Re: [Lcd4linux-devel] [lcd4linux] Layout transitions

[Scott F. <sc...@st...>]

On Sun, May 17, 2009 at 2:24 AM, Scott Flynn <sc...@st...> wrote:
>> Ok, good point. I went the route you suggested by clearing the FB, and
>> it brought up another intrusive point about the patch. It defaulted
>> all layouts to a timeout. That causes the framebuffer to be cleared,
>> interrupting the timing, and causing a noticeable change in the
>> display. I defaulted the timeout to 0 (no timeout), but that can be
>> overridden in the Display section.
>>
>> Display CF635 {
>>    Icons 2
>>    Driver 'Crystalfontz'
>>    Model '635'
>>    Port '/dev/ttyUSB1'
>>    Speed 115200
>>    Contrast 120
>>    Backlight 100
>>    DefaultTimeout 5000
>> }
>>
>>>
>
> I found that not all drivers use a text framebuffer. I made that
> assumption and didn't check to see if the text framebuffer existed
> before trying to clear it. It caused a crash of course. Attached is
> the updated patch that checks like it should and it also clears any
> graphic displays. I pulled a fresh copy off the SVN repo for it.
>

Oops. Sorry, I shouldn't be programming C. Or at least I should be
reading more of your code (and more C documentation) before writing
anything. ;)

Make that:
void drv_generic_text_clear(void) {
    if(LayoutFB == NULL) { return; }
    memset(LayoutFB, ' ', LROWS * LCOLS * sizeof(*LayoutFB));
    drv_generic_text_blit(0, 0, LROWS, LCOLS);
}