改善drawRect的性能: [英] Improve performance of drawRect:

问题描述

我每隔0.1秒从一个带有NSTimer的网格中绘制一个单元.大小约为96x64 => 6144个单元/图像.如果我要绘制图像而不是(例如)绿色矩形，则速度要慢4倍！

I am drawing cells from a grid with a NSTimer every 0.1 Seconds. The size is about 96x64 => 6144 cells / images. If i am drawing images instead of (e.g.) green rectangles it is 4 times slower !

- (void)drawRect:(CGRect)rect
{
    CGContextRef context = UIGraphicsGetCurrentContext();
    UIGraphicsPushContext(context);
    CGContextSetRGBFillColor(context, 0, 0, 0, 1);
    CGContextFillRect(context, CGRectMake(0, 0, self.bounds.size.width, self.bounds.size.height));
    int cellSize = self.bounds.size.width / WIDTH;
    double xOffset = 0;
    for (int i = 0; i < WIDTH;i++)
    {
        for (int j = 0; j < HEIGHT;j++)
        {                
                NSNumber *currentCell = [self.state.board objectAtIndex:(i*HEIGHT)+j];
                if (currentCell.intValue == 1)
                {
                   [image1 drawAtPoint:CGPointMake(xOffset + (cellSize * i),cellSize * j )];
                }
                else if (currentCell.intValue == 0){
                   [image2 drawAtPoint:CGPointMake(xOffset + (cellSize * i),cellSize * j )];
                }
        }
    }
    UIGraphicsPopContext();
}

如果我想在每个矩形中绘制png或jpg，有什么主意如何使它更快?图像已经按比例缩放到合适的大小.

Any idea how to makes this faster if i want to draw png or jpg in each rectangle? The images are already scaled to an appropriate size.

推荐答案

• a)不要重绘视图范围之外的图像/矩形.

  • a) Don't redraw the images/rects that are outside the view's bounds.

    b)不要重新绘制dirtyRect外部的图像/矩形

    b) Don't redraw the images/rects that are outside the dirtyRect

    c)不要重绘自以前的更新.

    c) Don't redraw the images/rects that haven't changes since the previous update.

    d)使用图层预渲染图像，因此您无需渲染他们在绘图时.

    d) Use a layer to prerender the images, so you don't need to render them at drawing time.

    这篇关于改善drawRect的性能:的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！