94 lines
3.8 KiB
Swift
94 lines
3.8 KiB
Swift
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import XCTest
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import Foundation
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@testable import ForgeVideo
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final class PNGTests: XCTestCase {
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// PNG signature + chunk layout (IHDR/IDAT/IEND).
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func testStructure() {
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let frame = VideoFrame(
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width: 2, height: 2,
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pixels: [SIMD3(1, 0, 0), SIMD3(0, 1, 0), SIMD3(0, 0, 1), SIMD3(1, 1, 1)])
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let png = PNGWriter.encode(frame)
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// Signature.
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XCTAssertEqual([UInt8](png.prefix(8)), [0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A])
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// IHDR right after signature.
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XCTAssertEqual([UInt8](png[12..<16]), [UInt8]("IHDR".utf8))
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// Width/height big-endian in IHDR.
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XCTAssertEqual([UInt8](png[16..<24]), [0, 0, 0, 2, 0, 0, 0, 2])
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// Bit depth 8, color type 2 (truecolor).
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XCTAssertEqual(png[24], 8)
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XCTAssertEqual(png[25], 2)
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// Contains IDAT and ends with IEND.
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XCTAssertNotNil(png.range(of: Data("IDAT".utf8)))
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XCTAssertEqual([UInt8](png.suffix(8).prefix(4)), [UInt8]("IEND".utf8))
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}
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// zlib stream inside IDAT decodes back to original scanlines (via system python zlib).
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func testPixelsRoundTripViaPython() throws {
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let frame = VideoFrame(
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width: 3, height: 2,
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pixels: [
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SIMD3(1, 0, 0), SIMD3(0, 1, 0), SIMD3(0, 0, 1),
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SIMD3(0.5, 0.5, 0.5), SIMD3(0, 0, 0), SIMD3(1, 1, 1),
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])
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let png = PNGWriter.encode(frame)
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let path = NSTemporaryDirectory() + "forge-png-\(UUID().uuidString).png"
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defer { try? FileManager.default.removeItem(atPath: path) }
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try png.write(to: URL(fileURLWithPath: path))
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// Python: parse IDAT, inflate, check first pixel bytes.
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let script = """
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import struct, zlib, sys
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data = open('\(path)', 'rb').read()
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pos = 8
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idat = b''
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while pos < len(data):
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length, ctype = struct.unpack('>I4s', data[pos:pos+8])
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if ctype == b'IDAT':
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idat += data[pos+8:pos+8+length]
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pos += 12 + length
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raw = zlib.decompress(idat)
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# Row 0: filter byte 0 then RGB bytes.
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assert raw[0] == 0, 'filter'
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assert raw[1:4] == bytes([255, 0, 0]), raw[1:4]
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assert raw[4:7] == bytes([0, 255, 0]), raw[4:7]
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# Row 1 first pixel = 128 gray.
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row1 = raw[1 + 3*3:]
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assert row1[0] == 0, 'filter row1'
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assert row1[1:4] == bytes([128, 128, 128]), row1[1:4]
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print('PNG-OK')
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"""
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let proc = Process()
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proc.executableURL = URL(fileURLWithPath: "/usr/bin/python3")
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proc.arguments = ["-c", script]
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let pipe = Pipe()
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proc.standardOutput = pipe
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proc.standardError = pipe
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try proc.run()
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proc.waitUntilExit()
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let out = String(data: pipe.fileHandleForReading.readDataToEndOfFile(), encoding: .utf8) ?? ""
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XCTAssertEqual(proc.terminationStatus, 0, out)
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XCTAssertTrue(out.contains("PNG-OK"), out)
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}
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// Values clamp.
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func testClamping() {
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let frame = VideoFrame(width: 1, height: 1, pixels: [SIMD3(2.0, -1.0, 0.5)])
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let png = PNGWriter.encode(frame)
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XCTAssertGreaterThan(png.count, 40)
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}
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// StillGrabber PNG mode writes .png beside proper name.
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func testStillGrabberPNG() throws {
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let dir = NSTemporaryDirectory() + "forge-pngstill-\(UUID().uuidString)"
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defer { try? FileManager.default.removeItem(atPath: dir) }
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let frame = VideoFrame(width: 4, height: 4, pixels: .init(repeating: SIMD3(0.2, 0.4, 0.8), count: 16))
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let path = try StillGrabber(directory: dir, format: .png).grab(frame: frame, clipName: "R001C001")
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XCTAssertTrue(path.hasSuffix(".png"))
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let data = try Data(contentsOf: URL(fileURLWithPath: path))
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XCTAssertEqual([UInt8](data.prefix(4)), [0x89, 0x50, 0x4E, 0x47])
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}
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}
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