从左到右的渐变方向 [英] gradient direction from left to right

问题描述

我对这个问题完全感到困惑，它应该是如此简单，以至于让我发疯.

I am completely stumped on this problem and it should be so simple that its driving me nuts.

我正在使用这个苹果反射教程.

I am working with this apple reflection tutorial.

它们具有从上到下显示的图像渐变.

They have the image gradient that shows up from top to bottom.

• 如何从左到右进行渐变
• 如何水平翻转图像.在他们的示例中，他们垂直翻转图像.

有什么帮助吗?

//The gradient code is here but I don't know what should be the gradient start / end points
CGImageRef CreateGradientImage(int pixelsWide, int pixelsHigh)
{
.....
gradientStartPoint = CGPointZero;
        gradientEndPoint = CGPointMake(0, pixelsHigh);
}

//similarly I know the image flip happens here but for life of me I cannot make it flip horizontally

- (UIImage *)reflectedImage:(UIImageView *)fromImage withHeight:(NSUInteger)height
{
.....
CGContextTranslateCTM(mainViewContentContext, 0.0, height);
        CGContextScaleCTM(mainViewContentContext, 1.0, -1.0);
}

推荐答案

尝试一下:

//horizontal gradient
CGImageRef CreateGradientImage(int pixelsWide, int pixelsHigh)
{
    .....
    gradientStartPoint = CGPointZero;
    gradientEndPoint = CGPointMake(pixelsWide, 0);
}

//horizontal flip

- (UIImage *)reflectedImage:(UIImageView *)fromImage withWidth:(NSUInteger)width
{
    .....
    CGContextTranslateCTM(mainViewContentContext, width, 0,0);
    CGContextScaleCTM(mainViewContentContext, -1.0, 1.0);
}

对于水平翻转，您应该添加一个新方法，因为您必须指定宽度，而不是高度.

For the horizontal flip you should add a new method, since you have to specify the width, no the height.

祝你好运！

为了获得渐变，您应该对ReflectedImage:withWidth添加另一个修改.

In order to get the gradient, you should add another modification to reflectedImage:withWidth.

- (UIImage *)reflectedImage:(UIImageView *)fromImage withWidth:(NSUInteger)width
{
    .....
    CGImageRef gradientMaskImage = CreateGradientImage(width, 1);
    .....
}

这篇关于从左到右的渐变方向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！