723 lines
28 KiB
Swift
723 lines
28 KiB
Swift
//
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// Copyright (c) 2019 Open Whisper Systems. All rights reserved.
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//
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import UIKit
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public class EditorTextLayer: CATextLayer {
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let itemId: String
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public init(itemId: String) {
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self.itemId = itemId
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super.init()
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}
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@available(*, unavailable, message: "use other init() instead.")
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required public init?(coder aDecoder: NSCoder) {
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notImplemented()
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}
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}
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// MARK: -
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// A view for previewing an image editor model.
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@objc
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public class ImageEditorCanvasView: UIView {
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private let model: ImageEditorModel
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private let itemIdsToIgnore: [String]
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// We want strokes to be rendered above the image and behind text.
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private static let brushLayerZ: CGFloat = +1
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// We want text to be rendered above the image and strokes.
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private static let textLayerZ: CGFloat = +2
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// We leave space for 10k items/layers of each type.
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private static let zPositionSpacing: CGFloat = 0.0001
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@objc
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public required init(model: ImageEditorModel,
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itemIdsToIgnore: [String] = []) {
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self.model = model
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self.itemIdsToIgnore = itemIdsToIgnore
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super.init(frame: .zero)
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model.add(observer: self)
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}
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@available(*, unavailable, message: "use other init() instead.")
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required public init?(coder aDecoder: NSCoder) {
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notImplemented()
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}
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// MARK: - Views
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// contentView is used to host the layers used to render the content.
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//
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// The transform for the content is applied to it.
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public let contentView = OWSLayerView()
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// clipView is used to clip the content. It reflects the actual
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// visible bounds of the "canvas" content.
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private let clipView = OWSLayerView()
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private var contentViewConstraints = [NSLayoutConstraint]()
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private var srcImage: UIImage?
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private var imageLayer = CALayer()
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@objc
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public func configureSubviews() {
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self.backgroundColor = .clear
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self.isOpaque = false
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self.srcImage = loadSrcImage()
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clipView.clipsToBounds = true
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clipView.backgroundColor = .clear
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clipView.isOpaque = false
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clipView.layoutCallback = { [weak self] (_) in
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guard let strongSelf = self else {
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return
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}
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strongSelf.updateLayout()
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}
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addSubview(clipView)
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if let srcImage = srcImage {
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imageLayer.contents = srcImage.cgImage
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imageLayer.contentsScale = srcImage.scale
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}
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contentView.backgroundColor = .clear
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contentView.isOpaque = false
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contentView.layer.addSublayer(imageLayer)
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contentView.layoutCallback = { [weak self] (_) in
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guard let strongSelf = self else {
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return
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}
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strongSelf.updateAllContent()
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}
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clipView.addSubview(contentView)
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contentView.autoPinEdgesToSuperviewEdges()
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updateLayout()
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}
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public var gestureReferenceView: UIView {
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return clipView
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}
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private func updateLayout() {
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NSLayoutConstraint.deactivate(contentViewConstraints)
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contentViewConstraints = ImageEditorCanvasView.updateContentLayout(transform: model.currentTransform(),
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contentView: clipView)
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}
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public class func updateContentLayout(transform: ImageEditorTransform,
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contentView: UIView) -> [NSLayoutConstraint] {
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guard let superview = contentView.superview else {
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owsFailDebug("Content view has no superview.")
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return []
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}
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let outputSizePixels = transform.outputSizePixels
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let aspectRatio = outputSizePixels
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var constraints = superview.applyScaleAspectFitLayout(subview: contentView, aspectRatio: aspectRatio.width / aspectRatio.height)
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let screenSize = UIScreen.main.bounds.size
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let maxScreenSize = max(screenSize.width, screenSize.height)
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let outputSizePoints = CGSize(width: maxScreenSize, height: maxScreenSize)
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// TODO: Add a "shouldFill" parameter.
