Let specifying the fallback style for custom styles

For example, you can call QQuickStyle::setStyle(":/mycontrols") and
QQuickStyle::setFallbackStyle("Material") to select a custom style so
that the missing files will fallback to the Material style.

Notice that the Material and Universal styles do not contain all files.
For example, the non-visual Control.qml, Container.qml are not duplicated.
For these, we must fallback to the Default style that is guaranteed to
contain them all.

[ChangeLog][Controls] Added support for specifying the fallback style for
custom styles via :/qtquickcontrols2.conf, QT_QUICK_CONTROLS_FALLBACK_STYLE
or QQuickStyle::setFallbackStyle().

Change-Id: I00be1c8c6aaca875ef851c90d018e9b5e2f501b7
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

5 files changed, 76 insertions, 7 deletions

diff --git a/tests/auto/qquickstyleselector/data/Control.qml b/tests/auto/qquickstyleselector/data/Control.qml
new file mode 100644
index 00000000..697662f6
--- /dev/null
+++ b/tests/auto/qquickstyleselector/data/Control.qml
@@ -0,0 +1,2 @@
+import QtQuick.Templates 2.1 as T
+T.Control { }
diff --git a/tests/auto/qquickstyleselector/data/FallbackStyle/Button.qml b/tests/auto/qquickstyleselector/data/FallbackStyle/Button.qml
new file mode 100644
index 00000000..ee17c230
--- /dev/null
+++ b/tests/auto/qquickstyleselector/data/FallbackStyle/Button.qml
@@ -0,0 +1,2 @@
+import QtQuick.Templates 2.1 as T
+T.Button { }
diff --git a/tests/auto/qquickstyleselector/data/FallbackStyle/Label.qml b/tests/auto/qquickstyleselector/data/FallbackStyle/Label.qml
new file mode 100644
index 00000000..8879d93f
--- /dev/null
+++ b/tests/auto/qquickstyleselector/data/FallbackStyle/Label.qml
@@ -0,0 +1,2 @@
+import QtQuick.Templates 2.1 as T
+T.Label { }
diff --git a/tests/auto/qquickstyleselector/data/Label.qml b/tests/auto/qquickstyleselector/data/Label.qml
new file mode 100644
index 00000000..8879d93f
--- /dev/null
+++ b/tests/auto/qquickstyleselector/data/Label.qml
@@ -0,0 +1,2 @@
+import QtQuick.Templates 2.1 as T
+T.Label { }
diff --git a/tests/auto/qquickstyleselector/tst_qquickstyleselector.cpp b/tests/auto/qquickstyleselector/tst_qquickstyleselector.cpp
index 6c2aebe4..1e7d7add 100644
--- a/tests/auto/qquickstyleselector/tst_qquickstyleselector.cpp
+++ b/tests/auto/qquickstyleselector/tst_qquickstyleselector.cpp
@@ -36,6 +36,7 @@
 
 #include <QtTest/qtest.h>
 #include <QtQuickControls2/qquickstyle.h>
+#include <QtQuickControls2/private/qquickstyle_p.h>
 #include <QtQuickControls2/private/qquickstyleselector_p.h>
 #include "../shared/util.h"
 
@@ -44,24 +45,82 @@ class tst_QQuickStyleSelector : public QQmlDataTest
     Q_OBJECT
 
 private slots:
+    void initTestCase();
+
     void select_data();
     void select();
 };
 
+void tst_QQuickStyleSelector::initTestCase()
+{
+    QQmlDataTest::initTestCase();
+    QQuickStylePrivate::init(dataDirectoryUrl());
+}
+
 void tst_QQuickStyleSelector::select_data()
 {
     QTest::addColumn<QString>("file");
     QTest::addColumn<QString>("style");
     QTest::addColumn<QString>("path");
+    QTest::addColumn<QString>("fallback");
     QTest::addColumn<QString>("expected");
 
