橡皮擦不工作在iOS绘图

本文介绍了橡皮擦不工作在iOS绘图的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在开发一个绘图项目，其中我有一个橡皮擦选项。下面给出的代码用于当我启动我的应用程序，绘制一些行，并继续使用橡皮擦。它工作正常，我得到橡皮擦效果。现在第二种情况是我绘制了10行，然后点击撤消按钮并撤消整个事情，然后我重做整个事情，现在当我点击橡皮擦按钮，并尝试擦除一些部分，而是清除整个图形。这是我想要弄清楚的，但我不知道我错了什么，所以朋友，请帮助我。

下面是我的代码。 / p>

   - （void）drawRect：（CGRect）rect 
 {
 
 
 case DRAW：
 {
 [m_curImage drawAtPoint：CGPointMake（0，0）]; 
 
 CGPoint mid1 = midPoint（m_previousPoint1，m_previousPoint2）; 
 CGPoint mid2 = midPoint（m_currentPoint，m_previousPoint1）; 
 CGContextRef context = UIGraphicsGetCurrentContext（）; 
 
 
 
 [self.layer renderInContext：context]; 
 CGContextMoveToPoint（context，mid1.x，mid1.y）; 
 CGContextAddQuadCurveToPoint（context，m_previousPoint1.x，m_previousPoint1.y，mid2.x，mid2.y）; 
 CGContextSetLineCap（context，kCGLineCapRound）; 
 CGContextSetLineWidth（context，self.lineWidth）; 
 CGContextSetStrokeColorWithColor（context，self.lineColor.CGColor）; 
 CGContextSetAlpha（context，self.lineAlpha）; 
 CGContextSetAllowsAntialiasing（context，YES）; 
 CGContextStrokePath（context）; 
 // [super drawRect：rect]; 
} 
 break; 
 
 
 
 case ERASE：
 {
 [m_curImage drawAtPoint：CGPointMake（0，0）]; 
 CGContextRef context = UIGraphicsGetCurrentContext（）; 
 CGContextClearRect（context，rect）; 
 CGContextSetBlendMode（context，kCGBlendModeClear）; 
 [super drawRect：rect]; 
 break; 
 
} 
 
 
 case UNDO：
 {
 [m_curImage drawInRect：self.bounds]; 
 break; 
 
} 
 
 case REDO：
 {
 [m_curImage drawInRect：self.bounds]; 
 break; 
} 
 
 
默认值：
 break; 
} 
}

这些是当我点击undo /重做。

   - （void）redrawLine 
 {
 UIGraphicsBeginImageContextWithOptions（self.bounds.size， 0.0f）; 
 [self.layer renderInContext：UIGraphicsGetCurrentContext（）]; 
 NSDictionary * lineInfo = [m_lineArray lastObject]; 
 m_curImage =（UIImage *）[lineInfo valueForKey：@IMAGE]; 
 UIGraphicsEndImageContext（）; 
 [self setNeedsDisplayInRect：self.bounds]; 
} 
 
 
  - （void）undoButtonClicked 
 {
 if（[m_lineArray count]> 0）
 {
 NSMutableArray * line = [m_lineArray lastObject]; 
 [m_bufferArray addObject：line]; 
 [m_lineArray removeLastObject]; 
 [self redrawLine]; 
} 
 m_drawStep = UNDO; 
 
} 
 
  - （void）redoButtonClicked 
 {
 if（[m_bufferArray count]> 0）
 {
 NSMutableArray * line = [m_bufferArray lastObject]; 
 [m_lineArray addObject：line]; 
 [m_bufferArray removeLastObject]; 
 [self redrawLine]; 
} 
 m_drawStep = REDO; 
 
}

请告诉我是否正确。 p>

尊敬的，

Ranjit

解决方案

我已经解决了这个问题，下面的问题和代码工作完美

  case：ERASE 
 {
 CGPoint mid1 = midPoint（m_previousPoint1，m_previousPoint2）; 
 CGPoint mid2 = midPoint（m_currentPoint，m_previousPoint1）; 
 
 [m_curImage drawAtPoint：CGPointMake（0，0）]; 
 CGContextRef context = UIGraphicsGetCurrentContext（）; 
 
 [self.layer renderInContext：context]; 
 CGContextMoveToPoint（context，mid1.x，mid1.y）; 
 CGContextAddQuadCurveToPoint（context，m_previousPoint1.x，m_previousPoint1.y，mid2.x，mid2.y）; 
 CGContextSetLineCap（context，kCGLineCapRound）; 
 
 
 CGContextSetBlendMode（context，kCGBlendModeClear）; 
 CGContextSetLineJoin（context，kCGLineJoinRound）; 
 CGContextSetLineWidth（context，self.lineWidth）; 
 CGContextSetStrokeColorWithColor（context，self.lineColor.CGColor）; 
 CGContextSetShouldAntialias（context，YES）; 
 CGContextSetAllowsAntialiasing（context，YES）; 
 CGContextSetFlatness（context，0.1f）; 
 
