OC, oc Language

OC, oc Language

 

Introduction

• Function

• Draw
• Drawing: lines, triangles, rectangles, circles, and Arcs
• Draw text
• Draw \ generate image (image)
• Read \ generate PDF
• \ Crop an image
• Custom UI controls (usually controls with complicated internal structures)
• Most of the controls in UIKit are drawn by the system.
• Matrix operation (changes all paths shown in the following figure)
• Zoom
• Rotate
• Translation

• Introduction

  • Z2d belongs to the Core Graphic framework. It is a two-dimensional Drawing Engine that operates directly on layers. It usually obtains the context in-drawRect: method, draw the content to be drawn to the graphic context, then render the layer to the control, and finally close the graphic context.
  • -(Void) drawRect :( CGRect) rect. This method is called only once when the interface is to be displayed. To call this method, call the repainting method-(void) setNeedsDisplay.

Common drawing operations

• Draw a straight line (three methods)

  • Draw a straight line by adding a path, and then render the context of the path.

  • Enable Context

    • CGContextRef context = UIGraphicsGetCurrentContext ()

  • Description of the path to be drawn

    • Create path
      CGMutablePathRef CGPathCreateMutable (void)
    • Set start point
      Void CGPathMoveToPoint (CGMutablePathRef path, const CGAffineTransform * m, CGFloat x, CGFloat y)
    • Link
      Void CGPathAddLineToPoint (CGMutablePathRef path, const CGAffineTransform * m, CGFloat x, CGFloat y)

  • Add path to context

    • Void CGContextAddPath (CGContextRef context, CGPathRef path)

  • Rendering context

    • Void CGContextStrokePath (CGContextRef c)
  • Draw a straight line directly in the context

  • Enable Context

    • CGContextRef context = UIGraphicsGetCurrentContext ()

  • Description of the path to be drawn

    • Set start point
      Void CGContextMoveToPoint (CGContextRef c, CGFloat x, CGFloat y)
    • Link
      Void CGContextAddLineToPoint (CGContextRef c, CGFloat x, CGFloat y)

  • Rendering context

    • Void CGContextStrokePath (CGContextRef c)
  • Draw a straight line through besell

  • Common besell paths (the most common paths)

    • (UIBezierPath *) bezierPath

  • Set start point

    • (Void) moveToPoint :( CGPoint) point

  • Link

    • (Void) addLineToPoint :( CGPoint) point

  • Rendering

    • (Void) stroke

• Draw a curve

  • Get Context
  • CGContextRef UIGraphicsGetCurrentContext (void)
  • Draw path
  • Set start point
    Void CGContextMoveToPoint (CGContextRef c, CGFloat x, CGFloat y)
  • Link
    Void CGContextAddQuadCurveToPoint (CGContextRef c, CGFloat cpx, CGFloat cpy, CGFloat x, CGFloat y)
  • Rendering context
    Void CGContextStrokePath (CGContextRef c)

• Draw an arc (using the besell path)

  • Create besell path
  • + (UIBezierPath *) bezierPathWithArcCenter :( CGPoint) center radius :( CGFloat) radius startAngle :( CGFloat) startAngle endAngle :( CGFloat) endAngle clockwise :( BOOL) clockwise
  • -(Void) stroke

• Create a pie chart

  • Ideas:
    1) a pie chart is completed by adding two lines to the ARC.
  • Steps

  • Draw an arc using the besell path

    • + (UIBezierPath *) bezierPathWithArcCenter :( CGPoint) center radius :( CGFloat) radius startAngle :( CGFloat) startAngle endAngle :( CGFloat) endAngle clockwise :( BOOL) clockwise

  • Add a straight line to close the path

    • Add a straight line from the path end point to the arc Center
    • -(Void) addLineToPoint :( CGPoint) point
    • The straight line from the path start point to the arc center will be automatically added
      The call-(void) fill method is automatically added

  • Set fill color

    • -(Void) set. This method is used to set the color of the context fill or rendering object.

  • Fill and close the path and render it

    • -(Void) fill, which calls this method through the besell path

• Draw a bar chart

  • Ideas
    1) The bar chart can be drawn directly through the besell path.
  • Steps

  • Create besell path

    • + (UIBezierPath *) bezierPathWithRect :( CGRect) rect

  • Set fill color

    • -(Void) set. This method is used to set the color of the filling or rendering in the context.