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// let outputSizePoints = CGSizeScale(outputSizePixels, 1.0 / UIScreen.main.scale)
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NSLayoutConstraint.autoSetPriority(UILayoutPriority.defaultLow) {
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constraints.append(contentsOf: contentView.autoSetDimensions(to: outputSizePoints))
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}
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return constraints
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}
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@objc
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public func loadSrcImage() -> UIImage? {
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return ImageEditorCanvasView.loadSrcImage(model: model)
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}
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@objc
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public class func loadSrcImage(model: ImageEditorModel) -> UIImage? {
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let srcImageData: Data
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do {
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let srcImagePath = model.srcImagePath
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let srcImageUrl = URL(fileURLWithPath: srcImagePath)
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srcImageData = try Data(contentsOf: srcImageUrl)
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} catch {
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owsFailDebug("Couldn't parse srcImageUrl")
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return nil
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}
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// We use this constructor so that we can specify the scale.
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//
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// UIImage(contentsOfFile:) will sometimes use device scale.
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guard let srcImage = UIImage(data: srcImageData, scale: 1.0) else {
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owsFailDebug("Couldn't load background image.")
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return nil
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}
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// We normalize the image orientation here for the sake
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// of code simplicity. We could modify the image layer's
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// transform to handle the normalization, which would
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// have perf benefits.
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return srcImage.normalized()
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}
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// MARK: - Content
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var contentLayerMap = [String: CALayer]()
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internal func updateAllContent() {
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AssertIsOnMainThread()
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// Don't animate changes.
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CATransaction.begin()
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CATransaction.setDisableActions(true)
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for layer in contentLayerMap.values {
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layer.removeFromSuperlayer()
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}
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contentLayerMap.removeAll()
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let viewSize = clipView.bounds.size
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let transform = model.currentTransform()
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if viewSize.width > 0,
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viewSize.height > 0 {
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applyTransform()
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updateImageLayer()
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for item in model.items() {
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guard !itemIdsToIgnore.contains(item.itemId) else {
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// Ignore this item.
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continue
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}
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guard let layer = ImageEditorCanvasView.layerForItem(item: item,
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model: model,
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transform: transform,
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viewSize: viewSize) else {
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continue
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}
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contentView.layer.addSublayer(layer)
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contentLayerMap[item.itemId] = layer
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}
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}
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updateLayout()
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// Force layout now.
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setNeedsLayout()
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layoutIfNeeded()
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CATransaction.commit()
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}
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internal func updateContent(changedItemIds: [String]) {
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AssertIsOnMainThread()
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// Don't animate changes.
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CATransaction.begin()
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CATransaction.setDisableActions(true)
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// Remove all changed items.
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for itemId in changedItemIds {
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if let layer = contentLayerMap[itemId] {
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layer.removeFromSuperlayer()
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}
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contentLayerMap.removeValue(forKey: itemId)
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}
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let viewSize = clipView.bounds.size
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let transform = model.currentTransform()
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if viewSize.width > 0,
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viewSize.height > 0 {
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applyTransform()
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updateImageLayer()
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// Create layers for inserted and updated items.
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for itemId in changedItemIds {
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guard let item = model.item(forId: itemId) else {
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// Item was deleted.
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continue
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}
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// Item was inserted or updated.
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guard let layer = ImageEditorCanvasView.layerForItem(item: item,
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model: model,
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transform: transform,
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viewSize: viewSize) else {
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continue
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}
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contentView.layer.addSublayer(layer)
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contentLayerMap[item.itemId] = layer
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}
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}
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CATransaction.commit()
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}
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private func applyTransform() {
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let viewSize = clipView.bounds.size
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contentView.layer.setAffineTransform(model.currentTransform().affineTransform(viewSize: viewSize))
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}
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private func updateImageLayer() {
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let viewSize = clipView.bounds.size
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ImageEditorCanvasView.updateImageLayer(imageLayer: imageLayer,
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viewSize: viewSize,
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imageSize: model.srcImageSizePixels,
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transform: model.currentTransform())
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}
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public class func updateImageLayer(imageLayer: CALayer, viewSize: CGSize, imageSize: CGSize, transform: ImageEditorTransform) {
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imageLayer.frame = imageFrame(forViewSize: viewSize, imageSize: imageSize, transform: transform)
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// This is the only place the isFlipped flag is consulted.
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// We deliberately do _not_ use it in the affine transforms, etc.
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// so that:
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//
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// * It doesn't affect text content & brush strokes.
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// * To not complicate the other "coordinate system math".
