Size the cable target box to the cross bar

The box hugged its own text, so it stayed small whatever room the end
zone gave, and its font shrank until the three lines squeezed into it.
It now spans the cross bar the cable bundle ends on -- the width the
strip already draws there -- and keeps the font of the drawing: when
its lines (Installation, Location and Label) are longer than that cross
bar, it is the box which grows, the text is never cut down to fit a box.
The end zone of the default layout leaves the room those three lines
need at that font, so a target is not squeezed by the drawing itself.
The setting still rules it: a smaller zone shrinks the text again.

tst_cabletarget checks the box is drawn three lines tall at the font
of the drawing, and that the default zone leaves that room.

tests/qttest/tst_cabletarget.cpp

@@ -47,6 +47,10 @@
 	its mark and the terminal -- it shrinks, and what does not fit is
 	clipped, so it never runs into the drawing of the terminal.
 
+	Also here: the box at the end of a cable is written at the font of
+	the drawing -- the end zone the settings leave is what gives it the
+	room, so three lines never end up squeezed into a tiny text.
+
 	fixtures/every_feature.qet has the strip X1 (elements 891b70f2 and
 	4861e268) and the contact fc9cc920 wired to 891b70f2 by the
 	conductor 8bd16d7a; the test gives the contact the Installation,
@@ -164,6 +168,7 @@ private slots:
 	void spareHasNoTarget();
 	void paintsWithTargetBox();
 	void wireLabelStaysOutOfTheTerminal();
+	void targetBoxKeepsTheDrawingFont();
 };
 
 void tst_cabletarget::init()
@@ -371,6 +376,75 @@ void tst_cabletarget::wireLabelStaysOutOfTheTerminal()
 	}
 }
 
+/**
+	The box at the end of a cable keeps the font of the drawing: with
+	its three lines (Installation, Location and Label) and the end zone
+	the settings leave, the text is still written at the font of the
+	strip instead of being squeezed into a tiny one. The box is the
+	lowest thing the strip draws, so its bottom line is the lowest
+	painted row, and it must land where three lines of that font need
+	it to.
+*/
+void tst_cabletarget::targetBoxKeepsTheDrawingFont()
+{
+	QVERIFY(wireCableToTheContact());
+
+	auto pattern_ = QSharedPointer<TerminalStripLayoutPattern>{new TerminalStripLayoutPattern};
+	const auto strips_ = m_project->terminalStrip();
+	QVERIFY(!strips_.isEmpty());
+	TerminalStripDrawer::TerminalStripDrawer drawer{
+		QSharedPointer<TerminalStripDrawer::TrueTerminalStrip>{
+			new TerminalStripDrawer::TrueTerminalStrip{strips_.first()}},
+		pattern_};
+
+	const QRectF bounds{drawer.boundingRect()};
+	QVERIFY(!bounds.isEmpty());
+	QImage image{bounds.size().toSize() + QSize{4, 4},
+				 QImage::Format_ARGB32_Premultiplied};
+	image.fill(Qt::transparent);
+	QPainter painter{&image};
+	painter.translate(-bounds.topLeft() + QPointF{2, 2});
+	drawer.paint(&painter);
+	painter.end();
+
+	qreal lowest{-1};
+	for (auto y = 0 ; y < image.height() ; ++y)
+	{
+		for (auto x = 0 ; x < image.width() ; ++x)
+		{
+			if (image.pixel(x, y) != qRgba(0, 0, 0, 0)) {
+				lowest = y;
+				break;
+			}
+		}
+	}
+	QVERIFY(lowest >= 0);
+
+		//The end zone the default layout leaves is what gives the box its
+		//room: three lines of the default font must fit in it, or the text
+		//of a target is squeezed down again by the drawing itself
+	const QFontMetricsF metrics{pattern_->font()};
+	const qreal room{pattern_->m_cable_end_length
+					 - qMin<qreal>(6, pattern_->m_cable_end_length)};
+	QVERIFY2(metrics.height() * 3 + 4 <= room,
+			 "the default end zone leaves no room for three lines of the "
+			 "default font, a target would be squeezed again");
+
+		//Where the bottom line of the box lands when it holds the three
+		//lines of its text at the font of the drawing
+	const qreal terminals_bottom{pattern_->m_terminal_rect.at(3).bottom()};
+	const qreal bar_2{terminals_bottom + pattern_->m_cable_wire_length
+					  + pattern_->m_cable_length};
+	const qreal box_bottom{bar_2 + qMin<qreal>(6, pattern_->m_cable_end_length)
+						   + metrics.height() * 3 + 4};
+
+		//The strip draws nothing under the box, so the lowest painted row
+		//is its bottom line -- within a pixel, the outline of a rectangle
+		//is painted on its edge
+	const qreal row{box_bottom - bounds.top() + 2};
+	QVERIFY(lowest + 2 >= row);
+}
+
 int main(int argc, char **argv)
 {
 	QStandardPaths::setTestModeEnabled(true);