渐变方向从左到右

Question

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

I am working with this apple reflection tutorial.

Apple Reflection Example

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

• How can I make a gradient from left to right
• how can I flip the image horizontally. In their example they flip the image vertically.

any help?

//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);
}

Answer 1

Try this:

//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);
}

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

Good Luck!

EDIT 1:

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);
    .....
}