first commit

.gitignore

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+# Xcode
+#
+# gitignore contributors: remember to update Global/Xcode.gitignore, Objective-C.gitignore & Swift.gitignore
+
+## User settings
+xcuserdata/
+
+## compatibility with Xcode 8 and earlier (ignoring not required starting Xcode 9)
+*.xcscmblueprint
+*.xccheckout
+
+## compatibility with Xcode 3 and earlier (ignoring not required starting Xcode 4)
+build/
+DerivedData/
+*.moved-aside
+*.pbxuser
+!default.pbxuser
+*.mode1v3
+!default.mode1v3
+*.mode2v3
+!default.mode2v3
+*.perspectivev3
+!default.perspectivev3
+
+## Obj-C/Swift specific
+*.hmap
+
+## App packaging
+*.ipa
+*.dSYM.zip
+*.dSYM
+
+## Playgrounds
+timeline.xctimeline
+playground.xcworkspace
+
+# Swift Package Manager
+#
+# Add this line if you want to avoid checking in source code from Swift Package Manager dependencies.
+# Packages/
+# Package.pins
+# Package.resolved
+# *.xcodeproj
+#
+# Xcode automatically generates this directory with a .xcworkspacedata file and xcuserdata
+# hence it is not needed unless you have added a package configuration file to your project
+.swiftpm
+
+.build/
+
+# CocoaPods
+#
+# We recommend against adding the Pods directory to your .gitignore. However
+# you should judge for yourself, the pros and cons are mentioned at:
+# https://guides.cocoapods.org/using/using-cocoapods.html#should-i-check-the-pods-directory-into-source-control
+#
+# Pods/
+#
+# Add this line if you want to avoid checking in source code from the Xcode workspace
+# *.xcworkspace
+
+# Carthage
+#
+# Add this line if you want to avoid checking in source code from Carthage dependencies.
+# Carthage/Checkouts
+
+Carthage/Build/
+
+# Accio dependency management
+Dependencies/
+.accio/
+
+# fastlane
+#
+# It is recommended to not store the screenshots in the git repo.
+# Instead, use fastlane to re-generate the screenshots whenever they are needed.
+# For more information about the recommended setup visit:
+# https://docs.fastlane.tools/best-practices/source-control/#source-control
+
+fastlane/report.xml
+fastlane/Preview.html
+fastlane/screenshots/**/*.png
+fastlane/test_output
+
+# Code Injection
+#
+# After new code Injection tools there's a generated folder /iOSInjectionProject
+# https://github.com/johnno1962/injectionforxcode
+
+iOSInjectionProject/

LICENSE

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+MIT License
+
+Copyright (c) 2019 Paolo Leonardi
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

Package.swift

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+// swift-tools-version:5.1
+
+//
+//  Copyright © 2019 Paolo Leonardi.
+//
+//  Licensed under the MIT license. See the LICENSE file for more info.
+//
+
+import PackageDescription
+
+let package = Package(
+    name: "WaterfallGrid",
+    platforms: [
+        .iOS(.v13),
+        .macOS(.v10_15),
+        .tvOS(.v13),
+        .watchOS(.v6)
+    ],
+    products: [
+        .library(
+            name: "WaterfallGrid",
+            targets: ["WaterfallGrid"]),
+    ],
+    dependencies: [],
+    targets: [
+        .target(
+            name: "WaterfallGrid",
+            dependencies: []),
+        .testTarget(
+            name: "WaterfallGridTests",
+            dependencies: ["WaterfallGrid"]),
+    ]
+)

README.md

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+# WaterfallGrid
+
+A waterfall grid layout view for SwiftUI.
+
+<center>
+<img src="Assets/demo1.png"/>
+</center>
+
+## Features
+
+- [x] Items fill the most available vertical space.
+- [x] Columns number different per device orientation.
+- [x] Spacing and grid padding customizable.
+- [x] Items update can be animated.
+
+## Requirements
+
+- iOS 13.0+ / macOS 10.15+ / tvOS 13.0+ / watchOS 6.0+
+- Xcode 11.0+
+- Swift 5.1+
+
+## Installation
+
+### Swift Package Manager
+
+The [Swift Package Manager](https://swift.org/package-manager/) is a tool for automating the distribution of Swift code and is integrated into the `swift` compiler.
+
+Once you have your Swift package set up, adding WaterfallGrid as a dependency is as easy as adding it to the `dependencies` value of your `Package.swift`.
+
+```swift
+dependencies: [
+    .package(url: "https://github.com/paololeonardi/WaterfallGrid.git"))
+]
+```
+
+## Usage
+
+```swift
+WaterfallGrid(images, columns: 2) { image in
+    Image(image.name)
+        .resizable()
+        .aspectRatio(contentMode: .fit)
+}
+```
+
+```swift
+WaterfallGrid((0..<cards.count),
+              id: \.self,
+              columnsInPortrait: 2,
+              columnsInLandscape: 3,
+              spacing: 8,
+              vPadding: 8,
+              hPadding: 8,
+              animation: .easeInOut
+) { index in
+    CardView(card: self.cards[index])
+}
+```
+
+## Versions
+
+For the versions available, see the [tags on this repository](https://github.com/paololeonardi/WaterfallGrid/tags). 
+
+## Author
+* [Paolo Leonardi](https://github.com/paololeonardi) ([@paololeonardi](https://twitter.com/paololeonardi))
+
+## Credits
+WaterfallGrid was ispired by the following projects:
+
+* QGrid - https://github.com/Q-Mobile/QGrid
+* Grid - https://github.com/SwiftUIExtensions/Grid
+* The SwiftUI Lab - https://swiftui-lab.com
+
+## License
+
+WaterfallGrid is available under the MIT license. See the [LICENSE](LICENSE) file for more info.
+

Sources/WaterfallGrid/ElementPreference.swift

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+//
+//  Copyright © 2019 Paolo Leonardi.
+//
+//  Licensed under the MIT license. See the LICENSE file for more info.
+//
+
+import SwiftUI
+
+struct ElementPreferenceData: Equatable {
+    let id: AnyHashable
+    let size: CGSize
+}
+
+struct ElementPreferenceKey: PreferenceKey {
+    typealias Value = [ElementPreferenceData]
+
+    static var defaultValue: [ElementPreferenceData] = []
+
+    static func reduce(value: inout [ElementPreferenceData], nextValue: () -> [ElementPreferenceData]) {
+        value.append(contentsOf: nextValue())
+    }
+}

Sources/WaterfallGrid/PositiveNumber.swift

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+//
+//  Copyright © 2019 Paolo Leonardi.
+//
+//  Licensed under the MIT license. See the LICENSE file for more info.
+//
+
+import Foundation
+
+@propertyWrapper
+struct PositiveNumber {
+    private var value: Int = 1
+
+    var wrappedValue: Int {
+        get { value }
+        set { value = max(1, newValue) }
+    }
+
+    init(wrappedValue initialValue: Int) {
+        self.wrappedValue = initialValue
+    }
+}

Sources/WaterfallGrid/PreferenceSetter.swift

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+//
+//  Copyright © 2019 Paolo Leonardi.
+//
+//  Licensed under the MIT license. See the LICENSE file for more info.
+//
+
+import SwiftUI
+
+struct PreferenceSetter<ID: Hashable>: View {
+    var id: ID
+    var body: some View {
+        return GeometryReader { geometry in
+            Color.clear
+                .preference(key: ElementPreferenceKey.self, value: [ElementPreferenceData(id: AnyHashable(self.id), size: geometry.size)])
+        }
+    }
+}