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Animate dimming view opacity based on sheet height

This commit is contained in:
Shadowfacts 2019-09-24 12:11:10 -04:00
parent 9ddd39da4c
commit 08846bbc09
Signed by: shadowfacts
GPG Key ID: 94A5AB95422746E5
3 changed files with 45 additions and 18 deletions
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4
SheetImagePicker.xcodeproj/project.pbxproj
View File

@ -18,6 +18,7 @@
D610D2F6233945C0009EB06A /* SheetImagePicker.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = D610D2D1233945AF009EB06A /* SheetImagePicker.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
D610D2FD23394E00009EB06A /* SheetContainerViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D610D2FC23394E00009EB06A /* SheetContainerViewController.swift */; };
D610D2FF23395975009EB06A /* Detent.swift in Sources */ = {isa = PBXBuildFile; fileRef = D610D2FE23395975009EB06A /* Detent.swift */; };
D6B61D63233A748300809DE7 /* MathHelpers.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6B61D62233A748300809DE7 /* MathHelpers.swift */; };
/* End PBXBuildFile section */
/* Begin PBXContainerItemProxy section */
@ -58,6 +59,7 @@
D610D2F0233945BB009EB06A /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
D610D2FC23394E00009EB06A /* SheetContainerViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SheetContainerViewController.swift; sourceTree = "<group>"; };
D610D2FE23395975009EB06A /* Detent.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Detent.swift; sourceTree = "<group>"; };
D6B61D62233A748300809DE7 /* MathHelpers.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MathHelpers.swift; sourceTree = "<group>"; };
/* End PBXFileReference section */
/* Begin PBXFrameworksBuildPhase section */
@ -102,6 +104,7 @@
isa = PBXGroup;
children = (
D610D2D4233945AF009EB06A /* SheetImagePicker.h */,
D6B61D62233A748300809DE7 /* MathHelpers.swift */,
D610D2FC23394E00009EB06A /* SheetContainerViewController.swift */,
D610D2FE23395975009EB06A /* Detent.swift */,
D610D2D5233945AF009EB06A /* Info.plist */,
@ -246,6 +249,7 @@
files = (
D610D2FD23394E00009EB06A /* SheetContainerViewController.swift in Sources */,
D610D2FF23395975009EB06A /* Detent.swift in Sources */,
D6B61D63233A748300809DE7 /* MathHelpers.swift in Sources */,
);
runOnlyForDeploymentPostprocessing = 0;
};

30
SheetImagePicker/MathHelpers.swift Normal file
View File

@ -0,0 +1,30 @@
//
// MathHelpers.swift
// SheetImagePicker
//
// Created by Shadowfacts on 9/24/19.
// Copyright © 2019 Shadowfacts. All rights reserved.
//
import UIKit
func clamp(_ value: CGFloat, from: CGFloat, to: CGFloat) -> CGFloat {
if value < from {
return from
} else if value > to {
return to
} else {
return value
}
}
func smoothstep(value: CGFloat, from: CGFloat, to: CGFloat) -> CGFloat {
let x = clamp((value - from) / (to - from), from: 0, to: 1)
// 3x^2 - 2x^3
return 3 * pow(x, 2) - 2 * pow(x, 3)
}
func lerp(_ value: CGFloat, min: CGFloat, max: CGFloat, from: CGFloat, to: CGFloat) -> CGFloat {
let value = clamp((value - min) / (max - min), from: 0, to: 1)
return value * (to - from) + from
}

25
SheetImagePicker/SheetContainerViewController.swift
View File

@ -31,6 +31,9 @@ public class SheetContainerViewController: UIViewController {
var topDetent: (detent: Detent, offset: CGFloat) {
return detents.map { ($0, $0.offset(in: view)) }.min(by: { $0.1 < $1.1 })!
}
var bottomDetent: (detent: Detent, offset: CGFloat) {
return detents.map { ($0, $0.offset(in: view)) }.max(by: { $0.1 < $1.1 })!
}
public var minimumDetentJumpVelocity: CGFloat = 500
public var maximumStretchDistance: CGFloat = 15
@ -39,6 +42,8 @@ public class SheetContainerViewController: UIViewController {
lazy var initialConstant: CGFloat = view.bounds.height / 2
var dimmingView: UIView!
public var minimumDimmingAlpha: CGFloat = 0
public var maximumDimmingAlpha: CGFloat = 0.75
public init(content: UIViewController) {
self.content = content
@ -56,7 +61,7 @@ public class SheetContainerViewController: UIViewController {
dimmingView = UIView()
dimmingView.translatesAutoresizingMaskIntoConstraints = false
dimmingView.backgroundColor = .systemGray
dimmingView.alpha = 0.5
dimmingView.alpha = (maximumDimmingAlpha - minimumDimmingAlpha) / 2
view.addSubview(dimmingView)
NSLayoutConstraint.activate([
dimmingView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
@ -88,27 +93,14 @@ public class SheetContainerViewController: UIViewController {
case .changed:
let translation = recognizer.translation(in: content.view)
var realOffset = initialConstant + translation.y
if realOffset < topDetent.offset {
func clamp(_ value: CGFloat, from: CGFloat, to: CGFloat) -> CGFloat {
if value < from {
return from
} else if value > to {
return to
} else {
return value
}
}
func smoothstep(value: CGFloat, from: CGFloat, to: CGFloat) -> CGFloat {
let x = clamp((value - from) / (to - from), from: 0, to: 1)
// 3x^2 - 2x^3
return 3 * pow(x, 2) - 2 * pow(x, 3)
}
let topOffset = topDetent.offset
if realOffset < topOffset {
let smoothed = smoothstep(value: realOffset, from: topOffset, to: 0)
realOffset = topOffset - smoothed * maximumStretchDistance
}
topConstraint.constant = realOffset
dimmingView.alpha = lerp(realOffset, min: topOffset, max: bottomDetent.offset, from: maximumDimmingAlpha, to: minimumDimmingAlpha)
case .ended:
let velocity = recognizer.velocity(in: view)
@ -130,6 +122,7 @@ public class SheetContainerViewController: UIViewController {
UIView.animate(withDuration: 0.35, delay: 0, usingSpringWithDamping: 0.6, initialSpringVelocity: springVelocity, animations: {
self.view.layoutIfNeeded()
self.dimmingView.alpha = lerp(springToDetent.1, min: self.topDetent.offset, max: self.bottomDetent.offset, from: self.maximumDimmingAlpha, to: self.minimumDimmingAlpha)
}, completion: { (finished) in
self.delegate?.sheetContainer(self, didSnapToDetent: springToDetent.0)
})