Re-fix output window. Scrolling was messed up when long paragraphs with

line wrap were appended, also appendOutput and appendOutputInline ended
up doing almost the same thing. It might be that appendOutput is called
in some places where appendOutputInline would be more adequate. The code
now tries to called QPlainTextEdit::appendPlainText() whenever it can
because of its update optimizations when it comes to enforcing maximum
block count. We want application output to be processed fast, even if
the maximum block count was reached!

src/plugins/projectexplorer/outputwindow.cpp

@@ -340,6 +340,8 @@ bool OutputPane::canNavigate()
 OutputWindow::OutputWindow(QWidget *parent)
     : QPlainTextEdit(parent)
 {
+    m_enforceNewline = false;
+
     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
     //setCenterOnScroll(false);
     setWindowTitle(tr("Application Output Window"));
@@ -392,14 +394,13 @@ OutputWindow::~OutputWindow()
 
 void OutputWindow::appendOutput(const QString &out)
 {
+    QString s = out;
+    m_enforceNewline = true; // make appendOutputInline put in a newline next time
+    if (s.endsWith(QLatin1Char('\n'))) {
+        s.chop(1);
+    }
     setMaximumBlockCount(MaxBlockCount);
-    moveCursor(QTextCursor::End);
-    if (out.endsWith('\n'))
-        insertPlainText(out.right(out.length()-1));
-    else
-        insertPlainText(out);
-    // insert newline and get automatic scroll behavior
-    appendPlainText(""); // makes sure that there's an newline in front
+    appendPlainText(out);
     enableUndoRedo();
 }
 
@@ -408,26 +409,32 @@ void OutputWindow::appendOutputInline(const QString &out)
 {
     setMaximumBlockCount(MaxBlockCount);
 
-    int newline = out.indexOf(QLatin1Char('\n'));
-    if (newline < 0) {
+    int newline = -1;
+    bool enforceNewline = m_enforceNewline;
+    m_enforceNewline = false;
+
+    if (!enforceNewline) {
+        newline = out.indexOf(QLatin1Char('\n'));
         moveCursor(QTextCursor::End);
-        insertPlainText(out); // doesn't insert additional '\n' like appendPlainText
-    }else{
-        int lastnewline = out.lastIndexOf(QLatin1Char('\n'));
-        // make sure that we use appendPlainText to add the last newline
-        // in the string, so we get automatic scrolling
-        // and work around the fact that appendPlainText also ensures
-        // a newline in front of the appended text
-        if (lastnewline > 0) {
-            moveCursor(QTextCursor::End);
-            insertPlainText(out.left(lastnewline));
-        }
-        appendPlainText(""); // add the newline
-        if (lastnewline < out.length()-1) { // newline is not last character
-            moveCursor(QTextCursor::End);
-            insertPlainText(out.mid(lastnewline+1));
-        }
+        bool atBottom = (blockBoundingRect(document()->lastBlock()).bottom() + contentOffset().y()
+                         <= viewport()->rect().bottom());
+        insertPlainText(newline < 0 ? out : out.left(newline)); // doesn't enforce new paragraph like appendPlainText
+        if (atBottom)
+            verticalScrollBar()->setValue(verticalScrollBar()->maximum());
     }
+
+    QString s = out.mid(newline+1);
+    if (s.isEmpty()) {
+        m_enforceNewline = true;
+    } else {
+        if (s.endsWith(QLatin1Char('\n'))) {
+            m_enforceNewline = true;
+            qDebug() << "CHOP";
+            s.chop(1);
+        }
+        appendPlainText(s);
+    }
+
     enableUndoRedo();
 }
 

src/plugins/projectexplorer/outputwindow.h

@@ -129,6 +129,7 @@ public:
 private:
     Core::BaseContext *m_outputWindowContext;
     void enableUndoRedo();
+    bool m_enforceNewline;
 };
 
 #if 0