Puzzle about ExtSelectClipRgn?

[Changhui Liu]

Dear all, I test this code :

void test (HDC hdc, HRGN hregion)
{
    RECT srcbox;
    RECT dstbox;

GetClipBox(hdc, &dstbox);
    GetRgnBox(hregion, &srcbox);

TRACE("Before ExtSelectClipRgn:%s,%s\n",
            wine_dbgstr_rect(&srcbox), wine_dbgstr_rect(&dstbox) );

ExtSelectClipRgn(hdc, hregion, RGN_AND );

GetClipBox(graphics->hdc,&dstbox);

TRACE("After ExtSelectClipRgn:%s,%s\n", wine_dbgstr_rect(&dstbox) ); 
}

It output in wine is : 
Before ExtSelectClipRgn:(693,5)-(763,28),(693,5)-(763,28) 
After ExtSelectClipRgn:(693,5)-(693,5)

But I think it should be output:
Before ExtSelectClipRgn:(693,5)-(763,28),(693,5)-(763,28) 
After ExtSelectClipRgn:(693,5)-(763,28)

Where is my understanding mistake, or is it a bug in ExtSelectClipRgn?

Thank you!

[Vincent Povirk]

This is possible if both regions are more complex shapes (not just one
rectangle) that do not share any pixels. For example, the clip region
could consist of the rectangles (693,5)-(694,6) and (762,27)-(763,28);
and hregion could be (762,5)-(763,6) and (693,27)-(694,28).

You can use GetRegionData to determine the exact set of rectangles in
the region.

[Thomas Faber]

On 2014-12-03 03:36, Changhui Liu wrote:
> Dear all, I test this code :
>
> void test (HDC hdc, HRGN hregion)
> {
>      RECT srcbox;
>      RECT dstbox;
>  GetClipBox(hdc, &dstbox);
>  GetRgnBox(hregion, &srcbox);
>
>
>  TRACE("Before ExtSelectClipRgn:%s,%s\n",
>          wine_dbgstr_rect(&srcbox), wine_dbgstr_rect(&dstbox) );
>
>
>  ExtSelectClipRgn(hdc, hregion, RGN_AND );
>
>  GetClipBox(graphics->hdc,&dstbox);
>
>  TRACE("After ExtSelectClipRgn:%s,%s\n", wine_dbgstr_rect(&dstbox) );

The second %s here will print random memory.
> }
>
> It output in wine is :
> Before ExtSelectClipRgn:(693,5)-(763,28),(693,5)-(763,28)
> After ExtSelectClipRgn:(693,5)-(693,5)
>
> But I think it should be output:
> Before ExtSelectClipRgn:(693,5)-(763,28),(693,5)-(763,28)
> After ExtSelectClipRgn:(693,5)-(763,28)
>
> Where is my understanding mistake, or is it a bug in ExtSelectClipRgn?

[Changhui Liu]

Dear Thomas:
It should be :
TRACE("After ExtSelectClipRgn:%s\n", wine_dbgstr_rect(&dstbox) );
I want make the output clear so I remove the  wine_dbgstr_rect(&srcbox), but I forgot remove the second %s. 
Thank you.

------------------ Original ------------------
From:  "Thomas Faber";
Date:  Mon, Dec 8, 2014 04:05 AM
To:  "Changhui Liu"; 
Cc:  "Sebastian Lackner"; "Vincent Povirk"; "wine-devel"; "洪谦"; 
Subject:  Re: Puzzle about ExtSelectClipRgn?

On 2014-12-03 03:36, Changhui Liu wrote:
> Dear all, I test this code :
>
> void test (HDC hdc, HRGN hregion)
> {
>      RECT srcbox;
>      RECT dstbox;
>  GetClipBox(hdc, &dstbox);
>  GetRgnBox(hregion, &srcbox);
>
>
>  TRACE("Before ExtSelectClipRgn:%s,%s\n",
>          wine_dbgstr_rect(&srcbox), wine_dbgstr_rect(&dstbox) );
>
>
>  ExtSelectClipRgn(hdc, hregion, RGN_AND );
>
>  GetClipBox(graphics->hdc,&dstbox);
>
>  TRACE("After ExtSelectClipRgn:%s,%s\n", wine_dbgstr_rect(&dstbox) );

The second %s here will print random memory.
> }
>
> It output in wine is :
> Before ExtSelectClipRgn:(693,5)-(763,28),(693,5)-(763,28)
> After ExtSelectClipRgn:(693,5)-(693,5)
>
> But I think it should be output:
> Before ExtSelectClipRgn:(693,5)-(763,28),(693,5)-(763,28)
> After ExtSelectClipRgn:(693,5)-(763,28)
>
> Where is my understanding mistake, or is it a bug in ExtSelectClipRgn?

------------------
Regards.