Add a Representation component

Add a Page-derived component intended as a root
for full representations.
It may go over the plasmoid edges (both on desktop and popups)
with the properties applyHorizontalPadding and applyVerticalPadding.
When the contentItem is a ScrollView or a Scrollarea,
the plasmoid margins will be automatically removed.

src/declarativeimports/plasmaextracomponents/qml/PlasmoidHeading.qml

@@ -39,22 +39,25 @@ import QtQuick.Templates 2.12 as T
     property int location: PlasmoidHeading.Location.Header
 
     Layout.fillWidth: true
-    bottomPadding: location == PlasmoidHeading.Location.Footer ? 0 : headingSvg.fixedMargins.top
-    topPadding: location == PlasmoidHeading.Location.Footer ? headingSvg.fixedMargins.bottom : 0
+    bottomPadding: !headingSvg.applicationFormFactor && location == PlasmoidHeading.Location.Footer ? 0 : headingSvg.fixedMargins.bottom
+    topPadding: headingSvg.applicationFormFactor || location == PlasmoidHeading.Location.Footer ? headingSvg.fixedMargins.bottom : 0
+    leftPadding: headingSvg.applicationFormFactor ? headingSvg.fixedMargins.left : 0
+    rightPadding: headingSvg.applicationFormFactor ? headingSvg.fixedMargins.right : 0
 
     implicitHeight: Math.max(implicitBackgroundHeight + topInset + bottomInset, implicitContentHeight + topPadding + bottomPadding)
     implicitWidth: Math.max(implicitBackgroundWidth + leftInset + rightInset, implicitContentWidth + leftPadding + rightPadding)
 
-    leftInset: -headingSvg.fixedMargins.left
-    rightInset: -headingSvg.fixedMargins.right
-    topInset: location == PlasmoidHeading.Location.Footer ? 0 : -headingSvg.fixedMargins.top
-    bottomInset: location == PlasmoidHeading.Location.Footer ? -headingSvg.fixedMargins.bottom : 0
+    leftInset: headingSvg.applicationFormFactor ? 0 : -headingSvg.fixedMargins.left
+    rightInset: headingSvg.applicationFormFactor ? 0 : -headingSvg.fixedMargins.right
+    topInset: headingSvg.applicationFormFactor || location == PlasmoidHeading.Location.Footer ? 0 : -headingSvg.fixedMargins.top
+    bottomInset: !headingSvg.applicationFormFactor && location == PlasmoidHeading.Location.Footer ? -headingSvg.fixedMargins.bottom : 0
 
     PlasmaCore.ColorScope.colorGroup: location == PlasmoidHeading.Location.Header ? PlasmaCore.Theme.HeaderColorGroup : PlasmaCore.Theme.WindowColorGroup
     PlasmaCore.ColorScope.inherit: false
 
     background: PlasmaCore.FrameSvgItem {
         id: headingSvg
+        readonly property bool applicationFormFactor: typeof plasmoid !== "undefined" && plasmoid.formFactor === PlasmaCore.Types.Application
         visible: fromCurrentTheme
         imagePath: "widgets/plasmoidheading"
         prefix: location == PlasmoidHeading.Location.Header? 'header' : 'footer'

