JKQTMathText: added support for \\bigl,\\bigr,\\Bigr,... commands for fixed-size but enlarged paramtheses

doc/dox/jkqtmathtext_supportedlatex.dox

@@ -109,14 +109,25 @@
       - \c \\left( \c \\right) : default meaning (), \image html jkqtmathtext/jkqtmathtext_brace_round.png
       - \c \\left[ \c \\right] : default meaning [], \image html jkqtmathtext/jkqtmathtext_brace_rect.png
       - \c \\left\\{ \c \\right\\} : default meaning {}, \image html jkqtmathtext/jkqtmathtext_brace_curly.png
-      - \c \\left< \c \\right> : "averaging" braces , \image html jkqtmathtext/jkqtmathtext_brace_tri.png
+      - \c \\left\\langle \c \\right\\rangle : "averaging" braces , \image html jkqtmathtext/jkqtmathtext_brace_tri.png
       - \c \\left\\lfloor \c \\right\\rfloor : floor braces , \image html jkqtmathtext/jkqtmathtext_brace_floor.png
-      - \c \\left~ \c \\right~ \c \\left\\lceil \c \\right\\rceil : ceil braces , \image html jkqtmathtext/jkqtmathtext_brace_ceil.png
+      - \c \\left\\lceil \c \\right\\rceil : ceil braces , \image html jkqtmathtext/jkqtmathtext_brace_ceil.png
-      - \c \\left| \c \\right| : absolute value braces | |, \image html jkqtmathtext/jkqtmathtext_brace_oneline.png
+      - \c \\left| \c \\right| : absolute value braces | |, \image html jkqtmathtext/jkqtmathtext_bracejkqtmathtext_brace_ucorner_oneline.png
       - \c \\left\\| \c \\right\\| \endcode : norm braces || ||, \image html jkqtmathtext/jkqtmathtext_brace_dblline.png
+      - \c \\left\\llcorner \c \\right\\lrcorner : lower corner braces , \image html jkqtmathtext/jkqtmathtext_brace_lcorner.png
+      - \c \\left\\ulcorner \c \\right\\urcorner : upper corner braces , \image html jkqtmathtext/.png
       - You can use \c \\left. or \c \\right. to have only right or only left brace
     .
     
+    In additional fixed-size parantheses are available with the following family of instructions:
+      - \c \\bigl([\\{\\langle... , \c \\big([\\{\\langle... and \c \\bigr)]\\}\\rangle... \image html jkqtmathtext/jkqtmathtext_brace_big.png
+      - \c \\Bigl([\\{\\langle... , \c \\Big([\\{\\langle... and \c \\Bigr)]\\}\\rangle... \image html jkqtmathtext/jkqtmathtext_brace_bbig.png
+      - \c \\biggl([\\{\\langle... , \c \\bigg([\\{\\langle... and \c \\biggr)]\\}\\rangle... \image html jkqtmathtext/jkqtmathtext_brace_bigg.png
+      - \c \\Biggl([\\{\\langle... , \c \\Bigg([\\{\\langle... and \c \\Biggr)]\\}\\rangle... \image html jkqtmathtext/jkqtmathtext_brace_bbigg.png
+    .
+    They use the same rendering code as the standard \c \\left and \c \\right instructions. Here is an example:
+    \image html jkqtmathtext/jkqtmathtext_brace_bigfamily.png generated by <code> $\Biggl\langle\biggl\{\Bigl[\bigl( r^{123}\bigr)\Bigr]\biggr\}\Biggr\rangle$</code>
+
     \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

doc/dox/todo.dox

@@ -40,7 +40,6 @@ This page lists several todos and wishes for future version of JKQTPlotter
   </ul></li>
   <li>JKQTMathText:<ul>
     <li>check sub/superscript with italic text in math mode, possibly a correction is necessary</li>
-    <li>add support for \\bigl,\\bigr,\\Bigr,... commands for fixed-size but large paramtheses</li>
     <li>explore options to make font-environment-modifying commands avails, like "{blacktext\\color{red}redtext}", today only commands like "\\textcolor{red}{redtext}" work</li>
     <li>maybe: add support for text with linebreaks by adding a JKQTMathTextVerticalListNode in addition to JKQTMathTextListNode</li>
     <li>maybe: add tool programs to auto-generate some example images</li>

