Canvas: Handle switching between object and string based colors

When switching between the two it should respect whatever the color is
regardless of whether it is a color value or a string based color. This
also accounts for "invalid" colors as this should set the stroke-style
to be #000000 to be inline with the default stroke-style indicated in
the specification.

Change-Id: I00bee6c9a85787762271882838510b4187798ee0
Fixes: QTBUG-42155
Fixes: QTBUG-52959
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

2 files changed, 42 insertions, 2 deletions

diff --git a/src/quick/items/context2d/qquickcontext2d.cpp b/src/quick/items/context2d/qquickcontext2d.cpp
index 66727e7845..57e697bdd1 100644
--- a/src/quick/items/context2d/qquickcontext2d.cpp
+++ b/src/quick/items/context2d/qquickcontext2d.cpp
@@ -1548,7 +1548,7 @@ QV4::ReturnedValue QQuickJSContext2D::method_set_strokeStyle(const QV4::Function
     if (value->as<Object>()) {
         QColor color = scope.engine->toVariant(value, qMetaTypeId<QColor>()).value<QColor>();
         if (color.isValid()) {
-            r->d()->context()->state.fillStyle = color;
+            r->d()->context()->state.strokeStyle = color;
             r->d()->context()->buffer()->setStrokeStyle(color);
             r->d()->context()->m_strokeStyle.set(scope.engine, value);
         } else {
@@ -1559,7 +1559,12 @@ QV4::ReturnedValue QQuickJSContext2D::method_set_strokeStyle(const QV4::Function
                 r->d()->context()->m_strokeStyle.set(scope.engine, value);
                 r->d()->context()->state.strokePatternRepeatX = style->d()->patternRepeatX;
                 r->d()->context()->state.strokePatternRepeatY = style->d()->patternRepeatY;
-
+            } else if (!style && r->d()->context()->state.strokeStyle != QBrush(QColor())) {
+                // If there is no style object, then ensure that the strokeStyle is at least
+                // QColor in case it was previously set
+                r->d()->context()->state.strokeStyle = QBrush(QColor());
+                r->d()->context()->buffer()->setStrokeStyle(r->d()->context()->state.strokeStyle);
+                r->d()->context()->m_strokeStyle.set(scope.engine, value);
             }
         }
     } else if (value->isString()) {
diff --git a/tests/auto/quick/qquickcanvasitem/data/tst_strokeStyle.qml b/tests/auto/quick/qquickcanvasitem/data/tst_strokeStyle.qml
index 22803a19ce..a3f1ab0a9b 100644
--- a/tests/auto/quick/qquickcanvasitem/data/tst_strokeStyle.qml
+++ b/tests/auto/quick/qquickcanvasitem/data/tst_strokeStyle.qml
@@ -3,6 +3,8 @@ import QtQuick 2.0
 CanvasTestCase {
    id:testCase
    name: "strokeStyle"
+   property color anotherColor: "#0000ff"
+   property color emptyColor
    function init_data() { return testData("2d"); }
    function test_default(row) {
        var canvas = createCanvasObject(row);
@@ -46,4 +48,37 @@ CanvasTestCase {
        comparePixel(ctx,0,0,255,255,255,255);
        canvas.destroy()
    }
+   function test_colorFromObjectToString(row) {
+       var canvas = createCanvasObject(row);
+       var ctx = canvas.getContext('2d');
+
+       ctx.reset();
+       ctx.strokeStyle = anotherColor
+       ctx.strokeStyle = "red";
+       compare(ctx.strokeStyle, "#ff0000");
+
+       ctx.strokeStyle = anotherColor
+       ctx.strokeStyle = "black";
+       compare(ctx.strokeStyle, "#000000");
+
+       ctx.strokeStyle = "white";
+       ctx.strokeStyle = anotherColor
+       compare(ctx.strokeStyle, "#0000ff");
+       canvas.destroy()
+   }
+   function test_withInvalidColor(row) {
+       var canvas = createCanvasObject(row);
+       var ctx = canvas.getContext('2d');
+
+       ctx.reset();
+       ctx.strokeStyle = emptyColor
+       compare(ctx.strokeStyle, "#000000");
+       ctx.strokeStyle = "red";
+       compare(ctx.strokeStyle, "#ff0000");
+       ctx.strokeStyle = emptyColor
+       compare(ctx.strokeStyle, "#000000");
+       ctx.strokeStyle = anotherColor;
+       compare(ctx.strokeStyle, "#0000ff");
+       canvas.destroy()
+   }
 }