CoreGraphics中呈現兩個或更多個行具有不同顏色的

Question

我有一個UIView稱爲MyView的

@interface MyView : UIView { UIImage *myPic; 
     NSMutableArray *myDrawing; } 

@end 

和我更新此數組使用觸摸開始，並且在觸摸移動和觸摸通過加入值結束。

-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
// myDrawing = [[NSMutableArray alloc] initWithCapacity:4]; 
    [myDrawing addObject:[[NSMutableArray alloc] initWithCapacity:4]]; 
    CGPoint curPoint = [[touches anyObject] locationInView:self]; 
    [[myDrawing lastObject] addObject:[NSNumber numberWithFloat:curPoint.x]]; 
    [[myDrawing lastObject] addObject:[NSNumber numberWithFloat:curPoint.y]]; 
} 

-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
    CGPoint curPoint = [[touches anyObject] locationInView:self]; 
    [[myDrawing lastObject] addObject:[NSNumber numberWithFloat:curPoint.x]]; 
    [[myDrawing lastObject] addObject:[NSNumber numberWithFloat:curPoint.y]]; 
    [self setNeedsDisplay]; 
} 

-(void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
    CGPoint curPoint = [[touches anyObject] locationInView:self]; 
    [[myDrawing lastObject] addObject:[NSNumber numberWithFloat:curPoint.x]]; 
    [[myDrawing lastObject] addObject:[NSNumber numberWithFloat:curPoint.y]]; 
    [self setNeedsDisplay]; 
} 

然後我使用繪圖RECT方法來更新線路

- (void)drawRect:(CGRect)rect 
{ 
    // Drawing code 


    float newHeight; 
    float newWidth; 

    if (!myDrawing) { 
     myDrawing = [[NSMutableArray alloc] initWithCapacity:0]; 
    } 

    CGContextRef ctx = UIGraphicsGetCurrentContext(); 

    if (myPic != NULL) 
    { 
     float ratio = myPic.size.height/460; 
     if (myPic.size.width/320 > ratio) 
     { 
      ratio = myPic.size.width/320; 
     } 

     newHeight = myPic.size.height/ratio; 
     newWidth = myPic.size.width/ratio; 
     [myPic drawInRect:CGRectMake(0,0,newWidth,newHeight)]; 
    } 

    if ([myDrawing count] > 0) { 
     CGContextSetLineWidth(ctx, 3); 
     NSData *colorData = [[NSUserDefaults standardUserDefaults] objectForKey:@"SwatchColor"]; 
     UIColor *color; 
     if (colorData!=nil) { 
      // If the data object is valid, unarchive the color we've stored in it. 
      color = (UIColor *)[NSKeyedUnarchiver unarchiveObjectWithData:colorData]; 

     } 
     if (color) 
     { 
      CGContextSetStrokeColorWithColor(ctx, color.CGColor); 
     } 
     else 
     { 
      CGContextSetStrokeColorWithColor(ctx,[UIColor blackColor].CGColor); 
     } 

     for (int i = 0 ; i < [myDrawing count] ; i++) { 
      NSArray *thisArray = [myDrawing objectAtIndex:i]; 
      if ([thisArray count] > 2) 
      { 
       float thisX = [[thisArray objectAtIndex:0] floatValue]; 
       float thisY = [[thisArray objectAtIndex:1] floatValue]; 



       CGContextBeginPath(ctx); 
       CGContextMoveToPoint(ctx, thisX, thisY); 

      for (int j = 2; j < [thisArray count] ; j+=2) 
      { 
       thisX = [[thisArray objectAtIndex:j] floatValue]; 
       thisY = [[thisArray objectAtIndex:j+1] floatValue]; 

       CGContextAddLineToPoint(ctx, thisX,thisY); 
       //CGContextAddQuadCurveToPoint(ctx, 150, 10, thisX, thisY); 
       // CGContextAddCurveToPoint(ctx , 0, 50, 300, 250, thisX, thisY); 
      } 
       CGContextStrokePath(ctx); 

      } 
     } 
    } 

} 

我有一個顏色選擇器中我的代碼來改變顏色，我想得出的不同顏色的線，每次通過選擇顏色，但現在，因爲我正在構建線條和渲染它，當我最初選擇紅色並繪製線條，然後選擇藍色並繪製線條，現在舊線條也變成藍色而不是紅色，但是我想要紅色保持紅色，藍色可以幫助任何人？

Answer 1

您總是畫出畫出的線條。清除myDrawing以使其僅存儲需要處理的點，如果需要撤消/優化保存功能，則將已處理的點保留在另一個陣列中。