Mobile: Dealing with keyboard height

The software keyboard obstructs part of the UI, so need to offset the view if the focused input widget would not be visible.

1 files changed, 53 insertions, 16 deletions

diff --git a/src/ios.m b/src/ios.m
index 5abf87df..4d1aac37 100644
--- a/src/ios.m
+++ b/src/ios.m
@@ -31,28 +31,63 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
 static iBool isSystemDarkMode_ = iFalse;
 static iBool isPhone_ = iFalse;
 
+static UIViewController *viewController_(iWindow *window) {
+    SDL_SysWMinfo wm;
+    SDL_VERSION(&wm.version);
+    if (SDL_GetWindowWMInfo(window->win, &wm)) {
+        return wm.info.uikit.window.rootViewController;
+    }
+    iAssert(false);
+    return NULL;
+}
+
+@interface KeyboardObserver : NSObject
+-(void)keyboardOnScreen:(NSNotification *)notification;
+@end
+
+@implementation KeyboardObserver
+-(void)keyboardOnScreen:(NSNotification *)notification {
+    NSDictionary *info   = notification.userInfo;
+    NSValue      *value  = info[UIKeyboardFrameEndUserInfoKey];
+    CGRect rawFrame      = [value CGRectValue];
+    UIView *view         = [viewController_(get_Window()) view];
+    CGRect keyboardFrame = [view convertRect:rawFrame fromView:nil];
+//    NSLog(@"keyboardFrame: %@", NSStringFromCGRect(keyboardFrame));
+    iWindow *window = get_Window();
+    const iInt2 rootSize = rootSize_Window(window);
+    const int keyTop = keyboardFrame.origin.y * window->pixelRatio;
+    setKeyboardHeight_Window(window, rootSize.y - keyTop);
+}
+
+-(void)keyboardOffScreen:(NSNotification *)notification {
+    setKeyboardHeight_Window(get_Window(), 0);
+}
+@end
+
 static void enableMouse_(iBool yes) {
     SDL_EventState(SDL_MOUSEBUTTONDOWN, yes);
     SDL_EventState(SDL_MOUSEMOTION, yes);
     SDL_EventState(SDL_MOUSEBUTTONUP, yes);
 }
 
+KeyboardObserver *keyObs_;
+
 void setupApplication_iOS(void) {
     enableMouse_(iFalse);
     NSString *deviceModel = [[UIDevice currentDevice] model];
     if ([deviceModel isEqualToString:@"iPhone"]) {
         isPhone_ = iTrue;
     }
-}
-
-static UIViewController *viewController_(iWindow *window) {
-    SDL_SysWMinfo wm;
-    SDL_VERSION(&wm.version);
-    if (SDL_GetWindowWMInfo(window->win, &wm)) {
-        return wm.info.uikit.window.rootViewController;
-    }
-    iAssert(false);
-    return NULL;
+    keyObs_ = [[KeyboardObserver alloc] init];
+    NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
+    [center addObserver:keyObs_
+               selector:@selector(keyboardOnScreen:)
+                   name:UIKeyboardWillShowNotification
+                 object:nil];
+    [center addObserver:keyObs_
+               selector:@selector(keyboardOffScreen:)
+                   name:UIKeyboardWillHideNotification
+                 object:nil];
 }
 
 static iBool isDarkMode_(iWindow *window) {
@@ -71,13 +106,15 @@ void safeAreaInsets_iOS(float *left, float *top, float *right, float *bottom) {
     UIViewController *ctl = viewController_(window);
     if (@available(iOS 11.0, *)) {
         const UIEdgeInsets safe = ctl.view.safeAreaInsets;
-        *left = safe.left * window->pixelRatio;
-        *top = safe.top * window->pixelRatio;
-        *right = safe.right * window->pixelRatio;
-        *bottom = safe.bottom * window->pixelRatio;
+        if (left) *left = safe.left * window->pixelRatio;
+        if (top) *top = safe.top * window->pixelRatio;
+        if (right) *right = safe.right * window->pixelRatio;
+        if (bottom) *bottom = safe.bottom * window->pixelRatio;
     } else {
-        // Fallback on earlier versions
-        *left = *top = *right = *bottom = 0.0f;
+        if (left) *left = 0.0f;
+        if (top) *top = 0.0f;
+        if (right) *right = 0.0f;
+        if (bottom) *bottom = 0.0f;
     }
 }