1.绘图总结:
绘图前设置:
CGContextSetRGBFillColor/CGContextSetFillColorWithColor //填充色
CGContextSetRGBStrokeColor/CGContextSetStrokeColorWithColor //笔颜色
CGContextSetLineWidth //线宽度
绘图后设置:
注: 画完图后,必须
先用CGContextStrokePath来描线,即形状
后用CGContextFillPath来填充形状内的颜色.
2.常见图形绘制:
CGContextFillRect/CGContextFillRects
CGContextFillEllipseInRect
CGContextAddRect/CGContextAddRects
CGContextAddEllipseInRect
CGContextAddLines
CGContextMoveToPoint
CGContextAddLineToPoint
3.常见控制方法:
CGContextSaveGState
CGContextRestoreGState
4.创建内存图像context:
CGBitmapContextCreate <-----CGContextRlease释放
CGColorSpaceCreateWithName (KCGColorSpaceGenericRGB)
CGColorSpaceRlease
CGBitmapContextCreateImage() <-----CGImageRlease 释放.
eg:
CGContextRef MyCreateBitmapContext (int pixelsWide,int pixelsHigh)
{
CGContextRef context = NULL;
CGColorSpaceRef colorSpace;
void * bitmapData;
int bitmapByteCount;
int bitmapBytesPerRow;
bitmapBytesPerRow = (pixelsWide * 4);
bitmapByteCount = (bitmapBytesPerRow * pixelsHigh);
colorSpace = CGColorSpaceCreateDeviceRGB();
bitmapData = malloc( bitmapByteCount );
if (bitmapData == NULL)
{
fprintf (stderr, "Memory not allocated!");
return NULL;
}
context = CGBitmapContextCreate (bitmapData, pixelsWide, pixelsHigh, 8, bitmapBytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast);
if (context== NULL)
{
free (bitmapData);
fprintf (stderr, "Context not created!");
return NULL;
}
CGColorSpaceRelease( colorSpace );
return context;
}
5.图形的变换:
CGContextTranslateCTM
CGContextRotateCTM
CGContextScaleCTM
6.常用函数:
CGRectContainsPoint();
CGRectContainsRect();
CGRectIntersectsRect();
CGRectIntersection();
CGPointEqualToPoint();
CGSizeEqualToSize();
7.从原图片中取小图.
CGImageCreateWithImageInRect
8.屏幕快照:
#import "QuartzCore/QuartzCore.h"
UIGraphicsBeginImageContext(yourView.frame.size);
[[yourView layer] renderInContext:UIGraphicsGetCurrentContext()];
UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();