iPhone目标C:UIImage-感兴趣区域
有没有办法获得包含UIImage所有不透明部分的最小矩形区域 逐像素读取以检查alpha==0的位置…我认为这不是一个好方法 还有更好的办法吗iPhone目标C:UIImage-感兴趣区域,iphone,uiimage,transparent,roi,Iphone,Uiimage,Transparent,Roi,有没有办法获得包含UIImage所有不透明部分的最小矩形区域 逐像素读取以检查alpha==0的位置…我认为这不是一个好方法 还有更好的办法吗 非常感谢您阅读我认为如果不逐像素检查图像,就没有办法做到这一点。这些图像来自哪里?如果你控制它们,你至少可以只做一次逐像素部分,然后缓存信息,或者在人们下载图像时将其与图像一起分发。如果不逐像素检查图像,我认为没有办法做到这一点。这些图像来自哪里?如果你控制它们,你至少可以只做一次逐像素部分,然后缓存信息,或者在人们下载图像时将其与图像一起分发。好的,这
非常感谢您阅读我认为如果不逐像素检查图像,就没有办法做到这一点。这些图像来自哪里?如果你控制它们,你至少可以只做一次逐像素部分,然后缓存信息,或者在人们下载图像时将其与图像一起分发。如果不逐像素检查图像,我认为没有办法做到这一点。这些图像来自哪里?如果你控制它们,你至少可以只做一次逐像素部分,然后缓存信息,或者在人们下载图像时将其与图像一起分发。好的,这是我解决这个问题的丑陋方法。我希望有更好的方法来做到这一点
- (CGRect) getROIRect:(UIImage*)pImage {
CGRect roiRect = {{0,0}, {0,0}};
int vMaxX = -999;
int vMinX = 999;
int vMaxY = -999;
int vMinY = 999;
int x,y;
CGImageRef inImage = pImage.CGImage;
// Create off screen bitmap context to draw the image into. Format ARGB is 4 bytes for each pixel: Alpa, Red, Green, Blue
CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];
if (cgctx == NULL) { return roiRect; /* error */ }
size_t w = CGImageGetWidth(inImage);
size_t h = CGImageGetHeight(inImage);
CGRect rect = {{0,0},{w,h}};
// Draw the image to the bitmap context. Once we draw, the memory
// allocated for the context for rendering will then contain the
// raw image data in the specified color space.
CGContextDrawImage(cgctx, rect, inImage);
// Now we can get a pointer to the image data associated with the bitmap
// context.
unsigned char* data ;
BOOL tSet = NO;
data= CGBitmapContextGetData (cgctx);
if (data != NULL) {
for (x=0;x<w;x++) {
for (y=0;y<h;y++) {
//offset locates the pixel in the data from x,y.
//4 for 4 bytes of data per pixel, w is width of one row of data.
int offset = 4*((w*round(y))+round(x));
int alpha = data[offset];
if (alpha > 0) {
tSet = YES;
if (x > vMaxX) {
vMaxX = x;
}
if (x < vMinX) {
vMinX = x;
}
if (y > vMaxY) {
vMaxY = y;
}
if (y < vMinY) {
vMinY = y;
}
}
}
}
}
if (!tSet) {
vMaxX = w;
vMinX = 0;
vMaxY = h;
vMinY = 0;
}
// When finished, release the context
CGContextRelease(cgctx);
// Free image data memory for the context
if (data) { free(data); }
CGRect roiRect2 = {{vMinX,vMinY},{vMaxX - vMinX,vMaxY - vMinY}};
return roiRect2;
}
- (CGContextRef) createARGBBitmapContextFromImage:(CGImageRef) inImage {
CGContextRef context = NULL;
CGColorSpaceRef colorSpace;
void * bitmapData;
int bitmapByteCount;
int bitmapBytesPerRow;
// Get image width, height. We'll use the entire image.
size_t pixelsWide = CGImageGetWidth(inImage);
size_t pixelsHigh = CGImageGetHeight(inImage);
// Declare the number of bytes per row. Each pixel in the bitmap in this
// example is represented by 4 bytes; 8 bits each of red, green, blue, and
// alpha.
bitmapBytesPerRow = (pixelsWide * 4);
bitmapByteCount = (bitmapBytesPerRow * pixelsHigh);
// Use the generic RGB color space.
