- Qt 5.15
- Qt Quick Demo - Calqlatr
- Qt 5.15.18 Reference Documentation

# Qt Quick Demo - Calqlatr

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     import QtQuick 2.0
     import QtQuick.Window 2.0

     Item {
         id: display
         property real fontSize: Math.floor(Screen.pixelDensity * 5.0)
         property bool enteringDigits: false
         property int maxDigits: (width / fontSize) + 1
         property string displayedOperand
         property string errorString: qsTr("ERROR")
         property bool isError: displayedOperand === errorString

         function displayOperator(operator)
         {
             listView.model.append({ "operator": operator, "operand": "" })
             enteringDigits = true
             listView.positionViewAtEnd()
         }

         function newLine(operator, operand)
         {
             displayedOperand = displayNumber(operand)
             listView.model.append({ "operator": operator, "operand": displayedOperand })
             enteringDigits = false
             listView.positionViewAtEnd()
         }

         function appendDigit(digit)
         {
             if (!enteringDigits)
                 listView.model.append({ "operator": "", "operand": "" })
             var i = listView.model.count - 1;
             listView.model.get(i).operand = listView.model.get(i).operand + digit;
             enteringDigits = true
             listView.positionViewAtEnd()
         }

         function setDigit(digit)
         {
             var i = listView.model.count - 1;
             listView.model.get(i).operand = digit;
             listView.positionViewAtEnd()
         }

         function clear()
         {
             displayedOperand = ""
             if (enteringDigits) {
                 var i = listView.model.count - 1
                 if (i >= 0)
                     listView.model.remove(i)
                 enteringDigits = false
             }
         }

         // Returns a string representation of a number that fits in
         // display.maxDigits characters, trying to keep as much precision
         // as possible. If the number cannot be displayed, returns an
         // error string.
         function displayNumber(num) {
             if (typeof(num) != "number")
                 return errorString;

             var intNum = parseInt(num);
             var intLen = intNum.toString().length;

             // Do not count the minus sign as a digit
             var maxLen = num < 0 ? maxDigits + 1 : maxDigits;

             if (num.toString().length <= maxLen) {
                 if (isFinite(num))
                     return num.toString();
                 return errorString;
             }

             // Integer part of the number is too long - try
             // an exponential notation
             if (intNum == num || intLen > maxLen - 3) {
                 var expVal = num.toExponential(maxDigits - 6).toString();
                 if (expVal.length <= maxLen)
                     return expVal;
             }

             // Try a float presentation with fixed number of digits
             var floatStr = parseFloat(num).toFixed(maxDigits - intLen - 1).toString();
             if (floatStr.length <= maxLen)
                 return floatStr;

             return errorString;
         }

         Item {
             id: theItem
             width: parent.width + 32
             height: parent.height

             Rectangle {
                 id: rect
                 x: 16
                 color: "white"
                 height: parent.height
                 width: display.width - 16
             }
             Image {
                 anchors.right: rect.left
                 source: "images/paper-edge-left.png"
                 height: parent.height
                 fillMode: Image.TileVertically
             }
             Image {
                 anchors.left: rect.right
                 source: "images/paper-edge-right.png"
                 height: parent.height
                 fillMode: Image.TileVertically
             }

             Image {
                 id: grip
                 source: "images/paper-grip.png"
                 anchors.horizontalCenter: parent.horizontalCenter
                 anchors.bottom: parent.bottom
                 anchors.bottomMargin: 20
             }

             ListView {
                 id: listView
                 x: 16; y: 30
                 width: display.width
                 height: display.height - 50 - y
                 delegate: Item {
                     height: display.fontSize * 1.1
                     width: parent.width
                     Text {
                         id: operator
                         x: 6
                         font.pixelSize: display.fontSize
                         color: "#6da43d"
                         text: model.operator
                     }
                     Text {
                         id: operand
                         font.pixelSize: display.fontSize
                         anchors.right: parent.right
                         anchors.rightMargin: 22
                         text: model.operand
                     }
                 }
                 model: ListModel { }
             }

         }

     }