当摄像头打开时，如何绘制网格线avcapturemanager [英] how to draw grid lines when camera is open avcapturemanager

问题描述

我想显示网格线，就像打开相机时出现的那样。我使用的是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？

感谢

解决方案

确实可以将自定义视图添加为相机视图上的叠加层使用QuartzCore绘制网格。

这就是我在我的应用程序Subvision中做的：

我用它来绘制它的代码（ 请注意：我的网格可调，因此它可以是10x10，2x2等）：

  //  - -------------------------------------------------- ---------------------------- 
 //用于绘制视图端口上的网格
 // -------------------------------------------------- ----------------------------- 
  - （void）drawRect：（CGRect）rect 
 {
 CGContextRef context = UIGraphicsGe tCurrentContext（）; 
 CGContextSetLineWidth（context，0.5）; 
 CGContextSetStrokeColorWithColor（context，[UIColor whiteColor] .CGColor）; 
 
 // --------------------------- 
 //绘制列线
 // --------------------------- 
 
 //计算列宽
 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）; 
} 
 
 // --------------------------- 
 //绘图行行
 // --------------------------- 
 
 //计算行高
 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）; 
 
 
 
 
 $ b $ p 
 $ b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拥有无限可调的网格细分。
 
I want to display grid line like the one which appears when a camera is open.I am using AVCaptureManager.Should i use core graphics to draw grid lines?what is the size of those grid lines?

thanks
解决方案
You can indeed add a custom view as an overlay over your camera view to draw the grid using QuartzCore.

That is how I did it in my app Subvision:



The code I use to draw it (note: my grid is adjustable so it's can be 10x10, 2x2 etc):
// -------------------------------------------------------------------------------
// 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);
    }
}
In my GridView class, I have defined 2 properties numberOfRows and numberOfColumns:
#import <UIKit/UIKit.h>

@interface GridView : UIView

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

@end
Doing so means I can modify these two values and have infinitely adjustable grid subdivisions.

                        
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