GraphicsContext application for IOS development

GraphicsContext for IOS developmentThe application class is the content to be introduced in this article, mainly to understand and learnGraphicsContextFor more information about how to use the application class, see this article.

1. CGContext class.

2. UIView: DrawRect Function

3. UIGraphicsGetCurrentContext () function

4. The UIView coordinate system is opposite to the Quartz coordinate system.

5. CGContextRef myContext = [[NSGraphicsContext currentContext] graphicsPort];

6. initWithFrame, intWithCoder, DrawRect

7. cgw.contextcreatewithurl, cgw.contextcreate

 
 

  
  
CFURLCreateWithFileSystemPath(), CGDataConsumerCreateWithURL() 
 
 

8. We recommend that you use uigraphicsbeginimagecontextwitexceptions for iOS, which automatically performs coordinate transformation between Quartz and UIKit.

9. CGBitmapContextCreate

10. Pixel Format

 
 

  
  
NULL color space:  
  
  
kCGImageAlphaoOnly 8bpp = A8 
 
 

Gray color space:

 
 

  
  
kCGImageAlphaNone 8bpp = L8 
  
  
kCGImageAlphaOnly 8bpp = A8 
  
  
kCGImageAlphaNone 16bpp = L16 
  
  
KCGImageAlphaNone|kCGBitmapfloatComponents = L32F 
 
 

RGB color space:

 
 

  
  
kCGImageAlphaNoneSkipFirst, 16bpp, 5bpc = R5G5B5X1 
  
  
kCGImageAlphaNoneSkipFirst, 32bpp, 8bpc = R8G8B8X8 
  
  
kCGImageAlphaNoneSkipLast, 32bpp, 8bpc = X8R8G8B8 
  
  
kCGImageAlphaPremultipliedFirst, 32bpp, 8bpc = R8G8B8A8 
  
  
kCGImageAlphaPremultipliedLast, 32bpp, 8bpc = A8R8G8B8 
  
  
kCGImageAlphaPremultipledLast, 64bpp, 16bpc = A16R16G16B16 
  
  
kCGImageAlphaNonSkipLast, 64bpp, 16bpc = X16R16G16B16 
  
  
kCGImageAlphaNoneSkipLast|kCGBitmapFloatComponents, 128bpp, 32bpc = X32R32G32B32F 
  
  
kCGImageAlphaPremultipliedLast | kCGBitmapFloatComponents, 128bpp, 32bpc = A32R32G32B32F 
 
 

CMYK space:

 
 

  
  
- kCGImageAlphaNone 32bpp, 8bpc = C8M8Y8K8 
  
  
kCGImageAlphaNone 64bpp, 16bpx = C16M16Y16K16 
  
  
kCGImageAlphaNone|kCGBitmapFloatComponents = C32M32Y32K32F 
 
 

11,

 
 

  
  
CGContextSetShouldAntialias for bitmap context,   
  
  
CGContextSetAllowAntialasing for graphics context. 
 
 

Summary: DetailsGraphicsContext for IOS developmentThe application class has been introduced. I hope this article will help you!