components/private/TextControlsPrivate/src/BaseStyle/MDCTextControlVerticalPositioningReferenceBase.m

// Copyright 2019-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 "MDCTextControlVerticalPositioningReferenceBase.h"
#import "MaterialMath.h"

static const CGFloat kMinPaddingBetweenContainerTopAndFloatingLabel = (CGFloat)6.0;
static const CGFloat kMaxPaddingBetweenContainerTopAndFloatingLabel = (CGFloat)10.0;
static const CGFloat kMinPaddingBetweenFloatingLabelAndEditingText = (CGFloat)3.0;
static const CGFloat kMaxPaddingBetweenFloatingLabelAndEditingText = (CGFloat)6.0;
static const CGFloat kMinPaddingBetweenEditingTextAndContainerBottom = (CGFloat)3.0;
static const CGFloat kMaxPaddingBetweenEditingTextAndContainerBottom = (CGFloat)6.0;
static const CGFloat kMinPaddingAboveAssistiveLabels = (CGFloat)0.0;
static const CGFloat kMaxPaddingAboveAssistiveLabels = (CGFloat)0.0;
static const CGFloat kMinPaddingBelowAssistiveLabels = (CGFloat)3.0;
static const CGFloat kMaxPaddingBelowAssistiveLabels = (CGFloat)6.0;

@interface MDCTextControlVerticalPositioningReferenceBase ()
@end

@implementation MDCTextControlVerticalPositioningReferenceBase

@synthesize paddingBetweenContainerTopAndFloatingLabel =
    _paddingBetweenContainerTopAndFloatingLabel;
@synthesize paddingBetweenContainerTopAndNormalLabel = _paddingBetweenContainerTopAndNormalLabel;
@synthesize paddingBetweenFloatingLabelAndEditingText = _paddingBetweenFloatingLabelAndEditingText;
@synthesize paddingBetweenEditingTextAndContainerBottom =
    _paddingBetweenEditingTextAndContainerBottom;
@synthesize paddingAboveAssistiveLabels = _paddingAboveAssistiveLabels;
@synthesize paddingBelowAssistiveLabels = _paddingBelowAssistiveLabels;
@synthesize containerHeight = _containerHeight;

- (instancetype)initWithFloatingFontLineHeight:(CGFloat)floatingLabelHeight
                          normalFontLineHeight:(CGFloat)normalFontLineHeight
                                 textRowHeight:(CGFloat)textRowHeight
                              numberOfTextRows:(CGFloat)numberOfTextRows
                                       density:(CGFloat)density
                      preferredContainerHeight:(CGFloat)preferredContainerHeight {
  self = [super init];
  if (self) {
    [self calculatePaddingValuesWithFoatingFontLineHeight:floatingLabelHeight
                                     normalFontLineHeight:normalFontLineHeight
                                            textRowHeight:textRowHeight
                                         numberOfTextRows:numberOfTextRows
                                                  density:density
                                 preferredContainerHeight:preferredContainerHeight];
  }
  return self;
}

- (void)calculatePaddingValuesWithFoatingFontLineHeight:(CGFloat)floatingLabelHeight
                                   normalFontLineHeight:(CGFloat)normalFontLineHeight
                                          textRowHeight:(CGFloat)textRowHeight
                                       numberOfTextRows:(CGFloat)numberOfTextRows
                                                density:(CGFloat)density
                               preferredContainerHeight:(CGFloat)preferredContainerHeight {
  BOOL isMultiline = numberOfTextRows > 1 || numberOfTextRows == 0;
  CGFloat normalizedDensity = [self normalizeDensity:density];

  _paddingBetweenContainerTopAndFloatingLabel =
      [self paddingValueWithMinimumPadding:kMinPaddingBetweenContainerTopAndFloatingLabel
                            maximumPadding:kMaxPaddingBetweenContainerTopAndFloatingLabel
                                   density:normalizedDensity];

  _paddingBetweenFloatingLabelAndEditingText =
      [self paddingValueWithMinimumPadding:kMinPaddingBetweenFloatingLabelAndEditingText
                            maximumPadding:kMaxPaddingBetweenFloatingLabelAndEditingText
                                   density:normalizedDensity];

  _paddingBetweenEditingTextAndContainerBottom =
      [self paddingValueWithMinimumPadding:kMinPaddingBetweenEditingTextAndContainerBottom
                            maximumPadding:kMaxPaddingBetweenEditingTextAndContainerBottom
                                   density:normalizedDensity];

  _paddingAboveAssistiveLabels =
      [self paddingValueWithMinimumPadding:kMinPaddingAboveAssistiveLabels
                            maximumPadding:kMaxPaddingAboveAssistiveLabels
                                   density:normalizedDensity];

  _paddingBelowAssistiveLabels =
      [self paddingValueWithMinimumPadding:kMinPaddingBelowAssistiveLabels
                            maximumPadding:kMaxPaddingBelowAssistiveLabels
                                   density:normalizedDensity];

