Core Graphics

最新推荐文章于 2025-09-12 15:58:40 发布

转载最新推荐文章于 2025-09-12 15:58:40 发布 · 60 阅读

0 ·

CC 4.0 BY-SA版权

原文链接：https://my.oschina.net/u/2499773/blog/541029

文章标签：

#python

本文介绍了一个iOS应用中使用Core Graphics进行复杂绘图的方法，包括文本绘制、图片展示及如何实现带有水印效果的图片。通过具体的代码实例展示了如何在iOS应用中实现这些功能。

2019独角兽企业重金招聘Python工程师标准>>>

// MyView.m

// Core Graphics第二天

// Created by dc008 on 15/12/8.

#import "MyView.h"

@implementation MyView

- (void)drawRect:(CGRect)rect {

CGContextRef context = UIGraphicsGetCurrentContext();

// [self drawText:context];

// [self drawImage:context];

[self drawImageAtImageContext:context];

}

#pragma mark 绘制文字

- (void)drawText : (CGContextRef) context{

NSString *str = @"今天我们举办了一年一度的绘图大赛，同学们踊跃参与。";

//定义文字显示区域

CGRect rect = CGRectMake(20, 50, 335, 300);

//建立一个段落样式

NSMutableParagraphStyle *style = [[NSMutableParagraphStyle alloc]init];

style.alignment = NSTextAlignmentCenter;//居中

//绘制文字，设置属性（字体大小，颜色）

[str drawInRect:rect withAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:18],NSForegroundColorAttributeName:[UIColor whiteColor],NSParagraphStyleAttributeName:style}];

}

#pragma mark 绘制图片

- (void) drawImage : (CGContextRef) context

{

UIImage *image = [UIImage imageNamed:@"1"];

//1.从某一点开始绘制

// [image drawAtPoint:CGPointMake(0, 20)];

//2.绘制到指定的矩形中，注意：如果大小不合适会进行拉伸

[image drawInRect:CGRectMake(0, 100, 375, 667)];

UIImage *imageTwo = [UIImage imageNamed:@"2"];

[image drawInRect:CGRectMake(0, 300, 200, 200)];

//3.平铺绘制

// [image drawAsPatternInRect:CGRectMake(0, 0, 375, 667)];

}

#pragma mark 水印（图片上添加图片）

- (void)drawImageAtImageContext : (CGContextRef) context{

//开始图片上下文（设置画布大小）

UIGraphicsBeginImageContext(CGSizeMake(375, 667));

//创建图片

UIImage *image = [UIImage imageNamed:@"2"];

//裁剪图片->椭圆

context=UIGraphicsGetCurrentContext();//重新获取上下文

CGContextAddEllipseInRect(context, CGRectMake(0, 0, 375, 375));

CGContextClip(context);//裁剪

[image drawInRect:CGRectMake(0, 0, 375, 375)];

//添加水印

NSString *str = @"Photo by cxy";

[str drawInRect:CGRectMake(375/2.0-50, 667/2-10, 100, 30) withAttributes:@{NSFontAttributeName:[UIFont fontWithName:@"Arial" size:15],NSForegroundColorAttributeName:[UIColor whiteColor]}];

//返回绘制的新图像

UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

//关闭对应的上下文

UIGraphicsEndImageContext();

[newImage drawInRect:CGRectMake(0, 0, 375, 667)];

//保存图片

NSData *data = UIImagePNGRepresentation(newImage) ;

[data writeToFile:@"/Users/dc008/Desktop/photo.png" atomically:YES];

UIGraphicsBeginImageContext(CGSizeMake(375, 667));

UIImage *imageTwo = [UIImage imageNamed:@"1"];

context = UIGraphicsGetCurrentContext();

CGContextAddEllipseInRect(context, CGRectMake(0, 0, 375, 375));

CGContextClip(context);

[imageTwo drawInRect:CGRectMake(0, 0, 375, 667)];

NSString *strTwo = @"Photo by cxy";

[strTwo drawInRect:CGRectMake(375/2.0-50, 667/2-10, 100, 30) withAttributes:@{NSFontAttributeName:[UIFont fontWithName:@"Arial" size:15],NSForegroundColorAttributeName:[UIColor whiteColor]}];