[raster] reduce the copious quantity of double truncation/clamping warnings

[dustymugs]

Minimize the volume of double value truncation warnings. This will entail the addition of the ./configure flag —with-raster-dblwarning.

If —with-raster-dblwarning is passed to ./configure, the current behavior of providing a warning for every truncation/clamping will continue.

If —with-raster-dblwarning is NOT passed, a minimal (one-time?) warning should occur.

Once the minimal warning is set, all regressions will need to be updated.

[dustymugs]

Instead of providing a minimal warning if —with-raster-dblwarning is NOT passed, NO warning should be provided.

[dustymugs]

Resolved in r8181.

[pracine]

So there will be no option for those not compiling PostGIS to know if the values have been clamped or not?

[dustymugs]

Unfortunately yes. The problem is many-fold.

Having the warnings enabled will cause flooding as rasters get larger and does affect the amount of data transmitted between the server and the client.

On the other hand, having no warning can cause ignorance on the part of the end-user. And if you have a flood, the end-user is most likely to ignore the warnings anyways. Granted, it isn't like the end-user is able to prevent the truncation/clamping/conversion process anyways as all values are handled as doubles until burning into the band object.

The ideal would be to warn that a raster may experience truncation/clamping/conversion but every raster regardless of pixel type can experience truncation/clamping/conversion so the warning is kinda frivolous.