LEWatermark.h文件
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
NS_ASSUME_NONNULL_BEGIN
@interface LEWatermark : NSObject
/**
添加字符串水印到图片,水印大小根据图片大小等比设置
@param originalImage 需要添加水印的图片
@param text 水印字符串
@param scale 水印的大小比例,默认1
@return 添加了水印的图片
*/
+ (UIImage *)watermardImageWithImage:(UIImage *)originalImage text:(NSString *)text watermardScale:(CGFloat)scale;
/**
添加属性文本水印到图片
@param originalImage 需要添加水印的图片
@param title 水印属性文本
@param horizontalSpace 水印水平间隔
@param verticalSpace 水印竖直间隔
@param angle 水印旋转弧度
@return 添加了水印的图片
*/
+ (UIImage *)watermardImageWithImage:(UIImage *)originalImage watermark:(NSAttributedString *)title horizontalSpace:(CGFloat)horizontalSpace verticalSpace:(CGFloat)verticalSpace angle:(CGFloat)angle;
@end
NS_ASSUME_NONNULL_END
LEWatermark.m文件
#import "LEWatermark.h"
@implementation LEWatermark
// 水印按比例图片大小的比例设置
+ (UIImage *)watermardImageWithImage:(UIImage *)originalImage text:(NSString *)text watermardScale:(CGFloat)scale {
CGFloat viewWidth = originalImage.size.width;
CGFloat viewHeight = originalImage.size.height;
CGFloat min = MIN(viewWidth, viewHeight);
CGFloat inScale = min / 1242 * scale;
CGFloat horizzontalSpace = 200.0 * inScale;
CGFloat verticalSpace = 150.0 * inScale;
CGFloat angle = (M_PI_2/ -2);
CGFloat fontSize = MAX(10, (70 * inScale));
NSShadow *shadow = [[NSShadow alloc] init];
[shadow setShadowOffset:CGSizeMake(5 * inScale, 8 * inScale)];
shadow.shadowColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:0.6];
//文字的属性
NSDictionary *attr = @{
// 设置字体大小
NSFontAttributeName : [UIFont systemFontOfSize:fontSize],
// 设置文字颜色
NSForegroundColorAttributeName : [UIColor colorWithRed:1 green:1 blue:1 alpha:0.2],
// 设置阴影
NSShadowAttributeName : shadow
};
NSMutableAttributedString *attrStr = [[NSMutableAttributedString alloc] initWithString:text attributes:attr];
UIImage *image = [LEWatermark watermardImageWithImage:originalImage watermark:attrStr horizontalSpace:horizzontalSpace verticalSpace:verticalSpace angle:angle];
return image;
}
// 基础方法
+ (UIImage *)watermardImageWithImage:(UIImage *)originalImage watermark:(NSAttributedString *)title horizontalSpace:(CGFloat)horizontalSpace verticalSpace:(CGFloat)verticalSpace angle:(CGFloat)angle {
if (!originalImage) {
return originalImage;
}
if (!title || title.length == 0) {
return originalImage;
}
//原始image的宽高
CGFloat viewWidth = originalImage.size.width;
CGFloat viewHeight = originalImage.size.height;
//为了防止图片失真，绘制区域宽高和原始图片宽高一样
UIGraphicsBeginImageContext(CGSizeMake(viewWidth, viewHeight));
//先将原始image绘制上
[originalImage drawInRect:CGRectMake(0, 0, viewWidth, viewHeight)];
//sqrtLength：原始image的对角线length。在水印旋转矩阵中只要矩阵的宽高是原始image的对角线长度，无论旋转多少度都不会有空白。
CGFloat sqrtLength = sqrt(viewWidth*viewWidth + viewHeight*viewHeight);
//绘制文字的宽高
CGFloat strWidth = title.size.width;
CGFloat strHeight = title.size.height;
//开始旋转上下文矩阵，绘制水印文字
CGContextRef context = UIGraphicsGetCurrentContext();
//将绘制原点（0，0）调整到源image的中心
CGContextConcatCTM(context, CGAffineTransformMakeTranslation(viewWidth/2, viewHeight/2));
//以绘制原点为中心旋转
CGContextConcatCTM(context, CGAffineTransformMakeRotation(angle));
//将绘制原点恢复初始值，保证当前context中心和源image的中心处在一个点(当前context已经旋转，所以绘制出的任何layer都是倾斜的)
CGContextConcatCTM(context, CGAffineTransformMakeTranslation(-viewWidth/2, -viewHeight/2));
//计算需要绘制的列数和行数
int horCount = sqrtLength / (strWidth + horizontalSpace) + 1;
int verCount = sqrtLength / (strHeight + verticalSpace) + 1;
//此处计算出需要绘制水印文字的起始点，由于水印区域要大于图片区域所以起点在原有基础上移
CGFloat orignX = -(sqrtLength-viewWidth)/2;
CGFloat orignY = -(sqrtLength-viewHeight)/2;
//在每列绘制时X坐标叠加
CGFloat tempOrignX = orignX;
//在每行绘制时Y坐标叠加
CGFloat tempOrignY = orignY;
for (int i = 0; i < horCount * verCount; i++) {
[title drawInRect:CGRectMake(tempOrignX, tempOrignY, strWidth, strHeight)];
if (i % horCount == 0 && i != 0) {
tempOrignX = orignX;
tempOrignY += (strHeight + verticalSpace);
}else{
tempOrignX += (strWidth + horizontalSpace);
}
}
//根据上下文制作成图片
UIImage *finalImg = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGContextRestoreGState(context);
return finalImg;
}
@end