doc/dox/whatsnew.dox

@@ -77,6 +77,7 @@ Changes, compared to  \ref page_whatsnew_V4_0_0 "v4.0.0" include:
     <li>NEW: added support for framed/shaded/snugshade-environments with linebreaks and framed</li>
     <li>NEW: added support for -- and --- for en- and em-dashes</li>
     <li>NEW: added support for \c \\char"HEX , \c \\char'OCTAL and \c \\charDECIMAL for inserting any uicode character code</li>
+    <li>NEW: added support for \\bigl,\\bigr,\\Bigr,... commands for fixed-size but enlarged paramtheses</li>
   </ul></li>
 </ul>
 

examples/jkqtmathtext_test/testform.cpp

@@ -195,6 +195,7 @@ TestForm::TestForm(QWidget *parent) :
     ui->cmbTestset->addItem("text/math: brace test:  non-left/right top-corner", "text: \\ulcorner\\ulcorner\\ulcorner r^{123}\\urcorner\\urcorner\\urcorner -- math: $\\ulcorner\\ulcorner\\ulcorner r^{123}\\urcorner\\urcorner\\urcorner$");
     ui->cmbTestset->addItem("text/math: brace test:  non-left/right bottom-corner", "text: \\llcorner\\llcorner\\llcorner r^{123}\\lrcorner\\lrcorner\\lrcorner -- math: $\\llcorner\\llcorner\\llcorner r^{123}\\lrcorner\\lrcorner\\lrcorner$");
     ui->cmbTestset->addItem("text/math: brace test:  non-left/right { | }", "text: \\{r^{123}|r\\equiv 5\\} -- math: $\\{r^{123}|r\\equiv 5\\}$");
+    ui->cmbTestset->addItem("math: brace test:  bigl/Bigl/... mixed", "math: $\\Biggl\\langle\\biggl\\{\\Bigl[\\bigl(( r^{123})\\bigr)\\Bigr]\\biggr\\}\\Biggr\\rangle$");
     ui->cmbTestset->addItem("text/math: sub-, superscript test", "text: r^{1234}_{321} r_{321}^{1234} -- math: $r^{1234}_{321} r_{321}^{1234} -- \\kappa^2 -- \\kappa_2 -- \\kappa_2^2$");
     ui->cmbTestset->addItem("text/math: super-, subscript test", "text: r^{123}_{4321} r_{4321}^{123} -- math: $r^{123}_{4321} r_{4321}^{123} -- \\kappa^2 -- \\kappa_2 -- \\kappa_2^2$");
     //ui->cmbTestset->addItem("", "");
@@ -462,6 +463,7 @@ QTreeWidgetItem *TestForm::createTree(JKQTMathTextNode *node, QTreeWidgetItem* p
     JKQTMathTextFracNode* fracN=dynamic_cast<JKQTMathTextFracNode*>(node);
     JKQTMathTextMatrixNode* matrixN=dynamic_cast<JKQTMathTextMatrixNode*>(node);
     JKQTMathTextDecoratedNode* decoN=dynamic_cast<JKQTMathTextDecoratedNode*>(node);
+    JKQTMathTextEmptyBoxNode* emptyN=dynamic_cast<JKQTMathTextEmptyBoxNode*>(node);
 
