[PATCH v2 weston 2/4] zoom: Call weston_output_activate_zoom() appropriately

[Derek Foreman]

On 23/07/15 07:02 PM, Bryce Harrington wrote:
> On Thu, Jul 23, 2015 at 02:55:13PM -0500, Derek Foreman wrote:
>> No longer call weston_output_update_zoom() when trying to zoom out
>> on an unzoomed output.
>>
>> Add an assert() to make sure update_zoom is never called without an
>> active zoom.
>>
>> Signed-off-by: Derek Foreman <derekf at osg.samsung.com>
> 
> A few probably dumb questions...
> 
>> ---
>>  desktop-shell/shell.c | 5 ++++-
>>  src/zoom.c            | 3 +++
>>  2 files changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/desktop-shell/shell.c b/desktop-shell/shell.c
>> index 0137ca3..8f90710 100644
>> --- a/desktop-shell/shell.c
>> +++ b/desktop-shell/shell.c
>> @@ -4804,7 +4804,10 @@ do_zoom(struct weston_seat *seat, uint32_t time, uint32_t key, uint32_t axis,
>>  				output->zoom.level = 0.0;
>>  			else if (output->zoom.level > output->zoom.max_level)
>>  				output->zoom.level = output->zoom.max_level;
>> -			else if (!output->zoom.active) {
>> +
>> +			if (!output->zoom.active) {
> 
> What exactly is zoom.active tracking?  That there is a zoom operation
> undergoing, or the individual zoom animation steps?

That zoom is enabled for an output.  It's not a temporary transitional
state, it just indicates we've got output magnification turned on.

We get into do_zoom() from either mousewheel bind or key bind.  We could
be starting a new zoom (output->zoom.active is false) or adjusting an
old one (output->zoom.active is true)


>> +				if (output->zoom.level <= 0.0)
>> +					continue;
> 
> The first part of the earlier if statement already checks for zoom.level
> less than 0; perhaps it could be altered to check for <= 0.0 and
> continue at that point?  Might make for clearer logic.

Still need to only do the continue when !output->zoom.active so I don't
think there's a great simplification to be had here.

The first part is just clamping to min/max legitimate values, and is
pretty clear as it is.  I don't think I'd want to combine the "do we
need to enable zoom?" check with that.

> (Does negative zoom have any particular meaning?  If not, why not make
> the value unsigned?)

Need the float precision, so we get the sign for free :)

>>  				weston_output_activate_zoom(output);
>>  			}
>> diff --git a/src/zoom.c b/src/zoom.c
>> index 878ecc2..39515d4 100644
>> --- a/src/zoom.c
>> +++ b/src/zoom.c
>> @@ -25,6 +25,7 @@
>>  
>>  #include "config.h"
>>  
>> +#include <assert.h>
>>  #include <stdlib.h>
>>  #include <stdbool.h>
>>  
>> @@ -135,6 +136,8 @@ weston_output_update_zoom(struct weston_output *output)
>>  {
>>  	struct weston_seat *seat = weston_zoom_pick_seat(output->compositor);
>>  
>> +	assert(output->zoom.active);
>> +
>>  	output->zoom.current.x = seat->pointer->x;
>>  	output->zoom.current.y = seat->pointer->y;
>>  
>> -- 
>> 2.1.4
>>
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>> wayland-devel at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/wayland-devel
> 
> Bryce
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