我有一个应用程序，我在其中对 View 进行一些草绘。

到目前为止，在我安装 ios7 之前一切正常。

我的应用程序使用触摸移动方法来识别移动的变化。但是，当我画一条线时，会调用 touches 方法，但直到我在 ios7 中 touch 结束时，线才会更新。

所以画图有一点点滞后。

它在 ios6 和 ios7 模拟器上工作正常，但是当我在真实的 ios7 设备上测试它时，绘图有延迟算法。

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
if (!isImageSelection) {

            mouseSwiped = NO;
            UITouch *touch = [touches anyObject];

            if ( [touch view] != baseview) {

                lastPoint2 = [touch locationInView:self.viewDrawing2];
            }
        }
    }

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
 if (!isImageSelection) {

          //  NSLog(@"in image selection==%d touch moved   ",isImageSelection );

            mouseSwiped = YES;

            UITouch *touch = [touches anyObject];
            // if (([touch view] != btnInkColor) || ([touch view] != btnPenSize)  || ([touch view] != baseview)) {
            if ( [touch view] != baseview) {

                CGPoint currentPoint = [touch locationInView:self.viewDrawing];



                if(isEraser) {
                    // [[NSUserDefaults standardUserDefaults] floatForKey:@"strokeValue"];
                    UIGraphicsBeginImageContext(self.viewDrawing.frame.size);
                    [imgDrawing.image drawInRect:CGRectMake(0, 0, self.viewDrawing.frame.size.width, self.viewDrawing.frame.size.height)];
                    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
                    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), stroke);
                    //uncommented by prerak
                        CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, 1.0);

                    CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeClear);
                    CGContextBeginPath(UIGraphicsGetCurrentContext());
                    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
                    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
                    CGContextStrokePath(UIGraphicsGetCurrentContext());
                    imgDrawing.image = UIGraphicsGetImageFromCurrentImageContext();
                    UIGraphicsEndImageContext();
                } else {
                    float strokeT= [[NSUserDefaults standardUserDefaults] floatForKey:@"strokeValue"];
                    //   NSLog(@"strokeT=%f",strokeT);
                    UIGraphicsBeginImageContext(self.viewDrawing.frame.size);
                    [imgDrawing.image drawInRect:CGRectMake(0, 0, self.viewDrawing.frame.size.width, self.viewDrawing.frame.size.height)];
                    //   NSLog(@"STROKE %f",stroke);
                    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), strokeT);
                    CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeCopy);
                    float redT=[[NSUserDefaults standardUserDefaults] floatForKey:@"redvalue"];
                    float greenT= [[NSUserDefaults standardUserDefaults] floatForKey:@"greenvalue"];
                    float blueT= [[NSUserDefaults standardUserDefaults] floatForKey:@"bluevalue"];

                    //   NSLog(@"red=%f",redT);
                    //   NSLog(@"green=%f",greenT);
                    //   NSLog(@"blue=%f",blueT);

                    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), redT, greenT, blueT, 1.0);
                    CGContextSetRGBFillColor(UIGraphicsGetCurrentContext(), redT, greenT, blueT, 1.0);

                    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
                    CGContextSetLineJoin(UIGraphicsGetCurrentContext(), kCGLineJoinRound);
                    CGContextBeginPath(UIGraphicsGetCurrentContext());
                    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
                    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
                    CGContextStrokePath(UIGraphicsGetCurrentContext());
                    imgDrawing.image = UIGraphicsGetImageFromCurrentImageContext();
                    UIGraphicsEndImageContext();
                }
                lastPoint = currentPoint;
            }
        }
    }

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
  UITouch *touch = [touches anyObject];


        //if (([touch view] != btnInkColor) || ([touch view] != btnPenSize) || ([touch view] != baseview)) {
        if ( [touch view] != baseview) {

            if (!isImageSelection) {

                if(!mouseSwiped) {
                    if (isEraser) {
                        UIGraphicsBeginImageContext(self.viewDrawing.frame.size);
                        [imgDrawing.image drawInRect:CGRectMake(0, 0, self.viewDrawing.frame.size.width, self.viewDrawing.frame.size.height)];
                        CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
                        CGContextSetLineWidth(UIGraphicsGetCurrentContext(), stroke);
                        // CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, 1.0);
                        CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeClear);
                        CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
                        CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
                        CGContextStrokePath(UIGraphicsGetCurrentContext());
                        CGContextFlush(UIGraphicsGetCurrentContext());
                        imgDrawing.image = UIGraphicsGetImageFromCurrentImageContext();
                        UIGraphicsEndImageContext();
                    } else {
                        UIGraphicsBeginImageContext(self.viewDrawing.frame.size);
                        [imgDrawing.image drawInRect:CGRectMake(0, 0, self.viewDrawing.frame.size.width, self.viewDrawing.frame.size.height)];

                        CGContextSetLineWidth(UIGraphicsGetCurrentContext(), stroke);
                        CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeCopy);

                        CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, 1.0);
                        CGContextSetRGBFillColor(UIGraphicsGetCurrentContext(), red, green, blue, 1.0);

                        CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
                        CGContextSetLineJoin(UIGraphicsGetCurrentContext(), kCGLineJoinRound);
                        CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
                        CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
                        CGContextStrokePath(UIGraphicsGetCurrentContext());
                        CGContextFlush(UIGraphicsGetCurrentContext());
                        imgDrawing.image = UIGraphicsGetImageFromCurrentImageContext();
                        UIGraphicsEndImageContext();
                    }
                }
            }
        }
    }
}

我该如何解决这个问题？

最佳答案

要找到即时解决方案，请替换此行

 mainImage.image = UIGraphicsGetImageFromContext(UIGraphicsGetCurrentContext());

与

[mainImage performSelectorInBackground:@selector(setImage:) withObject:UIGraphicsGetImageFromCurrentImageContext()];

如果您需要一个详尽而准确的解决方案，请尝试将 MoveTo 替换为 CGMutablepath 。 希望这会有所帮助。

关于iphone - 在 ios7 中绘图时滞后，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19108185/