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Interacting
with C APIs
shibuya.swift #4
@nakajijapan
Use GIFLIB in Swift
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About Me
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@nakajijapan
Software Engineer
GMO PEPABO inc.
iOS / Web / OS X
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NKJMultiMovieCaptureView
NKJMovieComposer
NKJPagerViewController
PhotoSlider
Teiten
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ϋϯυϝΠυ࡞Λ
ചΕΔɺങ͑Δɻ
ࠃ࠷େڃͷ
ϋϯυϝΠυϚʔέοτ
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࠷ۙ
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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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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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Stop
SFDPSE
Crop
Record
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Sengiri is
• OS X Application
• ࠷খݶͷૢ࡞ͰGIFಈըΛ࡞͢Δ
• ࣄޮԽπʔϧ
• OSS (coming soon…)
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No content
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͏গ͠ؤுΖ͏
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࣌ʑɺը࣭͕
ྼԽ
ͯ͠͠·͏
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͏গ͠
ਂງ͍͖͍ͯͨ͠
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ௐࠪ
• FFmpeg
• GIFLIB
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FFmpeg
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FFmpeg
• ༷ʑͳencode/decodeʹରԠ
• ༷ΛѲ͢Δ͜ͱ͔Β
• େ
• ίʔυྔ͕ଟ͍
•
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GIFLIB
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GIFLIB
• GIFͷencode/decodeʹಛԽ
• ༷ΛѲ͍͢͠
• ίʔυྔ͕গͳ͍
• FFmpegΑΓগͳ͍
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But
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C
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Use C API
in Swift
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Talk about
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Interacting
with C APIs
Use giflib in Swift
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Premise
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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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C
516918f8
p number
10
516918dc
p = &number;
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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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C
516918f8
p
c[]
516918dc
p = &c;
a b c d
*(c + 1)
*(c + 2)
*(c + 3)
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C API -> Swift
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Primitive Types
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Primitive Types
or Int8
or Int
or Int32
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$ 4XJGU
1PJOUFS
DPOTU5ZQF 6OTBGF1PJOUFS5ZQF
5ZQF 6OTBGF.VUBCMF1PJOUFS5ZQF
WPJE 6OTBGF.VUBCMF1PJOUFS7PJE
Pointer
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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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Swift
// int *p;
var p:UnsafeMutablePointer
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Swift
// int *p;
var p = UnsafeMutablePointer.alloc(1)
// *p = 100;
p.memory = 100
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Swift
// int *p;
var p = UnsafeMutablePointer.alloc(1)
// *p = 100;
p.memory = 100
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Swift
// int *p;
var p = UnsafeMutablePointer.alloc(1)
// *p = 100;
p.memory = 100
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Swift
// int *p;
var p = UnsafeMutablePointer.alloc(1)
// *p = 100;
p.memory = 100
WBSNFNPSZ.FNPSZ\HFUOPONVUBUJOHTFU^
6OTBGF.VUBCMF1PJOUFS
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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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Swift
let p = UnsafeMutablePointer.alloc(4)
or
let p = UnsafeMutablePointer.alloc(4)
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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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Swift
let p = UnsafeMutablePointer.alloc(4)
p.advancedBy(1).memory
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Swift
let p = UnsafeMutablePointer.alloc(4)
p.advancedBy(1).memory
TVCTDSJQU @J*OU
.FNPSZ\HFUOPONVUBUJOHTFU^
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Swift
let p = UnsafeMutablePointer.alloc(4)
p[1]
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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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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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Swift
unsigned char controlExtension[3] =
{0x04, 0x00, 0x00, 0xff};
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Swift
let controlExtension =
UnsafeMutablePointer.alloc(4)
controlExtension[0] = 0x04
controlExtension[1] = 0x00
controlExtension[2] = 0x00
controlExtension[3] = 0xff
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Type Casting
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Type Casting
UnsafeMutablePointer.self
UnsafeMutablePointer.self
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Type Casting
let address = baseAddress as UnsafeMutablePointer
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Type Casting
let address = baseAddress as UnsafeMutablePointer
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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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Swift
let address = CVPixelBufferGetBaseAddress(imageBuffer!)
let address2 = unsafeBitCast(
baseAddress,
UnsafeMutablePointer.self
)
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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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Memory
Management
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Memory Management
• SwiftͰCͷ͕ؔར༻Ͱ͖Δ
• ͍ํಉ͡
• UnsafeMutablePointerͰಉ༷ͷϝιου͕༻
ҙ͞Ε͍ͯΔ
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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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Swift
let buffer = UnsafeMutablePointer.alloc(
width * height * 4
)
memset(buffer, 0, width * height * 4)
(…snip…)
free(buffer)
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Swift
let buffer = UnsafeMutablePointer.alloc(
width * height * 4
)
memset(buffer, 0, width * height * 4)
(…snip…)
free(buffer)
buffer.destroy()
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C APIs
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C APIs
• SwiftC APIʹΞΫηεग़དྷΔेͳ
ػೳΛ࣋ͪ߹Θ͍ͤͯΔϨΠϠʔ
ͳϞδϡʔϧʹͰ͖Δͷศར
• ϙΠϯλɺϝϞϦཧͷࣝඞਢ
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UnsafeMutablePointer
IUUQTEFWFMPQFSBQQMFDPNMJCSBSZXBUDIPTEPDVNFOUBUJPO4XJGU
[email protected]@4USVDUVSFJOEFYIUNM
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GIFLIBΛ͍͍ͨ
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• ༷Ѳෆ…
• ΧϥʔϚοϓ
• ؔ
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ࠂ
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iOSDC
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Thanks.