From 1237d944057d10ac68236405b7bcba9c686cf94c Mon Sep 17 00:00:00 2001
From: Hugo Mercier <hugo.mercier@oslandia.com>
Date: Fri, 3 Apr 2020 16:11:58 +0200
Subject: [PATCH] Defer mask source widget population (fixes #34942)

---
 src/gui/qgsmaskingwidget.cpp              | 19 +++++-
 src/gui/qgsmaskingwidget.h                |  4 +-
 src/gui/qgsmasksourceselectionwidget.cpp  |  1 +
 src/gui/qgssymbollayerselectionwidget.cpp |  1 +
 src/ui/qgsmaskingwidgetbase.ui            | 73 ++++++++++++-----------
 5 files changed, 61 insertions(+), 37 deletions(-)

diff --git a/src/gui/qgsmaskingwidget.cpp b/src/gui/qgsmaskingwidget.cpp
index 053020bcc54..4ff23ace0bc 100644
--- a/src/gui/qgsmaskingwidget.cpp
+++ b/src/gui/qgsmaskingwidget.cpp
@@ -14,6 +14,7 @@
  ***************************************************************************/
 
 #include <QSet>
+#include <QCheckBox>
 
 #include "qgsmaskingwidget.h"
 #include "qgsmasksourceselectionwidget.h"
@@ -42,6 +43,14 @@ QgsMaskingWidget::QgsMaskingWidget( QWidget *parent ) :
   {
     emit widgetChanged();
   } );
+
+  connect( mEditMaskSettingsGroup, &QGroupBox::toggled, this, [&]( bool on )
+  {
+    if ( on && mLayer )
+    {
+      populate();
+    }
+  } );
 }
 
 /**
@@ -133,8 +142,16 @@ QList<QPair<QgsSymbolLayerId, QList<QgsSymbolLayerReference>>> symbolLayerMasks(
 void QgsMaskingWidget::setLayer( QgsVectorLayer *layer )
 {
   mLayer = layer;
+  if ( mEditMaskSettingsGroup->isChecked() )
+  {
+    populate();
+  }
+}
+
+void QgsMaskingWidget::populate()
+{
   mMaskSourcesWidget->update();
-  mMaskTargetsWidget->setLayer( layer );
+  mMaskTargetsWidget->setLayer( mLayer );
 
   // collect masks and filter on those which have the current layer as destination
   QSet<QgsSymbolLayerId> maskedSymbolLayers;
diff --git a/src/gui/qgsmaskingwidget.h b/src/gui/qgsmaskingwidget.h
index 4d13a9d2893..13cb7af486b 100644
--- a/src/gui/qgsmaskingwidget.h
+++ b/src/gui/qgsmaskingwidget.h
@@ -48,7 +48,9 @@ class GUI_EXPORT QgsMaskingWidget: public QgsPanelWidget, private Ui::QgsMasking
     void widgetChanged();
 
   private:
-    QgsVectorLayer *mLayer;
+    QgsVectorLayer *mLayer = nullptr;
+    //! Populate the mask source and target widgets
+    void populate();
 };
 
 #endif
diff --git a/src/gui/qgsmasksourceselectionwidget.cpp b/src/gui/qgsmasksourceselectionwidget.cpp
index 576a4f387d9..8fc3d99241b 100644
--- a/src/gui/qgsmasksourceselectionwidget.cpp
+++ b/src/gui/qgsmasksourceselectionwidget.cpp
@@ -63,6 +63,7 @@ QgsMaskSourceSelectionWidget::QgsMaskSourceSelectionWidget( QWidget *parent )
 
   // place the tree in a layout
   QVBoxLayout *vbox = new QVBoxLayout();
+  vbox->setContentsMargins( 0, 0, 0, 0 );
   vbox->addWidget( mTree );
 
   setLayout( vbox );
diff --git a/src/gui/qgssymbollayerselectionwidget.cpp b/src/gui/qgssymbollayerselectionwidget.cpp
index b7368a9d8a0..fe27527221d 100644
--- a/src/gui/qgssymbollayerselectionwidget.cpp
+++ b/src/gui/qgssymbollayerselectionwidget.cpp
@@ -37,6 +37,7 @@ QgsSymbolLayerSelectionWidget::QgsSymbolLayerSelectionWidget( QWidget *parent )
 
   // place the tree in a layout
   QVBoxLayout *vbox = new QVBoxLayout();
+  vbox->setContentsMargins( 0, 0, 0, 0 );
   vbox->addWidget( mTree );
 
   setLayout( vbox );
diff --git a/src/ui/qgsmaskingwidgetbase.ui b/src/ui/qgsmaskingwidgetbase.ui
index a0e58a370ba..bca2671bc6c 100644
--- a/src/ui/qgsmaskingwidgetbase.ui
+++ b/src/ui/qgsmaskingwidgetbase.ui
@@ -6,51 +6,54 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>637</width>
-    <height>409</height>
+    <width>863</width>
+    <height>461</height>
    </rect>
   </property>
   <property name="windowTitle">
    <string>Form</string>
   </property>
-  <layout class="QVBoxLayout" name="verticalLayout">
-   <property name="spacing">
-    <number>0</number>
-   </property>
-   <property name="leftMargin">
-    <number>0</number>
-   </property>
-   <property name="topMargin">
-    <number>0</number>
-   </property>
-   <property name="rightMargin">
-    <number>0</number>
-   </property>
-   <property name="bottomMargin">
-    <number>0</number>
-   </property>
+  <layout class="QVBoxLayout" name="verticalLayout_2">
    <item>
-    <widget class="QLabel" name="label">
-     <property name="text">
-      <string>Masked symbol layers</string>
+    <widget class="QGroupBox" name="mEditMaskSettingsGroup">
+     <property name="title">
+      <string>Edit mask settings</string>
      </property>
-    </widget>
-   </item>
-   <item>
-    <widget class="QgsSymbolLayerSelectionWidget" name="mMaskTargetsWidget" native="true"/>
-   </item>
-   <item>
-    <widget class="QLabel" name="label_2">
-     <property name="text">
-      <string>Mask sources</string>
+     <property name="checkable">
+      <bool>true</bool>
      </property>
-    </widget>
-   </item>
-   <item>
-    <widget class="QgsMaskSourceSelectionWidget" name="mMaskSourcesWidget" native="true">
-     <property name="enabled">
+     <property name="checked">
       <bool>false</bool>
      </property>
+     <layout class="QVBoxLayout" name="verticalLayout">
+      <property name="leftMargin">
+       <number>9</number>
+      </property>
+      <item>
+       <widget class="QLabel" name="label">
+        <property name="text">
+         <string>Masked symbol layers</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QgsSymbolLayerSelectionWidget" name="mMaskTargetsWidget" native="true"/>
+      </item>
+      <item>
+       <widget class="QLabel" name="label_2">
+        <property name="text">
+         <string>Mask sources</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QgsMaskSourceSelectionWidget" name="mMaskSourcesWidget" native="true">
+        <property name="enabled">
+         <bool>false</bool>
+        </property>
+       </widget>
+      </item>
+     </layout>
     </widget>
    </item>
   </layout>