     QTreeWidgetItem* ti=nullptr;
     if (parent) ti=new QTreeWidgetItem(parent);
@@ -527,6 +529,8 @@ QTreeWidgetItem *TestForm::createTree(JKQTMathTextNode *node, QTreeWidgetItem* p
         name=QString("WhitespaceNode :type=%1, count=%2").arg(spN->Type2String(spN->getWhitespaceType())).arg(spN->getWhitespaceCount());
     } else if (txtN)  {
         name=QString("TextNode: \'%1\'").arg(txtN->getText());
+    } else if (emptyN)  {
+        name=QString("EmptyBoxNode %1%2 x %3%4").arg(emptyN->getWidth()).arg(JKQTMathTextEmptyBoxNode::Units2String(emptyN->getWidthUnit())).arg(emptyN->getHeight()).arg(JKQTMathTextEmptyBoxNode::Units2String(emptyN->getHeightUnit()));
     } else {
         name=QString("unknown");
     }

lib/jkqtmathtext/jkqtmathtext.cpp

@@ -1008,8 +1008,10 @@ JKQTMathText::tokenType JKQTMathText::getToken() {
         auto fAddUml=[](const QString& cmd, const QChar& letter, const QChar& ch) {
             QString i;
             if (cmd.size()>0 && !letter.isNull()) {
-                i="\\"+cmd+letter;
+                if (cmd.size()==1 && !cmd[0].isLetter()) {
-                accentLetters[i]=ch; accentLetters_LenBackslash.insert(i.size());
+                    i="\\"+cmd+letter;
+                    accentLetters[i]=ch; accentLetters_LenBackslash.insert(i.size());
+                }
                 i="{\\"+cmd+letter+"}";
                 accentLetters[i]=ch; accentLetters_LenCurly.insert(i.size());
                 i="\\"+cmd+"{"+letter+"}";
@@ -1490,6 +1492,11 @@ JKQTMathText::tokenType JKQTMathText::getToken() {
     return currentToken=MTTnone;
 }
 
+void JKQTMathText::giveBackToTokenizer(size_t count)
+{
+    currentTokenID-=count;
+}
+
 JKQTMathTextNode* JKQTMathText::parseLatexString(bool get, JKQTMathTextBraceType quitOnClosingBrace, const QString& quitOnEnvironmentEnd, bool quitOnClosingBracket) {
     //std::cout<<"    entering parseLatexString()\n";
     JKQTMathTextHorizontalListNode* nl=new JKQTMathTextHorizontalListNode(this);
@@ -1499,7 +1506,7 @@ JKQTMathTextNode* JKQTMathText::parseLatexString(bool get, JKQTMathTextBraceType
     // initialize some static sets for easy and fast character lookup
     static QSet<QString> mathEnvironmentSpecialText;
     if (mathEnvironmentSpecialText.size()==0) {
-        mathEnvironmentSpecialText<<"+"<<"-"<<"="<<"*"<<"<"<<">"<<"|"<<"/";
+        mathEnvironmentSpecialText<<"+"<<"-"<<"="<<"*"<<"<"<<">";
     }
 
     bool getNew=true;
@@ -1769,6 +1776,28 @@ JKQTMathTextNode* JKQTMathText::parseLatexString(bool get, JKQTMathTextBraceType
 }
 