src/declarativeimports/plasmaextracomponents/qml/Representation.qml

@@ -0,0 +1,75 @@
+/*
+    SPDX-FileCopyrightText: 2020 Marco Martin <mart@kde.org>
+
+    SPDX-License-Identifier: LGPL-2.0-or-later
+*/
+
+import QtQuick 2.12
+import QtQuick.Layouts 1.12
+import QtQuick.Window 2.2
+
+import org.kde.plasma.core 2.0 as PlasmaCore
+import org.kde.plasma.components 3.0 as PlasmaComponents
+import org.kde.plasma.components 2.0 as PlasmaExtras
+
+ /**
+  * Item to be used as root item for representations (full and compact) of plasmoids.
+  * It's a QtQuickControls2 Page, and like that one, has an header, a contentItem and a Footer
+  * It may go over the plasmoid edges (both on desktop and popups) with the properties applyHorizontalPadding and applyVerticalPadding.
+  * When the contentItem is a ScrollView or a Scrollarea, the plasmoid margins will be automatically removed.
+  *
+  * This code will create a full representation with a listview that will automatically 
+  * full the whole area without margins from the plasmoid popup borders
+  * @code
+  * Plasmoid.Representation: PlasmaExtras.Representation {
+  *     header: PlasmaExtras.BasicPlasmoidHeading{}
+  *     contentItem: PlasmaComponent.ScrollView {
+  *         ListView {
+  *             ....
+  *         }
+  *     }
+  * }
+  * @endcode
+  *
+  * @since 5.77
+  * @inherit QtQuick.Templates.Page
+  */
+ 
+ PlasmaComponents.Page {
+    id: control
+
+    // TODO KF6: should become possible to set the paddings directly (which won't be negative anymore)
+    /**
+     * collapseMarginsHint: bool
+     * if true, the representation will remove any borders its container may have put and will be collapsed above its borders
+     */
+    property bool collapseMarginsHint: (control.contentItem instanceof PlasmaComponents.ScrollView) || (control.contentItem instanceof ScrollArea)
+
+    leftPadding: backgroundMetrics.getMargin("left")
+    rightPadding: backgroundMetrics.getMargin("right")
+    topPadding: header ? 0 : backgroundMetrics.getMargin("top")
+    bottomPadding: footer ? 0 : backgroundMetrics.getMargin("bottom")
+
+    PlasmaCore.FrameSvgItem {
+        id: backgroundMetrics
+        visible: false
+        imagePath: {
+            if (control.Window.window && (control.Window.window instanceof PlasmaCore.Dialog)) {
+                return "dialogs/background";
+            } else if (plasmoid.formFactor == PlasmaCore.Types.Planar) {
+                return "widgets/background";
+            // panels and other formfactors are explicitly not supported
+            } else {
+                return "";
+            }
+        }
+        readonly property bool hasInset: backgroundMetrics.inset.left >= 0 && backgroundMetrics.inset.right >= 0 && backgroundMetrics.inset.top >= 0 && backgroundMetrics.inset.bottom >= 0
+        function getMargin(margin) {
+            if (!hasInset) {
+                return 0;
+            } else {
+                return control.collapseMarginsHint ? -backgroundMetrics.fixedMargins[margin] + backgroundMetrics.inset[margin] : 0
+            }
+        }
+    }
+ }

src/declarativeimports/plasmaextracomponents/qml/qmldir

@@ -14,6 +14,7 @@ Title 2.0 Title.qml
 DescriptiveLabel 2.0 DescriptiveLabel.qml
 PlasmoidHeading 2.0 PlasmoidHeading.qml
 BasicPlasmoidHeading 2.0 BasicPlasmoidHeading.qml
+Representation 2.0 Representation.qml
 
 ActivateAnimation 2.0 animations/ActivateAnimation.qml
 AppearAnimation 2.0 animations/AppearAnimation.qml

src/plasmaquick/dialog.cpp

@@ -1079,6 +1079,11 @@ QObject *Dialog::margins() const
     return d->frameSvgItem->fixedMargins();
 }
 
+QObject *Dialog::inset() const
+{
+    return d->frameSvgItem->inset();
+}
+
 void Dialog::setFramelessFlags(Qt::WindowFlags flags)
 {
     if (d->type == Dialog::Normal)

src/plasmaquick/dialog.h

@@ -89,6 +89,13 @@ class PLASMAQUICK_EXPORT Dialog : public QQuickWindow, public QQmlParserStatus
      */
     Q_PROPERTY(QObject *margins READ margins CONSTANT)
 
+    /**
+     * Margins where the dialog background actually starts, excluiding things like shadows or borders
+     * @see DialogMargins
+     * @since 5.77
+     */
+    Q_PROPERTY(QObject *inset READ inset CONSTANT)
+
     /**
      * Plasma Location of the dialog window. Useful if this dialog is a popup for a panel
      */
@@ -170,6 +177,7 @@ public:
     void setLocation(Plasma::Types::Location location);
 
     QObject *margins() const;
+    QObject *inset() const;
 
     void setFramelessFlags(Qt::WindowFlags flags);