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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