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我试图弄清楚如何在 Quartz 2D 中展平或合并许多动态绘制的线，

我在舞台上随着时间的推移绘制随机线，我每次向数组添加新的线坐标并绘制数组（使用我的 drawRect 并使用计时器和 setNeedDisplay 在数组中推送一条新线以实际重绘所有前几行加上新行）

现在的问题：一段时间后它开始变得越来越慢，因为数组变得很长，所以我虽然应该将坐标合并到平面图像或其他东西中并清除数组以保持内存健康，但是我该怎么做做这个？

这是我目前的工作流程：

  • 通话计时器

    [NSTimer scheduledTimerWithTimeInterval:0.1 目标：自我选择器：@selector(drawdrawdraw) userInfo:nil repeats:YES];

  • 在我的“drawdrawdraw”函数中刷新drawRect

    -(void)drawdrawdraw{ [self setNeedsDisplay]; }

  • 我的drawRect

    -(void)drawRect:(CGRect)rect{
    viewContext = UIGraphicsGetCurrentContext();

    int count = [mijnArray_r_x count];

    float r_x = (float)(random() % 768);
    [mijnArray_r_x insertObject:[NSNumber numberWithFloat:r_x] atIndex:count];

    float r_y = (float)(random() % 1004);
    [mijnArray_r_y insertObject:[NSNumber numberWithFloat:r_y] atIndex:count];

    float r_w = (float)(random() % 100);
    [mijnArray_r_w insertObject:[NSNumber numberWithFloat:r_w] atIndex:count];

    float r_a = (float)(random() % 100);
    [mijnArray_r_a insertObject:[NSNumber numberWithFloat:r_a] atIndex:count];


    CGContextSetLineWidth(viewContext, 2.0);
    CGContextSetStrokeColorWithColor(viewContext, [UIColor blackColor].CGColor);
    for (int k = 0; k <= count; k++) {

        float temp_x = [[mijnArray_r_x objectAtIndex: k] floatValue];
        float temp_y = [[mijnArray_r_y objectAtIndex: k] floatValue];
        float temp_w = [[mijnArray_r_w objectAtIndex: k] floatValue];
        float temp_a = [[mijnArray_r_a objectAtIndex: k] floatValue];

        CGPoint pointpointpoint = CGPointMake(temp_x, temp_y);
        CGPoint pointpointpointpoint = CGPointMake(temp_w, temp_a);
        CGContextMoveToPoint(viewContext, pointpointpoint.x, pointpointpoint.y);
        CGContextAddLineToPoint(viewContext, pointpointpoint.x - pointpointpointpoint.x, pointpointpoint.y + pointpointpointpoint.y);
        CGContextStrokePath(viewContext);
    }
} }
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1 回答 1

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您可以UIImage使用UIGraphicsBeginImageContext(). 这样，绘制所需的时间将保持不变，因为在每次迭代中，您只是将缓存的图像绘制为位图和添加的新行。

- (void)drawRect:(CGRect)rect {
  [self.currentImage drawInRect:[self bounds]];
  UIGraphicsBeginImageContext([self bounds].size);
  CGContextRef cgContext = UIGraphicsGetCurrentContext();
  //Draw your lines into the cgContext here...
  self.currentImage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
}

这假定您已声明currentImage类型的属性。UIImage

于 2011-01-14T21:13:44.010 回答