feat: implement canvas

2026-05-20 14:47:09 +02:00 · 2024-05-04 13:58:47 +07:00
parent 4c2cff3e7f
commit fb66b38230
54 changed files with 3035 additions and 1 deletions
@@ -0,0 +1,129 @@
+//
+//  GraphicContext.swift
+//  Memola
+//
+//  Created by Dscyre Scotti on 5/4/24.
+//
+
+import Combine
+import MetalKit
+import Foundation
+
+protocol GraphicContextDelegate: AnyObject {
+    var didUpdate: PassthroughSubject<Void, Never> { get set }
+}
+
+class GraphicContext: Codable {
+    var strokes: [Stroke] = []
+    var currentStroke: Stroke?
+    var previousStroke: Stroke?
+    var currentPoint: CGPoint?
+
+    var renderType: RenderType = .finished
+
+    var vertices: [ViewPortVertex] = []
+    var vertexCount: Int = 4
+    var vertexBuffer: MTLBuffer?
+
+    weak var delegate: GraphicContextDelegate?
+
+    init() {
+        setViewPortVertices()
+    }
+
+    enum CodingKeys: CodingKey {
+        case strokes
+    }
+
+    required init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        self.strokes = try container.decode([Stroke].self, forKey: .strokes)
+        setViewPortVertices()
+    }
+
+    func encode(to encoder: Encoder) throws {
+        var container = encoder.container(keyedBy: CodingKeys.self)
+        try container.encode(self.strokes, forKey: .strokes)
+    }
+
+    func setViewPortVertices() {
+        vertexBuffer = nil
+        vertices = [
+            ViewPortVertex(x: -1, y: -1, textCoord: CGPoint(x: 0, y: 1)),
+            ViewPortVertex(x: -1, y: 1, textCoord: CGPoint(x: 0, y: 0)),
+            ViewPortVertex(x: 1, y: -1, textCoord: CGPoint(x: 1, y: 1)),
+            ViewPortVertex(x: 1, y: 1, textCoord: CGPoint(x: 1, y: 0)),
+        ]
+    }
+
+    func undoGraphic() {
+        guard !strokes.isEmpty else { return }
+        strokes.removeLast()
+        previousStroke = nil
+        delegate?.didUpdate.send()
+    }
+
+    func redoGraphic(for event: HistoryEvent) {
+        switch event {
+        case .stroke(let stroke):
+            strokes.append(stroke)
+            previousStroke = nil
+        }
+        delegate?.didUpdate.send()
+    }
+}
+
+extension GraphicContext: Drawable {
+    func prepare(device: MTLDevice) {
+        guard vertexBuffer == nil else {
+            return
+        }
+        vertexCount = vertices.count
+        vertexBuffer = device.makeBuffer(bytes: vertices, length: vertexCount * MemoryLayout<ViewPortVertex>.stride, options: [])
+    }
+
+    func draw(device: MTLDevice, renderEncoder: MTLRenderCommandEncoder) {
+        prepare(device: device)
+        renderEncoder.setVertexBuffer(vertexBuffer, offset: 0, index: 0)
+        renderEncoder.drawPrimitives(type: .triangleStrip, vertexStart: 0, vertexCount: vertices.count)
+    }
+}
+
+extension GraphicContext {
+    func beginStroke(at point: CGPoint, pen: Pen) -> Stroke {
+        let stroke = Stroke(
+            color: pen.color,
+            style: pen.style,
+            thickness: pen.thickness
+        )
+        strokes.append(stroke)
+        currentStroke = stroke
+        currentPoint = point
+        currentStroke?.begin(at: point)
+        return stroke
+    }
+
+    func appendStroke(with point: CGPoint) {
+        guard let currentStroke else { return }
+        guard let currentPoint, point.distance(to: currentPoint) > currentStroke.thickness * currentStroke.style.stepRate else { return }
+        currentStroke.append(to: point)
+        self.currentPoint = point
+    }
+
+    func endStroke(at point: CGPoint) {
+        guard currentPoint != nil else { return }
+        currentStroke?.finish(at: point)
+        previousStroke = currentStroke
+        currentStroke = nil
+        self.currentPoint = nil
+        delegate?.didUpdate.send()
+    }
+}
+
+extension GraphicContext {
+    enum RenderType {
+        case inProgress
+        case newlyFinished
+        case finished
+    }
+}