  • Fill and close the path and render it

    • -(Void) fill

• Draw text

  • Ideas

  • NSString classification NSStringDrawing implements the NSString object painting Method

    • -(Void) drawAtPoint :( CGPoint) point withAttributes :( NSDictionary *) attrs, draw text from a certain point
    • -(Void) drawInRect :( CGRect) rect withAttributes :( NSDictionary *) attrs, draw text in the rect Area
  • When drawing text, you can also set its properties through the attrs Parameter
  • Steps
  • Create an NSString object

  • Set text attributes (the attribute does not exist in a dictionary, and the corresponding attributes are set using the specified key)

    • Set text color
      NSForegroundColorAttributeName
    • Set Font
      NSFontAttributeName
    • Set the rendering width
      NSStrokeWidthAttributeName
    • Set the rendering color
      NSStrokeColorAttributeName
    • Set background attributes
      NSShadowAttributeName
      Set background color: shadowColor (UIColor)
      Fuzzy attribute: shadowBlurRadius (CGFloat)
      Offset: shadowOffset

  • Draw text

    • -(Void) drawInRect :( CGRect) rect withAttributes :( NSDictionary *) attrs
    • -(Void) drawAtPoint :( CGPoint) point withAttributes :( NSDictionary *) attrs. If this method is used, the text is displayed on a single line.

• Draw Images

  • Ideas
    You can directly call the method of the object that is used to draw the UIImage.
  • Steps
  • Create a UIImage object
  • Create a drawing Area
  • Content set to exceed the drawing area is cut
    UIRectClip (CGRect rect)

  • Draw Images

    • -(Void) drawAsPatternInRect :( CGRect) rect: displays the image in Tiled mode and overwrites the entire rect area)
    • -(Void) drawAtPoint :( CGPoint) point: displays an image of the same size as the original image.
    • -(Void) drawInRect :( CGRect) rect. The image is stretched and the size is equal to rect.
    • -(Void) drawAtPoint :( CGPoint) point blendMode :( CGBlendMode) blendMode alpha :( CGFloat) alpha

--- Restore content end ---

Introduction

• Function

  • Draw
  • Drawing: lines, triangles, rectangles, circles, and Arcs
  • Draw text
  • Draw \ generate image (image)
  • Read \ generate PDF
  • \ Crop an image
  • Custom UI controls (usually controls with complicated internal structures)
  • Most of the controls in UIKit are drawn by the system.
  • Matrix operation (changes all paths shown in the following figure)
  • Zoom
  • Rotate
  • Translation

• Introduction

  • Z2d belongs to the Core Graphic framework. It is a two-dimensional Drawing Engine that operates directly on layers. It usually obtains the context in-drawRect: method, draw the content to be drawn to the graphic context, then render the layer to the control, and finally close the graphic context.
  • -(Void) drawRect :( CGRect) rect. This method is called only once when the interface is to be displayed. To call this method, call the repainting method-(void) setNeedsDisplay.

Common drawing operations

• Draw a straight line (three methods)

  • Draw a straight line by adding a path, and then render the context of the path.

  • Enable Context

    • CGContextRef context = UIGraphicsGetCurrentContext ()

  • Description of the path to be drawn

    • Create path
      CGMutablePathRef CGPathCreateMutable (void)
    • Set start point
      Void CGPathMoveToPoint (CGMutablePathRef path, const CGAffineTransform * m, CGFloat x, CGFloat y)
    • Link
      Void CGPathAddLineToPoint (CGMutablePathRef path, const CGAffineTransform * m, CGFloat x, CGFloat y)

  • Add path to context

    • Void CGContextAddPath (CGContextRef context, CGPathRef path)

  • Rendering context

    • Void CGContextStrokePath (CGContextRef c)
  • Draw a straight line directly in the context

  • Enable Context

    • CGContextRef context = UIGraphicsGetCurrentContext ()

  • Description of the path to be drawn

    • Set start point
      Void CGContextMoveToPoint (CGContextRef c, CGFloat x, CGFloat y)
    • Link
      Void CGContextAddLineToPoint (CGContextRef c, CGFloat x, CGFloat y)

  • Rendering context

    • Void CGContextStrokePath (CGContextRef c)
  • Draw a straight line through besell

