[gui] intro: add prune preference

Adds a checkbox to the introduction screen letting the user enable pruning from the start.
Disable checkbox when launched with -prune

src/qt/bitcoin.cpp

@@ -492,8 +492,9 @@ int GuiMain(int argc, char* argv[])
     /// 5. Now that settings and translations are available, ask user for data directory
     // User language is set up: pick a data directory
     bool did_show_intro = false;
+    bool prune = false; // Intro dialog prune check box
     // Gracefully exit if the user cancels
-    if (!Intro::showIfNeeded(*node, did_show_intro)) return EXIT_SUCCESS;
+    if (!Intro::showIfNeeded(*node, did_show_intro, prune)) return EXIT_SUCCESS;
 
     /// 6. Determine availability of data directory and parse bitcoin.conf
     /// - Do not call GetDataDir(true) before this step finishes
@@ -567,6 +568,11 @@ int GuiMain(int argc, char* argv[])
     // Load GUI settings from QSettings
     app.createOptionsModel(gArgs.GetBoolArg("-resetguisettings", false));
 
+    if (did_show_intro) {
+        // Store intro dialog settings other than datadir (network specific)
+        app.SetPrune(prune, true);
+    }
+
     if (gArgs.GetBoolArg("-splash", DEFAULT_SPLASHSCREEN) && !gArgs.GetBoolArg("-min", false))
         app.createSplashScreen(networkStyle.data());
 

src/qt/forms/intro.ui

@@ -210,6 +210,16 @@
      </property>
     </widget>
    </item>
+   <item>
+    <widget class="QCheckBox" name="prune">
+     <property name="toolTip">
+      <string>Reverting this setting requires re-downloading the entire blockchain. It is faster to download the full chain first and prune it later. Disables some advanced features.</string>
+     </property>
+     <property name="text">
+      <string></string>
+     </property>
+    </widget>
+   </item>
    <item>
     <widget class="QLabel" name="lblExplanation2">
      <property name="text">

src/qt/intro.cpp

@@ -131,6 +131,11 @@ Intro::Intro(QWidget *parent, uint64_t blockchain_size, uint64_t chain_state_siz
     ui->lblExplanation2->setText(ui->lblExplanation2->text().arg(PACKAGE_NAME));
 
     uint64_t pruneTarget = std::max<int64_t>(0, gArgs.GetArg("-prune", 0));
+    if (pruneTarget > 1) { // -prune=1 means enabled, above that it's a size in MB
+        ui->prune->setChecked(true);
+        ui->prune->setEnabled(false);
+    }
+    ui->prune->setText(tr("Discard blocks after verification, except most recent %1 GB (prune)").arg(pruneTarget ? pruneTarget / 1000 : 2));
     requiredSpace = m_blockchain_size;
     QString storageRequiresMsg = tr("At least %1 GB of data will be stored in this directory, and it will grow over time.");
     if (pruneTarget) {
@@ -180,7 +185,7 @@ void Intro::setDataDirectory(const QString &dataDir)
     }
 }
 
-bool Intro::showIfNeeded(interfaces::Node& node, bool& did_show_intro)
+bool Intro::showIfNeeded(interfaces::Node& node, bool& did_show_intro, bool& prune)
 {
     did_show_intro = false;
 
@@ -230,6 +235,9 @@ bool Intro::showIfNeeded(interfaces::Node& node, bool& did_show_intro)
             }
         }
 
+        // Additional preferences:
+        prune = intro.ui->prune->isChecked();
+
         settings.setValue("strDataDir", dataDir);
         settings.setValue("fReset", false);
     }

src/qt/intro.h

@@ -39,6 +39,7 @@ public:
 
     /**
      * Determine data directory. Let the user choose if the current one doesn't exist.
+     * Let the user configure additional preferences such as pruning.
      *
      * @returns true if a data directory was selected, false if the user cancelled the selection
      * dialog.
@@ -46,7 +47,7 @@ public:
      * @note do NOT call global GetDataDir() before calling this function, this
      * will cause the wrong path to be cached.
      */
-    static bool showIfNeeded(interfaces::Node& node, bool& did_show_intro);
+    static bool showIfNeeded(interfaces::Node& node, bool& did_show_intro, bool& prune);
 
 Q_SIGNALS:
     void requestCheck();