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Adding a bunch of features and refactoring the code to make it more reusable #2

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dcea4ed
Create LICENSE
plivesey Nov 20, 2019
ed75acf
This commit adds some features and cleans up some code to make it mor…
plivesey Nov 20, 2019
090462b
This makes visibleRows a calculated property
plivesey Nov 21, 2019
7bfd055
Improved the rows(in rect:) calculation to be faster
plivesey Nov 21, 2019
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8 changes: 6 additions & 2 deletions CollectionThing.xcodeproj/project.pbxproj
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
objects = {

/* Begin PBXBuildFile section */
365E19532385C868003FC01B /* FastCollection.swift in Sources */ = {isa = PBXBuildFile; fileRef = 365E19522385C868003FC01B /* FastCollection.swift */; };
83060F432381FE2000FDF0AD /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 83060F422381FE2000FDF0AD /* AppDelegate.swift */; };
83060F452381FE2000FDF0AD /* SceneDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 83060F442381FE2000FDF0AD /* SceneDelegate.swift */; };
83060F472381FE2000FDF0AD /* ContentView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 83060F462381FE2000FDF0AD /* ContentView.swift */; };
Expand All @@ -21,6 +22,7 @@
/* End PBXBuildFile section */

/* Begin PBXFileReference section */
365E19522385C868003FC01B /* FastCollection.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FastCollection.swift; sourceTree = "<group>"; };
83060F3F2381FE2000FDF0AD /* CollectionThing.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = CollectionThing.app; sourceTree = BUILT_PRODUCTS_DIR; };
83060F422381FE2000FDF0AD /* AppDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
83060F442381FE2000FDF0AD /* SceneDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SceneDelegate.swift; sourceTree = "<group>"; };
Expand Down Expand Up @@ -82,6 +84,7 @@
83060F422381FE2000FDF0AD /* AppDelegate.swift */,
83060F442381FE2000FDF0AD /* SceneDelegate.swift */,
83060F462381FE2000FDF0AD /* ContentView.swift */,
365E19522385C868003FC01B /* FastCollection.swift */,
83060F482381FE2200FDF0AD /* Assets.xcassets */,
83060F4D2381FE2200FDF0AD /* LaunchScreen.storyboard */,
83060F502381FE2200FDF0AD /* Info.plist */,
Expand Down Expand Up @@ -222,6 +225,7 @@
buildActionMask = 2147483647;
files = (
83060F432381FE2000FDF0AD /* AppDelegate.swift in Sources */,
365E19532385C868003FC01B /* FastCollection.swift in Sources */,
83060F452381FE2000FDF0AD /* SceneDelegate.swift in Sources */,
83060F472381FE2000FDF0AD /* ContentView.swift in Sources */,
);
Expand Down Expand Up @@ -308,7 +312,7 @@
GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
GCC_WARN_UNUSED_FUNCTION = YES;
GCC_WARN_UNUSED_VARIABLE = YES;
IPHONEOS_DEPLOYMENT_TARGET = 13.2;
IPHONEOS_DEPLOYMENT_TARGET = 13.0;
MTL_ENABLE_DEBUG_INFO = INCLUDE_SOURCE;
MTL_FAST_MATH = YES;
ONLY_ACTIVE_ARCH = YES;
Expand Down Expand Up @@ -362,7 +366,7 @@
GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
GCC_WARN_UNUSED_FUNCTION = YES;
GCC_WARN_UNUSED_VARIABLE = YES;
IPHONEOS_DEPLOYMENT_TARGET = 13.2;
IPHONEOS_DEPLOYMENT_TARGET = 13.0;
MTL_ENABLE_DEBUG_INFO = NO;
MTL_FAST_MATH = YES;
SDKROOT = iphoneos;
Expand Down
185 changes: 9 additions & 176 deletions CollectionThing/ContentView.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -7,65 +7,6 @@
//

import SwiftUI
import Combine

struct WrappedLayout<Item: Identifiable> {
/// The items to be laid out
let items: [Item]

/// The (maximum) number of items to be placed in a row
let columns: Int

/// A model representing the row of items
struct Row: Identifiable {
let id: Int
let frame: CGRect
let items: ArraySlice<Item>

func translatingY(_ y: CGFloat) -> Row {
return Row(id: id, frame: frame.offsetBy(dx: 0, dy: y), items: items)
}

func width(_ width: CGFloat) -> Row {
return Row(id: id, frame: CGRect(x: frame.origin.x, y: frame.origin.y, width: width, height: frame.size.height), items: items)
}
}

let contentSize: CGSize
let rows: [Row]
let rowHeight: CGFloat

init(items: [Item], columns: Int) {
let rowHeight: CGFloat = 80

func rangeForRow(_ index: Int) -> Range<Int> {
return ((index * columns) ..< ((index + 1) * columns)).clamped(to: items.indices)
}

