[vlc-devel] [PATCH 02/17] video_output: translate the mouse coordinates to display coordinates early

[Zhao Zhili]

Hi Steve,

> On Sep 14, 2020, at 10:03 PM, Steve Lhomme <robux4 at ycbcr.xyz> wrote:
> 
> We can do this in the UI thread, the processing is light.
> Locking the display_lock doesn't have a big impact on lag as it's only taking
> time when reloading a display module, which is very rare.
> ---
> src/video_output/video_output.c | 21 ++++++++++++---------
> 1 file changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/src/video_output/video_output.c b/src/video_output/video_output.c
> index cbc66b9dbc0..ed1e3bfcb07 100644
> --- a/src/video_output/video_output.c
> +++ b/src/video_output/video_output.c
> @@ -389,7 +389,14 @@ void vout_MouseState(vout_thread_t *vout, const vlc_mouse_t *mouse)
>     assert(mouse);
>     vout_control_cmd_t cmd;
>     vout_control_cmd_Init(&cmd, VOUT_CONTROL_MOUSE_STATE);
> -    cmd.mouse = *mouse;
> +
> +    /* Translate window coordinates to video coordinates */
> +    vlc_mutex_lock(&sys->display_lock);

This change leads to a deadlock on macOS.

* thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
  * frame #0: 0x00007fff6dcdd882 libsystem_kernel.dylib`__psynch_cvwait + 10
    frame #1: 0x00007fff6dd9e425 libsystem_pthread.dylib`_pthread_cond_wait + 698
    frame #2: 0x000000010023d27c libvlccore.dylib`vlc_atomic_wait(addr=0x000000010ef31ff0, value=2) at wait.c:84:9
    frame #3: 0x0000000100226d4e libvlccore.dylib`vlc_mutex_lock(mtx=0x000000010ef31ff0) at threads.c:175:9
    frame #4: 0x00000001001eb968 libvlccore.dylib`vout_MouseState(vout=0x000000010ef31d50, mouse=0x000000010ed8e4a8) at video_output.c:389:5
    frame #5: 0x00000001002005f4 libvlccore.dylib`vout_display_window_MouseEvent(window=0x000000010ed8e370, ev=0x00007ffeefbfdd80) at window.c:321:5
    frame #6: 0x0000000107fc11b9 libvout_macosx_plugin.dylib`vout_window_SendMouseEvent(window=0x000000010ed8e370, mouse=0x00007ffeefbfdd80) at vlc_vout_window.h:595:9
    frame #7: 0x0000000107fc1239 libvout_macosx_plugin.dylib`vout_window_ReportMouseMoved(window=0x000000010ed8e370, x=2038, y=943) at vlc_vout_window.h:614:5
    frame #8: 0x0000000107fc05b8 libvout_macosx_plugin.dylib`vout_display_SendMouseMovedDisplayCoordinates(vd=0x0000000110911340, m_x=2038, m_y=943) at vlc_vout_display.h:467:5
    frame #9: 0x0000000107fc0507 libvout_macosx_plugin.dylib`-[VLCOpenGLVideoView mouseMoved:](self=0x0000000110911da0, _cmd="mouseMoved:", o_event=0x0000000100676520) at macosx.m:778:17


  thread #42
    frame #0: 0x00007fff6dcdc55e libsystem_kernel.dylib`__ulock_wait + 10
    frame #1: 0x00007fff6dd909c3 libsystem_platform.dylib`_os_unfair_lock_lock_slow + 160
    frame #2: 0x00007fff6c9e8dc7 libobjc.A.dylib`objc_sync_enter + 27
    frame #3: 0x0000000107fbf4e4 libvout_macosx_plugin.dylib`-[VLCOpenGLVideoView setVoutFlushing:](self=0x0000000110911da0, _cmd="setVoutFlushing:", flushing=YES) at macosx.m:550:5
    frame #4: 0x0000000107fc0cf0 libvout_macosx_plugin.dylib`PictureDisplay(vd=0x0000000110911340, pic=0x000000010ae1d640) at macosx.m:331:5
    frame #5: 0x00000001001f2b09 libvlccore.dylib`vout_display_Display(vd=0x0000000110911340, picture=0x000000010ae1d640) at vlc_vout_display.h:431:9
    frame #6: 0x00000001001f2127 libvlccore.dylib`ThreadDisplayRenderPicture(vout=0x000000010ef31d50, render_now=false) at video_output.c:1446:5
    frame #7: 0x00000001001edf69 libvlccore.dylib`ThreadDisplayPicture(vout=0x000000010ef31d50, deadline=0x00007000061d6fa0) at video_output.c:1572:15
    frame #8: 0x00000001001f0409 libvlccore.dylib`Thread(object=0x000000010ef31d50) at video_output.c:1914:16
    frame #9: 0x00007fff6dd9e109 libsystem_pthread.dylib`_pthread_start + 148
    frame #10: 0x00007fff6dd99b8b libsystem_pthread.dylib`thread_start + 15



> +    if (sys->display)
> +        vout_display_TranslateMouseState(sys->display, &cmd.mouse, mouse);
> +    else
> +        cmd.mouse = *mouse;
> +    vlc_mutex_unlock(&sys->display_lock);
> 
>     vout_control_Push(&sys->control, &cmd);
> }
> @@ -1678,17 +1685,13 @@ void vout_ChangeSpuRate(vout_thread_t *vout, size_t channel_id, float rate)
> static void ThreadProcessMouseState(vout_thread_sys_t *p_vout,
>                                     const vlc_mouse_t *win_mouse)
> {
> -    vlc_mouse_t vid_mouse, tmp1, tmp2, *m;
> +    vlc_mouse_t tmp1, tmp2;
> +    const vlc_mouse_t *m;
>     vout_thread_t *vout = &p_vout->obj;
>     vout_thread_sys_t *sys = p_vout;
> 
> -    /* Translate window coordinates to video coordinates */
> -    vlc_mutex_lock(&sys->display_lock);
> -    vout_display_TranslateMouseState(sys->display, &vid_mouse, win_mouse);
> -    vlc_mutex_unlock(&sys->display_lock);
> -
> -    /* Then pass up the filter chains. */
> -    m = &vid_mouse;
> +    /* pass mouse coordinates in the filter chains. */
> +    m = win_mouse;
>     vlc_mutex_lock(&sys->filter.lock);
>     if (sys->filter.chain_static && sys->filter.chain_interactive) {
>         if (!filter_chain_MouseFilter(sys->filter.chain_interactive,
> -- 
> 2.26.2
> 
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