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!