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let transform = CGAffineTransform.identity.scaledBy(x: transform.isFlipped ? -1 : +1, y: 1)
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imageLayer.setAffineTransform(transform)
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}
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public class func imageFrame(forViewSize viewSize: CGSize, imageSize: CGSize, transform: ImageEditorTransform) -> CGRect {
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guard viewSize.width > 0, viewSize.height > 0 else {
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owsFailDebug("Invalid viewSize")
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return .zero
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}
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guard imageSize.width > 0, imageSize.height > 0 else {
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owsFailDebug("Invalid imageSize")
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return .zero
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}
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// The image content's default size (at scaling = 1) is to fill the output/canvas bounds.
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// This makes it easier to clamp the scaling to safe values.
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// The downside is that rotation has the side effect of changing the render size of the
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// image, which complicates the crop view logic.
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//
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// Find the smallest possible image size that will completely fill the output size.
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//
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// NOTE: The "bounding box" of the output size that we need to fill needs to
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// reflect the rotation.
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let sinValue = abs(sin(transform.rotationRadians))
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let cosValue = abs(cos(transform.rotationRadians))
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let outputSize = CGSize(width: viewSize.width * cosValue + viewSize.height * sinValue,
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height: viewSize.width * sinValue + viewSize.height * cosValue)
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var width = outputSize.width
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var height = outputSize.width * imageSize.height / imageSize.width
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if height < outputSize.height {
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width = outputSize.height * imageSize.width / imageSize.height
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height = outputSize.height
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}
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let imageFrame = CGRect(x: (width - viewSize.width) * -0.5,
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y: (height - viewSize.height) * -0.5,
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width: width,
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height: height)
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return imageFrame
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}
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private class func imageLayerForItem(model: ImageEditorModel,
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transform: ImageEditorTransform,
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viewSize: CGSize) -> CALayer? {
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guard let srcImage = loadSrcImage(model: model) else {
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owsFailDebug("Could not load src image.")
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return nil
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}
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let imageLayer = CALayer()
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imageLayer.contents = srcImage.cgImage
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imageLayer.contentsScale = srcImage.scale
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updateImageLayer(imageLayer: imageLayer,
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viewSize: viewSize,
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imageSize: model.srcImageSizePixels,
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transform: transform)
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return imageLayer
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}
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private class func layerForItem(item: ImageEditorItem,
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model: ImageEditorModel,
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transform: ImageEditorTransform,
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viewSize: CGSize) -> CALayer? {
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AssertIsOnMainThread()
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switch item.itemType {
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case .test:
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owsFailDebug("Unexpected test item.")
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return nil
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case .stroke:
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guard let strokeItem = item as? ImageEditorStrokeItem else {
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owsFailDebug("Item has unexpected type: \(type(of: item)).")
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return nil
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}
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return strokeLayerForItem(item: strokeItem,
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model: model,
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transform: transform,
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viewSize: viewSize)
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case .text:
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guard let textItem = item as? ImageEditorTextItem else {
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owsFailDebug("Item has unexpected type: \(type(of: item)).")
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return nil
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}
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return textLayerForItem(item: textItem,
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model: model,
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transform: transform,
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viewSize: viewSize)
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}
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}
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private class func strokeLayerForItem(item: ImageEditorStrokeItem,
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model: ImageEditorModel,
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transform: ImageEditorTransform,
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viewSize: CGSize) -> CALayer? {
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AssertIsOnMainThread()
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let strokeWidth = ImageEditorStrokeItem.strokeWidth(forUnitStrokeWidth: item.unitStrokeWidth,
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dstSize: viewSize)
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let unitSamples = item.unitSamples
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guard unitSamples.count > 0 else {
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// Not an error; the stroke doesn't have enough samples to render yet.
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return nil
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}
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let shapeLayer = CAShapeLayer()
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shapeLayer.lineWidth = strokeWidth
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shapeLayer.strokeColor = item.color.cgColor
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shapeLayer.frame = CGRect(origin: .zero, size: viewSize)
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// Stroke samples are specified in "image unit" coordinates, but
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// need to be rendered in "canvas" coordinates. The imageFrame
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// is the bounds of the image specified in "canvas" coordinates,
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// so to transform we can simply convert from image frame units.
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let imageFrame = ImageEditorCanvasView.imageFrame(forViewSize: viewSize, imageSize: model.srcImageSizePixels, transform: transform)
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let transformSampleToPoint = { (unitSample: CGPoint) -> CGPoint in
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return unitSample.fromUnitCoordinates(viewBounds: imageFrame)
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}
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// Use bezier curves to smooth stroke.
