[Qemu-devel] [PATCH v3] ui/cocoa.m: prevent stuck key situation

[Qemu-devel] [PATCH v3] ui/cocoa.m: prevent stuck key situation

[Programmingkid]

When the user puts QEMU in the background while holding
down a key, QEMU will not receive the keyup event when
the user lets go of the key. When the user goes back to
QEMU, QEMU will think the key is still down causing
stuck key symptoms. This patch fixes this problem by
releasing all down keys when QEMU goes into the
background. 

Signed-off-by: John Arbuckle <programmingkidx@gmail.com>

---
Changed value of max_index variable.
Added more to raiseAllKeys method's comment.

 ui/cocoa.m |   26 ++++++++++++++++++++++++++
 1 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/ui/cocoa.m b/ui/cocoa.m
index 334e6f6..ee88a9e 100644
--- a/ui/cocoa.m
+++ b/ui/cocoa.m
@@ -304,6 +304,7 @@ static void handleAnyDeviceErrors(Error * err)
 - (float) cdx;
 - (float) cdy;
 - (QEMUScreen) gscreen;
+- (void) raiseAllKeys;
 @end
 
 QemuCocoaView *cocoaView;
@@ -798,6 +799,24 @@ QemuCocoaView *cocoaView;
 - (float) cdx {return cdx;}
 - (float) cdy {return cdy;}
 - (QEMUScreen) gscreen {return screen;}
+
+/*
+ * Makes the target think all down keys are being released.
+ * This prevents a stuck key problem, since we will not see
+ * key up events for those keys after we have lost focus.
+ */
+- (void) raiseAllKeys
+{
+    int index;
+    const int max_index = ARRAY_SIZE(modifiers_state);
+
+   for (index = 0; index < max_index; index++) {
+       if (modifiers_state[index]) {
+           modifiers_state[index] = 0;
+           qemu_input_event_send_key_number(dcl->con, index, false);
+       }
+   }
+}
 @end
 
 
@@ -933,6 +952,13 @@ QemuCocoaView *cocoaView;
     return YES;
 }
 
+/* Called when QEMU goes into the background */
+- (void) applicationWillResignActive: (NSNotification *)aNotification
+{
+    COCOA_DEBUG("QemuCocoaAppController: applicationWillResignActive\n");
+    [cocoaView raiseAllKeys];
+}
+
 - (void)startEmulationWithArgc:(int)argc argv:(char**)argv
 {
     COCOA_DEBUG("QemuCocoaAppController: startEmulationWithArgc\n");
-- 
1.7.5.4

Re: [Qemu-devel] [PATCH v3] ui/cocoa.m: prevent stuck key situation

[Peter Maydell]

On 23 September 2015 at 18:21, Programmingkid <programmingkidx@gmail.com> wrote:
> When the user puts QEMU in the background while holding
> down a key, QEMU will not receive the keyup event when
> the user lets go of the key. When the user goes back to
> QEMU, QEMU will think the key is still down causing
> stuck key symptoms. This patch fixes this problem by
> releasing all down keys when QEMU goes into the
> background.
>
> Signed-off-by: John Arbuckle <programmingkidx@gmail.com>

Thanks, applied to cocoa.next.

(That's at https://git.linaro.org/people/peter.maydell/qemu-arm.git cocoa.next).

-- PMM