 JKQTMathTextNode* JKQTMathText::parseInstruction(bool *_foundError, bool* getNew) {
+    static QHash<QString,double> big_instructions_family;
+    if (big_instructions_family.size()==0) {
+        big_instructions_family["big"]=0.85;//1.2;
+        big_instructions_family["bigl"]=0.85;//1.2;
+        big_instructions_family["bigm"]=0.85;//1.2;
+        big_instructions_family["bigr"]=0.85;//1.2;
+
+        big_instructions_family["Big"]=1.15;//1.85;
+        big_instructions_family["Bigl"]=1.15;//1.85;
+        big_instructions_family["Bigm"]=1.15;//1.85;
+        big_instructions_family["Bigr"]=1.15;//1.85;
+
+        big_instructions_family["bigg"]=1.45;//2.4;
+        big_instructions_family["biggl"]=1.45;//2.4;
+        big_instructions_family["biggm"]=1.45;//2.4;
+        big_instructions_family["biggr"]=1.45;//2.4;
+
+        big_instructions_family["Bigg"]=1.75;//3.1;
+        big_instructions_family["Biggl"]=1.75;//3.1;
+        big_instructions_family["Biggm"]=1.75;//3.1;
+        big_instructions_family["Biggr"]=1.75;//3.1;
+    }
     if (currentToken!=MTTinstruction) {
         if (_foundError) *_foundError=true;
         if (getNew) *getNew=false;
@@ -1788,6 +1817,42 @@ JKQTMathTextNode* JKQTMathText::parseInstruction(bool *_foundError, bool* getNew
             child->setSubSuperscriptAboveBelowNode(true);
         }
         if (getNew) *getNew=true;
+    } else if (big_instructions_family.contains(currentInstructionName)) {
+        // after \big,\bigl... we expect a symbol-instruction or at least one character of text
+        while (getToken()==MTTwhitespace);// eat whitespace
+
+        JKQTMathTextBraceType bracetype=MTBTUnknown;
+        bool openbrace=true;
+        if (currentToken==MTTinstruction) {
+            bracetype=TokenName2JKQTMathTextBraceType(currentTokenName, &openbrace);
+        } else if (currentToken==MTTtext) {
+            const QString firstTokenChar(currentTokenName[0]);
+            bracetype=TokenName2JKQTMathTextBraceType(firstTokenChar, &openbrace);
+            if (bracetype!=MTBTUnknown) {
+                giveBackToTokenizer(currentTokenName.size()-1);
+            } else {
+                giveBackToTokenizer(currentTokenName.size());
+            }
+        } else if (currentToken==MTTopenbracket) {
+            bracetype=MTBTSquareBracket;
+            openbrace=true;
+        } else if (currentToken==MTTclosebracket) {
+            bracetype=MTBTSquareBracket;
+            openbrace=false;
+        } else {
+            error_list.append(tr("error @ ch. %1: expected symbol-encoding instruction or a character after '\\%2' command, but found token type %3").arg(currentTokenID).arg(currentInstructionName).arg(tokenType2String(currentToken)));
+        }
+        if (bracetype!=MTBTUnknown) {
+            JKQTMathTextEmptyBoxNode* sizeChild=new JKQTMathTextEmptyBoxNode(this, 0, JKQTMathTextEmptyBoxNode::EBUem, big_instructions_family[currentInstructionName], JKQTMathTextEmptyBoxNode::EBUem);
+            if (openbrace) {
+                child=new JKQTMathTextBraceNode(this, bracetype, MTBTNone, sizeChild);
+            } else {
+                child=new JKQTMathTextBraceNode(this, MTBTNone, bracetype, sizeChild);
+            }
+        } else {
+            error_list.append(tr("error @ ch. %1: expected symbol-encoding instruction or character after '\\%2' command").arg(currentTokenID).arg(currentInstructionName));
+        }
+        if (getNew) *getNew=true;
     } else if (JKQTMathTextModifiedTextPropsInstructionNode::supportsInstructionName(currentInstructionName)) {
         const size_t Nparams=JKQTMathTextModifiedTextPropsInstructionNode::countParametersOfInstruction(currentInstructionName);
         bool foundError=false;
@@ -2128,6 +2193,29 @@ JKQTMathTextNode *JKQTMathText::getNodeTree() const {
     return parsedNode;
 }
 
+QString JKQTMathText::tokenType2String(tokenType type)
+{
+    switch(type) {
+      case MTTnone: return "MTTnone";
+      case MTTtext: return "MTTtext";
+      case MTTinstruction: return "MTTinstruction";
+      case MTTinstructionNewline: return "MTTinstructionNewline";
+      case MTTunderscore: return "MTTunderscore";
+      case MTThat: return "MTThat";
+      case MTTdollar: return "MTTdollar";
+      case MTTopenbrace: return "MTTopenbrace";
+      case MTTclosebrace: return "MTTclosebrace";
+      case MTTopenbracket: return "MTTopenbracket";
+      case MTTclosebracket: return "MTTclosebracket";
+      case MTTwhitespace: return "MTTwhitespace";
+      case MTTampersand: return "MTTampersand";
+      case MTThyphen: return "MTThyphen";
+      case MTTendash: return "MTTendash";
+      case MTTemdash: return "MTTemdash";
+    }
+    return "???";
+}
+
 
