Chart BackgroundImage

[pex]

Hello,
I was using TeeChart Pro v2013.08.130521 32bit VCL with XE3 C++ Builder and recently switched to XE6 with TeeChart v2014.11.140512.

I'm using teechart as kind of a graphic osciloscope. Picture generated elsewhere and stored in TBitmap is shown as a background of a chart using TChart->BackImage->Assign(TBitmap). In old version it looked like this:



Pixels could be clearly distinguished even with zoom.
With new version it looks like this:



Picture is anti-aliased and white background become grayish. No code has changed since the upgrade. Is there any way to make it look like before?
P.S. I have also noticed that the new version is significantly slower, than before.

[Yeray]

Hi,

Last versions of TeeChart switched the default engine from GDI to GDIPlus but you can still activate GDI as mentioned here.

If changing to GDI doesn't make it work as you wish, please don't hesitate to let us know.

[pex]

I was/am using GDI in old and new version and haven't add new tchart, there already was one. So it would not be affected by default settings. (unless it changes it, but other properties stayed same, so it is not probably the case)

The problem was, that there is (new?) property in Chart->Panel->Image->Options->DrawQuality. It is by default "High" and was causing my trouble. I set it to Low and now it is fine.

P.S. To be honest it is really unfortunate and IMHO even misleading choice of property name, because it does anti-aliasing when it is set to High. For me is higher quality not anti-aliased...

[Yeray]

Hello,

The TBackImage DrawQuality property, TCanvasStretchQuality=( sqHigh, sqLow ), was introduced in 2013.09.131119.
I think whether anti-alias should be considered higher or worse quality is a subjective point of view. Some will probably think a smoother is better while others think the contrary. But changing the behaviour now, after various releases, would undoubtedly induce confusion.