Various improvements to Canvas examples

I noticed these examples were rather "aestetically
challenged" and decided to make it a test case for our
WIP style guidelines.

- Use consistent margins (12 px)
- Use proposed color palettes
- Use proposed fonts and header styles

I created a new Slider graphic and moved this into
the shared folder as I think it is useful for other examples.

I removed a lot of unused files which seem to have been added
but never actually used.

I also found several bugs in our implementation, including
not scaling or rotation around the correct origin.

In many cases I simplified the examples, removing
variables/sliders where they did not add significantly
to the example itself.

Change-Id: Ie09da33deaf56a3ec45a2031b87a24a8602e994a
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>

1 files changed, 102 insertions, 105 deletions

diff --git a/examples/quick/canvas/squircle/squircle.qml b/examples/quick/canvas/squircle/squircle.qml
index 3044816479..4e5c5a49fc 100644
--- a/examples/quick/canvas/squircle/squircle.qml
+++ b/examples/quick/canvas/squircle/squircle.qml
@@ -40,114 +40,111 @@
 
 import QtQuick 2.0
 import "../contents"
+import "../../shared"
+
 Item {
-  id:container
-  width:320
-  height:480
-
-  Column {
-    spacing:5
-    anchors.fill:parent
-    Text { font.pointSize:15; text:"Squircles"; anchors.horizontalCenter:parent.horizontalCenter}
-    Image {
-       anchors.horizontalCenter:parent.horizontalCenter
-       source:"squircle.png"
-       width:250
-       height:25
-    }
-    Canvas {
-        id:canvas
-        width:320
-        height:250
-        antialiasing: true
-
-        property string strokeStyle:"blue"
-        property string fillStyle:"steelblue"
-        property int lineWidth:2
-        property int nSize:nCtrl.value
-        property real radius:rCtrl.value
-        property bool fill:true
-        property bool stroke:false
-        property real px:xCtrl.value
-        property real py:yCtrl.value
-        property real alpha:alphaCtrl.value
-
-        onAlphaChanged:requestPaint();
-        onRadiusChanged:requestPaint();
-        onLineWidthChanged:requestPaint();
-        onNSizeChanged:requestPaint();
-        onFillChanged:requestPaint();
-        onStrokeChanged:requestPaint();
-        onPxChanged:requestPaint();
-        onPyChanged:requestPaint();
-
-
-        onPaint: squcirle();
-
-        function squcirle() {
-          var ctx = canvas.getContext("2d");
-          var N = canvas.nSize;
-          var R = canvas.radius;
-
-          N=Math.abs(N);
-          var M=N;
-          if (N>100) M=100;
-          if (N<0.00000000001) M=0.00000000001;
-
-          ctx.save();
-          ctx.globalAlpha =canvas.alpha;
-          ctx.fillStyle = "gray";
-          ctx.fillRect(0, 0, canvas.width, canvas.height);
-
-          ctx.strokeStyle = canvas.strokeStyle;
-          ctx.fillStyle = canvas.fillStyle;
-          ctx.lineWidth = canvas.lineWidth;
-
-          ctx.beginPath();
-          var i = 0, x, y;
-          for (i=0; i<(2*R+1); i++){
-             x = Math.round(i-R) + canvas.px;
-             y = Math.round(Math.pow(Math.abs(Math.pow(R,M)-Math.pow(Math.abs(i-R),M)),1/M)) + canvas.py;
-
-             if (i == 0)
-               ctx.moveTo(x, y);
-             else
-               ctx.lineTo(x, y);
-          }
-
-          for (i=(2*R); i<(4*R+1); i++){
-            x =Math.round(3*R-i)+canvas.px;
-            y = Math.round(-Math.pow(Math.abs(Math.pow(R,M)-Math.pow(Math.abs(3*R-i),M)),1/M)) + canvas.py;
-            ctx.lineTo(x, y);
-          }
-          ctx.closePath();
-          if (canvas.stroke) {
-              ctx.stroke();
-          }
-
-          if (canvas.fill) {
-              ctx.fill();
-          }
-
-          ctx.fillStyle = "yellow";
-          ctx.font = "Helvetica  16px";
-          ctx.fillText("|X-" + Math.round(canvas.px) + "|^" + N + " + |Y-"+Math.round(canvas.py)+"|^" + N + " = |" + Math.round(R) + "|^" + N, canvas.px - 125, canvas.py);
-          ctx.restore();
+    id: container
+    width: 320
+    height: 480
+
+    Column {
+        spacing: 6
+        anchors.fill: parent
+        anchors.topMargin: 12
+        Text {
+            font.pointSize: 24
+            font.bold: true
+            text: "Squircles"
+            anchors.horizontalCenter: parent.horizontalCenter
+            color: "#777"
         }
-    }
 
