如何在相机打开avcapturemanager时绘制网格线

Question

我想显示网格线,就像相机打开时出现的那样.我正在使用AVCaptureManager.我应该使用核心图形来绘制网格线吗？这些网格线的大小是多少？

谢谢

Answer 1

您确实可以在相机视图上添加自定义视图作为叠加层,以使用QuartzCore绘制网格.

这就是我在我的应用程序Subvision中做到的方式:

我用来绘制它的代码(注意:我的网格是可调整的,所以它可以是10x10,2x2等):

// -------------------------------------------------------------------------------
// Used for drawing the grids ontop of the view port
// -------------------------------------------------------------------------------
- (void)drawRect:(CGRect)rect
{
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetLineWidth(context, 0.5);
    CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor);

    // ---------------------------
    // Drawing column lines
    // ---------------------------

    // calculate column width
    CGFloat columnWidth = self.frame.size.width / (self.numberOfColumns + 1.0);

    for(int i = 1; i <= self.numberOfColumns; i++)
    {
        CGPoint startPoint;
        CGPoint endPoint;

        startPoint.x = columnWidth * i;
        startPoint.y = 0.0f;

        endPoint.x = startPoint.x;
        endPoint.y = self.frame.size.height;

        CGContextMoveToPoint(context, startPoint.x, startPoint.y);
        CGContextAddLineToPoint(context, endPoint.x, endPoint.y);
        CGContextStrokePath(context);
    }

    // ---------------------------
    // Drawing row lines
    // ---------------------------

    // calclulate row height
    CGFloat rowHeight = self.frame.size.height / (self.numberOfRows + 1.0);

    for(int j = 1; j <= self.numberOfRows; j++)
    {
        CGPoint startPoint;
        CGPoint endPoint;

        startPoint.x = 0.0f;
        startPoint.y = rowHeight * j;

        endPoint.x = self.frame.size.width;
        endPoint.y = startPoint.y;

        CGContextMoveToPoint(context, startPoint.x, startPoint.y);
        CGContextAddLineToPoint(context, endPoint.x, endPoint.y);
        CGContextStrokePath(context);
    }
}

在我的GridView类中,我定义了2个属性numberOfRows和numberOfColumns:

#import <UIKit/UIKit.h>

@interface GridView : UIView

@property (nonatomic, assign) int numberOfColumns;
@property (nonatomic, assign) int numberOfRows;

@end

这样做意味着我可以修改这两个值并具有无限可调的网格细分.