假设我有一个点数组,这些点形成一条线和一个文本。我怎样才能沿着这条线绘制文本
- (void)drawRect:(CGRect)rect
一个 UIView?
我可以毫无问题地绘制路径。是否有我忽略的标准方法或允许我沿着该路径绘制文本的框架?理想情况下,我想只使用 QuartzCore/CoreGraphics 来做到这一点。
我尝试计算每个字符的宽度并旋转每个字符。这种方法可行,但我想知道是否有更优雅的方法。
最佳答案
我相信您可以在 Mac OS X 中执行此操作,但在 iPhone 上最接近的是 CGContextShowGlyphsWithAdvances,它甚至不会旋转。
使用循环并使用类似以下内容绘制每个字符应该不会太难。这是改编自 Apple 的文档且未经测试,因此请注意:
CGContextSelectFont(myContext, "Helvetica", 12, kCGEncodingMacRoman);
CGContextSetCharacterSpacing(myContext, 10);
CGContextSetTextDrawingMode(myContext, kCGTextFillStroke);
CGContextSetRGBFillColor(myContext, 0, 0, 0, 1);
CGContextSetRGBStrokeColor(myContext, 0, 0, 0, 1);
NSUInteger charIndex = 0;
for(NSString *myChar in arrayOfChars) {
char *cString = [myChar UTF8String];
CGPoint charOrigin = originForPositionAlongPath(charIndex, myPath);
CGFloat slope = slopeForPositionAlongPath(charIndex, myPath);
CGContextSetTextMatrix(myContext, CGAffineTransformMakeRotation(slope));
CGContextShowTextAtPoint(myContext, charOrigin.x, charOrigin.y, cString, 1);
}
编辑:这是 PositionAlongPath 函数的概念。同样,它们没有经过测试,但应该接近。 originAlong...如果您用完路径,则返回 (-1, -1)。
CGPoint originForPositionAlongPath(int index, NSArray *path) {
CGFloat charWidth = 12.0;
CGFloat widthToGo = charWidth * index;
NSInteger i = 0;
CGPoint position = [path objectAtIndex:i];
while(widthToGo >= 0) {
//out of path, return invalid point
if(i >= [path count]) {
return CGPointMake(-1, -1);
}
CGPoint next = [path objectAtIndex:i+1];
CGFloat xDiff = next.x - position.x;
CGFloat yDiff = next.y - position.y;
CGFloat distToNext = sqrt(xDiff*xDiff + yDiff*yDiff);
CGFloat fracToGo = widthToGo/distToNext
//point is before next point in path, interpolate the answer
if(fracToGo < 1) {
return CGPointMake(position.x+(xDiff*fracToGo), position.y+(yDiff*fracToGo));
}
//advance to next point on the path
widthToGo -= distToNext;
position = next;
++i;
}
}
CGFloat slopeForPositionAlongPath(int index, NSArray *path) {
CGPoint begin = originForPositionAlongPath(index, path);
CGPoint end = originForPositionAlongPath(index+1, path);
CGFloat xDiff = end.x - begin.x;
CGFloat yDiff = end.y - begin.y;
return atan(yDiff/xDiff);
}
关于objective-c - 在 QuartzCore 中沿路径绘制文本,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/2067166/