缩放和旋转UITextView后渲染文本

Question

问题

使用手势缩放和旋转UITextView后，文本有时会模糊，因为转换应用于栅格化的位图。

提议的解决方案

手势完成后，我需要将变换返回到身份变换，根据比例调整帧大小，根据比例调整字体大小，然后重新应用旋转变换。

实施尝试

// Store original center before making changes

CGPoint originalCenter = textView.center;

// Restore transform to identity (frame property is invalid while transform is not identity)

[textView setTransform:CGAffineTransformIdentity];


// Attempt 1 - sizeThatFits /////////////////////////////////////////////////////////////////

// Scale font

[textView setFont:[UIFont fontWithName:textView.font.fontName size:textView.font.pointSize*scale]]; // scale refers to the scale of the pinch gesture that just ended

// Set frame to sizeThatFits

CGSize size = [textView sizeThatFits:maxSize]; // maxSize begins with the view frame size and is scaled at the end of each pinch gesture
[textView setFrame:CGRectMake(0, 0, size.width, size.height)];

// Restore Center

[textView setCenter:originalCenter];

// Re-apply rotation

[textView setTransform:CGAffineTransformMakeRotation(rotation)]; // refers to the total rotation from all rotation gestures


// Attempt 2 - manually scale /////////////////////////////////////////////////////////////////

// Scale font

[textView setFont:[UIFont fontWithName:textView.font.fontName size:textView.font.pointSize*scale]];

// Scale frame

[textView setFrame:CGRectMake(0, 0, textView.frame.size.width*scale, textView.frame.size.height*scale)];

// Restore Center

[textView setCenter:originalCenter];

// Re-apply rotation

[textView setTransform:CGAffineTransformMakeRotation(rotation)];

备注

我尝试的所有内容几乎都有效。在某些情况下，特别是在多次手势（复合错误）之后，文本不完全正确，并且会导致之前没有的换行符。