//colorSpace = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
colorSpace = CGColorSpaceCreateDeviceRGB();
if (colorSpace == NULL)
{
fprintf(stderr, "Error allocating color space\n");
return NULL;
}
// Allocate memory for image data. This is the destination in memory
// where any drawing to the bitmap context will be rendered.
bitmapData = malloc( bitmapByteCount );
if (bitmapData == NULL)
{
fprintf (stderr, "Memory not allocated!");
CGColorSpaceRelease( colorSpace );
return NULL;
}
// Create the bitmap context. We want pre-multiplied ARGB, 8-bits
// per component. Regardless of what the source image format is
// (CMYK, Grayscale, and so on) it will be converted over to the format
// specified here by CGBitmapContextCreate.
context = CGBitmapContextCreate (bitmapData, pixelsWide, pixelsHigh, 8, bitmapBytesPerRow, colorSpace, kCGImageAlphaPremultipliedFirst);
if (context == NULL)
{
free (bitmapData);
fprintf (stderr, "Context not created!");
}
// Make sure and release colorspace before returning
CGColorSpaceRelease( colorSpace );
return context;
}
-(CGRect)getROIRect:(UIImage*)pImage{
CGRect roiRect={0,0},{0,0};
int vMaxX=-999;
int-vMinX=999;
int-vMaxY=-999;
int-vMinY=999;
int x,y;
CGImageRef inImage=pImage.CGImage;
//创建屏幕外位图上下文以绘制图像。格式ARGB为每个像素4个字节:Alpa、红色、绿色、蓝色
CGContextRef cgctx=[self-createARGBBitmapContextFromImage:inImage];
如果(cgctx==NULL){return roiRect;/*error*/}
尺寸w=CGImageGetWidth(InImages);
大小\u t h=CGImageGetHeight(InImages);
CGRect rect={{0,0},{w,h};
//将图像绘制到位图上下文。一旦绘制,内存
//然后,为渲染上下文分配的将包含
//指定颜色空间中的原始图像数据。
CGContextDrawImage(cgctx、rect、inImage);
//现在我们可以得到一个指向与位图关联的图像数据的指针
//上下文。
无符号字符*数据;
BOOL-tSet=否;
数据=CGBitmapContextGetData(cgctx);
如果(数据!=NULL){
对于(x=0;x vMaxX){
vMaxX=x;
}
if(xvMaxY){
vMaxY=y;
}
if(y
好的,这是我对这个问题的丑陋解决方案。我希望有更好的方法来做到这一点
- (CGRect) getROIRect:(UIImage*)pImage {
CGRect roiRect = {{0,0}, {0,0}};
int vMaxX = -999;
int vMinX = 999;
int vMaxY = -999;
int vMinY = 999;
int x,y;
CGImageRef inImage = pImage.CGImage;
// Create off screen bitmap context to draw the image into. Format ARGB is 4 bytes for each pixel: Alpa, Red, Green, Blue
CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];
if (cgctx == NULL) { return roiRect; /* error */ }
size_t w = CGImageGetWidth(inImage);
size_t h = CGImageGetHeight(inImage);
CGRect rect = {{0,0},{w,h}};
// Draw the image to the bitmap context. Once we draw, the memory
// allocated for the context for rendering will then contain the
// raw image data in the specified color space.
CGContextDrawImage(cgctx, rect, inImage);
// Now we can get a pointer to the image data associated with the bitmap
// context.
unsigned char* data ;
BOOL tSet = NO;
data= CGBitmapContextGetData (cgctx);
if (data != NULL) {
for (x=0;x<w;x++) {
for (y=0;y<h;y++) {
//offset locates the pixel in the data from x,y.
