C4保存屏幕为C4Image

Question

我尝试过改编Travis＆＃39;他上周在这里给我（C4 saving part of an image）将屏幕保存为C4Image。 我认为它应该像这样工作：

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];

......即使Log给了我

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

......屏幕上没有显示任何内容......但是，画布上的内容本应该被捕获......

而且，我不知道什么是错的。使用objectiveC的其他尝试也没有解决（例如，iOS Screenshot part of the screen）

Answer 1

我发现它需要一些解决方法。如上所示的代码在C4Workspace中工作正常，但在尝试将子视图保存为图像时

1. 需要在主视图中运行保存功能
2. 向主视图发送通知以运行此功能
3. 无法从该视图的设置发送通知。

所以我的代码现在看起来像这样 的 C4Workspace.h

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

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

<强> C4Workspace.m

导入“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

<强> testView.h

#import "C4CanvasController.h"

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

<强> 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