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Display full screen jpg images without rolling effect - FT813

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Rudolph:
The chance of getting an answer from the community might be a little higer over in the BRT community forum. :-)

Annother solution would be to scale the images down untill they fit into the designated memory space.
With 200k available this would be 400x240.
And then let EVE scale the images to the desired size.
See cmd_scale

I just tried this in the EVE Screen Editor and the result looked okay.
And as a nice side-effect, the smaller images are loaded faster from SD, transfered faster to EVE and EVE needs less time to unpack these to RAM_G.

FTDI Community:
That's another good suggestion Rudolph,

You could either scale the image up for the main image or could even load a small version of the same high quality image currently displayed, scale it up and display it in place of the main image whilst replacing the data of the main image. That way the image would appear to remain on-screen whilst you change the high quality one un-seen by the user.

Alternatively, with fast SPI transfers, you can load the image very quickly and so the user won't notice the change (some of our examples where we play video are basically loading a series of images from an SD or camera in this way such as this one https://brtchip.com/wp-content/uploads/Support/Documentation/Application_Notes/ICs/MCU/BRT_AN_018-FT90x-Camera-to-EVE.pdf)

Best Regards, FTDI Community

marbalon:
Hi,
Back to the suggestion about checking decompressed data, I'm trying to get these values, and this command is not working. I get correct width and height values but the size is always 0.

I'm using this library:
https://github.com/RudolphRiedel/FT800-FT813/blob/4.x/EVE_commands.c

And checked the command implementation and it looks fine. The user manual says that it is RAM_G address of the image and this is true - I'm loading the image to the address 0, but how to check end address?

Any suggestion?

BR,
Marcin.

Rudolph:
Yes, cmd_getprops returns the start-address and this is kind of useless since we already know the start-adress, we just fed it into cmd_loadimage.
And since the random image we just loaded could be either using 8 bit per pixel or 16 bit per pixel we can not really calculate the end-address from the size.
However, we do need to know the format to properly display the image, so it can not be all random.
And if the only allowed images are regular full color .jpg we can calculate the size as: width * height * 2
This is also at least safe in case a monochrome image is processed.

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