[plasma-mobile/qmlkonsole/release/26.08] /: Properly implement setting background opacity

Git commit 8de80665ff2a99c77aa682a2b8ee34fc6d503725 by Devin Lin.
Committed on 19/07/2026 at 17:59.
Pushed by devinlin into branch 'release/26.08'.

Properly implement setting background opacity

Currently the opacity setting sets the entire terminal opacity, including the foreground text. Fix it so that it only sets the background color opacity.

M  +17   -6    lib/TerminalDisplay.cpp
M  +6    -5    lib/TerminalDisplay.h
M  +1    -1    src/contents/ui/TerminalPage.qml

https://invent.kde.org/plasma-mobile/qmlkonsole/-/commit/8de80665ff2a99c77aa682a2b8ee34fc6d503725

diff --git a/lib/TerminalDisplay.cpp b/lib/TerminalDisplay.cpp
index bc5f260..b9768bf 100644
--- a/lib/TerminalDisplay.cpp
+++ b/lib/TerminalDisplay.cpp
@@ -298,7 +298,7 @@ TerminalDisplay::TerminalDisplay(QQuickItem *parent)
     , _outputSuspendedLabel(nullptr)
     , _lineSpacing(0)
     , _colorsInverted(false)
-    , _opacity(static_cast<qreal>(1))
+    , _backgroundOpacity(static_cast<qreal>(1))
     , _filterChain(std::make_unique<TerminalImageFilterChain>())
     , _cursorShape(Emulation::KeyboardCursorShape::BlockCursor)
     , mMotionAfterPasting(NoMoveScreenWindow)
@@ -362,6 +362,7 @@ TerminalDisplay::TerminalDisplay(QQuickItem *parent)
     // TODO Forcing rendering to Framebuffer. We need to determine if this is ok
     // always or if we need to make this customizable.
     setRenderTarget(QQuickPaintedItem::FramebufferObject);
+    setFillColor(Qt::transparent);
 
     //  setFocusPolicy( Qt::WheelFocus );
 
@@ -641,10 +642,21 @@ QColor TerminalDisplay::keyboardCursorColor() const
     return _cursorColor;
 }
 
-void TerminalDisplay::setOpacity(qreal opacity)
+qreal TerminalDisplay::backgroundOpacity() const
 {
-    _opacity = qBound(static_cast<qreal>(0), opacity, static_cast<qreal>(1));
+    return _backgroundOpacity;
+}
+
+void TerminalDisplay::setBackgroundOpacity(qreal opacity)
+{
+    const qreal boundedOpacity = qBound(static_cast<qreal>(0), opacity, static_cast<qreal>(1));
+    if (qFuzzyCompare(_backgroundOpacity, boundedOpacity)) {
+        return;
+    }
+
+    _backgroundOpacity = boundedOpacity;
     update();
+    Q_EMIT backgroundOpacityChanged();
 }
 
 void TerminalDisplay::drawBackground(QPainter &painter, const QRect &rect, const QColor &backgroundColor, bool useOpacitySetting)
@@ -654,7 +666,7 @@ void TerminalDisplay::drawBackground(QPainter &painter, const QRect &rect, const
     // left to the widget style for a consistent look.
     if (useOpacitySetting) {
         QColor color(backgroundColor);
-        color.setAlphaF(_opacity);
+        color.setAlphaF(color.alphaF() * _backgroundOpacity);
 
         painter.save();
         painter.setCompositionMode(QPainter::CompositionMode_Source);
@@ -1367,7 +1379,7 @@ QRect TerminalDisplay::calculateTextArea(int topLeftX, int topLeftY, int startCo
 
 void TerminalDisplay::drawContents(QPainter &paint, const QRect &rect)
 {
-    // Draw opaque background
+    // Draw background
     drawBackground(paint, contentsRect(), _colorTable[DEFAULT_BACK_COLOR].color, true);
 
     QPoint tL = contentsRect().topLeft();
@@ -2978,7 +2990,6 @@ void TerminalDisplay::setColorScheme(const QString &name)
 
         setColorTable(cs->getColorTable());
 
-        setFillColor(cs->backgroundColor());
         _colorScheme = name;
         Q_EMIT colorSchemeChanged();
     }
diff --git a/lib/TerminalDisplay.h b/lib/TerminalDisplay.h
index 721272a..8448d9c 100644
--- a/lib/TerminalDisplay.h
+++ b/lib/TerminalDisplay.h
@@ -108,7 +108,7 @@ class KONSOLEPRIVATE_EXPORT TerminalDisplay : public QQuickPaintedItem
     Q_PROPERTY(bool blinkingCursor READ blinkingCursor WRITE setBlinkingCursor NOTIFY blinkingCursorStateChanged)
     Q_PROPERTY(bool antialiasText READ antialias WRITE setAntialias)
     Q_PROPERTY(QStringList availableColorSchemes READ availableColorSchemes NOTIFY availableColorSchemesChanged)
-    Q_PROPERTY(qreal backgroundOpacity READ opacity WRITE setOpacity NOTIFY opacityChanged)
+    Q_PROPERTY(qreal backgroundOpacity READ backgroundOpacity WRITE setBackgroundOpacity NOTIFY backgroundOpacityChanged)
 
 public:
     /** Constructs a new terminal display widget with the specified parent. */
@@ -133,8 +133,8 @@ public:
      */
     uint randomSeed() const;
 
-    /** Sets the opacity of the terminal display. */
-    void setOpacity(qreal opacity);
+    qreal backgroundOpacity() const;
+    void setBackgroundOpacity(qreal opacity);
 
     /**
      * This enum describes the location where the scroll bar is positioned in the display widget.
@@ -698,6 +698,7 @@ Q_SIGNALS:
     void fullCursorHeightChanged();
     void blinkingCursorStateChanged();
     void boldIntenseChanged();
+    void backgroundOpacityChanged();
 
 protected:
     bool event(QEvent *) override;
@@ -794,7 +795,7 @@ private:
     void drawTextFragment(QPainter &painter, const QRect &rect, const QString &text, const Character *style);
     // draws the background for a text fragment
     // if useOpacitySetting is true then the color's alpha value will be set to
-    // the display's transparency (set with setOpacity()), otherwise the background
+    // the display's transparency (set with setBackgroundOpacity()), otherwise the background
     // will be drawn fully opaque
     void drawBackground(QPainter &painter, const QRect &rect, const QColor &color, bool useOpacitySetting);
     // draws the cursor character
@@ -944,7 +945,7 @@ private:
 
     QSize _size;
 
-    qreal _opacity;
+    qreal _backgroundOpacity;
 
     // list of filters currently applied to the display.  used for links and
     // search highlight
diff --git a/src/contents/ui/TerminalPage.qml b/src/contents/ui/TerminalPage.qml
index 502b171..0e3dd2f 100644
--- a/src/contents/ui/TerminalPage.qml
+++ b/src/contents/ui/TerminalPage.qml
@@ -468,7 +468,7 @@ Kirigami.Page {
                         font.pixelSize: TerminalSettings.fontSize
 
                         colorScheme: TerminalSettings.colorScheme
-                        opacity: TerminalSettings.windowOpacity
+                        backgroundOpacity: TerminalSettings.windowOpacity
 
                         Component.onCompleted: {
                             if (!root.initialSessionCreated) {