Eraser tool with background color

[JohnWickham]

If the background color is anything but clear, the eraser tool draws like a normal pen tool

[ghost]

+1

[prrane]

well, that is how it's implemented! Eraser in real world is nothing but a magical pen which gives back you White Paper to scratch more! Here, Eraser and a White Colored Pen are abstractions used to understand layman in a proper Domain Terms; I hope this clears the confusion.

[0xPr0xy]

To be able to set the background color to white, and still use the eraser tool change the following pieces of code:

In ACEDrawingTools.m

- (void)draw
{
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSaveGState(context);
    CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor);
    CGContextAddPath(context, path);
    CGContextSetLineCap(context, kCGLineCapRound);
    CGContextSetLineWidth(context, self.lineWidth);

    // disable blend mode and set stroke color to white since we do not want a transparent bg
    // https://github.com/acerbetti/ACEDrawingView/issues/8
    // CGContextSetBlendMode(context, kCGBlendModeClear);

    CGContextStrokePath(context);
    CGContextRestoreGState(context);
}

In ACEDrawingView.m

- (void)configure
{
    // init the private arrays
    self.pathArray = [NSMutableArray array];
    self.bufferArray = [NSMutableArray array];

    // set the default values for the public properties
    self.lineColor = kDefaultLineColor;
    self.lineWidth = kDefaultLineWidth;
    self.lineAlpha = kDefaultLineAlpha;

    // set the transparent background
    // set to white instead... 
    // https://github.com/acerbetti/ACEDrawingView/issues/8

    self.backgroundColor = [UIColor whiteColor];

    self.originalFrameYPos = self.frame.origin.y;
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidShow:) name:UIKeyboardDidShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidHide:) name:UIKeyboardDidHideNotification object:nil];
}

- (void)updateCacheImage:(BOOL)redraw
{
    // init a context
    UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, 0.0);

    // draw white rectangle to use as background as workaround for
    // https://github.com/acerbetti/ACEDrawingView/issues/8

    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetRGBFillColor(context, 1.0, 1.0, 1.0, 1.0);
    CGContextFillRect(context, self.bounds);

    if (redraw) {
        // erase the previous image
        self.image = nil;

        // load previous image (if returning to screen)
        [[self.prev_image copy] drawInRect:self.bounds];

        // I need to redraw all the lines
        for (id<ACEDrawingTool> tool in self.pathArray) {
            [tool draw];
        }
    } else {
        // set the draw point
        [self.image drawAtPoint:CGPointZero];
        [self.currentTool draw];
    }
    // store the image
    self.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
}

[xiao99xiao]

@0xPr0xy 's code wouldn't solve it when the drawingView load a UIImage as background, Just to make it clear.

[Alisha786]

In My project i can change the background color when i am drawing,any body resolve this issue?? please explain