material-components_material-components-ios/components/FlexibleHeader/examples/FlexibleHeaderConfiguratorExample.m

// Copyright 2015-present the Material Components for iOS authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#import <UIKit/UIKit.h>

#import "MaterialFlexibleHeader.h"
#import "supplemental/FlexibleHeaderConfiguratorSupplemental.h"

#import "MaterialFlexibleHeader+CanAlwaysExpandToMaximumHeight.h"

@interface FlexibleHeaderConfiguratorExample ()
@property(nonatomic) BOOL overrideStatusBarHidden;
@end

@implementation FlexibleHeaderConfiguratorExample

// Invoked when the user has changed a control's value.
- (void)field:(FlexibleHeaderConfiguratorField)field didChangeValue:(NSNumber *)value {
  MDCFlexibleHeaderView *headerView = self.fhvc.headerView;
  switch (field) {
    // Basic behavior

    case FlexibleHeaderConfiguratorFieldCanOverExtend:
      headerView.canOverExtend = [value boolValue];
      break;

    case FlexibleHeaderConfiguratorFieldInFrontOfInfiniteContent:
      headerView.inFrontOfInfiniteContent = [value boolValue];
      break;

    case FlexibleHeaderConfiguratorFieldHideStatusBar: {
      self.overrideStatusBarHidden = [value boolValue];

      BOOL statusBarCanBeVisible = !self.overrideStatusBarHidden;
      headerView.statusBarHintCanOverlapHeader = statusBarCanBeVisible;

      [UIView animateWithDuration:0.4
                       animations:^{
                         [self setNeedsStatusBarAppearanceUpdate];
                       }];
      break;
    }

    // Shift behavior

    case FlexibleHeaderConfiguratorFieldShiftBehaviorEnabled: {
      BOOL isOn = [value boolValue];
      if (!isOn) {
        headerView.shiftBehavior = MDCFlexibleHeaderShiftBehaviorDisabled;
        [self
            didChangeValueForField:FlexibleHeaderConfiguratorFieldShiftBehaviorEnabledWithStatusBar
                          animated:YES];
      } else {
        headerView.shiftBehavior = MDCFlexibleHeaderShiftBehaviorEnabled;
      }
      break;
    }

    case FlexibleHeaderConfiguratorFieldShiftBehaviorEnabledWithStatusBar: {
      BOOL isOn = [value boolValue];
      if (!isOn) {
        headerView.shiftBehavior = MDCFlexibleHeaderShiftBehaviorEnabled;
      } else {
        headerView.shiftBehavior = MDCFlexibleHeaderShiftBehaviorEnabledWithStatusBar;
        [self didChangeValueForField:FlexibleHeaderConfiguratorFieldShiftBehaviorEnabled
                            animated:YES];
      }
      break;
    }

    case FlexibleHeaderConfiguratorFieldContentImportance:
      headerView.headerContentImportance =
          ([value boolValue] ? MDCFlexibleHeaderContentImportanceHigh
                             : MDCFlexibleHeaderContentImportanceDefault);
      break;

    case FlexibleHeaderConfiguratorFieldShiftOffscreen: {
      [headerView shiftHeaderOffScreenAnimated:YES];
      break;
    }

    case FlexibleHeaderConfiguratorFieldShiftOnscreen: {
      [headerView shiftHeaderOnScreenAnimated:YES];
      break;
    }

      // Header height

    case FlexibleHeaderConfiguratorFieldMinimumHeight:
      headerView.minimumHeight = [self heightDenormalized:[value floatValue]];
      break;

    case FlexibleHeaderConfiguratorFieldMaximumHeight:
      headerView.maximumHeight = [self heightDenormalized:[value floatValue]];
      break;

    case FlexibleHeaderConfiguratorFieldMinMaxHeightIncludeSafeArea:
      headerView.minMaxHeightIncludesSafeArea = [value boolValue];
      break;

    case FlexibleHeaderConfiguratorFieldCanAlwaysExpandToMaximumHeight:
      headerView.canAlwaysExpandToMaximumHeight = [value boolValue];
      break;
  }
}

#pragma mark - Typical Flexible Header implementations

// Required for shiftBehavior == MDCFlexibleHeaderShiftBehaviorEnabledWithStatusBar.
- (BOOL)prefersStatusBarHidden {
  return _overrideStatusBarHidden || self.fhvc.prefersStatusBarHidden;
}

- (UIStatusBarAnimation)preferredStatusBarUpdateAnimation {
  return UIStatusBarAnimationSlide;
}

#pragma mark - UIScrollViewDelegate

// Note that, unlike the Typical Use example, we are explicitly forwarding the UIScrollViewDelegate
// methods to the header view. This is because this example controller also needs to handle other
// UITableViewDelegate events.

