Upstream Chrome on iOS source code [6/11].

ios/chrome/browser/ui/qr_scanner/qr_scanner_transitioning_delegate.mm

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/chrome/browser/ui/qr_scanner/qr_scanner_transitioning_delegate.h"
+
+#include "base/ios/block_types.h"
+
+namespace {
+
+// The default animation duration.
+const NSTimeInterval kDefaultDuration = 0.25;
+
+enum QRScannerTransition { PRESENT, DISMISS };
+
+}  // namespace
+
+// Animates the QR Scanner transition. If initialized with the |PRESENT|
+// transition, positions the QR Scanner view below its presenting view
+// controller's view in the container view and animates the presenting view to
+// slide up. If initialized with the |DISMISS| transition, positions the
+// presenting view controller's view above the QR Scanner view in the container
+// view and animates the presenting view to slide down.
+@interface QRScannerTransitionAnimator
+    : NSObject<UIViewControllerAnimatedTransitioning> {
+  QRScannerTransition _transition;
+}
+
+- (instancetype)initWithTransition:(QRScannerTransition)transition;
+
+@end
+
+@implementation QRScannerTransitionAnimator
+
+- (instancetype)initWithTransition:(QRScannerTransition)transition {
+  self = [super init];
+  if (self) {
+    _transition = transition;
+  }
+  return self;
+}
+
+- (void)animateTransition:
+    (id<UIViewControllerContextTransitioning>)transitionContext {
+  UIView* containerView = [transitionContext containerView];
+  UIView* presentedView =
+      [transitionContext viewForKey:UITransitionContextToViewKey];
+  UIView* presentingView =
+      [transitionContext viewForKey:UITransitionContextFromViewKey];
+
+  // Get the final frame for the presented view.
+  UIViewController* presentedViewController = [transitionContext
+      viewControllerForKey:UITransitionContextToViewControllerKey];
+  CGRect finalFrame =
+      [transitionContext finalFrameForViewController:presentedViewController];
+
+  CGRect initialFrame;
+  ProceduralBlock animations;
+
+  switch (_transition) {
+    case PRESENT:
+      [containerView insertSubview:presentedView belowSubview:presentingView];
+      initialFrame = finalFrame;
+      finalFrame.origin.y = -finalFrame.size.height;
+      animations = ^void {
+        [presentingView setFrame:finalFrame];
+      };
+      break;
+    case DISMISS:
+      [containerView insertSubview:presentedView aboveSubview:presentingView];
+      initialFrame = finalFrame;
+      initialFrame.origin.y = -initialFrame.size.height;
+      animations = ^void {
+        [presentedView setFrame:finalFrame];
+      };
+      break;
+  }
+
+  // Set the frame for the presented view.
+  if (!CGRectIsEmpty(initialFrame)) {
+    [presentedView setFrame:initialFrame];
+  }
+  [presentedView layoutIfNeeded];
+
+  void (^completion)(BOOL) = ^void(BOOL finished) {
+    [transitionContext completeTransition:finished];
+  };
+
+  // Animate the transition.
+  [UIView animateWithDuration:kDefaultDuration
+                        delay:0
+                      options:UIViewAnimationOptionCurveEaseInOut
+                   animations:animations
+                   completion:completion];
+}
+
+- (void)animationEnded:(BOOL)transitionCompleted {
+  return;
+}
+
+- (NSTimeInterval)transitionDuration:
+    (id<UIViewControllerContextTransitioning>)transitionContext {
+  return kDefaultDuration;
+}
+
+@end
+
+@implementation QRScannerTransitioningDelegate
+
+- (id<UIViewControllerAnimatedTransitioning>)
+animationControllerForPresentedController:(UIViewController*)presented
+                     presentingController:(UIViewController*)presenting
+                         sourceController:(UIViewController*)source {
+  return [[[QRScannerTransitionAnimator alloc] initWithTransition:PRESENT]
+      autorelease];
+}
+
+- (id<UIViewControllerAnimatedTransitioning>)
+animationControllerForDismissedController:(UIViewController*)dismissed {
+  return [[[QRScannerTransitionAnimator alloc] initWithTransition:DISMISS]
+      autorelease];
+}
+
+@end