHeight;
+    const double sqrtwidth=fm.boundingRect("X").width()*parentMathText->getSqrtWidthXFactor();
+    const double newAscent=qMax(baselineHeight*parentMathText->getSqrtHeightFactor(), fm.ascent());
+    const double newDescent=qMax(descent*parentMathText->getSqrtHeightFactor(), fm.descent());
+    const double linewidth=fm.lineWidth();
+    const double tinyhookSize=sqrtwidth*0.1;
+    const double smalltextIndent=0.6*sqrtwidth;
+    const QString degreetext=(degree!=2)?QLocale::c().toString(degree):"";
+    const double degwidth=fmsmall.width(degreetext);
+    const double degheight=fmsmall.boundingRect(degreetext).height();
+    const double degree_overwidth=(degwidth>smalltextIndent)?(degwidth-smalltextIndent):0.0;
+
     //painter.save(); auto __finalpaint=JKQTPFinally([&painter]() {painter.restore();});
     QPen p=painter.pen();
     p.setColor(currentEv.color);
-    p.setWidthF(fm.lineWidth());
+    p.setWidthF(linewidth);
+    p.setCapStyle(Qt::RoundCap);
+    p.setJoinStyle(Qt::RoundJoin);
     //painter.setPen(p);
+
+    double xnew=getChild()->draw(painter, x+sqrtwidth+degree_overwidth, y, currentEv);
+
+    const bool useAltForm=overallHeight>4.0*sqrtwidth;
+    const double y_tinyhooktop=y-strikeoutPos;
+    const double y_bottom=y+newDescent-linewidth/2.0;
+    const double y_top=y-newAscent+linewidth/2.0;
+    const double x_start=x+degree_overwidth+linewidth/2.0;
+    const double x_tinyhooktop=x_start+tinyhookSize;
+    const double x_hookbottom=(!useAltForm)?(x_start+0.33*sqrtwidth):(x_start+0.66*sqrtwidth);
+    const double x_hooktop=(!useAltForm)?(x_start+sqrtwidth):x_hookbottom;
+    const double x_smalltextend=x_start+smalltextIndent;
+    const double y_smalltext=y_top+fmsmall.ascent()+(fabs(y_top-(y_tinyhooktop-linewidth))-degheight)/2.0;
+    if (sqrtwidth>0) {
         QPainterPath path;
-    if (w>0) {
-        path.moveTo(x+0.1*w, y-0.4*a);
-        path.lineTo(x+0.33*w, y-0.4*a);
-        path.lineTo( x+0.66*w, y+0.5*d);
-        path.lineTo(x+w, y-a);
-    }
-    if (degree!=2) {
-        fsmall.setPointSizeF(fsmall.pointSizeF()/2.0);
-        fsmall.setItalic(false);
-        painter.setFont(fsmall);
-        painter.drawText(QPointF(x+0.33*w, y-0.55*a), QLocale::c().toString(degree));
-    }
-    //painter.restore();
-    double xnew=getChild()->draw(painter, x+1.2*w, y, currentEv);
-    painter.save(); auto __finalpaint=JKQTPFinally([&painter]() {painter.restore();});
+        path.moveTo(x_start, y_tinyhooktop+tinyhookSize);
+        path.lineTo(x_tinyhooktop, y_tinyhooktop);
+        path.lineTo(x_hookbottom, y_bottom);
+        path.lineTo(x_hooktop, y_top);
+        path.lineTo(xnew-linewidth/2.0, y_top);
+        path.moveTo(x_tinyhooktop,y_tinyhooktop);
+        path.lineTo(x_tinyhooktop+linewidth*0.8, y_tinyhooktop-linewidth*0.8);
+        path.lineTo(x_hookbottom, y_bottom-2.0*linewidth);
         painter.setPen(p);
-    if (w>0) {
-        path.lineTo( xnew+0.2*w, y-a);
-        path.lineTo(xnew+0.2*w, y-0.8*a);
         painter.drawPath(path);
     }
+    if (degree!=2) {
+        painter.setFont(fsmall);
+        painter.drawText(QPointF(x_smalltextend-degwidth, y_smalltext), degreetext);
+    }
 
-    return xnew+0.33*w;
+    return xnew;
 }
 
 bool JKQTMathTextSqrtNode::toHtml(QString &html, JKQTMathTextEnvironment currentEv, JKQTMathTextEnvironment defaultEv) {

lib/jkqtmathtext/nodes/jkqtmathtextsqrtnode.h

@@ -35,6 +35,10 @@ class JKQTMathText; // forward
 
 /** \brief subclass representing a sqrt node
  *  \ingroup jkqtmathtext_items
+ *
+ *  This node renders square roots without and with an explicitly shown degree:
+ *  \image html jkqtmathtext/jkqtmathtext_sqrt.png
+ *  \image html jkqtmathtext/jkqtmathtext_cbrt.png
   */
 class JKQTMATHTEXT_LIB_EXPORT JKQTMathTextSqrtNode: public JKQTMathTextSingleChildNode {
     public: