iOS修改图片颜色的方法
发表于 - 3 分钟 | --1. 图片染色
将图片染成想要的颜色，适合带有透明度的png图片。
以下为UIImage的类扩展：
.h文件：
#import <UIKit/UIKit.h>
NS_ASSUME_NONNULL_BEGIN
@interface UIImage (ChangeColor)
-(UIImage*)imageWithColor:(UIColor*)color;
- (UIImage *)originalImageWithColor:(UIColor *)color;
@end
NS_ASSUME_NONNULL_END
.m文件：
#import "UIImage+ChangeColor.h"
@implementation UIImage (ChangeColor)
//绘图
-(UIImage*)imageWithColor:(UIColor*)color
{
//获取画布
UIGraphicsBeginImageContextWithOptions(self.size, NO, 0.0f);
//画笔沾取颜色
[color setFill];
CGRect bounds = CGRectMake(0, 0, self.size.width, self.size.height);
UIRectFill(bounds);
//绘制一次
[self drawInRect:bounds blendMode:kCGBlendModeOverlay alpha:1.0f];
//再绘制一次
[self drawInRect:bounds blendMode:kCGBlendModeDestinationIn alpha:1.0f];
//获取图片
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
- (UIImage *)originalImageWithColor:(UIColor *)color {
UIImage *img = [self imageWithColor:color];
img = [img imageWithRenderingMode:(UIImageRenderingModeAlwaysOriginal)];
return img;
}
@end
当对作为tabbar的图标做染色时发现图片被显示成系统默认的蓝色了，此时可以调用以下方法对图片做进一层封装，调用时使用以下方法即可：
- (UIImage *)originalImageWithColor:(UIColor *)color {
UIImage *img = [self imageWithColor:color];
img = [img imageWithRenderingMode:(UIImageRenderingModeAlwaysOriginal)];
return img;
}
使用方式：
UIImage *image= [UIImage imageNamed:@"tab_home_selected"];
image = [image imageWithColor:[UIColor redColor]];
参考文章：iOS改变图片的颜色
2. 更改图片中的特定颜色
有时候如果要根据主题或者主色调对图片进行更改时，可调用以下方法，将一定范围内的颜色更改成指定的颜色。
以下为UIImage的类扩展：
.h文件：
#import <UIKit/UIKit.h>
NS_ASSUME_NONNULL_BEGIN
@interface UIImage (Rander)
- (UIImage *)translatePixelColorByTargetNearBlackColor:(UIColor *)nearBlackColor nearWhiteColor:(UIColor *)nearWhiteColor transColor:(UIColor *)transColor;
- (UIImage *)translatePixelColorByTargetNearBlackColorHex:(UInt32)nearBlackRGB nearWhiteColorHex:(UInt32)nearWhiteRGB transColorHex:(UInt32)transRGB;
- (UIImage *)translatePixelColorByTargetNearBlackColorRGBA:(UInt32)nearBlackRGBA nearWhiteColorRGBA:(UInt32)nearWhiteRGBA transColorRGBA:(UInt32)transRGBA inRect:(CGRect)rect;
@end
NS_ASSUME_NONNULL_END
.m文件
#import "UIImage+Rander.h"
#import "UIColor+RGB.h"
@implementation UIImage (Rander)
- (UIImage *)translatePixelColorByTargetNearBlackColor:(UIColor *)nearBlackColor
nearWhiteColor:(UIColor *)nearWhiteColor
transColor:(UIColor *)transColor {
CGRect rect = CGRectMake(0, 0, self.size.width, self.size.height);
return [self translatePixelColorByTargetNearBlackColor:nearBlackColor nearWhiteColor:nearWhiteColor transColor:transColor inRect:rect];
}
- (UIImage *)translatePixelColorByTargetNearBlackColor:(UIColor *)nearBlackColor
nearWhiteColor:(UIColor *)nearWhiteColor
transColor:(UIColor *)transColor
inRect:(CGRect)rect {
// UIColor 转 RGBA
UInt32 nearBlackRGBA = nearBlackColor.RGBA;
UInt32 nearWhiteRGBA = nearWhiteColor.RGBA;
UInt32 transRGBA = transColor.RGBA;
return [self translatePixelColorByTargetNearBlackColorRGBA:nearBlackRGBA nearWhiteColorRGBA:nearWhiteRGBA transColorRGBA:transRGBA inRect:rect];
}
- (UIImage *)translatePixelColorByTargetNearBlackColorHex:(UInt32)nearBlackRGB
nearWhiteColorHex:(UInt32)nearWhiteRGB
transColorHex:(UInt32)transRGB {
CGRect rect = CGRectMake(0, 0, self.size.width, self.size.height);
return [self translatePixelColorByTargetNearBlackColorHex:nearBlackRGB nearWhiteColorHex:nearWhiteRGB transColorHex:transRGB inRect:rect];
}
- (UIImage *)translatePixelColorByTargetNearBlackColorHex:(UInt32)nearBlackRGB