-    QTest::newRow("empty") << "Button.qml" << "" << dataDirectory() << testFileUrl("Button.qml").toString();
-    QTest::newRow("no such dir") << "Button.qml" << "Foo" << dataDirectory() << testFileUrl("Button.qml").toString();
-    QTest::newRow("no such file") << "Foo.qml" << "FileSystemStyle" << dataDirectory() << testFileUrl("Foo.qml").toString();
-    QTest::newRow("relative/path/to/FileSystemStyle") << "Button.qml" << "FileSystemStyle" << "data" << testFileUrl("FileSystemStyle/Button.qml").toString();
-    QTest::newRow("/absolute/path/to/FileSystemStyle") << "Button.qml" << "FileSystemStyle" << dataDirectory() << testFileUrl("FileSystemStyle/Button.qml").toString();
-    QTest::newRow(":/ResourceStyle") << "Button.qml" << "ResourceStyle" << ":/" << "qrc:/ResourceStyle/Button.qml";
-    QTest::newRow("qrc:/ResourceStyle") << "Button.qml" << "ResourceStyle" << "qrc:/" << "qrc:/ResourceStyle/Button.qml";
+    // Control.qml exists only in the default style
+    QTest::newRow("control") << "Control.qml" << "" << "data" << "" << testFileUrl("Control.qml").toString();
+    QTest::newRow("/control") << "Control.qml" << "" << dataDirectory() << "" << testFileUrl("Control.qml").toString();
+    QTest::newRow("fs/control") << "Control.qml" << "FileSystemStyle" << "data" << "" << testFileUrl("Control.qml").toString();
+    QTest::newRow("/fs/control") << "Control.qml" << "FileSystemStyle" << dataDirectory() << "" << testFileUrl("Control.qml").toString();
+    QTest::newRow(":/control") << "Control.qml" << "ResourceStyle" << ":/" << "" << testFileUrl("Control.qml").toString();
+    QTest::newRow("qrc:/control") << "Control.qml" << "ResourceStyle" << "qrc:/" << "" << testFileUrl("Control.qml").toString();
+    QTest::newRow("nosuch/control") << "Control.qml" << "NoSuchStyle" << "data" << "" << testFileUrl("Control.qml").toString();
+    QTest::newRow("/nosuch/control") << "Control.qml" << "NoSuchStyle" << dataDirectory() << "" << testFileUrl("Control.qml").toString();
+
+    QTest::newRow("control->base") << "Control.qml" << "" << "data" << "FallbackStyle" << testFileUrl("Control.qml").toString();
+    QTest::newRow("/control->base") << "Control.qml" << "" << dataDirectory() << "FallbackStyle" << testFileUrl("Control.qml").toString();
+    QTest::newRow("fs/control->base") << "Control.qml" << "FileSystemStyle" << "data" << "FallbackStyle" << testFileUrl("Control.qml").toString();
+    QTest::newRow("/fs/control->base") << "Control.qml" << "FileSystemStyle" << dataDirectory() << "FallbackStyle" << testFileUrl("Control.qml").toString();
+    QTest::newRow(":/control->base") << "Control.qml" << "ResourceStyle" << ":/" << "FallbackStyle" << testFileUrl("Control.qml").toString();
+    QTest::newRow("qrc:/control->base") << "Control.qml" << "ResourceStyle" << "qrc:/" << "FallbackStyle" << testFileUrl("Control.qml").toString();
+    QTest::newRow("nosuch/control->base") << "Control.qml" << "NoSuchStyle" << "data" << "FallbackStyle" << testFileUrl("Control.qml").toString();
+    QTest::newRow("/nosuch/control->base") << "Control.qml" << "NoSuchStyle" << dataDirectory() << "FallbackStyle" << testFileUrl("Control.qml").toString();
+
+    // Label.qml exists in the default and fallback styles
+    QTest::newRow("label") << "Label.qml" << "" << "data" << "" << testFileUrl("Label.qml").toString();
+    QTest::newRow("/label") << "Label.qml" << "" << dataDirectory() << "" << testFileUrl("Label.qml").toString();
+    QTest::newRow("fs/label") << "Label.qml" << "FileSystemStyle" << "data" << "" << testFileUrl("Label.qml").toString();
+    QTest::newRow("/fs/label") << "Label.qml" << "FileSystemStyle" << dataDirectory() << "" << testFileUrl("Label.qml").toString();
+    QTest::newRow(":/label") << "Label.qml" << "ResourceStyle" << ":/" << "" << testFileUrl("Label.qml").toString();
+    QTest::newRow("qrc:/label") << "Label.qml" << "ResourceStyle" << "qrc:/" << "" << testFileUrl("Label.qml").toString();
+    QTest::newRow("nosuch/label") << "Label.qml" << "NoSuchStyle" << "data" << "" << testFileUrl("Label.qml").toString();