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let bezierPath = UIBezierPath()
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let points = applySmoothing(to: unitSamples.map { (unitSample) in
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transformSampleToPoint(unitSample)
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})
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var previousForwardVector = CGPoint.zero
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for index in 0..<points.count {
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let point = points[index]
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let forwardVector: CGPoint
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if points.count <= 1 {
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// Skip forward vectors.
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forwardVector = .zero
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} else if index == 0 {
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// First sample.
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let nextPoint = points[index + 1]
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forwardVector = CGPointSubtract(nextPoint, point)
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} else if index == points.count - 1 {
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// Last sample.
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let previousPoint = points[index - 1]
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forwardVector = CGPointSubtract(point, previousPoint)
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} else {
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// Middle samples.
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let previousPoint = points[index - 1]
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let previousPointForwardVector = CGPointSubtract(point, previousPoint)
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let nextPoint = points[index + 1]
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let nextPointForwardVector = CGPointSubtract(nextPoint, point)
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forwardVector = CGPointScale(CGPointAdd(previousPointForwardVector, nextPointForwardVector), 0.5)
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}
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if index == 0 {
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// First sample.
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bezierPath.move(to: point)
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if points.count == 1 {
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bezierPath.addLine(to: point)
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}
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} else {
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let previousPoint = points[index - 1]
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// We apply more than one kind of smoothing.
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// This smoothing avoids rendering "angled segments"
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// by drawing the stroke as a series of curves.
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// We use bezier curves and infer the control points
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// from the "next" and "prev" points.
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//
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// This factor controls how much we're smoothing.
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//
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// * 0.0 = No smoothing.
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//
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// TODO: Tune this variable once we have stroke input.
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let controlPointFactor: CGFloat = 0.25
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let controlPoint1 = CGPointAdd(previousPoint, CGPointScale(previousForwardVector, +controlPointFactor))
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let controlPoint2 = CGPointAdd(point, CGPointScale(forwardVector, -controlPointFactor))
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// We're using Cubic curves.
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bezierPath.addCurve(to: point, controlPoint1: controlPoint1, controlPoint2: controlPoint2)
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}
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previousForwardVector = forwardVector
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}
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shapeLayer.path = bezierPath.cgPath
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shapeLayer.fillColor = nil
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shapeLayer.lineCap = CAShapeLayerLineCap.round
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shapeLayer.lineJoin = CAShapeLayerLineJoin.round
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shapeLayer.zPosition = zPositionForItem(item: item, model: model, zPositionBase: brushLayerZ)
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return shapeLayer
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}
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private class func zPositionForItem(item: ImageEditorItem,
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model: ImageEditorModel,
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zPositionBase: CGFloat) -> CGFloat {
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let itemIds = model.itemIds()
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guard let itemIndex = itemIds.firstIndex(of: item.itemId) else {
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owsFailDebug("Couldn't find index of item.")
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return zPositionBase
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}
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return zPositionBase + CGFloat(itemIndex) * zPositionSpacing
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}
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private class func textLayerForItem(item: ImageEditorTextItem,
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model: ImageEditorModel,
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transform: ImageEditorTransform,
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viewSize: CGSize) -> CALayer? {
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AssertIsOnMainThread()
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let imageFrame = ImageEditorCanvasView.imageFrame(forViewSize: viewSize, imageSize: model.srcImageSizePixels, transform: transform)
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// We need to adjust the font size to reflect the current output scale,
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// using the image width as reference.
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let fontSize = item.font.pointSize * imageFrame.size.width / item.fontReferenceImageWidth
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let text = item.text.filterForDisplay ?? ""
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let attributedString = NSAttributedString(string: text,
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attributes: [
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NSAttributedString.Key.font: item.font.withSize(fontSize),
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NSAttributedString.Key.foregroundColor: item.color.color
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])
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let layer = EditorTextLayer(itemId: item.itemId)
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layer.string = attributedString
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layer.foregroundColor = item.color.cgColor
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layer.font = CGFont(item.font.fontName as CFString)
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layer.fontSize = fontSize
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layer.isWrapped = true
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layer.alignmentMode = CATextLayerAlignmentMode.center
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// I don't think we need to enable allowsFontSubpixelQuantization
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// or set truncationMode.
