IPhone drawing Summary

1. Drawing summary:

Settings before drawing:

Cgcontextsetrgbfillcolor/cgcontextsetfillcolorwithcolor // fill color

Cgcontextsetrgbstrokecolor/cgcontextsetstrokecolorwithcolor // pen color

Cgcontextsetlinewidth // line width

 

Settings after drawing:

Note: The image must be painted

Use cgcontextstrokepath to describe the line, that is, the shape.

Then, cgcontextfillpath is used to fill the color in the shape.

 

2. Drawing common images:

Cgcontextfillrect/cgcontextfillrects

Cgcontextfillellipseinrect

 

Cgcontextaddrect/cgcontextaddrects

Cgcontextaddellipseinrect

 

Cgcontextaddlines

 

Cgcontextmovetopoint

Cgcontextaddlinetopoint

 

3. Common control methods:

Cgcontextsavegstate

Cgcontextrestoregstate

 

4. Create a memory image context:

Cgbitmapcontextcreate <----- cgcontextrlease release

 

Cgcolorspacecreatewithname (kcgcolorspacegenericrgb)

Cgcolorspacerlease

 

Cgbitmapcontextcreateimage () <----- cgimagerlease release.

 

Eg:

Cgcontextrefmycreatebitmapcontext (intpixelswide, intpixelshigh)

{

Cgcontextref context = NULL;

Cgcolorspacerefcolorspace;

Void * bitmapdata;

Int bitmapbytecount;

Int bitmapbytesperrow;

 

Bitmapbytesperrow = (pixelswide * 4 );

Bitmapbytecount = (bitmapbytesperrow * pixelshigh );

 

Colorspace = cgcolorspacecreatedevicergb ();

Bitmapdata = malloc (bitmapbytecount );

If (bitmapdata = NULL)

{

Fprintf (stderr, "memorynotallocated! ");

Returnnull;

}

Context = cgbitmapcontextcreate (bitmapdata, pixelswide, pixelshigh, 8, bitmapbytesperrow, colorspace, kcgimagealphapremultipliedlast );

If (context = NULL)

{

Free (bitmapdata );

Fprintf (stderr, "contextnotcreated! ");

Returnnull;

}

Cgcolorspacerelstrap (colorspace );

Returncontext;

}

 

5. Graphic Transformation:

Cgcontexttranslatectm

Cgcontextrotatectm

Cgcontextscalectm

6. Common functions:

Cgrectcontainspoint ();

Cgrectcontainsrect ();

Cgrectintersectsrect ();

Cgrectintersection ();

Cgpointequaltopoint ();

Cgsizeequaltosize ();

7. Small images from the source image.

 

Cgimagecreatewithimageinrect

8. screen snapshot:

# Import "quartzcore/quartzcore. H"

Uigraphicsbeginimagecontext (yourview. Frame. size );
[[Yourview layer] renderincontext: uigraphicsgetcurrentcontext ()];
Uiimage * screenshot = uigraphicsgetimagefromcurrentimagecontext ();
Uigraphicsendimagecontext ();

From: http://www.cppblog.com/zhangyuntaoshe/articles/123066.html

 

Merge two bit Graphs into one image

To graphically merge two images into a new image, you do something like this:

 

Uiimage * result = nil;

Unsignedchar * Data = calloc (1, size. Width * size. Height * kbytesperpixel );

 

If (Data! = NULL ){

// Kcgimagealphapremultipliedlast is the pre-recorded # define value

// Set Context

Cgcontextref context = cgbitmapcontextcreate (

Data, size. Width, size. Height, 8, size. Width * kbytesperpixel,

Cgcolorspacecreatedevicergb (), kcgimagealphapremultipliedlast );

If (context! = NULL ){

Uigraphicspushcontext (context );

 

// Image is the downloaded background image used to compare the context

Cgcontexttranslatectm (context, 0, size. Height );

Cgcontextscalectm (context, 1,-1 );

[Image drawinrect: imagerect];

[Image2 drawinrect: image2rect];

Uigraphicspopcontext ();

Cgimageref imageref = cgbitmapcontextcreateimage (context );

 

If (imageref! = NULL ){

Result = [uiimageimagewithcgimage: imageref];

Cgimagerelease (imageref );

}

Cgcontextrelease (context );

}

Free (data );

}

Return result;

Key Method: cgcontextref context = cgbitmapcontextcreate ();

Cgcontexttranslatectm ();

Cgcontextscalectm ();

Cgimageref imageref = cgbitmapcontextcreateimage (context );

Cgimagerelease (imageref );

From: http://wzn860701.blog.163.com/blog/static/361528062009102502716872/