func frameForRow(_ index: Int) -> CGRect {
return CGRect(x: 0, y: CGFloat(index) * rowHeight, width: 1, height: rowHeight)
}

let (quotient, remainder) = items.count.quotientAndRemainder(dividingBy: columns)
let rowCount = (remainder > 0) ? quotient + 1 : quotient

self.items = items
self.rows = (0 ..< rowCount).map { Row(id: $0, frame: frameForRow($0), items: items[rangeForRow($0)]) }
self.columns = columns
self.contentSize = CGSize(width: 1, height: CGFloat(rowCount) * rowHeight)
self.rowHeight = rowHeight
}

struct LayoutItem: Identifiable {
var id: Item.ID { item.id }
let item: Item
let frame: CGRect
}

func rows(in rect: CGRect) -> [Row] {
return rows.filter { $0.frame.intersects(rect) }.map { $0.width(rect.width) }
}
}

struct Item: Identifiable {
let id = UUID()
Expand All @@ -87,128 +28,20 @@ struct ItemView: View {
}
}

final class Store: ObservableObject {
@Published var value: WrappedLayout<Item>
init() {
self.value = WrappedLayout(items: (0 ..< 50000).map { Item(title: "\($0)") }, columns: 8)
}
}

struct ContentView: View {

@ObservedObject var store: Store
init() {
self.store = Store()
}

@State var fixedBounds: CGRect = .zero
@State var lastQueryRect: CGRect = .zero
@State var visibleRowBounds: CGRect = .zero
@State var visibleRows: [WrappedLayout<Item>.Row] = []

@ObservedObject private var store = Store()

var body: some View {
VStack {
ScrollView {
ZStack(alignment: .top) {
MovingView()
.frame(height: 0)

Color.clear
.frame(
width: self.store.value.contentSize.width,
height: self.store.value.contentSize.height
)
.hidden()

VStack(spacing: 0) {
ForEach(self.visibleRows) { row in
HStack(spacing: 0) {
ForEach(row.items) { item in
ItemView(item: item)
}
}
}
}
.frame(
width: self.fixedBounds.width,
height: self.visibleRowBounds.height,
alignment: .topLeading
)
.position(
x: self.fixedBounds.midX,
y: self.visibleRowBounds.midY
)
}
}
.background(FixedView().edgesIgnoringSafeArea(.all))
.onPreferenceChange(ViewFrames.self) { values in
let fixedBounds = values[.fixedView] ?? .zero
let movingBounds = values[.movingView] ?? .zero
let boundsDirty = fixedBounds != self.fixedBounds
if boundsDirty {
self.fixedBounds = values[.fixedView] ?? .zero
}

#if os(iOS)
let visibleRect = CGRect(
x: movingBounds.origin.x,
y: (fixedBounds.origin.y - movingBounds.origin.y),
width: fixedBounds.width,
height: fixedBounds.height)
#else
let visibleRect = CGRect(
x: movingBounds.origin.x,
y: movingBounds.origin.y - fixedBounds.height,
width: fixedBounds.width,
height: fixedBounds.height)
#endif

let queryRect = visibleRect.insetBy(dx: 0, dy: -(visibleRect.height / 8))

if boundsDirty || self.lastQueryRect.isEmpty || self.lastQueryRect.intersection(queryRect).height < (visibleRect.height * 1.2) {
self.lastQueryRect = queryRect

let rows = self.store.value.rows(in: queryRect)
let bounds = (rows.first?.frame ?? .zero).union(rows.last?.frame ?? .zero)

if rows.map({ $0.id }) != self.visibleRows.map({ $0.id }) {
self.visibleRows = rows
self.visibleRowBounds = bounds
}
}
}
}
}

struct MovingView: View {
var body: some View {
GeometryReader { proxy in
Color.clear.hidden().preference(key: ViewFrames.self, value: [.movingView: proxy.frame(in: .global)])
}.frame(height: 0)
FastCollection(items: store.value, columns: 8, buffer: 100, itemHeight: 80) { item in
ItemView(item: item)
}
}

struct FixedView: View {
var body: some View {
GeometryReader { proxy in
Color.clear.hidden().preference(key: ViewFrames.self, value: [.fixedView: proxy.frame(in: .global)])
}
}
}

struct ViewFrames: PreferenceKey {
enum ViewType: Int {
case movingView
case fixedView
}

static var defaultValue: [ViewType:CGRect] = [:]

static func reduce(value: inout [ViewType:CGRect], nextValue: () -> [ViewType:CGRect]) {
value.merge(nextValue(), uniquingKeysWith: { old, new in new })
}
}

typealias Value = [ViewType:CGRect]
final class Store: ObservableObject {
@Published var value: [Item]
init() {
self.value = (0 ..< 50000).map { Item(title: "\($0)") }
}
}

Expand Down
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