[Spice-devel] [PATCH spice-common] canvas: Fix some semi transparent drawing

[Christophe de Dinechin]

> Christophe de Dinechin


Le 24 janv. 2018 à 10:05, Frediano Ziglio <fziglio at redhat.com> a écrit :

>> 
>> This is reproducible using desktop icons on Windows XP.
>> 
>> These drawing are sent for the icons on the desktop.
>> To get an extends.x1 >= 32 you have to move an icon out of the
>> screen on the right side. Set the icon size to 72 as the icon has
> 
> Here is "left side", not left.
> 
>> to be out of the screen quite a lot.
>> Disable the grid alignment on the desktop and move an icon out of
>> the screen. Select and unselect the icon.
>> Using "/ 32" the icon will have a white background instead of a
>> transparent one.
>> Using a "/ 8" the icon is rendered correctly.
>> 
>> Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
>> ---
>> common/canvas_base.c | 12 ++++++++++--
>> 1 file changed, 10 insertions(+), 2 deletions(-)
>> 
>> diff --git a/common/canvas_base.c b/common/canvas_base.c
>> index 42f0eea..f0f6bbf 100644
>> --- a/common/canvas_base.c
>> +++ b/common/canvas_base.c
>> @@ -1941,8 +1941,16 @@ static void canvas_mask_pixman(CanvasBase *canvas,
>>     /* round down X to even 32 pixels (i.e. uint32_t) */
>>     extents.x1 = extents.x1 & ~(0x1f);
>> 
>> -    mask_data_src = (uint8_t *)mask_data + mask_stride * extents.y1 +
>> extents.x1 / 32;
>> -    mask_data = SPICE_UNALIGNED_CAST(uint32_t *, mask_data_src);
>> +    /* mask_data_src is surely aligned to 4 bytes:
>> +     * - pixman requires mask_data (pixman_image_get_data) to be
>> +     *   aligned to 4 bytes;
>> +     * - pixman requires mask_stride (pixman_image_get_stride) to be
>> +     *   multiple of 4;
>> +     * - extents.x1 is multiple of 32 (see previous line) so
>> +     *   extents.x1 / 8 is multiple of 4.
>> +     */
>> +    mask_data_src = (uint8_t *)mask_data + mask_stride * extents.y1 +
>> extents.x1 / 8;
>> +    mask_data = SPICE_ALIGNED_CAST(uint32_t *, mask_data_src);
>> 

ack

>>     mask_x -= extents.x1;
>>     mask_y -= extents.y1;
> 
> Frediano
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