 
 

lib/jkqtmathtext/jkqtmathtext.h

@@ -729,9 +729,13 @@ class JKQTMATHTEXT_LIB_EXPORT JKQTMathText : public QObject {
             MTTendash,  /*!< \brief the en-dash character sequence \c "--" in text-mode */
             MTTemdash,  /*!< \brief the em-dash character sequence \c "---" in text-mode */
         };
+        /** \biref convert a tokenType into a string, e.g. for debugging output */
+        static QString tokenType2String(tokenType type);
 
         /** \brief tokenizer for the LaTeX parser */
         tokenType getToken();
+        /** \brief returns some characters to the Tokenizer */
+        void giveBackToTokenizer(size_t count);
         /** \brief parse a LaTeX string
          *
          *  \param get if \c true this calls getToken()

lib/jkqtmathtext/jkqtmathtexttools.cpp

@@ -358,18 +358,29 @@ QString JKQTMathTextBraceType2String(JKQTMathTextBraceType type) {
     return "???";
 }
 
-JKQTMathTextBraceType TokenName2JKQTMathTextBraceType(const QString &tokenName)
+JKQTMathTextBraceType TokenName2JKQTMathTextBraceType(const QString &tokenName, bool* isOpening)
 {
-    if (tokenName=="(" || tokenName==")") return MTBTParenthesis;
+    if (tokenName=="(") { if (isOpening) *isOpening=true; return MTBTParenthesis; }
-    if (tokenName=="[" || tokenName=="]") return MTBTSquareBracket;
+    if (tokenName==")") { if (isOpening) *isOpening=false; return MTBTParenthesis; }
-    if (tokenName=="{" || tokenName=="}") return MTBTCurlyBracket;
+    if (tokenName=="[") { if (isOpening) *isOpening=true; return MTBTSquareBracket; }
-    if (tokenName=="|") return MTBTSingleLine;
+    if (tokenName=="]") { if (isOpening) *isOpening=false; return MTBTSquareBracket; }
-    if (tokenName=="||" || tokenName=="#") return MTBTDoubleLine;
+    if (tokenName=="{") { if (isOpening) *isOpening=true; return MTBTCurlyBracket; }
-    if (tokenName=="<" || tokenName==">" || tokenName=="langle" || tokenName=="rangle") return MTBTAngleBracket;
+    if (tokenName=="}") { if (isOpening) *isOpening=false; return MTBTCurlyBracket; }
-    if (tokenName=="_" || tokenName=="lfloor" || tokenName=="rfloor") return MTBTFloorBracket;
+    if (tokenName=="|") { if (isOpening) *isOpening=true; return MTBTSingleLine; }
-    if (tokenName=="~" || tokenName=="lceil" || tokenName=="rceil") return MTBTCeilBracket;
+    if (tokenName=="||" || tokenName=="#") { if (isOpening) *isOpening=true; return MTBTDoubleLine; }
-    if (tokenName=="ulcorner" || tokenName=="urcorner"||tokenName=="tlcorner" || tokenName=="trcorner") return MTBTTopCorner;
+
-    if (tokenName=="blcorner" || tokenName=="brcorner"||tokenName=="llcorner" || tokenName=="lrcorner") return MTBTBottomCorner;
+    if (tokenName=="<" || tokenName=="langle") { if (isOpening) *isOpening=true; return MTBTAngleBracket; }
+    if (tokenName==">" || tokenName=="rangle") { if (isOpening) *isOpening=false; return MTBTAngleBracket; }
+    if (tokenName=="_" || tokenName=="lfloor") { if (isOpening) *isOpening=true; return MTBTFloorBracket; }
+    if (tokenName=="_" || tokenName=="rfloor") { if (isOpening) *isOpening=false; return MTBTFloorBracket; }
+    if (tokenName=="~" || tokenName=="lceil") { if (isOpening) *isOpening=true; return MTBTCeilBracket; }
+    if (tokenName=="~" || tokenName=="rceil") { if (isOpening) *isOpening=false; return MTBTCeilBracket; }
+    if (tokenName=="ulcorner" || tokenName=="tlcorner") { if (isOpening) *isOpening=true; return MTBTTopCorner; }
+    if (tokenName=="urcorner" || tokenName=="trcorner") { if (isOpening) *isOpening=false; return MTBTTopCorner; }
+    if (tokenName=="blcorner" || tokenName=="llcorner") { if (isOpening) *isOpening=true; return MTBTBottomCorner; }
+    if (tokenName=="brcorner" || tokenName=="lrcorner") { if (isOpening) *isOpening=false; return MTBTBottomCorner; }
+    if (isOpening) *isOpening=true;
+
     if (tokenName=="any") return MTBTAny;
     if (tokenName=="." || tokenName=="" || tokenName=="none") return MTBTNone;
     return MTBTUnknown;

