Question

使用CAEmitterLayer，@ 2x（视网膜）图像不像iOS中的其他地方那样具有缩放属性。我得到的结果是@ 2x版本的显示尺寸是非视网膜图像的4倍，而不是按比例缩小。

知道怎么解决这个问题吗？我已经尝试在UIImageView中测试图像疼痛，结果是应该的，所以这似乎是CAEmitterLayer和CAEmitterCell的问题。图像具有正确的@ 2x.png说明符。

以下是我使用的代码：

CAEmitterLayer *fallingCoinEmitter = [CAEmitterLayer layer];
fallingCoinEmitter.emitterPosition = CGPointMake(self.view.bounds.size.width / 2.0, -30);
fallingCoinEmitter.emitterSize = CGSizeMake(self.view.bounds.size.width * 2.0, 0.0);;

    // Spawn points for the flakes are within on the outline of the line
fallingCoinEmitter.emitterMode  = kCAEmitterLayerOutline;
fallingCoinEmitter.emitterShape = kCAEmitterLayerLine;

    // Configure the snowflake emitter cell
CAEmitterCell *coin = [CAEmitterCell emitterCell];
coin.birthRate      = 8.0;
coin.lifetime       = 5.0;
coin.velocity       = -180;             // falling down slowly
coin.velocityRange = 80;
coin.yAcceleration = 40;
coin.emissionRange = 0.4 * M_PI;        // some variation in angle
coin.spinRange      = 0.45 * M_PI;      // slow spin
coin.contents       = (id) [[UIImage imageNamed:@"Coin_Generic_Emitter"] CGImage];
coin.scale          = 1.0;
coin.scaleRange     = 0.0;

    // Make the flakes seem inset in the background
fallingCoinEmitter.shadowOpacity = 1.0;
fallingCoinEmitter.shadowRadius  = 4.0;
fallingCoinEmitter.shadowOffset  = CGSizeMake(0.0, 3.0);
UIColor *darkGreenColor = [UIColor colorWithRed:0.005 green:0.163 blue:0.005 alpha:1.000];
fallingCoinEmitter.shadowColor   = [darkGreenColor CGColor];
[fallingCoinEmitter setContentsScale:[UIScreen mainScreen].scale];
//fallingCoinEmitter.shouldRasterize = YES;
//[fallingCoinEmitter setRasterizationScale:[UIScreen mainScreen].scale];
//fallingCoinEmitter.scale = fallingCoinEmitter.scale / [[UIScreen mainScreen] scale];

    // Add everything to our backing layer below the UIContol defined in the storyboard
fallingCoinEmitter.emitterCells = [NSArray arrayWithObject:coin];
[self.view.layer insertSublayer:fallingCoinEmitter atIndex:0];

谢谢！

更新

@Fabian，设置contentScale不起作用，至少不是我的解决方案

    [fallingCoinEmitter setContentsScale:[UIScreen mainScreen].scale];

我也尝试了这个没有结果..

    emitter.shouldRasterize = YES;
    [emitter setRasterizationScale:[UIScreen mainScreen].scale];

设置比例范围不起作用。 iPad 2和3（w RD）的尺寸之间仍有差异。

Answer 1

您应该尝试修改CAEmmitterCell s scale和scaleRange属性，具体取决于设备的屏幕。

cell.scale = cell.scale / [[UIScreen mainScreen] scale];

CAEmitterLayer：使用带有CAEmitterCell的@ 2x（视网膜）png图像

1 个答案: