how to save drawing ?

[wangsuikang]

Hi,
I want to save drawing ,when I finish drawing. I can open it again.Please tell me how to do it .Look forward to your reply .Thanks!

[acerbetti]

I think the best way is to apply the protocol NSCoding to each tool, so you can serialize the arrays of steps and apply them again in the future

[TripwireNL]

Can you give an example on how to do this, I can't seem to figure out how to save a drawing. I'm using Realm as a database and I want to save the drawing in Realm so I can reload it, but I'm stuck at implementing the NSCoding protocol in the Pen tool.

[acerbetti]

Try to look here to get some idea https://github.com/mro/MROGeometry/blob/master/MROGeometry/NSCoder_MROCGPath.m

[TripwireNL]

Still don't get how to do this. I've added the NSCoding protocol to the AceDrawingPenTool and tried to implement the example you gave. But I don't know when and where to call the encode feature to save it? Can you provide one example on one of the tools how to implement it please?

[acerbetti]

If you have implemented the NSCoding protocol correctly, saving it should be very easy. Here is a tutorial
https://www.raywenderlich.com/1914/nscoding-tutorial-for-ios-how-to-save-your-app-data

[TripwireNL]

Hi acerbetti,

I finally had some time to pick up where I left. I've wrote this code to save the UIBezierPath (As i understand correctly the UIBezierPath adheres to the NSCoding protocol so I didn't add that (just testing to save and load the lines). I've made the pathArray of the AceDrawingView class public so I can access it in my other classes. This is my code as of now but it doesn't work at the moment I see that the data is saved in NSData structure but it's not loading the drawing back.. :

-(NSData *)saveImageAsData {
    NSData *data;
    for (id tool in aceDrawingView.pathArray) {
        if ([tool isKindOfClass:[ACEDrawingPenTool class]]) {
            ACEDrawingPenTool *penTool = (ACEDrawingPenTool *) tool;
            UIBezierPath *path = [UIBezierPath bezierPathWithCGPath:penTool.path];
            data = [NSKeyedArchiver archivedDataWithRootObject:path];
        }
    }
    return data;
}

-(void)loadDrawing:(NSData *) data {
    UIBezierPath *path =  [NSKeyedUnarchiver unarchiveObjectWithData:data];
    CGMutablePathRef cgPath = CGPathCreateMutableCopy(path.CGPath);
    ACEDrawingPenTool *tool = [ACEDrawingPenTool new];
    tool.path = cgPath;
    [aceDrawingView.pathArray addObject:tool];
    [aceDrawingView updateCacheImage:FALSE];
    [aceDrawingView setNeedsDisplay];
}

[JinkProject]

@Tripwire999 That is the same issue I'm having. I am correctly storing and reloading the drawn paths, but when I run the method updateCacheImage:, nothing happens. @acerbetti Could you give some insight on how to achieve this?

[TripwireNL]

@JinkProject
Let's say we use the PenTool, I use the following function to load the data back from the NSData we archived with the NSCoding protocol (DrawPathObject is a Realm object):

+(ACEDrawingPenTool *)createPenTool:(DrawPathObject *)drawing {
    UIBezierPath *path = [NSKeyedUnarchiver unarchiveObjectWithData:drawing.drawPath];
    ACEDrawingPenTool *tool = [ACEDrawingPenTool new];
    tool.lineColor = [UIColor colorWithString:drawing.lineColor];
    tool.lineWidth = drawing.lineWidth;
    tool.lineAlpha = drawing.lineAlpha;
    tool.path = CGPathCreateMutableCopy(path.CGPath);
    return tool;
}

And the returned tool is added to the pathArray. After that I just call:

[aceDrawingView updateCacheImage:YES];
[aceDrawingView setNeedsLayout];

[JinkProject]

@Tripwire999 OK. Cool. Let me try that. Could this not be achieved the same why by just making ACEDrawingPenTool adhere to NSCoding protocol? Why did you use a separate object (DrawPathObject)

[TripwireNL]

@JinkProject It's because i'm using Realm and i'm not only storing the DrawPath stuff but also some other parts in Realm like lineAlpha, lineWidth, tooltype e.t.c.

[JinkProject]

@Tripwire999 How did you encode/decode the path?

[JinkProject]

@Tripwire999 Also, have you made the path variable from the ACEDrawingPenTool object a publicly, readwriteable property? I've done all of these things and I'm still not seeing the drawings on load.

[JinkProject]

@Tripwire999 NVM. Got it working. Looks great. Thanks for the help!

[JinkProject]

@acerbetti @Tripwire999 Would you guys be up for submitting a PR that supports storing drawings? We'd like to use this library as a pod in our projects, but we would obviously want to stay up to date on the latest changes.

[acerbetti]

Happy to accept and review any PR. But I don't have any bandwidth to maintain the lib right now

[JinkProject]

@acerbetti Roger that. I'll submit a PR.

[TripwireNL]

@JinkProject If you need help I'll be willing to lend a hand for saving and loading the drawings. Though I've modified the AceDrawingView code heavily the saving and loading shouldn't be that different than what i've got. Let me know!

[JinkProject]

@Tripwire999 Any help would be appreciated!