为了防止工程师泄露用户信息，我们有个需求是在列表上面添加水印。我封装了这个视图分享出来。
水印效果图.png
watermarkView.h
#import <UIKit/UIKit.h>
@interface watermarkView : UIImageView
/**
设置水印
@param frame 水印大小
@param markText 水印显示的文字
*/
- (instancetype)initWithFrame:(CGRect)frame WithText:(NSString *)markText;
@end
watermarkView.m
#import "watermarkView.h"
#define HORIZONTAL_SPACE 30//水平间距
#define VERTICAL_SPACE 50//竖直间距
#define CG_TRANSFORM_ROTATION (M_PI_2 / 3)//旋转角度(正旋45度 || 反旋45度)
@implementation watermarkView
- (instancetype)initWithFrame:(CGRect)frame WithText:(NSString *)markText{
if(self = [super initWithFrame:frame]){
UIFont *font = [UIFont systemFontOfSize:14];
UIColor *color = YTHColorAlpha(152, 152, 152, 0.1);
//原始image的宽高
CGFloat viewWidth = frame.size.width;
CGFloat viewHeight = frame.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));
//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);
//文字的属性
NSDictionary *attr = @{
//设置字体大小
NSFontAttributeName: font,
//设置文字颜色
NSForegroundColorAttributeName :color,
};
NSString* mark = markText;
NSMutableAttributedString *attrStr = [[NSMutableAttributedString alloc] initWithString:mark attributes:attr];
//绘制文字的宽高
CGFloat strWidth = attrStr.size.width;
CGFloat strHeight = attrStr.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）调整到原image的中心
CGContextConcatCTM(context, CGAffineTransformMakeTranslation(viewWidth/2, viewHeight/2));
//以绘制原点为中心旋转
CGContextConcatCTM(context, CGAffineTransformMakeRotation(CG_TRANSFORM_ROTATION));
//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 + HORIZONTAL_SPACE) + 1;
int verCount = sqrtLength / (strHeight + VERTICAL_SPACE) + 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++) {
[mark drawInRect:CGRectMake(tempOrignX, tempOrignY, strWidth, strHeight) withAttributes:attr];
if (i % horCount == 0 && i != 0) {
tempOrignX = orignX;
tempOrignY += (strHeight + VERTICAL_SPACE);
}else{
tempOrignX += (strWidth + HORIZONTAL_SPACE);
}
}
//根据上下文制作成图片
UIImage *finalImg = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGContextRestoreGState(context);
self.image = finalImg;
}
return self;
}
-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{
//1.判断自己能否接收事件
if(self.userInteractionEnabled == NO || self.hidden == YES || self.alpha <= 0.01) {
return nil;
}
//2.判断当前点在不在当前View.
if (![self pointInside:point withEvent:event]) {
return nil;
}
//3.从后往前遍历自己的子控件.让子控件重复前两步操作,(把事件传递给,让子控件调用hitTest)
int count = (int)self.subviews.count;
for (int i = count - 1; i >= 0; i--) {
//取出每一个子控件
UIView *chileV = self.subviews[I];
//把当前的点转换成子控件坐标系上的点.
CGPoint childP = [self convertPoint:point toView:chileV];
UIView *fitView = [chileV hitTest:childP withEvent:event];
//判断有没有找到最适合的View
if(fitView){
return fitView;
}
}
//4.没有找到比它自己更适合的View.那么它自己就是最适合的View
return self;
}
//作用:判断当前点在不在它调用View,(谁调用pointInside,这个View就是谁)
//什么时候调用:它是在hitTest方法当中调用的.
//注意:point点必须得要跟它方法调用者在同一个坐标系里面
-(BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event{
NSLog(@"%s",__func__);
return NO;
}
使用方法
//加水印
watermarkView *watermark = [[watermarkView alloc] initWithFrame:CGRectMake(0, 0, KScreenW, KScreenH) WithText:@"测试"];
[self.view addSubview:watermark];