-    Rectangle {
-        id:controls
-        width:320
-        height:150
-        Column {
-          spacing:3
-          Slider {id:nCtrl; width:300; height:20; min:1; max:10; init:4; name:"N"}
-          Slider {id:rCtrl; width:300; height:20; min:30; max:180; init:100; name:"Radius"}
-          Slider {id:xCtrl; width:300; height:20; min:50; max:300; init:180; name:"X"}
-          Slider {id:yCtrl; width:300; height:20; min:30; max:300; init:220; name:"Y"}
-          Slider {id:alphaCtrl; width:300; height:20; min:0; max:1; init:1; name:"Alpha"}
+        Image {
+            anchors.horizontalCenter: parent.horizontalCenter
+            source: "squircle.png"
+            width: 250
+            height: 25
         }
+
+        Canvas {
+            id: canvas
+            width: 320
+            height: 250
+            antialiasing: true
+
+            property color strokeStyle: Qt.darker(fillStyle, 1.2)
+            property color fillStyle: "#6400aa"
+
+            property int lineWidth: 2
+            property int nSize: nCtrl.value
+            property real radius: rCtrl.value
+            property bool fill: true
+            property bool stroke: false
+            property real px: width/2
+            property real py: height/2 + 10
+            property real alpha: 1.0
+
+            onRadiusChanged: requestPaint();
+            onLineWidthChanged: requestPaint();
+            onNSizeChanged: requestPaint();
+            onFillChanged: requestPaint();
+            onStrokeChanged: requestPaint();
+
+            onPaint: squcirle();
+
+            function squcirle() {
+                var ctx = canvas.getContext("2d");
+                var N = canvas.nSize;
+                var R = canvas.radius;
+
+                N=Math.abs(N);
+                var M=N;
+                if (N>100) M=100;
+                if (N<0.00000000001) M=0.00000000001;
+
+                ctx.save();
+                ctx.globalAlpha =canvas.alpha;
+                ctx.fillStyle = "white";
+                ctx.fillRect(0, 0, canvas.width, canvas.height);
+
+                ctx.strokeStyle = canvas.strokeStyle;
+                ctx.fillStyle = canvas.fillStyle;
+                ctx.lineWidth = canvas.lineWidth;
+
+                ctx.beginPath();
+                var i = 0, x, y;
+                for (i=0; i<(2*R+1); i++){
+                    x = Math.round(i-R) + canvas.px;
+                    y = Math.round(Math.pow(Math.abs(Math.pow(R,M)-Math.pow(Math.abs(i-R),M)),1/M)) + canvas.py;
+
+                    if (i == 0)
+                        ctx.moveTo(x, y);
+                    else
+                        ctx.lineTo(x, y);
+                }
+
+                for (i=(2*R); i<(4*R+1); i++){
+                    x =Math.round(3*R-i)+canvas.px;
+                    y = Math.round(-Math.pow(Math.abs(Math.pow(R,M)-Math.pow(Math.abs(3*R-i),M)),1/M)) + canvas.py;
+                    ctx.lineTo(x, y);
+                }
+                ctx.closePath();
+                if (canvas.stroke) {
+                    ctx.stroke();
+                }
+
+                if (canvas.fill) {
+                    ctx.fill();
+                }
+                ctx.restore();
+            }
+        }
+
+    }
+    Column {
+        anchors.bottom: parent.bottom
+        anchors.bottomMargin: 12
+        Slider {id: nCtrl ; min: 1 ; max: 10 ; init: 2 ; name: "N"}
+        Slider {id: rCtrl ; min: 30 ; max: 180 ; init: 60 ; name: "Radius"}
     }
-  }
 }