Introduce QUrlResourceProvider to load resources for HTML

QTextDocument and the text editor classes suggest to override
their loadResource() methods to provide data associated with
a text document. This approach has the following drawbacks:
- it requires subclassing
- there is no way to set a global resource provider
- QLabel is missing virtual loadResource() method and
  it can't be added without breaking ABI

QUrlResourceProvider is designed to solve these issues.
One should create a derived class that implements
QUrlResourceProvider::resource(). The objects of the derived
class then can be set for any text document.
The default resource provider can be set with
QUrlResourceProvider::setDefaultProvider().
This change also adds QLabel::setResourceProvider(),
which doesn't break ABI.

[ChangeLog][QtGui][Text] Introduced QUrlResourceProvider that allows to
load resources for HTML. It is intended to replace the use of
QTextDocument::loadResource().

Change-Id: Iaf19b229f522a73508f20715257450fe58f68daf
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 25 insertions, 0 deletions

diff --git a/tests/auto/gui/text/qtextdocument/tst_qtextdocument.cpp b/tests/auto/gui/text/qtextdocument/tst_qtextdocument.cpp
index c290305d2f..4e0b7f46df 100644
--- a/tests/auto/gui/text/qtextdocument/tst_qtextdocument.cpp
+++ b/tests/auto/gui/text/qtextdocument/tst_qtextdocument.cpp
@@ -47,6 +47,7 @@
 #include <qimage.h>
 #include <qtextlayout.h>
 #include <QDomDocument>
+#include <qurlresourceprovider.h>
 #include "common.h"
 
 // #define DEBUG_WRITE_OUTPUT
@@ -192,6 +193,8 @@ private slots:
     void clearUndoRedoStacks();
     void mergeFontFamilies();
 
+    void resourceProvider();
+
 private:
     void backgroundImage_checkExpectedHtml(const QTextDocument &doc);
     void buildRegExpData();
@@ -3593,6 +3596,28 @@ void tst_QTextDocument::clearUndoRedoStacks()
     QVERIFY(!doc.isUndoAvailable());
 }
 
+class UrlResourceProvider : public QUrlResourceProvider
+{
+public:
+    QVariant resource(const QUrl &url) override
+    {
+        resourseUrl = url;
+        return QVariant();
+    }
+
+    QUrl resourseUrl;
+};
+
+void tst_QTextDocument::resourceProvider()
+{
+    QTextDocument doc;
+    UrlResourceProvider resourceProvider;
+    doc.setResourceProvider(&resourceProvider);
+    QUrl url("test://img");
+    doc.setHtml(QStringLiteral("<img src='%1'/>").arg(url.toString()));
+    doc.resource(QTextDocument::UserResource, url);
+    QCOMPARE(url, resourceProvider.resourseUrl);
+}
 
 QTEST_MAIN(tst_QTextDocument)
 #include "tst_qtextdocument.moc"