drawRect的简单示例

头文件：

 

#import <UIKit/UIKit.h>
#include <math.h>

static inline double radians(double degrees) {
	return degrees * M_PI / 180;
}

#define FontSize 20.0f

@interface DrawScreen : UIView {
	
}

- (void)drawTextByString:(NSString *)drawText thePoisition:(CGPoint)point;
- (void)drawPicByImage:(UIImage *)theImage theRect:(CGRect)rect;
- (void)drawTextByQuartz:(CGContextRef)context theText:(const char *)drawtext 
			thePoisition:(CGPoint)point rotateAngle:(float)angle;
- (void)drawPicByQuartz:(CGContextRef)context thePic:(UIImage *)theImage theLocation:(CGRect)rect;

@end

 

实现文件：

 

#import "DrawScreen.h"

@implementation DrawScreen

- (id)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        self.backgroundColor = [UIColor blackColor];
    }
    return self;
}

- (void)drawRect:(CGRect)rect {
	CGContextRef context = UIGraphicsGetCurrentContext();
	CGContextSetFillColorWithColor(context, [UIColor greenColor].CGColor);
	
	//方式一：用NSString的方式画字，用UIImage的方式画图片，坐标原点在左上角
	NSString *textOne = [NSString stringWithFormat:@"iPad"];
	NSString *textTwo = [NSString stringWithFormat:@"iPhone"];
	[self drawTextByString:textOne thePoisition:CGPointMake(50.0f, 260.0f)];
	[self drawTextByString:textTwo thePoisition:CGPointMake(250.0f, 260.0f)];
	UIImage *flagOne = [UIImage imageNamed:@"flag.png"];
	[self drawPicByImage:flagOne theRect:CGRectMake(50.0f, 200.0f, 45.0f, 45.0f)];
	[self drawPicByImage:flagOne theRect:CGRectMake(250.0f, 200.0f, 45.0f, 45.0f)];
	
	//方式二：用Quartz2D的方式画字和图片，坐标原点移动到左下角
	CGContextTranslateCTM(context, 0, self.bounds.size.height);
	CGContextScaleCTM(context, 1, -1);
	UIImage *flagTwo = [UIImage imageNamed:@"location.png"];
	[self drawTextByQuartz:context theText:"Apple" thePoisition:CGPointMake(160.0f, 200.0f) rotateAngle:45.0f];
	[self drawTextByQuartz:context theText:"iPod" thePoisition:CGPointMake(50.0f, 100.0f) rotateAngle:45.0f];
	[self drawTextByQuartz:context theText:"iMac" thePoisition:CGPointMake(250.0f, 100.0f) rotateAngle:45.0f];
	[self drawPicByQuartz:context thePic:flagTwo theLocation:CGRectMake(160.0f, 230.0f, 50.0f, 50.0f)];
	[self drawPicByQuartz:context thePic:flagTwo theLocation:CGRectMake(50.0f, 130.0f, 50.0f, 50.0f)];
	[self drawPicByQuartz:context thePic:flagTwo theLocation:CGRectMake(250.0f, 130.0f, 50.0f, 50.0f)];
}

- (void)dealloc {
    [super dealloc];
}

- (void)drawTextByString:(NSString *)drawText thePoisition:(CGPoint)point {
	//方式一
	[drawText drawAtPoint:point withFont:[UIFont systemFontOfSize:FontSize]];
}

- (void)drawPicByImage:(UIImage *)theImage theRect:(CGRect)rect {
	//方式一
	[theImage drawInRect:rect];
}

- (void)drawTextByQuartz:(CGContextRef)context theText:(const char *)drawtext 
			thePoisition:(CGPoint)point rotateAngle:(float)angle {
	//方式二
	CGContextSelectFont(context, "Helvetica", FontSize, kCGEncodingMacRoman);
	CGContextSetTextDrawingMode(context, kCGTextFill);
	CGAffineTransform myTextTransform = CGAffineTransformMakeRotation(radians(angle)); 
	CGContextSetTextMatrix (context, myTextTransform);
	CGContextShowTextAtPoint(context, point.x, point.y, drawtext, strlen(drawtext));
}

- (void)drawPicByQuartz:(CGContextRef)context thePic:(UIImage *)theImage theLocation:(CGRect)rect {
	//方式二
	CGContextDrawImage(context, rect, theImage.CGImage);
}

@end

 

示例图：