标签: uiimage

我试图捕捉我的UIView的图像,但当我称这种方法

- (UIImage *) imageWithView:(UIView *)view
{
    UIGraphicsBeginImageContext(view.bounds.size);
    [view.layer renderInContext:UIGraphicsGetCurrentContext()];

    UIImage * img = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return img;
}

我的应用程序在我的视图的DrawRect方法中输入并停留在这些行的循环中

[super drawRect:rect];
[curImage drawAtPoint:CGPointMake(0, 0)];
mid1 = midPoint(previousPoint1, previousPoint2);
mid2 = midPoint(currentPoint, previousPoint1);

context = UIGraphicsGetCurrentContext();

[self.layer renderInContext:context];

这是我的drawRect方法

- (void)drawRect:(CGRect)rect
{

    [super drawRect:rect];
    [curImage drawAtPoint:CGPointMake(0, 0)];
    mid1 = midPoint(previousPoint1, previousPoint2);
    mid2 = midPoint(currentPoint, previousPoint1);

    context = UIGraphicsGetCurrentContext();

    [self.layer renderInContext:context];

    CGContextMoveToPoint(context, mid1.x, mid1.y);
    CGContextAddQuadCurveToPoint(context, previousPoint1.x, previousPoint1.y, mid2.x, mid2.y);

    CGContextSetLineCap(context, kCGLineCapRound);
    CGContextSetLineWidth(context, self.lineWidth);
    CGContextSetStrokeColorWithColor(context, self.lineColor.CGColor);

    CGContextStrokePath(context);
}

我将照片相册中的图像存储在我的应用文档目录中作为NSData,而不是在UITableView中显示它们.我的表现有问题.将图像保存到app目录需要花费几秒钟的时间,并且在将它们加载到TableView时遇到同样的问题.这是我存储图像的代码:

//Convert UIImage to NSData
NSData *imageData = [NSData dataWithData:UIImagePNGRepresentation(image)];

//Save image to app documents directory
NSError *error;
[imageData writeToFile:fullImagePath options:NSDataWritingAtomic error:&error];

这就是我将它们加载到UITableView中的方法:

NSData *imageData = [NSData dataWithContentsOfFile:path];
UIImage *myImage = [UIImage imageWithData:imageData];

cell.imageView.image = myImage;

什么可能导致这些性能问题？是否有任何其他方式来存储和检索应用程序文档目录中的图像？

从以下源文件,我尝试加载图像并保存到Core数据,并在imageView中显示,但它不起作用你可以帮我修复它.

- (IBAction)save:(id)sender
{
    NSLog(@"Telling the AddTrackingTVC Delegate that save was tapped on the     AddTrackingTVC");

    [self.delegate theSaveButtonOnTheAddPlantNoteTVCWasTapped:self];

    MyPlant *myTracking = [NSEntityDescription insertNewObjectForEntityForName:@"MyPlant" inManagedObjectContext:self.managedObjectContext];

    myTracking.name = nameTextField.text;
    myTracking.detail = detailTextField.text;
    myTracking.createdDate = [NSDate date];
    //myTracking.photo = [NSData ];
    [self.managedObjectContext save:nil]; // write data to database
    [self.delegate theSaveButtonOnTheAddPlantNoteTVCWasTapped:self];
}




- (IBAction)takePicture:(id)sender {
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
    // If our device has a camera, we want to take a picture, otherwise, we // just pick from photo library
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) …

我试着创建一个框架和颜色的UIImage,但不知道正确的方法.

UIImage *aImage = [UIImage imageWithCIImage:[CIImage imageWithColor:[CIColor colorWithCGColor:[UIColor redColor].CGColor]]];

以上行是否正确？如何创建图像大小？请帮忙!

问题:缩小图像的裁剪很好.使用放大的图像进行裁剪会将图像显示在应该是的上方.我在那里的yOffset是因为我想要的裁剪方块从scrollview所在的下方开始.

码:

CGRect rect;
float yOffset = 84;
rect.origin.x = floorf([scrollView contentOffset].x * zoomScale);
rect.origin.y = floorf(([scrollView contentOffset].y + yOffset) * zoomScale);
rect.size.width = floorf([scrollView bounds].size.width * zoomScale);
rect.size.height = floorf((320 * zoomScale));

if (rect.size.width > 320) {
    rect.size.width = 320;
}

if (rect.size.height > 320) {
    rect.size.height = 320;
}

CGImageRef cr = CGImageCreateWithImageInRect([[imageView image] CGImage], rect);

UIImage *img = imageView.image; //[UIImage imageWithCGImage:cr];

UIGraphicsBeginImageContext(rect.size);

// translated rectangle for drawing sub image
CGRect drawRect = CGRectMake(-rect.origin.x, -rect.origin.y, 320.0f, 320.0f);
NSLog(@"drawRect: …

我正在尝试为我的UIToolBar添加一个自定义按钮(形状和颜色),但它的结果与它应该有很大不同.

什么按钮看起来像:

酒吧里的样子:

这是我用来添加它的代码:

    UIImage *backButtonImage = [UIImage imageNamed:@"back-button.png"];
    UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithImage:backButtonImage style:UIBarButtonItemStylePlain target:self action:@selector(backButtonTapped)];
    [toolBarItems addObject:backButton];

我到底错在了什么？

我有一个UICollectionView,里面有一些图像.在第一次向下滚动时加载图像非常慢且不稳定.之后,当图像加载时,它很好.

我想问题是图像不会被加载,直到单元格到达屏幕导致滞后.我假设我需要做的是在图像出现在屏幕上之前加载图像.我不知道该怎么做,显然是在寻找错误的东西,因为我找不到任何答案.请有人指出我正确的方向吗？

这是加载图像的代码......图像在我的应用程序中没有下载或任何东西.

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    static NSString *CellIdentifier = @"Cell";
    CustomCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath];
    [[cell myImage]setImage:[UIImage imageNamed:[arrayOfImages objectAtIndex:indexPath.item]]];

    return cell;
}

谢谢!

我没有从远程服务器找到图像时加载默认图像:

   detailImageView.image = [UIImage imageNamed:@"noimageavailable.jpg"];

第二种选择:

detailImageView.image = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"noimageavailable" ofType:@"jpg"]];

我注意到在加载了另一个可从服务器获得的图像后,noimageavailable.jpg仍然出现在新图像后面,这意味着noimageavailable.jpg以某种方式缓存.我用两个选项imageNamed:和imageWithContentsOfFileAPI 得到了相同的结果.

这是我完成的代码:

        if (detailImageURL.length == 0) {
            detailImageView.image = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"noimageavailable" ofType:@"jpg"]];
//Once displayed, it's cached for all lifecycle


        }else{

        dispatch_async(DownloadQueue, ^{

            NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:detailImageURL]];
                dispatch_async(dispatch_get_main_queue(), ^{

                    detailImageView.image = nil;
                    UIImage *image = [UIImage imageWithData:imageData];
                    detailImageView.image = image;
                });
    });
    }

有什么方法可以清除缓存？

如何根据图像的高度对NSMutableArray图像进行排序？我是否需要找到每个图像的高度并按顺序添加它,还是有更简单的方法？

我想将CCSprite转换为UIImage.我写了一个简单的测试项目.但是,我发现它不起作用.尽管图像尺寸合适,但UIImage无法在屏幕上显示.你能告诉我原因吗？

测试项目的URL如下:https://github.com/HelloVicent/ConverCCSpriteTOUIImage

非常感谢.