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// This text needs to be rendered at a scale that reflects:
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//
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// * The screen scaling (so that text looks sharp on Retina devices.
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// * The item's scaling (so that text doesn't become blurry as you make it larger).
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// * Model transform (so that text doesn't become blurry as you zoom the content).
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layer.contentsScale = UIScreen.main.scale * item.scaling * transform.scaling
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// TODO: Min with measured width.
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let maxWidth = imageFrame.size.width * item.unitWidth
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let maxSize = CGSize(width: maxWidth, height: CGFloat.greatestFiniteMagnitude)
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// TODO: Is there a more accurate way to measure text in a CATextLayer?
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// CoreText?
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let textBounds = attributedString.boundingRect(with: maxSize,
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options: [
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.usesLineFragmentOrigin,
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.usesFontLeading
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],
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context: nil)
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// The text item's center is specified in "image unit" coordinates, but
|
|
// needs to be rendered in "canvas" coordinates. The imageFrame
|
|
// is the bounds of the image specified in "canvas" coordinates,
|
|
// so to transform we can simply convert from image frame units.
|
|
let centerInCanvas = item.unitCenter.fromUnitCoordinates(viewBounds: imageFrame)
|
|
let layerSize = textBounds.size.ceil
|
|
layer.frame = CGRect(origin: CGPoint(x: centerInCanvas.x - layerSize.width * 0.5,
|
|
y: centerInCanvas.y - layerSize.height * 0.5),
|
|
size: layerSize)
|
|
|
|
let transform = CGAffineTransform.identity.scaledBy(x: item.scaling, y: item.scaling).rotated(by: item.rotationRadians)
|
|
layer.setAffineTransform(transform)
|
|
|
|
layer.zPosition = zPositionForItem(item: item, model: model, zPositionBase: textLayerZ)
|
|
|
|
return layer
|
|
}
|
|
|
|
// We apply more than one kind of smoothing.
|
|
//
|
|
// This (simple) smoothing reduces jitter from the touch sensor.
|
|
private class func applySmoothing(to points: [CGPoint]) -> [CGPoint] {
|
|
AssertIsOnMainThread()
|
|
|
|
var result = [CGPoint]()
|
|
|
|
for index in 0..<points.count {
|
|
let point = points[index]
|
|
|
|
if index == 0 {
|
|
// First sample.
|
|
result.append(point)
|
|
} else if index == points.count - 1 {
|
|
// Last sample.
|
|
result.append(point)
|
|
} else {
|
|
// Middle samples.
|
|
let lastPoint = points[index - 1]
|
|
let nextPoint = points[index + 1]
|
|
let alpha: CGFloat = 0.1
|
|
let smoothedPoint = CGPointAdd(CGPointScale(point, 1.0 - 2.0 * alpha),
|
|
CGPointAdd(CGPointScale(lastPoint, alpha),
|
|
CGPointScale(nextPoint, alpha)))
|
|
result.append(smoothedPoint)
|
|
}
|
|
}
|
|
|
|
return result
|
|
}
|
|
|
|
// MARK: - Actions
|
|
|
|
// Returns nil on error.
|
|
//
|
|
// We render using the transform parameter, not the transform from the model.
|
|
// This allows this same method to be used for rendering "previews" for the
|
|
// crop tool and the final output.
|
|
@objc
|
|
public class func renderForOutput(model: ImageEditorModel, transform: ImageEditorTransform) -> UIImage? {
|
|
// TODO: Do we want to render off the main thread?
|
|
AssertIsOnMainThread()
|
|
|
|
// Render output at same size as source image.
|
|
let dstSizePixels = transform.outputSizePixels
|
|
let dstScale: CGFloat = 1.0 // The size is specified in pixels, not in points.
|
|
let viewSize = dstSizePixels
|
|
|
|
let hasAlpha = NSData.hasAlpha(forValidImageFilePath: model.srcImagePath)
|
|
|
|
// We use an UIImageView + UIView.renderAsImage() instead of a CGGraphicsContext
|
|
// Because CALayer.renderInContext() doesn't honor CALayer properties like frame,
|
|
// transform, etc.
|
|
let view = UIView()
|
|
view.backgroundColor = UIColor.clear
|
|
view.isOpaque = false
|
|
view.frame = CGRect(origin: .zero, size: viewSize)
|
|
|
|
// Rendering a UIView to an image will not honor the root image's layer transform.
