iphone - 如何在 GLPaint 示例代码中创建自己的 recordedPath

Question

我最近下载了 GLPaint 示例代码并查看了其中非常有趣的部分。有一个 recordedPaths NSMutableArray，其中包含点，然后由 GLPaint 读取和绘制。

这里声明:

NSMutableArray *recordedPaths;
recordedPaths = [NSMutableArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"Recording" ofType:@"data"]];
if([recordedPaths count])
     [self performSelector:@selector(playback:) withObject:recordedPaths afterDelay:0.2];

这是播放代码:

 - (void) playback:(NSMutableArray*)recordedPaths {

     NSData*                    data = [recordedPaths objectAtIndex:0];

     CGPoint*               point = (CGPoint*)[data bytes];

     NSUInteger               count = [data length] / sizeof(CGPoint),

                              i;



     //Render the current path

     for(i = 0; i < count - 1; ++i, ++point)

          [self renderLineFromPoint:*point toPoint:*(point + 1)];



     //Render the next path after a short delay 

     [recordedPaths removeObjectAtIndex:0];

     if([recordedPaths count])

          [self performSelector:@selector(playback:) withObject:recordedPaths afterDelay:0.01];

}

由此我了解到 recordedPaths 是一个可变数组，他在其中构造了 CGPoint 的 c 数组，然后读取和呈现这些数组。我想放入自己的数组，但一直遇到麻烦。

我尝试将 recordedPaths 声明更改为:

      NSMutableArray *myArray = [[NSMutableArray alloc] init];

      CGPoint* points;

      CGPoint a = CGPointMake(50,50);

      int i;

      for (i=0; i<100; i++,points++) {

           a = CGPointMake(i,i);

           points = &a;

      }

      NSData *data = [NSData dataWithBytes:&points length:sizeof(*points)];

      [myArray addObject:data];

虽然这没有用...有什么建议吗？

Answer 1

如果您查看 Recording.data，您会注意到每一行都是它自己的数组。要捕获墨水并播放它，您需要有一个数组数组。出于本演示的目的 - 声明一个可变数组 - writRay

    @synthesize writRay;
//init in code
 writRay = [[NSMutableArray alloc]init];

捕捉墨迹

// Handles the continuation of a touch.
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{  

 CGRect    bounds = [self bounds];
 UITouch*   touch = [[event touchesForView:self] anyObject];

 // Convert touch point from UIView referential to OpenGL one (upside-down flip)
 if (firstTouch) {
  firstTouch = NO;
  previousLocation = [touch previousLocationInView:self];
  previousLocation.y = bounds.size.height - previousLocation.y;
  /******************* create a new array for this stroke's points **************/
  [writRay addObject:[[NSMutableArray alloc]init]];
  /***** add 1st point *********/
  [[writRay objectAtIndex:[writRay count] -1]addObject:[NSValue valueWithCGPoint:previousLocation]];
 } else {
  location = [touch locationInView:self];
     location.y = bounds.size.height - location.y;
  previousLocation = [touch previousLocationInView:self];
  previousLocation.y = bounds.size.height - previousLocation.y;
  /********* add additional points *********/
  [[writRay objectAtIndex:[writRay count] -1]addObject:[NSValue valueWithCGPoint:previousLocation]];
 }

 // Render the stroke
 [self renderLineFromPoint:previousLocation toPoint:location];

}

回放墨迹。

- (void)playRay{

 if(writRay != NULL){

  for(int l = 0; l < [writRay count]; l++){
    //replays my writRay -1 because of location point
   for(int p = 0; p < [[writRay objectAtIndex:l]count] -1; p ++){
    [self renderLineFromPoint:[[[writRay objectAtIndex:l]objectAtIndex:p]CGPointValue] toPoint:[[[writRay objectAtIndex:l]objectAtIndex:p + 1]CGPointValue]];
   }
  }
 }
}

为了获得最佳效果，摇动屏幕以清除并从 AppController 中的 changeBrushColor 调用 playRay。