 CGContextSetAlpha（context，self.lineAlpha）; 
 CGContextStrokePath（context）; 
}

尊敬
Ranjit。

这解决了我的问题，如果任何人有相同的问题，请实施此。

I am working on a drawing project, where I have an eraser option. The code given below is for when I start my app and draw some lines and the proceed to use the eraser. It works fine and I get the eraser effect. Now the second scenario is where I draw some 10 lines and then click on the "undo button" and undo the whole thing, then I redo the whole thing, and now when I click on the "eraser button" and try to erase some part, but instead, it will clear the whole drawing. This is what I am trying to figure out, but i'm not understanding where I am going wrong so friends, please help me out.

Below is my code.

- (void)drawRect:(CGRect)rect
{


      case DRAW:
    {
        [m_curImage drawAtPoint:CGPointMake(0, 0)];

        CGPoint mid1 = midPoint(m_previousPoint1, m_previousPoint2);
        CGPoint mid2 = midPoint(m_currentPoint, m_previousPoint1);
        CGContextRef context = UIGraphicsGetCurrentContext();



        [self.layer renderInContext:context];
        CGContextMoveToPoint(context, mid1.x, mid1.y);
        CGContextAddQuadCurveToPoint(context, m_previousPoint1.x, m_previousPoint1.y, mid2.x, mid2.y);
        CGContextSetLineCap(context, kCGLineCapRound);
        CGContextSetLineWidth(context, self.lineWidth);
        CGContextSetStrokeColorWithColor(context, self.lineColor.CGColor);
        CGContextSetAlpha(context, self.lineAlpha);
        CGContextSetAllowsAntialiasing(context, YES);
        CGContextStrokePath(context);
       //            [super drawRect:rect];
    }
         break;



        case ERASE:
        {
            [m_curImage drawAtPoint:CGPointMake(0, 0)];
            CGContextRef context = UIGraphicsGetCurrentContext();
            CGContextClearRect(context, rect);
            CGContextSetBlendMode(context, kCGBlendModeClear);
            [super drawRect:rect];
            break;

  }


        case UNDO:
        {
            [m_curImage drawInRect:self.bounds];
             break;

        }

        case REDO:
        {
            [m_curImage drawInRect:self.bounds];
             break;
        }


        default:
            break;
    }
}

These are functions that run when I click on undo/redo.

-(void)redrawLine
{
    UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, 0.0f);
    [self.layer renderInContext:UIGraphicsGetCurrentContext()];
    NSDictionary *lineInfo = [m_lineArray lastObject];
    m_curImage = (UIImage*)[lineInfo valueForKey:@"IMAGE"];
    UIGraphicsEndImageContext();
    [self setNeedsDisplayInRect:self.bounds];
}


-(void)undoButtonClicked
{
    if([m_lineArray count] > 0)
    {
        NSMutableArray *line = [m_lineArray lastObject];
        [m_bufferArray addObject:line];
        [m_lineArray removeLastObject];
        [self redrawLine];
    }
    m_drawStep = UNDO;

}

-(void)redoButtonClicked
{
    if([m_bufferArray count] > 0)
    {
        NSMutableArray *line = [m_bufferArray lastObject];
        [m_lineArray addObject:line];
        [m_bufferArray removeLastObject];
        [self redrawLine];
    }
     m_drawStep = REDO;

}

Please tell me whether I am doing it right.

Regards,

Ranjit

解决方案

I have solved this issue, the problem and below is the code which works perfectly

case :ERASE
{
 CGPoint mid1 = midPoint(m_previousPoint1, m_previousPoint2);
            CGPoint mid2 = midPoint(m_currentPoint, m_previousPoint1);

            [m_curImage drawAtPoint:CGPointMake(0, 0)];
            CGContextRef context = UIGraphicsGetCurrentContext();

            [self.layer renderInContext:context];
            CGContextMoveToPoint(context, mid1.x, mid1.y);
            CGContextAddQuadCurveToPoint(context, m_previousPoint1.x, m_previousPoint1.y, mid2.x, mid2.y);
            CGContextSetLineCap(context, kCGLineCapRound);


            CGContextSetBlendMode(context, kCGBlendModeClear);
            CGContextSetLineJoin(context, kCGLineJoinRound);
            CGContextSetLineWidth(context, self.lineWidth);
            CGContextSetStrokeColorWithColor(context, self.lineColor.CGColor);
            CGContextSetShouldAntialias(context, YES);
            CGContextSetAllowsAntialiasing(context, YES);
            CGContextSetFlatness(context, 0.1f);

            CGContextSetAlpha(context, self.lineAlpha);
            CGContextStrokePath(context);
}

RegardsRanjit.

This solved my issue, if anyone has the same issue, please implement this.

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