  • Common besell paths (the most common paths)

    • (UIBezierPath *) bezierPath

  • Set start point

    • (Void) moveToPoint :( CGPoint) point

  • Link

    • (Void) addLineToPoint :( CGPoint) point

  • Rendering

    • (Void) stroke

• Draw a curve

  • Get Context
  • CGContextRef UIGraphicsGetCurrentContext (void)
  • Draw path
  • Set start point
    Void CGContextMoveToPoint (CGContextRef c, CGFloat x, CGFloat y)
  • Link
    Void CGContextAddQuadCurveToPoint (CGContextRef c, CGFloat cpx, CGFloat cpy, CGFloat x, CGFloat y)
  • Rendering context
    Void CGContextStrokePath (CGContextRef c)

• Draw an arc (using the besell path)

  • Create besell path
  • + (UIBezierPath *) bezierPathWithArcCenter :( CGPoint) center radius :( CGFloat) radius startAngle :( CGFloat) startAngle endAngle :( CGFloat) endAngle clockwise :( BOOL) clockwise
  • -(Void) stroke

• Create a pie chart

  • Ideas:
    1) a pie chart is completed by adding two lines to the ARC.
  • Steps

  • Draw an arc using the besell path

    • + (UIBezierPath *) bezierPathWithArcCenter :( CGPoint) center radius :( CGFloat) radius startAngle :( CGFloat) startAngle endAngle :( CGFloat) endAngle clockwise :( BOOL) clockwise

  • Add a straight line to close the path

    • Add a straight line from the path end point to the arc Center
    • -(Void) addLineToPoint :( CGPoint) point
    • The straight line from the path start point to the arc center will be automatically added
      The call-(void) fill method is automatically added

  • Set fill color

    • -(Void) set. This method is used to set the color of the context fill or rendering object.

  • Fill and close the path and render it

    • -(Void) fill, which calls this method through the besell path

• Draw a bar chart

  • Ideas
    1) The bar chart can be drawn directly through the besell path.
  • Steps

  • Create besell path

    • + (UIBezierPath *) bezierPathWithRect :( CGRect) rect

  • Set fill color

    • -(Void) set. This method is used to set the color of the filling or rendering in the context.

  • Fill and close the path and render it

    • -(Void) fill

• Draw text

  • Ideas

  • NSString classification NSStringDrawing implements the NSString object painting Method

    • -(Void) drawAtPoint :( CGPoint) point withAttributes :( NSDictionary *) attrs, draw text from a certain point
    • -(Void) drawInRect :( CGRect) rect withAttributes :( NSDictionary *) attrs, draw text in the rect Area
  • When drawing text, you can also set its properties through the attrs Parameter
  • Steps
  • Create an NSString object

  • Set text attributes (the attribute does not exist in a dictionary, and the corresponding attributes are set using the specified key)

    • Set text color
      NSForegroundColorAttributeName
    • Set Font
      NSFontAttributeName
    • Set the rendering width
      NSStrokeWidthAttributeName
    • Set the rendering color
      NSStrokeColorAttributeName
    • Set background attributes
      NSShadowAttributeName
      Set background color: shadowColor (UIColor)
      Fuzzy attribute: shadowBlurRadius (CGFloat)
      Offset: shadowOffset

  • Draw text

    • -(Void) drawInRect :( CGRect) rect withAttributes :( NSDictionary *) attrs
    • -(Void) drawAtPoint :( CGPoint) point withAttributes :( NSDictionary *) attrs. If this method is used, the text is displayed on a single line.

• Draw Images

  • Ideas
    You can directly call the method of the object that is used to draw the UIImage.
  • Steps
  • Create a UIImage object
  • Create a drawing Area
  • Content set to exceed the drawing area is cut
    UIRectClip (CGRect rect)

  • Draw Images

    • -(Void) drawAsPatternInRect :( CGRect) rect: displays the image in Tiled mode and overwrites the entire rect area)
    • -(Void) drawAtPoint :( CGPoint) point: displays an image of the same size as the original image.
    • -(Void) drawInRect :( CGRect) rect. The image is stretched and the size is equal to rect.
    • -(Void) drawAtPoint :( CGPoint) point blendMode :( CGBlendMode) blendMode alpha :( CGFloat) alpha