|
|
// We therefore use a subview.
|
|
let contentView = UIView()
|
|
contentView.backgroundColor = UIColor.clear
|
|
contentView.isOpaque = false
|
|
contentView.frame = CGRect(origin: .zero, size: viewSize)
|
|
view.addSubview(contentView)
|
|
|
|
CATransaction.begin()
|
|
CATransaction.setDisableActions(true)
|
|
|
|
contentView.layer.setAffineTransform(transform.affineTransform(viewSize: viewSize))
|
|
|
|
guard let imageLayer = imageLayerForItem(model: model,
|
|
transform: transform,
|
|
viewSize: viewSize) else {
|
|
owsFailDebug("Could not load src image.")
|
|
return nil
|
|
}
|
|
imageLayer.contentsScale = dstScale * transform.scaling
|
|
contentView.layer.addSublayer(imageLayer)
|
|
|
|
var layers = [CALayer]()
|
|
for item in model.items() {
|
|
guard let layer = layerForItem(item: item,
|
|
model: model,
|
|
transform: transform,
|
|
viewSize: viewSize) else {
|
|
owsFailDebug("Couldn't create layer for item.")
|
|
continue
|
|
}
|
|
layer.contentsScale = dstScale * transform.scaling * item.outputScale()
|
|
layers.append(layer)
|
|
}
|
|
// UIView.renderAsImage() doesn't honor zPosition of layers,
|
|
// so sort the item layers to ensure they are added in the
|
|
// correct order.
|
|
let sortedLayers = layers.sorted(by: { (left, right) -> Bool in
|
|
return left.zPosition < right.zPosition
|
|
})
|
|
for layer in sortedLayers {
|
|
contentView.layer.addSublayer(layer)
|
|
}
|
|
|
|
CATransaction.commit()
|
|
|
|
let image = view.renderAsImage(opaque: !hasAlpha, scale: dstScale)
|
|
return image
|
|
}
|
|
|
|
// MARK: -
|
|
|
|
public func textLayer(forLocation point: CGPoint) -> EditorTextLayer? {
|
|
guard let sublayers = contentView.layer.sublayers else {
|
|
return nil
|
|
}
|
|
|
|
// First we build a map of all text layers.
|
|
var layerMap = [String: EditorTextLayer]()
|
|
for layer in sublayers {
|
|
guard let textLayer = layer as? EditorTextLayer else {
|
|
continue
|
|
}
|
|
layerMap[textLayer.itemId] = textLayer
|
|
}
|
|
|
|
// The layer ordering in the model is authoritative.
|
|
// Iterate over the layers in _reverse_ order of which they appear
|
|
// in the model, so that layers "on top" are hit first.
|
|
for item in model.items().reversed() {
|
|
guard let textLayer = layerMap[item.itemId] else {
|
|
// Not a text layer.
|
|
continue
|
|
}
|
|
if textLayer.hitTest(point) != nil {
|
|
return textLayer
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// MARK: - Coordinates
|
|
|
|
public class func locationImageUnit(forLocationInView locationInView: CGPoint,
|
|
viewBounds: CGRect,
|
|
model: ImageEditorModel,
|
|
transform: ImageEditorTransform) -> CGPoint {
|
|
let imageFrame = self.imageFrame(forViewSize: viewBounds.size, imageSize: model.srcImageSizePixels, transform: transform)
|
|
let affineTransformStart = transform.affineTransform(viewSize: viewBounds.size)
|
|
let locationInContent = locationInView.minus(viewBounds.center).applyingInverse(affineTransformStart).plus(viewBounds.center)
|
|
let locationImageUnit = locationInContent.toUnitCoordinates(viewBounds: imageFrame, shouldClamp: false)
|
|
return locationImageUnit
|
|
}
|
|
}
|
|
|
|
// MARK: -
|
|
|
|
extension ImageEditorCanvasView: ImageEditorModelObserver {
|
|
|
|
public func imageEditorModelDidChange(before: ImageEditorContents,
|
|
after: ImageEditorContents) {
|
|
updateAllContent()
|
|
}
|
|
|
|
public func imageEditorModelDidChange(changedItemIds: [String]) {
|
|
updateContent(changedItemIds: changedItemIds)
|
|
}
|
|
}
|