Rotate Pan Zoom

------------------------------ rotate pan zoom ----------------------------------

-(void) DrawRect: (cgrect) rect

{

// Get context

Cgcontextref CTX = Uigraphicsgetcurrentcontext ();

//Current graphics state ' s transformation Matrix

// zoom

CGCONTEXTSCALECTM (CTX, 0.5, 0.5);

// panning

//CGCONTEXTTRANSLATECTM (CTX, N-max);

// rotate

//CGCONTEXTROTATECTM (CTX, m_pi_4);

// stitching paths Add paths to the context at the same time

// round

Cgcontextaddarc (CTX, 0, 2 * m_pi, 1);

// line

Cgcontextmovetopoint (CTX, 0, 0);

Cgcontextaddlinetopoint (CTX, + );

// Set line width

Cgcontextsetlinewidth (CTX, a);

// rendering

Cgcontextstrokepath (CTX);

}

--- rotate zoom pan

operation to rotate and pan scale The graphics context ( matrix operation )

Zoom

first parameter : the context that needs to be scaled

second parameter : scale of X-axis scaling

third parameter : scale of the y-axis scaling

CGCONTEXTSCALECTM (CTX, 1, 0.5);

panning

first parameter : the context that needs to be panned

second parameter : offset of x-axis

third parameter : offset of the y-axis

CGCONTEXTTRANSLATECTM (CTX, ,, );

Rotate

first parameter : the context that needs to be rotated

second parameter : angle of clockwise rotation

CGCONTEXTROTATECTM (CTX, m_pi_4);

---The graphics context stack

The graphics context stack is just the save state information ( style )

Saving state information

Cgcontextsavegstate (CTX);

Restore status information

Cgcontextrestoregstate (CTX);

---quartz2d memory management

If you include the Create copy keyword, remember to release

release 1

Cgpathrelease (path);

Release 2

Cfrelease (path);

--- drawing text

Draw - draw from (0,0) point

[str Drawatpoint:cgpointzero withattributes:dict];

Draw - draws to the specified area

[Str drawinrect:rect withattributes:nil];

Attributename-key in the NSAttributeName.h under UIKit .

Personal advice to remember one of them

Shadow

nsshadow* s = [[Nsshadow alloc] init];

S.shadowoffset = Cgsizemake (+ ); // offset

S.shadowblurradius = 0; //The smaller the less blurred

S.shadowcolor = [Uicolor Yellowcolor]; // color of shadow

If a text has a background color, the shaded section does not display text

--- drawing pictures

Draw - draw from a point

[Image Drawatpoint:cgpointzero];

Draw - draw to an area

[Image Drawinrect:rect];

Draw - tile

[Image Drawaspatterninrect:rect]; // You can consider setting a background image for a view

--- the area that the clipping context displays

premise : draw a graphic

crop a picture

Cgcontextclip (CTX);

tell the system that it has this shape to crop the image and then display it.

The so-called clipping is not to cut out the context is simply to cut out the area you want to display it !!!

---bitmap context

Create context ( picture )

Uigraphicsbeginimagecontext (Cgsizemake (+ ));

Create Context ( size , opacity , scale : 0)

Uigraphicsbeginimagecontextwithoptions (Cgsizemake (), NO, 0);

Close Context

Uigraphicsendimagecontext ();

get a picture from the graphics context of a picture

uiimage* image = Uigraphicsgetimagefromcurrentimagecontext ();

Save to Sandbox

nsstring* path = Nssearchpathfordirectoriesindomains (NSDocumentDirectory, Nsuserdomainmask, YES) [0] ;

Path = [path stringbyappendingpathcomponent:@ "Xx.png"];

convert image to nsdata type

nsdata* data = uiimagepngrepresentation (image);

NSLog (@ "%ld", data.length);

It is then written to the sandbox using the data object write to File

[Data Writetofile:path atomically:YES];

Rotate Pan Zoom