nearWhiteColorHex:(UInt32)nearWhiteRGB
transColorHex:(UInt32)transRGB
inRect:(CGRect)rect {
// RGB 转 RGBA
UInt32 nearBlackRGBA = (nearBlackRGB << 8) + 0xFF;
UInt32 nearWhiteRGBA = (nearWhiteRGB << 8) + 0xFF;
UInt32 transRGBA = (transRGB << 8) + 0xFF;
return [self translatePixelColorByTargetNearBlackColorRGBA:nearBlackRGBA nearWhiteColorRGBA:nearWhiteRGBA transColorRGBA:transRGBA inRect:rect];
}
/**
解释一下前两个参数的含义：
想象一个数轴，最左边是黑色（RGBX：0x000000FF），最右边是白色（0xFFFFFFFF），
nearBlackColor是靠近左边边界的色值，nearWhiteColor是靠近右边边界的色值，
它们中间则是需要被修改的色值范围
*/
- (UIImage *)translatePixelColorByTargetNearBlackColorRGBA:(UInt32)nearBlackRGBA
nearWhiteColorRGBA:(UInt32)nearWhiteRGBA
transColorRGBA:(UInt32)transRGBA
inRect:(CGRect)rect {
// 第一步：判断传入的rect是否在图片的bounds内
CGRect canvas = CGRectMake(0, 0, self.size.width, self.size.height);
if (!CGRectContainsRect(canvas, rect)) {
if (CGRectIntersectsRect(canvas, rect)) {
rect = CGRectIntersection(canvas, rect); // 取交集
} else {
return self;
}
}
UIImage *transImage = nil;
int imageWidth = self.size.width;
int imageHeight = self.size.height;
// 第二步：创建色彩空间、画布上下文，并将图片以bitmap（不含alpha通道）的方式画在画布上。
size_t bytesPerRow = imageWidth * 4;
uint32_t *rgbImageBuf = (uint32_t *)malloc(bytesPerRow * imageHeight);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(rgbImageBuf, imageWidth, imageHeight, 8, bytesPerRow, colorSpace,
kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast);
CGContextDrawImage(context, CGRectMake(0, 0, imageWidth, imageHeight), self.CGImage);
// 第三步：遍历并修改像素
uint32_t *pCurPtr = rgbImageBuf;
pCurPtr += (long)(rect.origin.y*imageWidth); // 将指针移动到初始行的起始位置
// 空间复杂度：O(rect.size.width * rect.size.height)
for (int i = rect.origin.y; i < CGRectGetMaxY(rect); i++) { // row
pCurPtr += (long)rect.origin.x; // 将指针移动到当前行的起始列
for (int j = rect.origin.x; j < CGRectGetMaxX(rect); j++, pCurPtr++) { // column
if (*pCurPtr < nearBlackRGBA || *pCurPtr > nearWhiteRGBA) { continue; }
// 将图片转成想要的颜色
uint8_t *ptr = (uint8_t *)pCurPtr;
ptr[3] = (transRGBA >> 24) & 0xFF; // R
ptr[2] = (transRGBA >> 16) & 0xFF; // G
ptr[1] = (transRGBA >> 8) & 0xFF; // B
}
pCurPtr += (long)(imageWidth - CGRectGetMaxX(rect)); // 将指针移动到下一行的起始列
}
// 第四步：输出图片
CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * imageHeight, providerReleaseDataCallback);
CGImageRef imageRef = CGImageCreate(imageWidth, imageHeight, 8, 32, bytesPerRow, colorSpace,
kCGImageAlphaLast | kCGBitmapByteOrder32Little, dataProvider,
NULL, true, kCGRenderingIntentDefault);
CGDataProviderRelease(dataProvider);
transImage = [UIImage imageWithCGImage:imageRef];
// end：清理空间
CGImageRelease(imageRef);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
return transImage ? : self;
}
void providerReleaseDataCallback (void *info, const void *data, size_t size) {
free((void*)data);
}
@end
该方法调用了UIColor的类扩展，以下是扩展内容
.h文件
#import <UIKit/UIKit.h>
NS_ASSUME_NONNULL_BEGIN
@interface UIColor (RGB)
- (UInt32)RGBA;
@end
NS_ASSUME_NONNULL_END
.m文件
#import "UIColor+RGB.h"
@implementation UIColor (RGB)
- (UInt32)RGBA {
CGFloat red = 0;
CGFloat green = 0;
CGFloat blue = 0;
CGFloat alpha = 0;
BOOL succ = [self getRed:&red green:&green blue:&blue alpha:&alpha];
UInt32 r = round(red*255);
UInt32 g = round(green*255);
UInt32 b = round(blue*255);
UInt32 a = round(alpha*255);
r = (r << 24);
g = (g << 16);
b = (b << 8);
UInt32 rgba = r + g + b + a;
return succ ? rgba : 0x00000000;
}
@end
参考文章：iOS修改图片颜色（修改像素色值）
Michael Lynx
三反昼夜