Qt 5.6 | Qt Quick | Qt Quick Examples - Canvas | quadraticCurveTo.qml Example File

Qt 5.6.2 Reference Documentation

# quadraticCurveTo.qml Example File

canvas/quadraticCurveTo/quadraticCurveTo.qml

      /****************************************************************************
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      ** Contact: http://www.qt.io/licensing/
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      ** This file is part of the examples of the Qt Toolkit.
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      ** $QT_BEGIN_LICENSE:BSD$
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      **     from this software without specific prior written permission.
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      import QtQuick 2.0
      import "../contents"
      import "../../shared"

      Item {
          id:container
          width:320
          height:480

          Column {
              spacing:5
              anchors.fill: parent
              anchors.topMargin: 12

              Text {
                  font.pointSize: 24
                  font.bold: true
                  text: "Quadratic Curve"
                  anchors.horizontalCenter: parent.horizontalCenter
                  color: "#777"
              }

              Canvas {
                  id: canvas
                  width: 320
                  height: 280

                  property color strokeStyle:  Qt.darker(fillStyle, 1.3)
                  property color fillStyle: "#14aaff" // blue
                  property int lineWidth: lineWidthCtrl.value
                  property bool fill: true
                  property bool stroke: true
                  property real alpha: 1.0
                  property real scale : scaleCtrl.value
                  property real rotate : rotateCtrl.value

                  antialiasing: true

                  onLineWidthChanged:requestPaint();
                  onFillChanged:requestPaint();
                  onStrokeChanged:requestPaint();
                  onScaleChanged:requestPaint();
                  onRotateChanged:requestPaint();

                  onPaint: {
                      var ctx = canvas.getContext('2d');
                      var originX = 75
                      var originY = 75

                      ctx.save();
                      ctx.clearRect(0, 0, canvas.width, canvas.height);
                      ctx.translate(originX, originX);
                      ctx.strokeStyle = canvas.strokeStyle;
                      ctx.fillStyle = canvas.fillStyle;
                      ctx.lineWidth = canvas.lineWidth;

                      ctx.translate(originX, originY)
                      ctx.rotate(canvas.rotate);
                      ctx.scale(canvas.scale, canvas.scale);
                      ctx.translate(-originX, -originY)

                      // ![0]
                      ctx.beginPath();
                      ctx.moveTo(75,25);
                      ctx.quadraticCurveTo(25,25,25,62.5);
                      ctx.quadraticCurveTo(25,100,50,100);
                      ctx.quadraticCurveTo(50,120,30,125);
                      ctx.quadraticCurveTo(60,120,65,100);
                      ctx.quadraticCurveTo(125,100,125,62.5);
                      ctx.quadraticCurveTo(125,25,75,25);
                      ctx.closePath();
                      // ![0]

                      if (canvas.fill)
                          ctx.fill();
                      if (canvas.stroke)
                          ctx.stroke();

                      // ![1]
                      ctx.fillStyle = "white";
                      ctx.font = "bold 17px sans-serif";
                      ctx.fillText("Qt Quick", 40, 70);
                      // ![1]
                      ctx.restore();
                  }
              }
          }
          Column {
              anchors.bottom: parent.bottom
              anchors.bottomMargin: 12
              Slider {id:lineWidthCtrl; min:1; max:10; init:2; name:"Outline"}
              Slider {id:scaleCtrl; min:0.1; max:10; init:1; name:"Scale"}
              Slider {id:rotateCtrl; min:0; max:Math.PI*2; init:0; name:"Rotate"}
          }
      }