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
  if (scrollView == self.fhvc.headerView.trackingScrollView) {
    [self.fhvc.headerView trackingScrollViewDidScroll];
  }
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
  if (scrollView == self.fhvc.headerView.trackingScrollView) {
    [self.fhvc.headerView trackingScrollViewDidEndDecelerating];
  }
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
  MDCFlexibleHeaderView *headerView = self.fhvc.headerView;
  if (scrollView == headerView.trackingScrollView) {
    [headerView trackingScrollViewDidEndDraggingWillDecelerate:decelerate];
  }
}

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView
                     withVelocity:(CGPoint)velocity
              targetContentOffset:(inout CGPoint *)targetContentOffset {
  MDCFlexibleHeaderView *headerView = self.fhvc.headerView;
  if (scrollView == headerView.trackingScrollView) {
    [headerView trackingScrollViewWillEndDraggingWithVelocity:velocity
                                          targetContentOffset:targetContentOffset];
  }
}

#pragma mark - Field data manipulation

static const CGFloat kHeightScalar = 300;

- (CGFloat)normalizedHeight:(CGFloat)height {
  return (height - self.minimumHeaderHeight) / (kHeightScalar - self.minimumHeaderHeight);
}

- (CGFloat)heightDenormalized:(CGFloat)normalized {
  return normalized * (kHeightScalar - self.minimumHeaderHeight) + self.minimumHeaderHeight;
}

- (NSNumber *)valueForField:(FlexibleHeaderConfiguratorField)field {
  switch (field) {
    case FlexibleHeaderConfiguratorFieldCanOverExtend:
      return @(self.fhvc.headerView.canOverExtend);

    case FlexibleHeaderConfiguratorFieldContentImportance:
      return @(
          (self.fhvc.headerView.headerContentImportance == MDCFlexibleHeaderContentImportanceHigh));

    case FlexibleHeaderConfiguratorFieldHideStatusBar:
      return @(self.overrideStatusBarHidden);

    case FlexibleHeaderConfiguratorFieldShiftBehaviorEnabled: {
      MDCFlexibleHeaderShiftBehavior behavior = self.fhvc.headerView.shiftBehavior;
      BOOL enabled = (behavior == MDCFlexibleHeaderShiftBehaviorEnabled ||
                      behavior == MDCFlexibleHeaderShiftBehaviorEnabledWithStatusBar);
      return @(enabled);
    }

    case FlexibleHeaderConfiguratorFieldShiftBehaviorEnabledWithStatusBar: {
      MDCFlexibleHeaderShiftBehavior behavior = self.fhvc.headerView.shiftBehavior;
      BOOL enabled = (behavior == MDCFlexibleHeaderShiftBehaviorEnabledWithStatusBar);
      return @(enabled);
    }

    // Buttons have no value
    case FlexibleHeaderConfiguratorFieldShiftOffscreen:
    case FlexibleHeaderConfiguratorFieldShiftOnscreen:
      return nil;

    case FlexibleHeaderConfiguratorFieldInFrontOfInfiniteContent:
      return @(self.fhvc.headerView.inFrontOfInfiniteContent);

    case FlexibleHeaderConfiguratorFieldMinimumHeight:
      return @([self normalizedHeight:self.fhvc.headerView.minimumHeight]);

    case FlexibleHeaderConfiguratorFieldMaximumHeight:
      return @([self normalizedHeight:self.fhvc.headerView.maximumHeight]);

    case FlexibleHeaderConfiguratorFieldMinMaxHeightIncludeSafeArea:
      return @(self.fhvc.headerView.minMaxHeightIncludesSafeArea);

    case FlexibleHeaderConfiguratorFieldCanAlwaysExpandToMaximumHeight:
      return @(self.fhvc.headerView.canAlwaysExpandToMaximumHeight);
  }
}

@end