lib/jkqtmathtext/jkqtmathtexttools.h

@@ -169,7 +169,7 @@ JKQTMATHTEXT_LIB_EXPORT QString JKQTMathTextBraceType2String(JKQTMathTextBraceTy
 /** \brief convert a string \a tokenName describing a LaTeX Token or Instruction into an opening or closing JKQTMathTextBraceType
  *  \ingroup jkqtmathtext_tools
  */
-JKQTMATHTEXT_LIB_EXPORT JKQTMathTextBraceType TokenName2JKQTMathTextBraceType(const QString& tokenName);
+JKQTMATHTEXT_LIB_EXPORT JKQTMathTextBraceType TokenName2JKQTMathTextBraceType(const QString& tokenName, bool *isOpening=nullptr);
 /** \brief convert a string \a tokenName describing a LaTeX Instruction into an opening JKQTMathTextBraceType
  *  \ingroup jkqtmathtext_tools
  *

lib/jkqtmathtext/nodes/jkqtmathtextinstructionnode.cpp

@@ -591,6 +591,32 @@ void JKQTMathTextModifiedTextPropsInstructionNode::fillInstructions()
         }, 0);
         instructions["scriptscriptstyle"]= i;
     }
+
+
+    {
+        InstructionProperties i([](JKQTMathTextEnvironment& ev, const QStringList& /*parameters*/) {
+            ev.fontSize=ev.fontSize*1.2;
+        }, 0);
+        instructions["bigsize"]= i;
+    }
+    {
+        InstructionProperties i([](JKQTMathTextEnvironment& ev, const QStringList& /*parameters*/) {
+            ev.fontSize=ev.fontSize*1.85;
+        }, 0);
+        instructions["Bigsize"]= i;
+    }
+    {
+        InstructionProperties i([](JKQTMathTextEnvironment& ev, const QStringList& /*parameters*/) {
+            ev.fontSize=ev.fontSize*2.4;
+        }, 0);
+        instructions["biggsize"]= i;
+    }
+    {
+        InstructionProperties i([](JKQTMathTextEnvironment& ev, const QStringList& /*parameters*/) {
+            ev.fontSize=ev.fontSize*3.1;
+        }, 0);
+        instructions["Biggsize"]= i;
+    }
 }
 
 JKQTMathTextModifiedTextPropsInstructionNode::InstructionProperties::InstructionProperties():

lib/jkqtmathtext/nodes/jkqtmathtextwhitespacenode.cpp

@@ -102,8 +102,9 @@ size_t JKQTMathTextWhitespaceNode::getWhitespaceCount() const
     return whitespace.count;
 }
 
-double JKQTMathTextWhitespaceNode::draw(QPainter &painter, double x, double /*y*/, JKQTMathTextEnvironment currentEv, const JKQTMathTextNodeSize *prevNodeSize)
+double JKQTMathTextWhitespaceNode::draw(QPainter &painter, double x, double y, JKQTMathTextEnvironment currentEv, const JKQTMathTextNodeSize *prevNodeSize)
 {
+    doDrawBoxes(painter, x,y,currentEv);
     double width=0, bh=0, oh=0, sp=0;
     getSize(painter, currentEv, width, bh, oh, sp, prevNodeSize);
     return x+width;
@@ -215,3 +216,101 @@ QString JKQTMathTextWhitespaceNode::Type2HTML(Types type)
     return " ";
 }
 
