Interacting with C APIs

shibuyaswift #4

Transcript

1. Interacting
   with C APIs
   shibuya.swift #4
   @nakajijapan
   Use GIFLIB in Swift
   

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2. About Me
   

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3. @nakajijapan
   Software Engineer
   GMO PEPABO inc.
   iOS / Web / OS X
   

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4. NKJMultiMovieCaptureView
   NKJMovieComposer
   NKJPagerViewController
   PhotoSlider
   Teiten
   

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5. ϋϯυϝΠυ࡞඼Λ
   ചΕΔɺങ͑Δɻ
   ࠃ಺࠷େڃͷ
   ϋϯυϝΠυϚʔέοτ
   

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6. ࠷ۙ
   

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7. Teiten
   Teiten is an app that fixed-point
   observation a lot earnestly yourself
   by using a PC camera.
   http://teiten.nakajijapan.net/
   

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8. Sengiri
   " Sengiri " from the screen recording
   until the animated GIF file , you can
   create as soon as a simple operation .
   Sengiri, in English, is the shred.
   http://sengiri.nakajijapan.net/
   

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9. Stop
   SFDPSE
   Crop
   Record
   

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10. Sengiri is
    • OS X Application
    • ࠷খݶͷૢ࡞ͰGIFಈըΛ࡞੒͢Δ
    • ࢓ࣄޮ཰Խπʔϧ
    • OSS (coming soon…)
    

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12. ΋͏গ͠ؤுΖ͏
    

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13. ࣌ʑɺը࣭͕
    ྼԽ
    ͯ͠͠·͏
    

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14. ΋͏গ͠
    ਂງ͍͖͍ͯͨ͠
    

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15. ௐࠪ
    • FFmpeg
    • GIFLIB
    

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16. FFmpeg
    

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17. FFmpeg
    • ༷ʑͳencode/decodeʹରԠ
    • ࢓༷Λ೺Ѳ͢Δ͜ͱ͔Β
    • ๲େ
    • ίʔυྔ͕ଟ͍
    •
    
    

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18. GIFLIB
    

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19. GIFLIB
    • GIFͷencode/decodeʹಛԽ
    • ࢓༷Λ೺Ѳ͠΍͍͢
    • ίʔυྔ͕গͳ͍
    • FFmpegΑΓ͸গͳ͍
    

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20. But
    

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21. C
    

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22. Use C API
    in Swift
    

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23. Talk about
    

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24. Interacting
    with C APIs
    Use giflib in Swift
    

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25. Premise
    

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26. C
    int number = 10;
    int *p;
    *p = 100;
    printf("%d %x \n", *p, p);
    p = &number;
    printf("%d %x \n", *p, p);
    

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27. C
    516918f8
    p number
    10
    516918dc
    p = &number;
    

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28. C
    char c[] = “abcd";
    char *p;
    p = &c;
    printf("*p = %c\n",*p);
    printf("p = %s\n", p);
    printf("*(p + 1) = %c\n", *(c + 1));
    printf("*p + 1 = %c\n", *c + 1);
    printf("c[1] = %c\n", c[1]);
    // *p = a
    // p = abcd
    // *(p + 1) = b
    // *p + 1 = b
    // c[1] = b
    

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29. C
    516918f8
    p
    c[]
    516918dc
    p = &c;
    a b c d
    *(c + 1)
    *(c + 2)
    *(c + 3)
    

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30. C API -> Swift
    

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31. Primitive Types
    

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32. Primitive Types
    or Int8
    or Int
    or Int32
    

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33. $ 4XJGU
    1PJOUFS
    DPOTU5ZQF 6OTBGF1PJOUFS5ZQF
    5ZQF 6OTBGF.VUBCMF1PJOUFS5ZQF
    WPJE 6OTBGF.VUBCMF1PJOUFS7PJE
    Pointer
    

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34. C
    int number = 10;
    int *p;
    *p = 100;
    printf("%d %x \n", *p, p);
    p = &number;
    printf("%d %x \n", *p, p);
    

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35. Swift
    // int *p;
    var p:UnsafeMutablePointer
    

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36. Swift
    // int *p;
    var p = UnsafeMutablePointer.alloc(1)
    // *p = 100;
    p.memory = 100
    

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37. Swift
    // int *p;
    var p = UnsafeMutablePointer.alloc(1)
    // *p = 100;
    p.memory = 100
    

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38. Swift
    // int *p;
    var p = UnsafeMutablePointer.alloc(1)
    // *p = 100;
    p.memory = 100
    

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39. Swift
    // int *p;
    var p = UnsafeMutablePointer.alloc(1)
    // *p = 100;
    p.memory = 100
    WBSNFNPSZ.FNPSZ\HFUOPONVUBUJOHTFU^
    6OTBGF.VUBCMF1PJOUFS
    

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40. C
    unsigned char c[] = “abcd";
    unsigned char *p;
    p = &c;
    printf("*p = %c\n",*p);
    printf("p = %s\n", p);
    printf("*(p + 1) = %c\n", *(c + 1));
    printf("*p + 1 = %c\n", *c + 1);
    printf("c[1] = %c\n", c[1]);
    // *p = a
    // p = abcd
    // *(p + 1) = b
    // *p + 1 = b
    // c[1] = b
    

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41. Swift
    let p = UnsafeMutablePointer.alloc(4)
    or
    let p = UnsafeMutablePointer.alloc(4)
    

