Mark insets with invalid buffer() in red in devel-mode.

We tend to have insets which buffer() member is invalid. To help
debugging, this commit paints their background in red when devel-mode
is on.

To this end, a new method develMode() is added to the Painter class.

With this commit, it is easy to see that macro template do not have a
proper buffer set!

src/MetricsInfo.cpp

@@ -158,19 +158,21 @@ ColorCode PainterInfo::backgroundColor(Inset const * inset, bool sel) const
 	if (selected && sel)
 		// This inset is in a selection
 		return Color_selection;
-	else {
-		if (color_bg != Color_none)
-			// This inset has its own color
-			return color_bg;
-		else {
-			if (background_color == Color_none)
-				// This inset has no own color and does not inherit a color
-				return Color_background;
-			else
-				// This inset has no own color, but inherits a color
-				return background_color;
-		}
-	}
+
+	if (pain.develMode() && !inset->isBufferValid())
+		// This inset is in error
+		return Color_error;
+
+	if (color_bg != Color_none)
+		// This inset has its own color
+		return color_bg;
+
+	if (background_color == Color_none)
+		// This inset has no own color and does not inherit a color
+		return Color_background;
+
+	// This inset has no own color, but inherits a color
+	return background_color;
 }
 
 

src/frontends/NullPainter.h

@@ -25,7 +25,7 @@ namespace frontend {
  */
 class NullPainter : public Painter {
 public:
-	NullPainter() : Painter(1) {}
+	NullPainter() : Painter(1, false) {}
 
 	~NullPainter() {}
 

src/frontends/Painter.h

@@ -49,7 +49,8 @@ namespace frontend {
  */
 class Painter {
 public:
-	Painter(double pixel_ratio) : pixel_ratio_(pixel_ratio) {}
+	Painter(double pixel_ratio, bool devel_mode)
+		: pixel_ratio_(pixel_ratio), devel_mode_(devel_mode) {}
 
 	static const int thin_line;
 
@@ -152,6 +153,8 @@ public:
 
 	double pixelRatio() const { return pixel_ratio_; }
 
+	double develMode() const { return devel_mode_; }
+
 	/// draw the underbar, strikeout, xout, uuline and uwave font attributes
 	virtual void textDecoration(FontInfo const & f, int x, int y, int width) = 0;
 
@@ -182,6 +185,8 @@ public:
 private:
 	/// Ratio between physical pixels and device-independent pixels
 	double pixel_ratio_;
+	/// True when developer more is on at application-level.
+	bool devel_mode_;
 };
 
 } // namespace frontend

src/frontends/qt/GuiPainter.cpp

@@ -39,8 +39,8 @@ namespace frontend {
 
 const int Painter::thin_line = 1;
 
-GuiPainter::GuiPainter(QPaintDevice * device, double pixel_ratio)
-	: QPainter(device), Painter(pixel_ratio)
+GuiPainter::GuiPainter(QPaintDevice * device, double pixel_ratio, bool devel_mode)
+	: QPainter(device), Painter(pixel_ratio, devel_mode)
 {
 	// set cache correctly
 	current_color_ = pen().color();

src/frontends/qt/GuiPainter.h

@@ -34,7 +34,7 @@ namespace frontend {
  */
 class GuiPainter : public QPainter, public Painter {
 public:
-	GuiPainter(QPaintDevice *, double pixel_ratio);
+	GuiPainter(QPaintDevice *, double pixel_ratio, bool devel_mode);
 	virtual ~GuiPainter();
 
 	/// This painter paints

src/frontends/qt/GuiWorkArea.cpp

@@ -1330,7 +1330,7 @@ void GuiWorkArea::paintEvent(QPaintEvent * ev)
 
 	d->last_pixel_ratio_ = pixelRatio();
 
-	GuiPainter pain(d->screenDevice(), pixelRatio());
+	GuiPainter pain(d->screenDevice(), pixelRatio(), d->lyx_view_->develMode());
 
 	d->buffer_view_->draw(pain, d->caret_visible_);
 

src/mathed/MathRow.cpp

@@ -326,6 +326,9 @@ void MathRow::draw(PainterInfo & pi, int x, int const y) const
 			Dimension d2 = d;
 			d2.wid -= e.before + e.after;
 			coords.insets().add(e.inset, d2);
+			if (pi.pain.develMode() && !e.inset->isBufferValid())
+				pi.pain.fillRectangle(x + e.before, y - d2.ascent(),
+				                      d2.width(), d2.height(), Color_error);
 			e.inset->draw(pi, x + e.before, y);
 			coords.insets().add(e.inset, x, y);
 			coords.insets().add(e.inset, d);