//4 for 4 bytes of data per pixel, w is width of one row of data.
int offset = 4*((w*round(y))+round(x));
int alpha = data[offset];
if (alpha > 0) {
tSet = YES;
if (x > vMaxX) {
vMaxX = x;
}
if (x < vMinX) {
vMinX = x;
}
if (y > vMaxY) {
vMaxY = y;
}
if (y < vMinY) {
vMinY = y;
}
}
}
}
}
if (!tSet) {
vMaxX = w;
vMinX = 0;
vMaxY = h;
vMinY = 0;
}
// When finished, release the context
CGContextRelease(cgctx);
// Free image data memory for the context
if (data) { free(data); }
CGRect roiRect2 = {{vMinX,vMinY},{vMaxX - vMinX,vMaxY - vMinY}};
return roiRect2;
}
- (CGContextRef) createARGBBitmapContextFromImage:(CGImageRef) inImage {
CGContextRef context = NULL;
CGColorSpaceRef colorSpace;
void * bitmapData;
int bitmapByteCount;
int bitmapBytesPerRow;
// Get image width, height. We'll use the entire image.
size_t pixelsWide = CGImageGetWidth(inImage);
size_t pixelsHigh = CGImageGetHeight(inImage);
// Declare the number of bytes per row. Each pixel in the bitmap in this
// example is represented by 4 bytes; 8 bits each of red, green, blue, and
// alpha.
bitmapBytesPerRow = (pixelsWide * 4);
bitmapByteCount = (bitmapBytesPerRow * pixelsHigh);
// Use the generic RGB color space.
//colorSpace = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
colorSpace = CGColorSpaceCreateDeviceRGB();
if (colorSpace == NULL)
{
fprintf(stderr, "Error allocating color space\n");
return NULL;
}
// Allocate memory for image data. This is the destination in memory
// where any drawing to the bitmap context will be rendered.
bitmapData = malloc( bitmapByteCount );
if (bitmapData == NULL)
{
fprintf (stderr, "Memory not allocated!");
CGColorSpaceRelease( colorSpace );
return NULL;
}
// Create the bitmap context. We want pre-multiplied ARGB, 8-bits
// per component. Regardless of what the source image format is
// (CMYK, Grayscale, and so on) it will be converted over to the format
// specified here by CGBitmapContextCreate.
context = CGBitmapContextCreate (bitmapData, pixelsWide, pixelsHigh, 8, bitmapBytesPerRow, colorSpace, kCGImageAlphaPremultipliedFirst);
if (context == NULL)
{
free (bitmapData);
fprintf (stderr, "Context not created!");
}
// Make sure and release colorspace before returning
CGColorSpaceRelease( colorSpace );
return context;
}
-(CGRect)getROIRect:(UIImage*)pImage{
CGRect roiRect={0,0},{0,0};
int vMaxX=-999;
int-vMinX=999;
int-vMaxY=-999;
int-vMinY=999;
int x,y;
CGImageRef inImage=pImage.CGImage;
//创建屏幕外位图上下文以绘制图像。格式ARGB为每个像素4个字节:Alpa、红色、绿色、蓝色
CGContextRef cgctx=[self-createARGBBitmapContextFromImage:inImage];
如果(cgctx==NULL){return roiRect;/*error*/}
尺寸w=CGImageGetWidth(InImages);
大小\u t h=CGImageGetHeight(InImages);
CGRect rect={{0,0},{w,h};
//将图像绘制到位图上下文。一旦绘制,内存
//然后,为渲染上下文分配的将包含
//指定颜色空间中的原始图像数据。
CGContextDrawImage(cgctx、rect、inImage);
//现在我们可以得到一个指向与位图关联的图像数据的指针
//上下文。
无符号字符*数据;
BOOL-tSet=否;
数据=CGBitmapContextGetData(cgctx);
如果(数据!=NULL){
对于(x=0;x vMaxX){
vMaxX=x;
}
if(xvMaxY){
vMaxY=y;
}
if(y