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42. C
    unsigned char c[] = “abcd";
    unsigned char *p;
    p = &c;
    printf("*p = %c\n",*p);
    printf("p = %s\n", p);
    printf("*(p + 1) = %c\n", *(c + 1));
    printf("*p + 1 = %c\n", *c + 1);
    printf("c[1] = %c\n", c[1]);
    // *p = a
    // p = abcd
    // *(p + 1) = b
    // *p + 1 = b
    // c[1] = b
    

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43. Swift
    let p = UnsafeMutablePointer.alloc(4)
    p.advancedBy(1).memory
    

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44. Swift
    let p = UnsafeMutablePointer.alloc(4)
    p.advancedBy(1).memory
    TVCTDSJQU @J*OU
    .FNPSZ\HFUOPONVUBUJOHTFU^
    

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45. Swift
    let p = UnsafeMutablePointer.alloc(4)
    p[1]
    
    

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46. Swift
    for i in 0..<256 {
    colorTypes.advancedBy(i).memory.Red =
    pixelColorMaps.advancedBy(i).memory.red
    colorTypes.advancedBy(i).memory.Green =
    pixelColorMaps.advancedBy(i).memory.green
    colorTypes.advancedBy(i).memory.Blue =
    pixelColorMaps.advancedBy(i).memory.blue
    }
    

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47. Swift
    for i in 0..<256 {
    colorTypes[i].Red = pixelColorMaps[i].red
    colorTypes[i].Green = pixelColorMaps[i].green
    colorTypes[i].Blue = pixelColorMaps[i].blue
    }
    
    

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48. Swift
    unsigned char controlExtension[3] =
    {0x04, 0x00, 0x00, 0xff};
    

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49. Swift
    
    let controlExtension =
    UnsafeMutablePointer.alloc(4)
    controlExtension[0] = 0x04
    controlExtension[1] = 0x00
    controlExtension[2] = 0x00
    controlExtension[3] = 0xff
    

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50. Type Casting
    

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51. Type Casting
    UnsafeMutablePointer.self
    UnsafeMutablePointer.self
    

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52. Type Casting
    let address = baseAddress as UnsafeMutablePointer
    

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53. Type Casting
    let address = baseAddress as UnsafeMutablePointer
    
    

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54. Type Casting
    /// Returns the bits of `x`, interpreted as having type `U`.
    ///
    /// - Warning: Breaks the guarantees of Swift's type system; use
    /// with extreme care. There's almost always a better way to do
    /// anything.
    ///
    @warn_unused_result
    public func unsafeBitCast(x: T, _: U.Type) -> U
    

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55. Swift
    let address = CVPixelBufferGetBaseAddress(imageBuffer!)
    let address2 = unsafeBitCast(
    baseAddress,
    UnsafeMutablePointer.self
    )
    

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56. Type Casting
    /// Returns the bits of `x`, interpreted as having type `U`.
    ///
    /// - Warning: Breaks the guarantees of Swift's type system; use
    /// with extreme care. There's almost always a better way to do
    /// anything.
    ///
    @warn_unused_result
    public func unsafeBitCast(x: T, _: U.Type) -> U
    

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57. Memory
    Management
    

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58. Memory Management
    • SwiftͰCͷؔ਺͕ར༻Ͱ͖Δ
    • ࢖͍ํ͸ಉ͡
    • UnsafeMutablePointerͰಉ༷ͷϝιου͕༻
    ҙ͞Ε͍ͯΔ
    

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59. Memory Management
    /* ANSI-C */
    public func memchr(_: UnsafePointer, _: Int32, _: Int) -> UnsafeMutablePointer
    public func memcmp(_: UnsafePointer, _: UnsafePointer, _: Int) -> Int32
    public func memcpy(_: UnsafeMutablePointer, _: UnsafePointer, _: Int) ->
    UnsafeMutablePointer
    public func memmove(_: UnsafeMutablePointer, _: UnsafePointer, _: Int) ->
    UnsafeMutablePointer
    public func memset(_: UnsafeMutablePointer, _: Int32, _: Int) ->
    UnsafeMutablePointer
    

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60. Swift
    let buffer = UnsafeMutablePointer.alloc(
    width * height * 4
    )
    memset(buffer, 0, width * height * 4)
    (…snip…)
    free(buffer)
    

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61. Swift
    let buffer = UnsafeMutablePointer.alloc(
    width * height * 4
    )
    memset(buffer, 0, width * height * 4)
    (…snip…)
    free(buffer)
    buffer.destroy()
    

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62. C APIs
    

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63. C APIs
    • Swift͸C APIʹΞΫηεग़དྷΔे෼ͳ
    ػೳΛ࣋ͪ߹Θ͍ͤͯΔ௿ϨΠϠʔ
    ͳϞδϡʔϧʹ௚઀Ͱ͖Δͷศར
    • ϙΠϯλɺϝϞϦ؅ཧͷ஌ࣝ͸ඞਢ
    

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64. UnsafeMutablePointer
    IUUQTEFWFMPQFSBQQMFDPNMJCSBSZXBUDIPTEPDVNFOUBUJPO4XJGU
    3FGFSFODF4XJGU@6OTBGF.VUBCMF1PJOUFS@4USVDUVSFJOEFYIUNM
    

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65. GIFLIBΛ࢖͍͍ͨ
    

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66. • ࢓༷೺Ѳෆ଍…
    • ΧϥʔϚοϓ
    • ؔ਺
    

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67. ࠂ஌
    

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68. iOSDC
    

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69. Thanks.
    
    

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