Basic introduction of QUART2D

DrawRect: How to make use of the method?
Drawing of common graphs: lines, polygons, circles

Drawing state settings:? text color, line width, etc.

The preservation and restoration of the state of the graph up and down
Graphics up and down, text stacks

What is quartz2d

• Quartz 2D is that a? Two-dimensional drawing engine, simultaneously? support for iOS and Mac systems

• Quartz 2D can be done? work

• ? Drawing: lines \ Three corners \ rectangles \ Circles \ Arcs, etc.

• ? Draw? text

• ? Draw \? Generate diagram Slice (image)

• ? Read \? Generate PDF

• ? \ crop chart? Slice

• ? ? Custom UI Control?......

• quartz2d instances

  Quartz 2D can do a lot of strong, big things, such as

  ? Crop graph?

  The value of quartz2d in iOS development

  To make it easy to build an aesthetically pleasing UI interface, iOS provides a uikit framework with a variety of UI controls? UILabel: Display text
  ? Uiimageview: showing the picture?
  ? UIButton: Simultaneous display of pictures and words (can click)

  ?......

  Lee? Use the controls provided by the Uikit framework to make a patchwork, to build and to be realistic? Some simple, common UI interface

  However, some UI boundaries are extremely complex, and, what are the more personal, more personalized, common UI controls? Can not be achieved, at this time the structure of the control inside the quartz2d technology to draw out,? Custom control of the sample child

  In fact, the contents of most controls in iOS are drawn through quartz2d.
  So, quartz2d is important in iOS development? A value is:? Custom View (? Custom UI Control)

  Graph up and down?

  Graphics context: Yes? A cgcontextref type of data

  How to make a graph up and down?
  ? Save drawing information, drawing status
  ? Decide which output to draw? Where do you draw the target? (output?) can the target be a PDF file, a bitmap or a display window?? On the mouth)

  The same? A set of drawing sequences that specify different graphics Context to draw the same image to a different target

  ? Custom View

  How do I use quartz2d? Custom view? (? Custom UI Control)

  How to use quartz2d to draw things to the view?
  First, you have to have a graph up and down, because it can save the drawing information and decide where to draw it? Secondly, the graphic must be associated with a view in order to draw the content onto the view?

  ? Steps for customizing view
  ? New? A class, Inherit? Self UIView
  ? Implementation-(void) DrawRect: (CGRect) Rect method, and then in this? method to get the graph associated with the current view up and down?
  Draw the appropriate graphic content
  Do you use graphics up and down? To render all the content that is drawn to the view?

  DrawRect:

  Why do you want to implement the DrawRect:? method to draw to the view?
  ? Because in the DrawRect:? method, you can obtain a graph that is associated with a view.

  DrawRect: When was the method transferred?
  ? When the view is displayed on the screen (is added to the UIWindow display)? To use the Setneedsdisplay or Setneedsdisplayinrect of a view:

  QUARTZ2D Notice

  Quartz2d's API is pure C language.
  quartz2d API to? From the core graphics framework

  A C-language drawing frame in iOS (coregraphics.framwork)

  Framework import, after XCODE5, so the framework named after the. Framework does not have to be imported

  are basic data types and functions prefixed with CG? Cgcontextref
  ? Cgpathref
  ? Cgcontextstrokepath (CTX);

  ? ......

  DrawRect: The top and bottom of the text

  After getting up and down in the DrawRect: method, you can draw things to the view
  There is a layer property inside the view, DrawRect:? The method gets a layer

  Graphics Context, so what you draw is actually drawn to the layer of view.

  The reason that view can be shown is because of its inner layer.

  quartz2d code steps for drawing

  1. Get the graph up and down text
  Cgcontextref CTX = Uigraphicsgetcurrentcontext ();

  2. Stitching path (the next polygon code is a line segment)

  Cgcontextmovetopoint (CTX, 10, 10);

  Cgcontextaddlinetopoint (CTX, 100, 100);

  3. Draw the Path
  Cgcontextstrokepath (CTX); Cgcontextfillpath (CTX);

  Common Use stitching path function

  New? A starting point
  void Cgcontextmovetopoint (Cgcontextref C, CGFloat x, cgfloat y)

  Add a new segment to a point
  void Cgcontextaddlinetopoint (Cgcontextref C, CGFloat x, cgfloat y)

  Add? a rectangle
  void Cgcontextaddrect (Cgcontextref C, CGRect rect)

  Add an ellipse
  void Cgcontextaddellipseinrect (Cgcontextref context, CGRect rect)

  Add? an arc
  void Cgcontextaddarc (Cgcontextref C, CGFloat x, CGFloat y,

  CGFloat radius, cgfloat startangle, CGFloat endangle, Intclockwise)

  Used to draw a path function

  Mode parameter determines the pattern to be drawn
  void Cgcontextdrawpath (cgcontextref C, Cgpathdrawingmode mode)

  Draw Empty Heart Path
  void Cgcontextstrokepath (Cgcontextref c)

  Draw a real heart path
  void Cgcontextfillpath (Cgcontextref c)

  Cgcontextdraw, Cgcontextstroke, and Cgcontextfill are all functions that are used to draw a path.

  The operation of the graph up and down

  Copy the current up and down text, save to the top of the stack (the stack is called "Graph up and down stack") void Cgcontextsavegstate (Cgcontextref c)

  Put the top of the stack up and down, replace the current up and down text
  void Cgcontextrestoregstate (Cgcontextref c)

Basic introduction of QUART2D