Custom video/camera overlay view on the iPhone

回転:http://blog.blackwhale.at/?p=443
Today I am going to show how we can add a custom overlay view to the standard iPhone video capturing functionlity.First of all I have to say，that since the iPhone OS 3.1 is published，a custom verlay allyempone。
Create a custom view with a transparent background.Add controlls and/or imags to the custom view as you like.Get a new instance of the UImagePicker Controller.Set the source type of the picker to video source.Hide unneccessary controls of the picker.Make the video image full-size(if you wish to).Set your custom overlay and present the picker.To prove that it is really so simple，I workd out an example for you，which adds a small image and a button to the custom overlay and shows this overlay on the marge picker.In my example I didn’adit font font and stration
First of all I subclassied Universal for my own custom Overlay view caled OverlayView.In this custom overlay I simply add a smarge and a button which will sketch the possility of scanning market widewand。

@implementation OverlayView
- (id)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        //clear the background color of the overlay
        self.opaque = NO;
        self.backgroundColor = [UIColor clearColor];
 
        //load an image to show in the overlay
        UIImage *searcher = [UIImage imageNamed:@"searcher.png"];
        UIImageView *searcherView = [[UIImageView alloc]
                            initWithImage:searcher];
        searcherView.frame = CGRectMake(30, 100, 260, 200);
        [self addSubview:searcherView];
        [searcherView release];
 
        //add a simple button to the overview
        //with no functionality at the moment
        UIButton *button = [UIButton
                            buttonWithType:UIButtonTypeRoundedRect];
        [button setTitle:@"Scan Now" forState:UIControlStateNormal];
        button.frame = CGRectMake(0, 430, 320, 40);
        [self addSubview:button];
    }
    return self;
}
...
@end

All I have to do now is to create a UImagePicker Controller instance and customize all specific properties of it to show the overlay video preview.This is very simple and the following could dread.Story.Stand。

//create an overlay view instance
OverlayView *overlay = [[OverlayView alloc]
        initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, SCREEN_HEIGTH)];
 
//create a new image picker instance
UIImagePickerController *picker =
                [[UIImagePickerController alloc] init];
//set source to video!
picker.sourceType = UIImagePickerControllerSourceTypeCamera;
//hide all controls
picker.showsCameraControls = NO;
picker.navigationBarHidden = YES;
picker.toolbarHidden = YES;
//make the video preview full size
picker.wantsFullScreenLayout = YES;
picker.cameraViewTransform =
CGAffineTransformScale(picker.cameraViewTransform,
            CAMERA_TRANSFORM_X,
            CAMERA_TRANSFORM_Y);
//set our custom overlay view
picker.cameraOverlayView = overlay;
 
//show picker
[self presentModalViewController:picker animated:YES];

The only things missing are my defines for the constants I am using、but I don’t wanna keep them away from you：

//transform values for full screen support
#define CAMERA_TRANSFORM_X 1
#define CAMERA_TRANSFORM_Y 1.12412
//iphone screen dimensions
#define SCREEN_WIDTH  320
#define SCREEN_HEIGTH 480

After all we get something like this:
So，that’s pretty all.Of course you have to add much more to get some functionly within your overlay，but this example was just a demontration how eay it is to create your custom video preview.ew.
You will find the source code of this example at my github repository.The project is caled Camera Overlay.
Cheers，Andreas