[FFmpeg-devel] gdigrab: Allow capturing a window by its handle

x11grab can capture windows by their ID, but gdigrab can only capture 
windows by their names, internally calling FindWindowW to lookup its handle.

This patch simply allows the user to specify a window handle directly.
Signed-off-by: Lena <lena@nihil.gay>
---
  libavdevice/gdigrab.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

      }

Lena via ffmpeg-devel:
> x11grab can capture windows by their ID, but gdigrab can only capture
> windows by their names, internally calling FindWindowW to lookup its
> handle.
> 
> This patch simply allows the user to specify a window handle directly.
> Signed-off-by: Lena <lena@nihil.gay>
> ---
>  libavdevice/gdigrab.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/libavdevice/gdigrab.c b/libavdevice/gdigrab.c
> index c069232472..05d3c0c929 100644
> --- a/libavdevice/gdigrab.c
> +++ b/libavdevice/gdigrab.c
> @@ -273,9 +273,13 @@ gdigrab_read_header(AVFormatContext *s1)
>          }
>      } else if (!strcmp(filename, "desktop")) {
>          hwnd = NULL;
> +    } else if (!strncmp(filename, "hwnd=", 5)) {
> +        name = filename + 5;
> +        +        hwnd = strtol(name, NULL, 0);

This won't even compile due to the extra '+'.

>      } else {
>          av_log(s1, AV_LOG_ERROR,
> -               "Please use \"desktop\" or \"title=<windowname>\" to
> specify your target.\n");
> +               "Please use \"desktop\", \"title=<windowname>\" or
> \"hwnd=<hwnd>\" to specify your target.\n");
>          ret = AVERROR(EIO);
>          goto error;
>      }

I'm so sorry, will resend immediately.


Andreas Rheinhardt via ffmpeg-devel:

> Lena via ffmpeg-devel:
>> x11grab can capture windows by their ID, but gdigrab can only capture
>> windows by their names, internally calling FindWindowW to lookup its
>> handle.
>>
>> This patch simply allows the user to specify a window handle directly.
>> Signed-off-by: Lena <lena@nihil.gay>
>> ---
>>   libavdevice/gdigrab.c | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/libavdevice/gdigrab.c b/libavdevice/gdigrab.c
>> index c069232472..05d3c0c929 100644
>> --- a/libavdevice/gdigrab.c
>> +++ b/libavdevice/gdigrab.c
>> @@ -273,9 +273,13 @@ gdigrab_read_header(AVFormatContext *s1)
>>           }
>>       } else if (!strcmp(filename, "desktop")) {
>>           hwnd = NULL;
>> +    } else if (!strncmp(filename, "hwnd=", 5)) {
>> +        name = filename + 5;
>> +        +        hwnd = strtol(name, NULL, 0);
> This won't even compile due to the extra '+'.
>
>>       } else {
>>           av_log(s1, AV_LOG_ERROR,
>> -               "Please use \"desktop\" or \"title=<windowname>\" to
>> specify your target.\n");
>> +               "Please use \"desktop\", \"title=<windowname>\" or
>> \"hwnd=<hwnd>\" to specify your target.\n");
>>           ret = AVERROR(EIO);
>>           goto error;
>>       }
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x11grab can capture windows by their ID, but gdigrab can only capture windows by their names, internally calling FindWindowW to lookup its handle.

This patch simply allows the user to specify a window handle directly.
Signed-off-by: Lena <lena@nihil.gay>
---
 libavdevice/gdigrab.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/libavdevice/gdigrab.c b/libavdevice/gdigrab.c
index c069232472..05d3c0c929 100644
--- a/libavdevice/gdigrab.c
+++ b/libavdevice/gdigrab.c
@@ -273,9 +273,13 @@ gdigrab_read_header(AVFormatContext *s1)
         }
     } else if (!strcmp(filename, "desktop")) {
         hwnd = NULL;
+    } else if (!strncmp(filename, "hwnd=", 5)) {
+        name = filename + 5;
+        
+        hwnd = strtol(name, NULL, 0);
     } else {
         av_log(s1, AV_LOG_ERROR,
-               "Please use \"desktop\" or \"title=<windowname>\" to specify your target.\n");
+               "Please use \"desktop\", \"title=<windowname>\" or \"hwnd=<hwnd>\" to specify your target.\n");
         ret = AVERROR(EIO);
         goto error;
     }

On date Monday 2023-12-11 02:52:01 +0100, ffmpeg-devel Mailing List wrote:
> x11grab can capture windows by their ID, but gdigrab can only capture windows by their names, internally calling FindWindowW to lookup its handle.
> 
> This patch simply allows the user to specify a window handle directly.
> Signed-off-by: Lena <lena@nihil.gay>
> ---

>  libavdevice/gdigrab.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)

Missing doc/indevs.texi updates.

> diff --git a/libavdevice/gdigrab.c b/libavdevice/gdigrab.c
> index c069232472..05d3c0c929 100644
> --- a/libavdevice/gdigrab.c
> +++ b/libavdevice/gdigrab.c
> @@ -273,9 +273,13 @@ gdigrab_read_header(AVFormatContext *s1)
>          }
>      } else if (!strcmp(filename, "desktop")) {
>          hwnd = NULL;

> +    } else if (!strncmp(filename, "hwnd=", 5)) {
> +        name = filename + 5;
> +        
> +        hwnd = strtol(name, NULL, 0);

This should fail in case the parsing failed, for this you can check
the second argument (see examples in the code).