[PATCH] Implemented support for mouse scrolling in weston-terminal

[Marek Chalupa]

Hi,
In the first place I'd lake to say: great feature!

On 08/05/14 15:05, maghoff+wayland at gmail.com wrote:
> From: Magnus Hoff <maghoff at gmail.com>
>
> ---
>   clients/terminal.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 48 insertions(+)
>
> diff --git a/clients/terminal.c b/clients/terminal.c
> index eb133cd..d238f04 100644
> --- a/clients/terminal.c
> +++ b/clients/terminal.c
> @@ -447,6 +447,7 @@ struct terminal {
>   	int width, height, row, column, max_width;
>   	uint32_t buffer_height;
>   	uint32_t start, end, saved_start, log_size;
> +	wl_fixed_t smooth_scroll;
>   	int saved_row, saved_column;
>   	int scrolling;
>   	int send_cursor_position;
> @@ -2785,6 +2786,52 @@ motion_handler(struct widget *widget,
>   	return CURSOR_IBEAM;
>   }
>   
> +// This magnitude is chosen rather arbitrarily. Really, the scrolling
> +// should happen on a (fractional) pixel basis, not a line basis.
> +#define AXIS_UNITS_PER_LINE 256
> +

Personally, I liked 512 more - but that is just my subjective feeling. 
It'd be nice to have it configurable.

> +static void
> +axis_handler(struct widget *widget,
> +	       struct input *input, uint32_t time,
> +	       uint32_t axis,
> +	       wl_fixed_t value,
> +	       void *data)
> +{
> +	struct terminal *terminal = data;
> +
> +	if (axis != WL_POINTER_AXIS_VERTICAL_SCROLL) return;
> +
> +	terminal->smooth_scroll += value;
> +	int lines = terminal->smooth_scroll / AXIS_UNITS_PER_LINE;
> +	terminal->smooth_scroll -= lines * AXIS_UNITS_PER_LINE;
> +
> +	if (lines > 0) {
> +		if (terminal->scrolling) {
> +			if ((uint32_t)lines > terminal->saved_start - terminal->start)
> +				lines = terminal->saved_start - terminal->start;
> +		} else {
> +			lines = 0;
> +		}
> +	} else if (lines < 0) {
> +		uint32_t neg_lines = -lines;
> +		if (neg_lines > terminal->log_size + terminal->start - terminal->end)
> +			lines = terminal->end - terminal->log_size - terminal->start;
> +	}
> +
> +	if (lines) {
> +		if (!terminal->scrolling)
> +			terminal->saved_start = terminal->start;
> +		terminal->scrolling = 1;
> +
> +		terminal->start += lines;
> +		terminal->row -= lines;
> +		terminal->selection_start_row -= lines;
> +		terminal->selection_end_row -= lines;
> +
> +		widget_schedule_redraw(widget);
> +	}
> +}
> +
>   static void
>   output_handler(struct window *window, struct output *output, int enter,
>   	       void *data)
> @@ -2880,6 +2927,7 @@ terminal_create(struct display *display)
>   	widget_set_button_handler(terminal->widget, button_handler);
>   	widget_set_enter_handler(terminal->widget, enter_handler);
>   	widget_set_motion_handler(terminal->widget, motion_handler);
> +	widget_set_axis_handler(terminal->widget, axis_handler);
>   	widget_set_touch_up_handler(terminal->widget, touch_up_handler);
>   	widget_set_touch_down_handler(terminal->widget, touch_down_handler);
>   	widget_set_touch_motion_handler(terminal->widget, touch_motion_handler);

So far I tried works good for most usecases. There's one usecase that is 
behaving incorrectly I think. When you put something into buffer, then 
scroll it up, back down, then resize the terminal so that it has k less 
lines than before and scroll again up and down, than the scrolling stops 
k lines above the end of buffer. The same way you can resize to the 
other side (and end up k lines after the buffer). Pressing enter clears 
it. But that's not critical, I think.

Regards,
Marek