Qt Quick Demo - Calqlatr

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 import QtQuick 2.0
 import "content"
 import "content/calculator.js" as CalcEngine

 Rectangle {
     id: window
     width: 320
     height: 480
     focus: true
     color: "#272822"

     onWidthChanged: controller.reload()
     onHeightChanged: controller.reload()

     function operatorPressed(operator) {
         CalcEngine.operatorPressed(operator)
         numPad.buttonPressed()
     }
     function digitPressed(digit) {
         CalcEngine.digitPressed(digit)
         numPad.buttonPressed()
     }
     function isButtonDisabled(op) {
         return CalcEngine.disabled(op)
     }

     Item {
         id: pad
         width: 180
         NumberPad { id: numPad; y: 10; anchors.horizontalCenter: parent.horizontalCenter }
     }

     AnimationController {
         id: controller
         animation: ParallelAnimation {
             id: anim
             NumberAnimation { target: display; property: "x"; duration: 400; from: -16; to: window.width - display.width; easing.type: Easing.InOutQuad }
             NumberAnimation { target: pad; property: "x"; duration: 400; from: window.width - pad.width; to: 0; easing.type: Easing.InOutQuad }
             SequentialAnimation {
                 NumberAnimation { target: pad; property: "scale"; duration: 200; from: 1; to: 0.97; easing.type: Easing.InOutQuad }
                 NumberAnimation { target: pad; property: "scale"; duration: 200; from: 0.97; to: 1; easing.type: Easing.InOutQuad }
             }
         }
     }

     Keys.onPressed: {
         if (event.key == Qt.Key_0)
             digitPressed("0")
         else if (event.key == Qt.Key_1)
             digitPressed("1")
         else if (event.key == Qt.Key_2)
             digitPressed("2")
         else if (event.key == Qt.Key_3)
             digitPressed("3")
         else if (event.key == Qt.Key_4)
             digitPressed("4")
         else if (event.key == Qt.Key_5)
             digitPressed("5")
         else if (event.key == Qt.Key_6)
             digitPressed("6")
         else if (event.key == Qt.Key_7)
             digitPressed("7")
         else if (event.key == Qt.Key_8)
             digitPressed("8")
         else if (event.key == Qt.Key_9)
             digitPressed("9")
         else if (event.key == Qt.Key_Plus)
             operatorPressed("+")
         else if (event.key == Qt.Key_Minus)
             operatorPressed("−")
         else if (event.key == Qt.Key_Asterisk)
             operatorPressed("×")
         else if (event.key == Qt.Key_Slash)
             operatorPressed("÷")
         else if (event.key == Qt.Key_Enter || event.key == Qt.Key_Return)
             operatorPressed("=")
         else if (event.key == Qt.Key_Comma || event.key == Qt.Key_Period)
             digitPressed(".")
         else if (event.key == Qt.Key_Backspace)
             operatorPressed("backspace")
     }

     Display {
         id: display
         x: -16
         width: window.width - pad.width
         height: parent.height

         MouseArea {
             id: mouseInput
             property real startX: 0
             property real oldP: 0
             property bool rewind: false

             anchors {
                 bottom: parent.bottom
                 left: parent.left
                 right: parent.right
             }
             height: 50
             onPositionChanged: {
                 var reverse = startX > window.width / 2
                 var mx = mapToItem(window, mouseInput.mouseX, mouseInput.mouseY).x
                 var p = Math.abs((mx - startX) / (window.width - display.width))
                 if (p < oldP)
                     rewind = reverse ? false : true
                 else
                     rewind = reverse ? true : false
                 controller.progress = reverse ? 1 - p : p
                 oldP = p
             }
             onPressed: startX = mapToItem(window, mouseInput.mouseX, mouseInput.mouseY).x
             onReleased: {
                 if (rewind)
                     controller.completeToBeginning()
                 else
                     controller.completeToEnd()
             }
         }
     }

 }