Simple usage of cgcontextref drawing line

Cgcontextref

Cgcontextmovetopoint (context,150,50);//Start point of Arc

Cgcontextaddarctopoint (context,100,80,130,150,50);

is to say from (150,50) to (100,80) draw a line, and then from (100,80) to (130,150) draw a line, from the two lines (infinitely extended) and RADIUS 50 can determine an arc,

and

Cgcontextaddarc (context, 0, M_PI, 1);

Relatively simple, (100,100) is the coordinate of the center, 30 is the radius, (0,M_PI) is the starting angle and end angle, 1 is clockwise, 0 is counterclockwise

is to say from (150,50) to (100,80) draw a line, and then from (100,80) to (130,150) draw a line, from the two lines (infinitely extended) and RADIUS 50 can determine an arc

Uigraphicsgetcurrentcontext () will take the cgcontextref at the top of the stack,

The correct approach is to call Uigraphicsgetcurrentcontext () only in DrawRect,

Because before DrawRect, the system pushes a valid cgcontextref into the stack,

Unless you maintain a cgcontextref, you should not take cgcontextref elsewhere.

0 Cgcontextref context = uigraphicsgetcurrentcontext (); Setting the context

1 Cgcontextmovetopoint Start drawing lines

2 Cgcontextaddlinetopoint Draw Straight line

4 Cgcontextaddellipseinrect Draw an ellipse

4 Cgcontextsetlinecap Set line End shape

4 Cgcontextsetlinedash Draw Dashed line

4 Cgcontextaddrect Draw one side box

4 Cgcontextstrokerect Specify Rectangle

4 Cgcontextstrokerectwithwidth Specify the width of the rectangle Line

4 Cgcontextstrokelinesegments Some straight lines

5 Cgcontextaddarc Draw already curved front two stores for center between two stores for the starting radian the last data is 0 clockwise draw 1 counterclockwise

5 Cgcontextaddarctopoint (context,0,0, 2, 9, 40);//Draw two lines from point to the Brother 1 points, from the Brother 1 point to the Brother 2 points of the line cut inside the circle

6 Cgcontextsetshadowwithcolor Setting Shadows

7 Cgcontextsetrgbfillcolor This fill color

7 Cgcontextsetrgbstrokecolor Brush Color settings

7 Cgcontextsetfillcolorspace Color Space fill

7 Cgconextsetstrokecolorspace Color Space Brush settings

8 Cgcontextfillrect complements the current fill color rect

8 Cgcontextsetalaha Transparency

9 CGCONTEXTTRANSLATECTM changing the canvas position

Cgcontextsetlinewidth set the width of the line

Draw Multiple Lines Cgcontextaddrects

Cgcontextaddquadcurvetopoint Draw Curve

Cgcontextstrokepath Start Drawing Pictures

Cgcontextdrawpath Set Drawing Mode

Cgcontextclosepath Close the current line

CGCONTEXTTRANSLATECTM (context, 0, rect.size.height); CGCONTEXTSCALECTM (Context, 1.0,-1.0); Invert canvas

Cgcontextsetinterpolationquality background built-in color quality level

Cgimagecreatewithimageinrect take a small picture from the original image

17 writing of the string can be used in the drawing method of the NSString itself – (cgsize) Drawinrect: (cgrect) rect withfont: (Uifont *) font Linebreakmode: (uilinebreakmode) Linebreakmode alignment: (uitextalignment) alignment; just write it in.

18 The function of zooming in and out of the picture is a little slow.

Uigraphicsbeginimagecontext (newSize);

uiimage* newimage = Uigraphicsgetimagefromcurrentimagecontext ();

Uigraphicsendimagecontext ();

Cgcolorgetcomponents () returns the individual values of the color and the transparency available as a read-only const float to receive the array

Drawing Sheet cgimageref image=cgimageretain (img. Cgimage);

Cgcontextdrawimage (Context, CGRectMake (10.0, height–

100.0, 90.0, 90.0), image);

21 Implement the variable color Fill method cgcontextclip (context);

Cgcolorspaceref RGB = Cgcolorspacecreatedevicergb ();

CGFloat colors[] =

{

204.0/255.0, 224.0/255.0, 244.0/255.0, 1.00,

29.0/255.0, 156.0/255.0, 215.0/255.0, 1.00,

0.0/255.0, 50.0/255.0, 126.0/255.0, 1.00,

};

Cggradientref gradient = cggradientcreatewithcolorcomponents

(RGB, colors, NULL, sizeof (colors)/(sizeof (COLORS[0)));

Cgcolorspacerelease (RGB);

Cgcontextdrawlineargradient (Context, Gradient,cgpointmake

(0.0,0.0), Cgpointmake (0.0,self.frame.size.height),

Kcggradientdrawsbeforestartlocation);

22 Note: Once you have finished drawing, you must

First use Cgcontextstrokepath to stroke the line, that is, the shape

Then use Cgcontextfillpath to fill the color inside the shape.

When a path is populated, the paths inside the path are filled independently.

If the path is overlapping, determine whether a point is filled, there are two rules

1,nonzero Winding Number rule: non-0 rules, if a point is crossed from left to right, counter +1, from right to left, counter-1, and finally, if the result is 0, then no padding, if nonzero, then padding.

2,even-odd rule: Parity rules, if a point is crossed, then +1, and finally an odd number, then to be filled, even the number is not filled, and the direction is not related.

Function

Description

Cgcontexteofillpath

Populating the current path with parity rules

Cgcontextfillpath

Populating the current path with a non-0-wrap rule

Cgcontextfillrect

Fills the specified rectangle

Cgcontextfillrects

Fills a specified number of rectangles

Cgcontextfillellipseinrect

Fills the ellipse in the specified rectangle

Cgcontextdrawpath

Two parameters determine the fill rule, Kcgpathfill represents the rule with a non-0 number of rules, kcgpatheofill represents a parity rule, kcgpathfillstroke represents a fill, kcgpatheofillstroke represents a stroke, not a fill

Set when a color is covered on another color, two colors how to mix

The default method is

result = (Alpha * foreground) + (1–alpha) * background

Cgcontextsetblendmode: Set blend mode.

Cgcontextsavegstate: Save blend mode.

Cgcontextrestoregstate: Use this function to restore the blend mode before saving.

Cgcontextsetblendmode Mix Two colors

Simple usage of cgcontextref drawing line