Wasm: Fix displaying frameless QWasmWindow with transparent content

Currently we render shadow and default background-color even for
frameless windows with transparent content.
This behavior is not consistent comparing to other platforms.

An example of such window is InputSelectionHandle from
VirtualKeyboard module.

This commit disables shadow-box and provides transparent
background-color for QWasmWindow which are frameless.
It also provides distinction between "frame" as logic property
of window and "border" as visual decoration.

Change-Id: I902692ea561a2e88e2e6ab7faad8e3eeb536a26b
Reviewed-by: Aleksandr Reviakin <[email protected]>
Reviewed-by: Mikołaj Boc <[email protected]>

3 files changed, 20 insertions, 8 deletions

diff --git a/src/plugins/platforms/wasm/qwasmcssstyle.cpp b/src/plugins/platforms/wasm/qwasmcssstyle.cpp
index 75b2aafa9a9..6ac4c8d884f 100644
--- a/src/plugins/platforms/wasm/qwasmcssstyle.cpp
+++ b/src/plugins/platforms/wasm/qwasmcssstyle.cpp
@@ -43,11 +43,15 @@ const char *Style = R"css(
     box-shadow: rgb(0 0 0 / 20%) 0px 10px 16px 0px, rgb(0 0 0 / 19%) 0px 6px 20px 0px;
 }
 
-.qt-window.has-frame {
+.qt-window.has-border {
     border: var(--border-width) solid lightgray;
     caret-color: transparent;
 }
 
+.qt-window.frameless {
+    background-color: transparent;
+}
+
 .resize-outline {
     position: absolute;
     display: none;
@@ -55,7 +59,7 @@ const char *Style = R"css(
 
 .qt-window.no-resize > .resize-outline { display: none; }
 
-.qt-window.has-frame:not(.maximized):not(.no-resize) .resize-outline {
+.qt-window.has-border:not(.maximized):not(.no-resize) .resize-outline {
     display: block;
 }
 
@@ -131,7 +135,7 @@ const char *Style = R"css(
     padding-bottom: 4px;
 }
 
-.qt-window.has-frame .title-bar {
+.qt-window.has-border .title-bar {
     display: flex;
 }
 
diff --git a/src/plugins/platforms/wasm/qwasmwindow.cpp b/src/plugins/platforms/wasm/qwasmwindow.cpp
index d2ab98bed9b..6ec8c510d0e 100644
--- a/src/plugins/platforms/wasm/qwasmwindow.cpp
+++ b/src/plugins/platforms/wasm/qwasmwindow.cpp
@@ -374,9 +374,10 @@ void QWasmWindow::setWindowFlags(Qt::WindowFlags flags)
     if (flags.testFlag(Qt::WindowStaysOnTopHint) != m_flags.testFlag(Qt::WindowStaysOnTopHint))
         m_compositor->windowPositionPreferenceChanged(this, flags);
     m_flags = flags;
-    dom::syncCSSClassWith(m_qtWindow, "has-frame", hasFrame());
-    dom::syncCSSClassWith(m_qtWindow, "has-shadow", !flags.testFlag(Qt::NoDropShadowWindowHint));
+    dom::syncCSSClassWith(m_qtWindow, "has-border", hasBorder());
+    dom::syncCSSClassWith(m_qtWindow, "has-shadow", hasShadow());
     dom::syncCSSClassWith(m_qtWindow, "has-title", flags.testFlag(Qt::WindowTitleHint));
+    dom::syncCSSClassWith(m_qtWindow, "frameless", flags.testFlag(Qt::FramelessWindowHint));
     dom::syncCSSClassWith(m_qtWindow, "transparent-for-input",
                           flags.testFlag(Qt::WindowTransparentForInput));
 
@@ -442,7 +443,7 @@ void QWasmWindow::applyWindowState()
     else
         newGeom = normalGeometry();
 
-    dom::syncCSSClassWith(m_qtWindow, "has-frame", hasFrame());
+    dom::syncCSSClassWith(m_qtWindow, "has-border", hasBorder());
     dom::syncCSSClassWith(m_qtWindow, "maximized", isMaximized);
 
     m_nonClientArea->titleBar()->setRestoreVisible(isMaximized);
@@ -559,12 +560,18 @@ void QWasmWindow::requestUpdate()
     m_compositor->requestUpdateWindow(this, QWasmCompositor::UpdateRequestDelivery);
 }
 
-bool QWasmWindow::hasFrame() const
+bool QWasmWindow::hasBorder() const
 {
     return !m_state.testFlag(Qt::WindowFullScreen) && !m_flags.testFlag(Qt::FramelessWindowHint)
             && !windowIsPopupType(m_flags);
 }
 
+bool QWasmWindow::hasShadow() const
+{
+    return !m_flags.testFlag(Qt::NoDropShadowWindowHint)
+            && !m_flags.testFlag(Qt::FramelessWindowHint);
+}
+
 bool QWasmWindow::hasMaximizeButton() const
 {
     return !m_state.testFlag(Qt::WindowMaximized) && m_flags.testFlag(Qt::WindowMaximizeButtonHint);
diff --git a/src/plugins/platforms/wasm/qwasmwindow.h b/src/plugins/platforms/wasm/qwasmwindow.h
index 1baa6994499..661a5160e89 100644
--- a/src/plugins/platforms/wasm/qwasmwindow.h
+++ b/src/plugins/platforms/wasm/qwasmwindow.h
@@ -96,7 +96,8 @@ private:
     static constexpr auto minSizeForRegularWindows = 100;
 
     void invalidate();
-    bool hasFrame() const;
+    bool hasBorder() const;
+    bool hasShadow() const;
     bool hasMaximizeButton() const;
     void applyWindowState();