绘制纹理

#define H_PATTERN_SIZE 16
#define V_PATTERN_SIZE 18
#define H_PSIZE 16
#define V_PSIZE 18

void MyDrawColoredPattern (void *info, CGContextRef myContext)
{
CGFloat subunit = 5; // the pattern cell itself is 16 by 18

CGRect myRect1 = {{0,0}, {subunit, subunit}},
myRect2 = {{subunit, subunit}, {subunit, subunit}},
myRect3 = {{0,subunit}, {subunit, subunit}},
myRect4 = {{subunit,0}, {subunit, subunit}};

CGContextSetRGBFillColor (myContext, 0, 0, 1, 1);
CGContextFillRect (myContext, myRect1);
CGContextSetRGBFillColor (myContext, 0, 0.5, .4, 1);
CGContextFillRect (myContext, myRect2);
CGContextSetRGBFillColor (myContext, 0, 1, 0, 1);
CGContextFillRect (myContext, myRect3);
CGContextSetRGBFillColor (myContext, .5, 0, 1.5, 1);
CGContextFillRect (myContext, myRect4);
}

void MyColoredPatternPainting (CGContextRef myContext,
CGRect rect)
{
CGPatternRef pattern;// 1
CGColorSpaceRef patternSpace;// 2
CGFloat alpha = 1,// 3
width, height;// 4
staticconst CGPatternCallbacks callbacks = {0, // 5
&MyDrawColoredPattern,
NULL};

CGContextSaveGState (myContext);

// CGContextTranslateCTM(myContext, rect.origin.x, rect.origin.y);
// CGContextTranslateCTM(myContext, 0, rect.size.height);
// CGContextScaleCTM(myContext, 1.0, -1.0);
// CGContextTranslateCTM(myContext, -rect.origin.x, -rect.origin.y);


patternSpace = CGColorSpaceCreatePattern (NULL);// 6
CGContextSetFillColorSpace (myContext, patternSpace);// 7
CGColorSpaceRelease (patternSpace);// 8

pattern = CGPatternCreate (NULL, // 9
CGRectMake (0, 0, H_PSIZE, V_PSIZE),// 10
CGAffineTransformMake (1, 0, 0, 1, 0, 0),// 11
H_PATTERN_SIZE, // 12
V_PATTERN_SIZE, // 13
kCGPatternTilingConstantSpacing,// 14
true, // 15
&callbacks);// 16

CGContextSetFillPattern (myContext, pattern, &alpha);// 17
CGPatternRelease (pattern);// 18
CGContextFillRect (myContext, rect);// 19
CGContextRestoreGState (myContext);
}