+
+QString JKQTMathTextEmptyBoxNode::Units2String(Units type)
+{
+    switch(type) {
+    case EBUem: return "em";
+    case EBUex: return "ex";
+    }
+    return "?";
+}
+
+JKQTMathTextEmptyBoxNode::Units JKQTMathTextEmptyBoxNode::String2Units(QString type)
+{
+    type=type.toLower().trimmed();
+    if (type=="ex") return EBUex;
+    if (type=="em") return EBUem;
+    return EBUem;
+}
+
+double JKQTMathTextEmptyBoxNode::Units2PixelWidth(double value, Units unit, JKQTMathTextEnvironment currentEv, QPaintDevice *pd) const
+{
+    const QFontMetricsF fm(currentEv.getFont(parentMathText), pd);
+    if (unit==EBUem) {
+#if (QT_VERSION>=QT_VERSION_CHECK(5, 15, 0))
+        const double em=fm.horizontalAdvance(QChar(0x2003));//currentEv.fontSize;
+#else
+        const double em=fm.width(QChar(0x2003));//currentEv.fontSize;
+#endif
+        return value*em;
+    } else if (unit==EBUex) {
+        const double ex=fm.xHeight();
+        return value*ex;
+    }
+    return 0;
+}
+
+JKQTMathTextEmptyBoxNode::JKQTMathTextEmptyBoxNode(JKQTMathText *parent, double width_, Units widthUnit_, double height_, Units heightUnit_):
+    JKQTMathTextNode(parent),
+    width(width_), widthUnit(widthUnit_),
+    height(height_),heightUnit(heightUnit_)
+{
+
+}
+
+JKQTMathTextEmptyBoxNode::~JKQTMathTextEmptyBoxNode()
+{
+
+}
+
+QString JKQTMathTextEmptyBoxNode::getTypeName() const
+{
+    return QString("JKQTMathTextEmptyBoxNode(%1%2 x %3%4)").arg(getWidth()).arg(JKQTMathTextEmptyBoxNode::Units2String(getWidthUnit())).arg(getHeight()).arg(JKQTMathTextEmptyBoxNode::Units2String(getHeightUnit()));
+}
+
+bool JKQTMathTextEmptyBoxNode::toHtml(QString &html, JKQTMathTextEnvironment currentEv, JKQTMathTextEnvironment defaultEv)
+{
+    return true;
+}
+
+JKQTMathTextEmptyBoxNode::Units JKQTMathTextEmptyBoxNode::getWidthUnit() const
+{
+    return widthUnit;
+}
+
+double JKQTMathTextEmptyBoxNode::getWidth() const
+{
+    return width;
+}
+
+JKQTMathTextEmptyBoxNode::Units JKQTMathTextEmptyBoxNode::getHeightUnit() const
+{
+    return heightUnit;
+}
+
+double JKQTMathTextEmptyBoxNode::getHeight() const
+{
+    return height;
+}
+
+double JKQTMathTextEmptyBoxNode::draw(QPainter &painter, double x, double y, JKQTMathTextEnvironment currentEv, const JKQTMathTextNodeSize *prevNodeSize)
+{
+    doDrawBoxes(painter, x,y,currentEv);
+    double width=0, bh=0, oh=0, sp=0;
+    getSize(painter, currentEv, width, bh, oh, sp, prevNodeSize);
+    return x+width;
+}
+
+void JKQTMathTextEmptyBoxNode::getSizeInternal(QPainter &painter, JKQTMathTextEnvironment currentEv, double &width, double &baselineHeight, double &overallHeight, double &strikeoutPos, const JKQTMathTextNodeSize */*prevNodeSize*/)
+{
+    const QFontMetricsF fm(currentEv.getFont(parentMathText), painter.device());
+    width=Units2PixelWidth(width, widthUnit, currentEv, painter.device());
+    overallHeight=Units2PixelWidth(height, heightUnit, currentEv, painter.device());
+    if (height>0) {
+        baselineHeight=overallHeight;
+    } else {
+        baselineHeight=0;
+    }
+    strikeoutPos=fm.strikeOutPos();
+}

