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adafruit / adafruit-raspberrypi-linux

Adafruit's hacking-friendly Raspberry Pi linux kernel
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Add support for 'rolling scrolling' to HX8357D pitft driver. #15

Open wziard opened 6 years ago

wziard commented 6 years ago

When you want to scroll your display by just redrawing it all the time it is very slow (fullscreen redraws over spi are quite slow). However, the HX8357D (and others probably too) chipset supports hardware scrolling. (horizontal wraparounf scrolling in landscape mode, or vertical in portrait) This changeset adds a sysfs param to set the start scanline. by changing the start scanline the whole display is scrolled. You then only need to redraw the wrapped around scanlines instead of the whole screen.

wziard commented 6 years ago

It's nice to be able to have somewhat smooth scrolling, despite the slow(ish) spi connection.