[Patch] Enforce end pressure not to be above starting pressure

[Linus Torvalds]

On Sat, Aug 2, 2014 at 4:13 PM, Dirk Hohndel <dirk at hohndel.org> wrote:
>
> I usually think the same, but we have several people filing bugs that
> complain that you can enter silly pressure values (start at 230bar, end at
> 1200bar)
>
> There's no way we'll make everyone happy.

How about showing them in red or something? We already do special
things for pressure: we set a different font when the pressure comes
from the samples, for example.

Here's a patch that does exactly that. It works, but I wouldn't
suggest taking it as-is simply because of the whole hardcoding of
red-vs-white background. There's presumably some way to set it to
default values - somebody who knows more about Qt would know.

I really think it's wrong to try to say "you can't do that". And part
of it really is that you might want to *fix* things, and then having
to fix it in "just the right order" (because the wrong order results
in higher end pressures than beginning pressures _momentarily_) is
actually really annoying.

Making it visually clear that "you did something wrong" is a *much*
better option, I think.

             Linus
-------------- next part --------------
 qt-ui/models.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/qt-ui/models.cpp b/qt-ui/models.cpp
index 6cf5c2bd24b3..c38b4b6bb35e 100644
--- a/qt-ui/models.cpp
+++ b/qt-ui/models.cpp
@@ -95,6 +95,15 @@ QVariant CylindersModel::data(const QModelIndex &index, int role) const
 
 	cylinder_t *cyl = &displayed_dive.cylinder[index.row()];
 	switch (role) {
+	case Qt::BackgroundRole: {
+		switch (index.column()) {
+		case START:
+		case END:
+			if (cyl->start.mbar < cyl->end.mbar)
+				return QColor("red");
+		}
+		return QColor("white");
+	}
 	case Qt::FontRole: {
 		QFont font = defaultModelFont();
 		switch (index.column()) {