  // The container height below is the "default" container height, given the density. This height
  // will be used if the client has not specified a preferredContainerHeight.
  CGFloat containerHeightWithPaddingsDeterminedByDensity = [self
      calculateContainerHeightWithFoatingLabelHeight:floatingLabelHeight
                                       textRowHeight:textRowHeight
                                    numberOfTextRows:numberOfTextRows
          paddingBetweenContainerTopAndFloatingLabel:_paddingBetweenContainerTopAndFloatingLabel
           paddingBetweenFloatingLabelAndEditingText:_paddingBetweenFloatingLabelAndEditingText
         paddingBetweenEditingTextAndContainerBottom:_paddingBetweenEditingTextAndContainerBottom];
  BOOL clientHasSpecifiedValidPreferredContainerHeight =
      preferredContainerHeight > containerHeightWithPaddingsDeterminedByDensity;
  if (clientHasSpecifiedValidPreferredContainerHeight && !isMultiline) {
    // modify the previously computed padding values so that they ultimately result in a container
    // with the preferred container height.
    CGFloat difference = preferredContainerHeight - containerHeightWithPaddingsDeterminedByDensity;
    CGFloat sumOfPaddingValues = _paddingBetweenContainerTopAndFloatingLabel +
                                 _paddingBetweenFloatingLabelAndEditingText +
                                 _paddingBetweenEditingTextAndContainerBottom;
    _paddingBetweenContainerTopAndFloatingLabel =
        _paddingBetweenContainerTopAndFloatingLabel +
        ((_paddingBetweenContainerTopAndFloatingLabel / sumOfPaddingValues) * difference);
    _paddingBetweenFloatingLabelAndEditingText =
        _paddingBetweenFloatingLabelAndEditingText +
        ((_paddingBetweenFloatingLabelAndEditingText / sumOfPaddingValues) * difference);
    _paddingBetweenEditingTextAndContainerBottom =
        _paddingBetweenEditingTextAndContainerBottom +
        ((_paddingBetweenEditingTextAndContainerBottom / sumOfPaddingValues) * difference);
  }

  if (clientHasSpecifiedValidPreferredContainerHeight) {
    _containerHeight = preferredContainerHeight;
  } else {
    _containerHeight = containerHeightWithPaddingsDeterminedByDensity;
  }

  CGFloat halfOfNormalFontLineHeight = (CGFloat)0.5 * normalFontLineHeight;
  if (isMultiline) {
    // For multiline text controls the normal label (i.e. the label when it's not floating) should
    // be positioned where it would be positioned if it were single-line.
    CGFloat heightWithOneRow = [self
        calculateContainerHeightWithFoatingLabelHeight:floatingLabelHeight
                                         textRowHeight:textRowHeight
                                      numberOfTextRows:1
            paddingBetweenContainerTopAndFloatingLabel:_paddingBetweenContainerTopAndFloatingLabel
             paddingBetweenFloatingLabelAndEditingText:_paddingBetweenFloatingLabelAndEditingText
           paddingBetweenEditingTextAndContainerBottom:
               _paddingBetweenEditingTextAndContainerBottom];
    CGFloat halfOfHeightWithOneRow = (CGFloat)0.5 * heightWithOneRow;
    _paddingBetweenContainerTopAndNormalLabel = halfOfHeightWithOneRow - halfOfNormalFontLineHeight;
  } else {
    // For single-line text controls the normal label (i.e. the label when it's not floating) should
    // be vertically centered.
    CGFloat halfOfContainerHeight = (CGFloat)0.5 * _containerHeight;
    _paddingBetweenContainerTopAndNormalLabel = halfOfContainerHeight - halfOfNormalFontLineHeight;
  }
}

- (CGFloat)paddingValueWithMinimumPadding:(CGFloat)minimumPadding
                           maximumPadding:(CGFloat)maximumPadding
                                  density:(CGFloat)density {
  if (minimumPadding > maximumPadding) {
    return 0;
  } else if (minimumPadding == maximumPadding) {
    return minimumPadding;
  } else {
    CGFloat minMaxPaddingDifference = maximumPadding - minimumPadding;
    CGFloat additionToMinPadding = minMaxPaddingDifference * (1 - density);
    return minimumPadding + additionToMinPadding;
  }
}

- (CGFloat)normalizeDensity:(CGFloat)density {
  CGFloat normalizedDensity = density;
  if (normalizedDensity < 0) {
    normalizedDensity = 0;
  } else if (normalizedDensity > 1) {
    normalizedDensity = 1;
  }
  return normalizedDensity;
}

- (CGFloat)calculateContainerHeightWithFoatingLabelHeight:(CGFloat)floatingLabelHeight
                                            textRowHeight:(CGFloat)textRowHeight
                                         numberOfTextRows:(CGFloat)numberOfTextRows
               paddingBetweenContainerTopAndFloatingLabel:
                   (CGFloat)paddingBetweenContainerTopAndFloatingLabel
                paddingBetweenFloatingLabelAndEditingText:
                    (CGFloat)paddingBetweenFloatingLabelAndEditingText
              paddingBetweenEditingTextAndContainerBottom:
                  (CGFloat)paddingBetweenEditingTextAndContainerBottom {
  CGFloat totalTextHeight = numberOfTextRows * textRowHeight;
  return paddingBetweenContainerTopAndFloatingLabel + floatingLabelHeight +
         paddingBetweenFloatingLabelAndEditingText + totalTextHeight +
         paddingBetweenEditingTextAndContainerBottom;
}

- (CGFloat)paddingBetweenContainerTopAndFloatingLabel {
  return _paddingBetweenContainerTopAndFloatingLabel;
}

- (CGFloat)paddingBetweenContainerTopAndNormalLabel {
  return _paddingBetweenContainerTopAndNormalLabel;
}

- (CGFloat)paddingBetweenFloatingLabelAndEditingText {
  return _paddingBetweenFloatingLabelAndEditingText;
}

- (CGFloat)paddingBetweenEditingTextAndContainerBottom {
  return _paddingBetweenEditingTextAndContainerBottom;
}

- (CGFloat)paddingAboveAssistiveLabels {
  return _paddingAboveAssistiveLabels;
}

- (CGFloat)paddingBelowAssistiveLabels {
  return _paddingBelowAssistiveLabels;
}

- (CGFloat)containerHeight {
  return _containerHeight;
}

@end