UIImage图片处理（更改颜色，修改透明度，缩小，合并图片）
(2013-10-29 11:34:53)
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//遍历图片像素，更改图片颜色
void ProviderReleaseData (void *info, constvoid *data, size_t size)
{
free((void*)data);
}
- (UIImage*) p_w_picpathBlackToTransparent:(UIImage*) p_w_picpath
{
// 分配内存
constint p_w_picpathWidth = p_w_picpath.size.width;
constint p_w_picpathHeight = p_w_picpath.size.height;
size_t bytesPerRow = p_w_picpathWidth * 4;
uint32_t* rgbImageBuf = (uint32_t*)malloc(bytesPerRow * p_w_picpathHeight);
// 创建context
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(rgbImageBuf, p_w_picpathWidth, p_w_picpathHeight, 8, bytesPerRow, colorSpace,
kCGBitmapByteOrder32Little |kCGImageAlphaNoneSkipLast);
CGContextDrawImage(context, CGRectMake(0, 0, p_w_picpathWidth, p_w_picpathHeight), p_w_picpath.CGImage);
// 遍历像素
int pixelNum = p_w_picpathWidth * p_w_picpathHeight;
uint32_t* pCurPtr = rgbImageBuf;
for (int i = 0; i < pixelNum; i++, pCurPtr++)
{
if ((*pCurPtr & 0xFFFFFF00) == 0xffffff00) //将白色变成透明
{
uint8_t* ptr = (uint8_t*)pCurPtr;
ptr[0] = 0;
}
else
{
// 改成下面的代码，会将图片转成想要的颜色
uint8_t* ptr = (uint8_t*)pCurPtr;
ptr[3] = 0; //0~255
ptr[2] = 0;
ptr[1] = 0;
}
}
// 将内存转成p_w_picpath
CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * p_w_picpathHeight, ProviderReleaseData);
CGImageRef p_w_picpathRef = CGImageCreate(p_w_picpathWidth, p_w_picpathHeight, 8, 32, bytesPerRow, colorSpace,
kCGImageAlphaLast | kCGBitmapByteOrder32Little, dataProvider,
NULL, true, kCGRenderingIntentDefault);
CGDataProviderRelease(dataProvider);
UIImage* resultUIImage = [UIImagep_w_picpathWithCGImage:p_w_picpathRef];
// 释放
CGImageRelease(p_w_picpathRef);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
// free(rgbImageBuf) 创建dataProvider时已提供释放函数，这里不用free
return resultUIImage;
}
//设置图片透明度
- (UIImage *)p_w_picpathByApplyingAlpha:(CGFloat)alpha p_w_picpath:(UIImage*)p_w_picpath
{
UIGraphicsBeginImageContextWithOptions(p_w_picpath.size,NO,0.0f);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGRect area = CGRectMake(0, 0, p_w_picpath.size.width, p_w_picpath.size.height);
CGContextScaleCTM(ctx,1, -1);
CGContextTranslateCTM(ctx,0, -area.size.height);
CGContextSetBlendMode(ctx, kCGBlendModeMultiply);
CGContextSetAlpha(ctx, alpha);
CGContextDrawImage(ctx, area, p_w_picpath.CGImage);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
//合并2张图片
- (UIImage *)addImage:(UIImage *)p_w_picpath1 toImage:(UIImage *)p_w_picpath2 {
UIGraphicsBeginImageContext(p_w_picpath2.size);
// Draw p_w_picpath1
[p_w_picpath1 drawInRect:CGRectMake(0, 0, p_w_picpath1.size.width, p_w_picpath1.size.height)];
// Draw p_w_picpath2
[p_w_picpath2 drawInRect:CGRectMake(0, 0, p_w_picpath2.size.width, p_w_picpath2.size.height)];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resultingImage;
}
//将UIImage缩放到指定大小尺寸：
- (UIImage *)scaleToSize:(UIImage *)img size:(CGSize)size{
// 创建一个bitmap的context
// 并把它设置成为当前正在使用的context
UIGraphicsBeginImageContext(size);
// 绘制改变大小的图片
[img drawInRect:CGRectMake(0,0, size.width, size.height)];
// 从当前context中创建一个改变大小后的图片
UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();
// 使当前的context出堆栈
UIGraphicsEndImageContext();
// 返回新的改变大小后的图片
return scaledImage;
}
//根据图片的大小等比例压缩返回图片
-(UIImage *)fitSmallImage:(UIImage *)p_w_picpath size:(CGSize)size
{
if (nil == p_w_picpath)
{
returnnil;
}
if (p_w_picpath.size.width<<span class="s5">200 && p_w_picpath.size.height<<span class="s5">200)
{
return p_w_picpath;
}
UIGraphicsBeginImageContext(size);
CGRect rect = CGRectMake(0, 0, size.width, size.height);
[p_w_picpath drawInRect:rect];
UIImage *newing = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newing;
}