From 726bf58428f937b9ef40684f2a5f38c590ce738b Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Tue, 15 Aug 2017 19:17:40 +0200
Subject: Handle multiscreen properly, make background persistent

---
 src/main.cpp | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 67 insertions(+), 7 deletions(-)

(limited to 'src/main.cpp')

diff --git a/src/main.cpp b/src/main.cpp
index c0ce7bc..50a8d38 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -11,18 +11,23 @@
 #include <QtDebug>
 #include <QSettings>
 #include <QIcon>
+#include <QPainter>
+#include <QMap>
 
 #include <iostream>
 
 #include "settings.h"
 #include "mainwindow.h"
+#include "x11util.h"
 
-QFile logfile;
-QTextStream ts;
+static void messageHandler(QtMsgType type, const QMessageLogContext&, const QString& msg)
+{
+    std::cerr << type << ": " << msg.toUtf8().constData() << '\n';
+}
 
-void messageHandler(QtMsgType type, const QMessageLogContext&, const QString& msg)
+static inline int size(const QRect& r)
 {
-    std::cerr << type << ": " << msg.toLatin1().data() << "\n";
+	return r.width() * r.height();
 }
 
 int main(int argc, char *argv[])
@@ -38,12 +43,66 @@ int main(int argc, char *argv[])
         QIcon::setThemeName(Settings().iconThemeName());
     }
 
+    // Build background for X server, in case we start a session that
+    // doesn't set one on its own this will make sure it's not simply
+    // black
+    QImage entire;
+	QSize desktopSize = QApplication::desktop()->size();
+	qDebug() << "Desktop full size is " << desktopSize;
+	entire = QImage(desktopSize, QImage::Format_RGB32);
+	QPainter painter(&entire);
+
+	// Get a list of non-overlapping screens, as this might lead to a broken
+	// greeter with main windows covering other login forms
+	QMap<int, QRect> screens;
+	for (int i = 0; i < QApplication::desktop()->screenCount(); ++i) {
+		QRect r = QApplication::desktop()->screenGeometry(i);
+		QMutableMapIterator<int, QRect>it(screens);
+		while (it.hasNext()) {
+			it.next();
+			if (!it.value().intersects(r))
+				continue;
+			// Overlap, bigger wins
+			if (size(it.value()) >= size(r)) {
+				// Existing is bigger
+				goto skip_rect;
+			}
+			// New is bigger, remove existing and keep going
+			it.remove();
+		}
+		// We reached here, so add new window
+		screens.insert(i, r);
+		skip_rect: ; // Do nothing
+	}
+	// Determine primary screen
+	int primary;
+	if (screens.contains(QApplication::desktop()->primaryScreen())) {
+		// Primary screen still in selection
+		primary = QApplication::desktop()->primaryScreen();
+	} else {
+		// Fallback to first one
+		primary = screens.begin().key();
+	}
+
+	// Now set up all the screens
     MainWindow *focusWindow = 0;
-    for (int i = 0; i < QApplication::desktop()->screenCount(); ++i) {
-        MainWindow *w = new MainWindow(i);
+    QMapIterator<int, QRect> it(screens);
+    while (it.hasNext()) {
+    	it.next();
+        MainWindow *w = new MainWindow(primary == it.key(), it.key(), it.value());
         w->show();
-        if (w->showLoginForm())
+        if (w->showLoginForm()) {
             focusWindow = w;
+        }
+        if (!entire.isNull()) {
+        	QPoint p = it.value().topLeft();
+        	painter.drawImage(p, w->getBackground());
+        }
+    }
+
+    if (!entire.isNull()) {
+    	qDebug() << "Setting x background";
+    	AddPixmapToBackground(entire.constBits(), entire.width(), entire.height(), 24, entire.bytesPerLine(), entire.byteCount());
     }
 
     // Ensure we set the primary screen's widget as active when there
@@ -55,3 +114,4 @@ int main(int argc, char *argv[])
 
     return a.exec();
 }
+
-- 
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