Support window masks on WASM

QWasmWindow is now implementing the setMask method, which translates
the received QRegion to a css clip path

Fixes: QTBUG-73260
Change-Id: Ie934c1e6ab650426bfc32154bf9e49a4a2aeb45b
Reviewed-by: Aleksandr Reviakin <aleksandr.reviakin@qt.io>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

2 files changed, 23 insertions, 2 deletions

diff --git a/src/plugins/platforms/wasm/qwasmwindow.cpp b/src/plugins/platforms/wasm/qwasmwindow.cpp
index be0dd74797..1dc43b61bb 100644
--- a/src/plugins/platforms/wasm/qwasmwindow.cpp
+++ b/src/plugins/platforms/wasm/qwasmwindow.cpp
@@ -20,9 +20,9 @@
 #include "qwasmaccessibility.h"
 
 #include <iostream>
-#include <emscripten/val.h>
+#include <sstream>
 
-#include <GL/gl.h>
+#include <emscripten/val.h>
 
 #include <QtCore/private/qstdweb_p.h>
 
@@ -544,6 +544,26 @@ bool QWasmWindow::windowEvent(QEvent *event)
     }
 }
 
+void QWasmWindow::setMask(const QRegion &region)
+{
+    if (region.isEmpty()) {
+        m_qtWindow["style"].set("clipPath", emscripten::val(""));
+        return;
+    }
+
+    std::ostringstream cssClipPath;
+    cssClipPath << "path('";
+    for (const auto &rect : region) {
+        const auto cssRect = rect.adjusted(0, 0, 1, 1);
+        cssClipPath << "M " << cssRect.left() << " " << cssRect.top() << " ";
+        cssClipPath << "L " << cssRect.right() << " " << cssRect.top() << " ";
+        cssClipPath << "L " << cssRect.right() << " " << cssRect.bottom() << " ";
+        cssClipPath << "L " << cssRect.left() << " " << cssRect.bottom() << " z ";
+    }
+    cssClipPath << "')";
+    m_qtWindow["style"].set("clipPath", emscripten::val(cssClipPath.str()));
+}
+
 std::string QWasmWindow::canvasSelector() const
 {
     return "!qtwindow" + std::to_string(m_winId);
diff --git a/src/plugins/platforms/wasm/qwasmwindow.h b/src/plugins/platforms/wasm/qwasmwindow.h
index d90e828283..7f4047b758 100644
--- a/src/plugins/platforms/wasm/qwasmwindow.h
+++ b/src/plugins/platforms/wasm/qwasmwindow.h
@@ -75,6 +75,7 @@ public:
     bool setKeyboardGrabEnabled(bool) override { return false; }
     bool setMouseGrabEnabled(bool grab) final;
     bool windowEvent(QEvent *event) final;
+    void setMask(const QRegion &region) final;
 
     QWasmScreen *platformScreen() const;
     void setBackingStore(QWasmBackingStore *store) { m_backingStore = store; }