+    QTest::newRow("/nosuch/label") << "Label.qml" << "NoSuchStyle" << dataDirectory() << "" << testFileUrl("Label.qml").toString();
+
+    QTest::newRow("label->base") << "Label.qml" << "" << "data" << "FallbackStyle" << testFileUrl("FallbackStyle/Label.qml").toString();
+    QTest::newRow("/label->base") << "Label.qml" << "" << dataDirectory() << "FallbackStyle" << testFileUrl("Label.qml").toString();
+    QTest::newRow("fs/label->base") << "Label.qml" << "FileSystemStyle" << "data" << "FallbackStyle" << testFileUrl("FallbackStyle/Label.qml").toString();
+    QTest::newRow("/fs/label->base") << "Label.qml" << "FileSystemStyle" << dataDirectory() << "FallbackStyle" << testFileUrl("FallbackStyle/Label.qml").toString();
+    QTest::newRow(":/label->base") << "Label.qml" << "ResourceStyle" << ":/" << "FallbackStyle" << testFileUrl("FallbackStyle/Label.qml").toString();
+    QTest::newRow("qrc:/label->base") << "Label.qml" << "ResourceStyle" << "qrc:/" << "FallbackStyle" << testFileUrl("FallbackStyle/Label.qml").toString();
+    QTest::newRow("nosuch/label->base") << "Label.qml" << "NoSuchStyle" << "data" << "FallbackStyle" << testFileUrl("FallbackStyle/Label.qml").toString();
+    QTest::newRow("/nosuch/label->base") << "Label.qml" << "NoSuchStyle" << dataDirectory() << "FallbackStyle" << testFileUrl("FallbackStyle/Label.qml").toString();
+
+    // Button.qml exists in all styles including the fs and qrc styles
+    QTest::newRow("button") << "Button.qml" << "" << "data" << "" << testFileUrl("Button.qml").toString();
+    QTest::newRow("/button") << "Button.qml" << "" << dataDirectory() << "" << testFileUrl("Button.qml").toString();
+    QTest::newRow("fs/button") << "Button.qml" << "FileSystemStyle" << "data" << "" << testFileUrl("FileSystemStyle/Button.qml").toString();
+    QTest::newRow("/fs/button") << "Button.qml" << "FileSystemStyle" << dataDirectory() << "" << testFileUrl("FileSystemStyle/Button.qml").toString();
+    QTest::newRow(":/button") << "Button.qml" << "ResourceStyle" << ":/" << "" << "qrc:/ResourceStyle/Button.qml";
+    QTest::newRow("qrc:/button") << "Button.qml" << "ResourceStyle" << "qrc:/" << "" << "qrc:/ResourceStyle/Button.qml";
+    QTest::newRow("nosuch/button") << "Button.qml" << "NoSuchStyle" << "data" << "" << testFileUrl("Button.qml").toString();
+    QTest::newRow("/nosuch/button") << "Button.qml" << "NoSuchStyle" << dataDirectory() << "" << testFileUrl("Button.qml").toString();
+
+    QTest::newRow("button->base") << "Button.qml" << "" << "data" << "FallbackStyle" << testFileUrl("FallbackStyle/Button.qml").toString();
+    QTest::newRow("/button->base") << "Button.qml" << "" << dataDirectory() << "FallbackStyle" << testFileUrl("Button.qml").toString();
+    QTest::newRow("fs/button->base") << "Button.qml" << "FileSystemStyle" << "data" << "FallbackStyle" << testFileUrl("FileSystemStyle/Button.qml").toString();
+    QTest::newRow("/fs/button->base") << "Button.qml" << "FileSystemStyle" << dataDirectory() << "FallbackStyle" << testFileUrl("FileSystemStyle/Button.qml").toString();
+    QTest::newRow(":/button->base") << "Button.qml" << "ResourceStyle" << ":/" << "FallbackStyle" << "qrc:/ResourceStyle/Button.qml";
+    QTest::newRow("qrc:/button->base") << "Button.qml" << "ResourceStyle" << "qrc:/" << "FallbackStyle" << "qrc:/ResourceStyle/Button.qml";
+    QTest::newRow("nosuch/button->base") << "Button.qml" << "NoSuchStyle" << "data" << "FallbackStyle" << testFileUrl("FallbackStyle/Button.qml").toString();
+    QTest::newRow("/nosuch/button->base") << "Button.qml" << "NoSuchStyle" << dataDirectory() << "FallbackStyle" << testFileUrl("FallbackStyle/Button.qml").toString();
 }
 
 void tst_QQuickStyleSelector::select()
@@ -69,9 +128,11 @@ void tst_QQuickStyleSelector::select()
     QFETCH(QString, file);
     QFETCH(QString, style);
     QFETCH(QString, path);
+    QFETCH(QString, fallback);
     QFETCH(QString, expected);
 
     QQuickStyle::setStyle(QDir(path).filePath(style));
+    QQuickStyle::setFallbackStyle(fallback);
 
     QQuickStyleSelector selector;
     selector.setBaseUrl(dataDirectoryUrl());