Qt: Force integer font metrics in the byte view.

Force the layout engine to use integer arithmetic so that we don't run
into wierd rounding artifacts.

Include the leading when applying formats.

Restrict the hover line width to either 0.5 or 1 logical pixels.

Change-Id: Icc992e085e96e328ed4ed247271f75ddd69637bc
Reviewed-on: https://code.wireshark.org/review/25381
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot
Reviewed-by: Gerald Combs <gerald@wireshark.org>

1 files changed, 15 insertions, 12 deletions

diff --git a/ui/qt/widgets/byte_view_text.cpp b/ui/qt/widgets/byte_view_text.cpp
index 58a0a6f75b..988f64c578 100644
--- a/ui/qt/widgets/byte_view_text.cpp
+++ b/ui/qt/widgets/byte_view_text.cpp
@@ -162,13 +162,15 @@ void ByteViewText::markAppendix(int start, int length)
 
 void ByteViewText::setMonospaceFont(const QFont &mono_font)
 {
-    mono_font_ = mono_font;
+    mono_font_ = QFont(mono_font);
+    mono_font_.setStyleStrategy(QFont::ForceIntegerMetrics);
 
-    const QFontMetricsF fm(mono_font);
+    const QFontMetricsF fm(mono_font_);
     font_width_  = fm.width('M');
 
-    setFont(mono_font);
-    layout_->setFont(mono_font);
+    setFont(mono_font_);
+    viewport()->setFont(mono_font_);
+    layout_->setFont(mono_font_);
 
     // We should probably use ProtoTree::rowHeight.
     line_height_ = fontMetrics().height();
@@ -181,7 +183,6 @@ void ByteViewText::paintEvent(QPaintEvent *)
 {
     QPainter painter(viewport());
     painter.translate(-horizontalScrollBar()->value() * font_width_, 0);
-    painter.setFont(mono_font_);
 
     // Pixel offset of this row
     int row_y = 0;
@@ -205,13 +206,14 @@ void ByteViewText::paintEvent(QPaintEvent *)
 
     // Data rows
     int widget_height = height();
+    int leading = fontMetrics().leading();
     painter.save();
 
     x_pos_to_column_.clear();
     while( (int) (row_y + line_height_) < widget_height && offset < (int) data_.count()) {
         drawLine(&painter, offset, row_y);
         offset += row_width_;
-        row_y += line_height_;
+        row_y += line_height_ + leading;
     }
 
     painter.restore();
@@ -219,14 +221,16 @@ void ByteViewText::paintEvent(QPaintEvent *)
     // We can't do this in drawLine since the next line might draw over our rect.
     if (!hover_outlines_.isEmpty()) {
         qreal pen_width = 1.0;
-    #if QT_VERSION >= QT_VERSION_CHECK(5, 1, 0)
-        pen_width = 1.0 / devicePixelRatio();
-    #endif
         QPen ho_pen;
         QColor ho_color = palette().text().color();
         ho_color.setAlphaF(0.5);
         ho_pen.setColor(ho_color);
         ho_pen.setWidthF(pen_width);
+#if QT_VERSION >= QT_VERSION_CHECK(5, 1, 0)
+        if (devicePixelRatio() > 1) {
+            pen_width = 0.5;
+        }
+#endif
 
         painter.save();
         painter.setPen(ho_pen);
@@ -451,7 +455,7 @@ void ByteViewText::drawLine(QPainter *painter, const int offset, const int row_y
     layout_->beginLayout();
     QTextLine tl = layout_->createLine();
     tl.setLineWidth(totalPixels());
-    tl.setPosition(QPointF(0.0, 0.0));
+    tl.setLeadingIncluded(true);
     layout_->endLayout();
     layout_->draw(painter, QPointF(0.0, row_y));
 }
@@ -464,7 +468,6 @@ bool ByteViewText::addFormatRange(QList<QTextLayout::FormatRange> &fmt_list, int
     QTextLayout::FormatRange format_range;
     format_range.start = start;
     format_range.length = length;
-    format_range.format.setProperty(QTextFormat::LineHeight, line_height_);
     switch (mode) {
     case ModeNormal:
         return false;
@@ -482,7 +485,7 @@ bool ByteViewText::addFormatRange(QList<QTextLayout::FormatRange> &fmt_list, int
         break;
     case ModeMarked:
         // XXX Should we get rid of byteViewMarkColor and just draw an
-        // overline + underline instead?
+        // outline instead?
         format_range.format.setForeground(ColorUtils::byteViewMarkColor(false));
         format_range.format.setBackground(ColorUtils::byteViewMarkColor(true));
         break;