【IT168技术】iPhone图形开发绘图教程是本文要介绍的内容，介绍了很多关于绘图类的使用，先来看详细内容讲解。
1、绘图总结:
绘图前设置:
1. CGContextSetRGBFillColor/CGContextSetFillColorWithColor //填充色
2. CGContextSetRGBStrokeColor/CGContextSetStrokeColorWithColor //笔颜色
3. 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:
1. CGContextFillRect/CGContextFillRects
2. CGContextFillEllipseInRect
3. CGContextAddRect/CGContextAddRects
4. CGContextAddEllipseInRect
5. CGContextAddLines
6. CGContextMoveToPoint
7. CGContextAddLineToPoint
3.常见控制方法:
1. CGContextSaveGState
2. CGContextRestoreGState
4.创建内存图像context:
1. CGBitmapContextCreate <-----CGContextRlease释放
2. CGColorSpaceCreateWithName (KCGColorSpaceGenericRGB)
3. CGColorSpaceRlease
4. CGBitmapContextCreateImage() <-----CGImageRlease 释放.
5. eg:
6. CGContextRefMyCreateBitmapContext(intpixelsWide,intpixelsHigh)
7. {
8. CGContextRef context=NULL;
9. CGColorSpaceRefcolorSpace;
10.void* bitmapData;
11.int bitmapByteCount;
12.int bitmapBytesPerRow;
13.bitmapBytesPerRow =(pixelsWide*4);
14.bitmapByteCount =(bitmapBytesPerRow*pixelsHigh);
15.colorSpace=CGColorSpaceCreateDeviceRGB();
16.bitmapData=malloc(bitmapByteCount);
17.if(bitmapData==NULL)
18.{
19.fprintf(stderr,"Memorynotallocated!");
20.returnNULL;
21.}
22.context=CGBitmapContextCreate(bitmapData,
23. pixelsWide, pixelsHigh, 8,
24.bitmapBytesPerRow, colorSpace,
25. kCGImageAlphaPremultipliedLast);
26.if(context==NULL)
27.{
28.free(bitmapData);
29.fprintf(stderr,"Contextnotcreated!");
30.returnNULL;
31.}
32.CGColorSpaceRelease(colorSpace);
33.returncontext;
34.}
5.图形的变换:
1. CGContextTranslateCTM
2. CGContextRotateCTM
3. CGContextScaleCTM
6.常用函数:
1. CGRectContainsPoint();
2. CGRectContainsRect();
3. CGRectIntersectsRect();
4. CGRectIntersection();
5. CGPointEqualToPoint();
6. CGSizeEqualToSize();
7.从原图片中取小图.
1. CGImageCreateWithImageInRect
8.屏幕快照:
1. #import "QuartzCore/QuartzCore.h"
2.
3. UIGraphicsBeginImageContext(yourView.frame.size);
4. [[yourView layer] renderInContext:UIGraphicsGetCurrentContext()];
5. UIImage*screenshot =UIGraphicsGetImageFromCurrentImageContext();
6. UIGraphicsEndImageContext();
7. from:http://www.cppblog.com/zhangyuntaoshe/articles/123066.html
合并两张bit图到一张image的方法
1. To graphically merge two images into a new image, you do something like this:
2. UIImage *result = nil;
3. unsignedchar *data = calloc(1,size.width*size.height*kBytesPerPixel);
4. if (data != NULL) {
5. // kCGImageAlphaPremultipliedLast 为预记录的#define value
6. // 设置context上下文
7. CGContextRef context = CGBitmapContextCreate(
8. data, size.width, size.height, 8, size.width*kBytesPerPixel,
9. CGColorSpaceCreateDeviceRGB(), kCGImageAlphaPremultipliedLast);
10.if (context != NULL) {
11.UIGraphicsPushContext(context);
12.// Image 为下载的背景图片,用于比较context
13.CGContextTranslateCTM(context, 0, size.height);
14.CGContextScaleCTM(context, 1, -1);
15.[image drawInRect:imageRect];
16.[image2 drawInRect:image2Rect];
17.UIGraphicsPopContext();
18.CGImageRef imageRef = CGBitmapContextCreateImage(context);
19.if (imageRef != NULL) {
20.result = [UIImageimageWithCGImage:imageRef];
21.CGImageRelease(imageRef);
22.}
23.CGContextRelease(context);
24.}
25.free(data);
26.}
27.return result;
关键方法：
1. CGContextRef context = CGBitmapContextCreate();
2. CGContextTranslateCTM();
3. CGContextScaleCTM();
4. CGImageRef imageRef = CGBitmapContextCreateImage(context);
5. CGImageRelease(imageRef);
小结：iPhone图形开发绘图教程的内容介绍完了，希望本文对你有所帮助!
