Creating a custom progress bar with images

问题:

Pretty much what I am trying to do, is create the following image:

So this is a progress bar, which will show how many votes the client get in that option. How can I do that? I was wondering if I can use a mask (as I would in flex), but all the masking implementations that I found on the web are doing masks for UIImages, and not for UIImageView. I cannot do the mask in the UIImage, because the two images have the same dimensions. I have to use the X and Y of the images to crop them?! So, any suggestions?

Here are the two images that I have to create that progress bar:

Cheers.

回答1:

you want to get rid of all of the same bit in the middle of each image. then do something like:

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self addProgressBarInFrame:CGRectMake(20.f, 20.f, 280.f, 50.f) withProgress:.9f];
    [self addProgressBarInFrame:CGRectMake(20.f, 100.f, 200.f, 25.f) withProgress:.1f];
}

-(void)addProgressBarInFrame:(CGRect)frame withProgress:(CGFloat)progress
{
    float widthOfJaggedBit = 4.0f;
    UIImage * imageA= [[UIImage imageNamed:@"imageA"] stretchableImageWithLeftCapWidth:widthOfJaggedBit topCapHeight:0.0f];
    UIImage * imageB= [[UIImage imageNamed:@"imageB"] stretchableImageWithLeftCapWidth:widthOfJaggedBit topCapHeight:0.0f];
    UIView * progressBar = [[UIView alloc] initWithFrame:frame];
    progressBar.backgroundColor = [UIColor whiteColor];
    UIImageView * imageViewA = [[UIImageView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, frame.size.width*progress, frame.size.height)];
    UIImageView * imageViewB = [[UIImageView alloc] initWithFrame:CGRectMake(frame.size.width*progress, 0.f, frame.size.width - (frame.size.width*progress), frame.size.height)];
    imageViewA.image = imageA;
    imageViewB.image = imageB;
   // imageViewA.contentStretch = CGRectMake(widthOfJaggedBit, 0, imageA.size.width - 2*widthOfJaggedBit, imageA.size.height) ;
   // imageViewB.contentStretch = CGRectMake(widthOfJaggedBit, 0, imageB.size.width - 2*widthOfJaggedBit, imageB.size.height) ;
    [self.view addSubview:progressBar];
    [progressBar addSubview:imageViewA];
    [progressBar addSubview:imageViewB];
}

回答2:

Grady Player's answer is great. Just a small note, for anyone that uses this. I tried to update the frames of the two UIImageView's to update the "progress". I tried to force an update with "setNeedsDisplay", but to no avail. (sizeToFit caused problems too).

Anyway, the only way I figured out how to update the progress of an existing progress bar was to call "setFrame:CGRectMake" with my new dimensions.