C4 save screen as C4Image

Question

I tried adapting Travis' example he gave me last week here (C4 saving part of an image) to save the screen as a C4Image. I thought it should work like this:

CGFloat scale = 5.0;

//begin an image context
CGSize  rect=CGSizeMake(self.canvas.width, self.canvas.height);
UIGraphicsBeginImageContextWithOptions(rect, NO, scale);

//create a new context ref
CGContextRef c = UIGraphicsGetCurrentContext();

//render the original image into the context
[self.canvas renderInContext:c];

//grab a UIImage from the context
UIImage *newUIImage = UIGraphicsGetImageFromCurrentImageContext();

//end the image context
UIGraphicsEndImageContext();

//create a new C4Image
self.currentAlphabetImage = [C4Image imageWithUIImage:newUIImage];

C4Log(@"self.currentAlphabetImage:%@", self.currentAlphabetImage);
self.currentAlphabetImage.width=self.canvas.width/2;
self.currentAlphabetImage.center=self.canvas.center;
self.currentAlphabetImage.backgroundColor=navBarColor;
[self.canvas addImage:self.currentAlphabetImage];

...even though the Log gives me

self.currentAlphabetImage:C4Image: 0x15840970; baseClass = UIControl; 
frame = (0 0; 320 568); layer = C4Layer: 0x15842590>>

...nothing is displayed on screen... But yes, there was stuff on the canvas that should have been captured...

And again, I don't know whats wrong. Also other attempts using objectiveC don't work out (e.g., iOS Screenshot part of the screen)

Your code works for me... Two qs, just to be clear: 1) Is this code running in your `C4WorkSpace.m`? 2) If not, are there things on the canvas in which this is running? — C4 - Travis, Oct 29 '13 at 17:33
no it's not running in the main canvas and 2 yes there are things on canvas in the space where it's running. I'll try again tomorrow morning — suMi, Oct 29 '13 at 18:18
Ok, so a subclassed C4CanvasController. I'll test this before tomorrow morning. — C4 - Travis, Oct 29 '13 at 18:37

score 0 · Answer 1 · edited Jun 20 '20 at 09:12

What I found out is it needs a bit of a workaround. The code as shown above works fine in C4Workspace but when trying to save a subview into an image one

needs to run the save function in the main view
sends a notification to the main view to run this function
the notification cannot be sent from the setup of that view.

So the code for me now looks like this C4Workspace.h

#import "C4CanvasController.h"
#import "testView.h"

@interface C4WorkSpace : C4CanvasController{
    testView *test;
}
@end

C4Workspace.m

import "C4Workspace.h"

@implementation C4WorkSpace

-(void)setup {
    test= [testView new];
    test.canvas.frame=CGRectMake(0, 0, self.canvas.width, self.canvas.height);
    [test setup];
    [self.canvas addSubview:test.canvas];

    [self listenFor:@"save" andRunMethod:@"save"];

}
-(void)save{
    CGFloat scale = 5.0;
    
    //begin an image context
    CGSize  rect=CGSizeMake(self.canvas.width, self.canvas.height);
    UIGraphicsBeginImageContextWithOptions(rect, NO, scale);
    
    //create a new context ref
    CGContextRef c = UIGraphicsGetCurrentContext();
    
    //render the original image into the context
    [test.canvas renderInContext:c];
    
    //grab a UIImage from the context
    UIImage *newUIImage = UIGraphicsGetImageFromCurrentImageContext();
    
    //end the image context
    UIGraphicsEndImageContext();
    
    //create a new C4Image
    test.currentAlphabetImage = [C4Image imageWithUIImage:newUIImage];
    
    C4Log(@"self.currentAlphabetImage:%@", test.currentAlphabetImage);
    test.currentAlphabetImage.width=test.canvas.width/2;
    test.currentAlphabetImage.center=test.canvas.center;
    [test.canvas addImage:test.currentAlphabetImage];
}
@end

testView.h

#import "C4CanvasController.h"

@interface testView : C4CanvasController{
    C4Shape *shape;
}
@property (readwrite, strong) C4Image *currentAlphabetImage;
@end

testView.m

#import "testView.h"

@implementation testView

-(void)setup{

    shape=[C4Shape rect:CGRectMake(0, 0, self.canvas.width, self.canvas.height)];
    shape.lineWidth=3;
    shape.fillColor=[UIColor colorWithRed:0.5 green:1 blue:0.2 alpha:1];
    [self.canvas addShape:shape];
    [self listenFor:@"touchesBegan" andRunMethod:@"saveFunc"];
    
}
-(void)saveFunc{
    [self postNotification:@"save"];
    C4Log(@"saving");
}

@end

C4 save screen as C4Image

1 Answers1

import "C4Workspace.h"