lib/jkqtmathtext/nodes/jkqtmathtextwhitespacenode.h

@@ -76,9 +76,9 @@ class JKQTMATHTEXT_LIB_EXPORT JKQTMathTextWhitespaceNode: public JKQTMathTextNod
         virtual QString getTypeName() const override;
         /** \copydoc JKQTMathTextNode::toHtml() */
         virtual bool toHtml(QString& html, JKQTMathTextEnvironment currentEv, JKQTMathTextEnvironment defaultEv) override;
-        /** \brief copydoc WhitespaceProps::type */
+        /** \copydoc WhitespaceProps::type */
         Types getWhitespaceType() const;
-        /** \brief copydoc WhitespaceProps::count */
+        /** \copydoc WhitespaceProps::count */
         size_t getWhitespaceCount() const;
         /** \copydoc JKQTMathTextNode::draw() */
         virtual double draw(QPainter& painter, double x, double y, JKQTMathTextEnvironment currentEv, const JKQTMathTextNodeSize* prevNodeSize=nullptr) override;
@@ -103,6 +103,53 @@ class JKQTMATHTEXT_LIB_EXPORT JKQTMathTextWhitespaceNode: public JKQTMathTextNod
         static void fillSupportedInstructions();
 };
 
+
+/** \brief subclass representing an empty bbox with defined width/height in the syntax tree
+ *  \ingroup jkqtmathtext_items
+ *
+ */
+class JKQTMATHTEXT_LIB_EXPORT JKQTMathTextEmptyBoxNode: public JKQTMathTextNode {
+    public:
+        enum Units {
+            EBUem,  /*!< \brief 1em = width('M') */
+            EBUex,  /*!< \brief 1ex = xHeight */
+        };
+        /** \brief converts Types \a type into a string */
+        static QString Units2String(Units type);
+        /** \brief converts Types \a type into a string */
+        static Units String2Units(QString type);
+        /** \brief converts Types \a type into its width in pixels, based on \a currentEv and \a pd */
+        double Units2PixelWidth(double value, Units unit, JKQTMathTextEnvironment currentEv, QPaintDevice *pd) const;
+        /** \brief constructs a node */
+        explicit JKQTMathTextEmptyBoxNode(JKQTMathText* parent, double width_, Units widthUnit_, double height_, Units heightUnit_);
+        virtual ~JKQTMathTextEmptyBoxNode() override;
+        /** \copydoc JKQTMathTextNode::getTypeName() */
+        virtual QString getTypeName() const override;
+        /** \copydoc JKQTMathTextNode::toHtml() */
+        virtual bool toHtml(QString& html, JKQTMathTextEnvironment currentEv, JKQTMathTextEnvironment defaultEv) override;
+        /** \copydoc widthUnit */
+        Units getWidthUnit() const;
+        /** \copydoc width */
+        double getWidth() const;
+        /** \copydoc heightUnit */
+        Units getHeightUnit() const;
+        /** \copydoc height */
+        double getHeight() const;
+        /** \copydoc JKQTMathTextNode::draw() */
+        virtual double draw(QPainter& painter, double x, double y, JKQTMathTextEnvironment currentEv, const JKQTMathTextNodeSize* prevNodeSize=nullptr) override;
+    protected:
+        /** \copydoc JKQTMathTextNode::getSizeInternal() */
+        virtual void getSizeInternal(QPainter& painter, JKQTMathTextEnvironment currentEv, double& width, double& baselineHeight, double& overallHeight, double& strikeoutPos, const JKQTMathTextNodeSize* prevNodeSize=nullptr) override;
+        /** \brief width of the (empty) box, units of this value defined in widthUnit */
+        double width;
+        /** \biref units to interpret width */
+        Units widthUnit;
+        /** \brief height of the (empty) box, units of this value defined in heightUnit */
+        double height;
+        /** \biref units to interpret height */
+        Units heightUnit;
+};
+
 #endif // JKQTMATHTEXTWHITESPACENODE_H