iPhone图形开发绘图小结

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:

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:

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;

}

CGColorSpaceRelease(colorSpace);

returncontext;

}

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();

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

合并两张bit图到一张image的方法

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 为预记录的#define value

// 设置context上下文

CGContextRef context = CGBitmapContextCreate(

data, size.width, size.height, 8, size.width*kBytesPerPixel,

CGColorSpaceCreateDeviceRGB(), kCGImageAlphaPremultipliedLast);

if (context != NULL) {

UIGraphicsPushContext(context);

// Image 为下载的背景图片,用于比较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;

关键方法：

CGContextRef context = CGBitmapContextCreate();

CGContextTranslateCTM();

CGContextScaleCTM();

CGImageRef imageRef = CGBitmapContextCreateImage(context);

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！