如何在永久性画布上绘制并将其绘制在视图中？
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我正在为iOS编写一个小型绘画应用程序。我在UIView广告的drawRect：方法中将其子类化。直到我开始有很多对象（实际上是折线），然后性能开始下降，一切都很好。
- (void)drawRect:(CGRect)rect {
[super drawRect:rect];
CGContextRef imageContext = UIGraphicsGetCurrentContext();
int i, j;
for(i = 0; i < [_strokes count]; i++) {
NSMutableArray *stroke = [_strokes objectAtIndex:i];
if([stroke count] < 2) {
continue;
}
CGContextSetStrokeColorWithColor(imageContext, [[_penColours objectAtIndex:i] CGColor]);
for(j = 0; j < [stroke count]-1; j++) {
CGPoint line[] = {
[[stroke objectAtIndex:j] CGPointValue],
[[stroke objectAtIndex:j+1] CGPointValue]
};
CGContextSetLineWidth(imageContext, _brushSize);
CGContextSetLineCap(imageContext, kCGLineCapRound);
CGContextSetLineJoin(imageContext, kCGLineJoinRound);
CGContextAddLines(imageContext, line, 2);
CGContextStrokePath(imageContext);
}
}
CGContextFlush(imageContext);
}
j = 0
j = [stroke count] - 2
- (void)drawRect:(CGRect)rect {
[super drawRect:rect];
UIGraphicsBeginImageContext(CGSizeMake(1024, 768));
CGContextRef imageContext = UIGraphicsGetCurrentContext();
if(_image != nil) {
CGContextDrawImage(imageContext, CGRectMake(0, 0, 1024, 768), [_image CGImage]);
}
int i, j;
for(i = 0; i < [_strokes count]; i++) {
NSMutableArray *stroke = [_strokes objectAtIndex:i];
if([stroke count] < 2) {
continue;
}
CGContextSetStrokeColorWithColor(imageContext, [[_penColours objectAtIndex:i] CGColor]);
for(j = [stroke count]-2; j < [stroke count]-1; j++) {
CGPoint line[] = {
[[stroke objectAtIndex:j] CGPointValue],
[[stroke objectAtIndex:j+1] CGPointValue]
};
CGContextSetLineWidth(imageContext, _brushSize);
CGContextSetLineCap(imageContext, kCGLineCapRound);
CGContextSetLineJoin(imageContext, kCGLineJoinRound);
CGContextAddLines(imageContext, line, 2);
CGContextStrokePath(imageContext);
}
}
_image = UIGraphicsGetImageFromCurrentImageContext();
[_image retain];
UIGraphicsEndImageContext();
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextDrawImage(context, CGRectMake(0, 0, 1024, 768), [_image CGImage]);
}
没有找到相关结果
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