ui/cocoa.m: prevent stuck key situation

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>
Message-id: 7A3FA6EE-84C8-4422-A786-C899B7229D32@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/ui/cocoa.m b/ui/cocoa.m
index 7c64e1a5aaf121d91d15e40fb7a89cc245aee592..d436780fafae9cdf8a3e632659a14c9c0a9f7a5a 100644 (file)
--- 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
 
 
@@ -955,6 +974,13 @@ QemuCocoaView *cocoaView;
     return NO;
 }
 
+/* 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");