Re: [PATCH 1/8] video: Add cursor support for DM_VIDEO consoles

[Andre Przywara <andre.przywara@arm.com>]

On Mon, 10 Jan 2022 10:41:14 +0100
Heinrich Schuchardt <heinrich.schuchardt@canonical.com> wrote:

Hi,

> On 1/10/22 01:56, Andre Przywara wrote:
> > So far the DM_VIDEO console is completely lacking any cursor, which makes
> > typing and correcting quite irritating.
> > 
> > Add a simple cursor display by writing a SPACE glyph in the background
> > colour to the next character position on the screen. Any typed character
> > will naturally overwrite it, so we need to only explicitly clear it if
> > the next character will appear somewhere else (newline, backspace).  
> 
> Does this work with (non-monospaced) Truetype fonts?
> Moving backwards in Truetype is awkward.

I don't know, I need to try this again. I think I tried TrueType (before
adding wide character bitmap support), but ran into some issues, might
well be due to the proportional fonts only.

In general I think *proper* cursor support can be tricky and tedious, so
this version here is deliberately made simple, to have at least *some*
cursor.
Shall we enable this code only for monospace fonts (both TT and bitmap)?

Cheers,
Andre

> > Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> > ---
> >   drivers/video/console_normal.c    |  1 +
> >   drivers/video/vidconsole-uclass.c | 42 +++++++++++++++++++++++++++++++
> >   include/video_console.h           |  1 +
> >   3 files changed, 44 insertions(+)
> > 
> > diff --git a/drivers/video/console_normal.c b/drivers/video/console_normal.c
> > index 04f022491e5..bfd3aab8d24 100644
> > --- a/drivers/video/console_normal.c
> > +++ b/drivers/video/console_normal.c
> > @@ -160,6 +160,7 @@ static int console_normal_probe(struct udevice *dev)
> >   	vc_priv->y_charsize = VIDEO_FONT_HEIGHT;
> >   	vc_priv->cols = vid_priv->xsize / VIDEO_FONT_WIDTH;
> >   	vc_priv->rows = vid_priv->ysize / VIDEO_FONT_HEIGHT;
> > +	vc_priv->cursor_visible = true;
> >   
> >   	return 0;
> >   }
> > diff --git a/drivers/video/vidconsole-uclass.c b/drivers/video/vidconsole-uclass.c
> > index f42db40d4cd..420fd86f9ac 100644
> > --- a/drivers/video/vidconsole-uclass.c
> > +++ b/drivers/video/vidconsole-uclass.c
> > @@ -70,6 +70,26 @@ static int vidconsole_entry_start(struct udevice *dev)
> >   	return ops->entry_start(dev);
> >   }
> >   
> > +static void draw_cursor(struct udevice *dev, bool state)
> > +{
> > +	struct vidconsole_priv *priv = dev_get_uclass_priv(dev);
> > +	struct video_priv *vid_priv = dev_get_uclass_priv(dev->parent);
> > +	u32 tmp;
> > +
> > +	if (!priv->cursor_visible)
> > +		return;
> > +
> > +	if (state) {
> > +		tmp = vid_priv->colour_bg;
> > +		vid_priv->colour_bg = vid_priv->colour_fg;
> > +	}
> > +
> > +	vidconsole_putc_xy(dev, priv->xcur_frac, priv->ycur, ' ');
> > +
> > +	if (state)
> > +		vid_priv->colour_bg = tmp;
> > +}
> > +
> >   /* Move backwards one space */
> >   static int vidconsole_back(struct udevice *dev)
> >   {
> > @@ -77,6 +97,8 @@ static int vidconsole_back(struct udevice *dev)
> >   	struct vidconsole_ops *ops = vidconsole_get_ops(dev);
> >   	int ret;
> >   
> > +	draw_cursor(dev, false);
> > +
> >   	if (ops->backspace) {
> >   		ret = ops->backspace(dev);
> >   		if (ret != -ENOSYS)
> > @@ -103,6 +125,8 @@ static void vidconsole_newline(struct udevice *dev)
> >   	const int rows = CONFIG_CONSOLE_SCROLL_LINES;
> >   	int i, ret;
> >   
> > +	draw_cursor(dev, false);
> > +
> >   	priv->xcur_frac = priv->xstart_frac;
> >   	priv->ycur += priv->y_charsize;
> >   
> > @@ -342,6 +366,14 @@ static void vidconsole_escape_char(struct udevice *dev, char ch)
> >   
> >   		break;
> >   	}
> > +	case 'l':
> > +		  draw_cursor(dev, false);
> > +		  priv->cursor_visible = 0;
> > +		  break;
> > +	case 'h':
> > +		  priv->cursor_visible = 1;
> > +		  draw_cursor(dev, true);
> > +		  break;
> >   	case 'J': {
> >   		int mode;
> >   
> > @@ -516,6 +548,11 @@ int vidconsole_put_char(struct udevice *dev, char ch)
> >   	struct vidconsole_priv *priv = dev_get_uclass_priv(dev);
> >   	int ret;
> >   
> > +	/*
> > +	 * We don't need to clear the cursor since we are going to overwrite
> > +	 * that character anyway.
> > +	 */
> > +
> >   	if (priv->escape) {
> >   		vidconsole_escape_char(dev, ch);
> >   		return 0;
> > @@ -530,6 +567,7 @@ int vidconsole_put_char(struct udevice *dev, char ch)
> >   		/* beep */
> >   		break;
> >   	case '\r':
> > +		draw_cursor(dev, false);
> >   		priv->xcur_frac = priv->xstart_frac;
> >   		break;
> >   	case '\n':
> > @@ -537,6 +575,7 @@ int vidconsole_put_char(struct udevice *dev, char ch)
> >   		vidconsole_entry_start(dev);
> >   		break;
> >   	case '\t':	/* Tab (8 chars alignment) */
> > +		draw_cursor(dev, false);
> >   		priv->xcur_frac = ((priv->xcur_frac / priv->tab_width_frac)
> >   				+ 1) * priv->tab_width_frac;
> >   
> > @@ -554,6 +593,8 @@ int vidconsole_put_char(struct udevice *dev, char ch)
> >   		break;
> >   	}
> >   
> > +	draw_cursor(dev, true);
> > +
> >   	return 0;
> >   }
> >   
> > @@ -620,6 +661,7 @@ static int vidconsole_pre_probe(struct udevice *dev)
> >   	struct video_priv *vid_priv = dev_get_uclass_priv(vid);
> >   
> >   	priv->xsize_frac = VID_TO_POS(vid_priv->xsize);
> > +	priv->cursor_visible = false;
> >   
> >   	return 0;
> >   }
> > diff --git a/include/video_console.h b/include/video_console.h
> > index 06b798ef10c..a908f1412e8 100644
> > --- a/include/video_console.h
> > +++ b/include/video_console.h
> > @@ -83,6 +83,7 @@ struct vidconsole_priv {
> >   	int escape_len;
> >   	int row_saved;
> >   	int col_saved;
> > +	bool cursor_visible;
> >   	char escape_buf[32];
> >   };
> >     
>