C4捕获相机图像示例

Question

嘿，

刚开始接触 C4，到目前为止我的经验非常好。 我现在正在复制使用相机示例拍照的过程，由于某种原因，当我按照教程 (http://www.c4ios.com/tutorials/takingSnapshots) 中的描述执行所有操作时，出现以下错误： “'TakePhoto' 没有可见的@interface 声明选择器'listenFor:from Object:'”（Take Photo 是我正在处理的文件） 我想我必须在类定义中声明“imageWasCaptured”，但我不知道是什么？ 有什么建议吗？

更新：这里是代码 https://github.com/susemiessner/Urban-Alphabets/tree/master/urbanAlphabets 或者只是简单地复制 TakePhoto.h

#import "C4CanvasController.h"

@interface TakePhoto : C4CanvasController

@end

TakePhoto.m

    #import "TakePhoto.h"
    #define NavBarHeight 42
    #define TopBarFromTop 20

    @interface TakePhoto ()

    @end

    @implementation TakePhoto {
        //common variables
        UIColor *navBarColor;
        UIColor *buttonColor;
        UIColor *typeColor;

        //top toolbar
        C4Shape *topNavBar;
        C4Font *fatFont;
        C4Label *takePhoto;



        //camera
        C4Camera *cam;

        //bottom Toolbar
        C4Shape *bottomNavBar;
        C4Button *takePhotoButton;
    }
    -(void) setup{
        navBarColor=[UIColor colorWithRed:0.96875 green:0.96875 blue:0.96875 alpha:1];
        buttonColor= [UIColor colorWithRed:0.8984275 green:0.8984275 blue:0.8984275 alpha:1];
        typeColor=[UIColor colorWithRed:0.19921875 green:0.19921875 blue:0.19921875 alpha:1];

        [self topBarSetup];
        [self bottomBarSetup];
        [self cameraSetup];

    }
    -(void)topBarSetup{
        topNavBar=[C4Shape rect:CGRectMake(0, TopBarFromTop, self.canvas.width, NavBarHeight)];
        topNavBar.fillColor=navBarColor;
        topNavBar.lineWidth=0;
        [self.canvas addShape:topNavBar];


        fatFont=[C4Font fontWithName:@"HelveticaNeue-Bold" size:17];
        takePhoto = [C4Label labelWithText:@"Take Photo" font:fatFont];
        takePhoto.center=topNavBar.center;
        [self.canvas addLabel:takePhoto];}

    -(void)cameraSetup{
        cam = [C4Camera cameraWithFrame:CGRectMake(0,TopBarFromTop+NavBarHeight, self.canvas.width, self.canvas.height-(2*NavBarHeight+TopBarFromTop))];
        [self.canvas addCamera:cam];
        [cam initCapture];
        //tapping to take image
        [self addGesture:TAP name:@"capture" action:@"capturedImage"];
        [self numberOfTouchesRequired:1 forGesture:@"capture"];
//the following line is where I get the error
        [self listenFor:@"imageWasCaptured" fromObject:@"putCapturedImageOnCanvas"];
    }
    -(void) bottomBarSetup{
        bottomNavBar=[C4Shape rect:CGRectMake(0, self.canvas.height-(NavBarHeight), self.canvas.width, NavBarHeight)];
        bottomNavBar.fillColor= navBarColor;
        bottomNavBar.lineWidth=0;
        [self.canvas addShape:bottomNavBar];

        takePhotoButton=[UIButton buttonWithType: ROUNDEDRECT];
        [takePhotoButton setTitle:@"TakePhoto" forState:UIControlStateNormal];
        takePhotoButton.frame=CGRectMake(self.canvas.width/2-50, self.canvas.height-(NavBarHeight), 100, NavBarHeight);
        takePhotoButton.backgroundColor=buttonColor;
        takePhotoButton.tintColor=typeColor;
        [self.canvas addSubview:takePhotoButton];

    }

    -(void) takingPhoto{
        [cam captureImage];
    }
    -(void) captureImage{
        [cam captureImage];
    }
    -(void)putCapturedImageOnCanvas{
        C4Image *img = cam.capturedImage;
        img.width=240;
        img.center=CGPointMake(self.canvas.width*2/3, self.canvas.center.y);

    }


    @end

Answer 1

为了让您的概念发挥作用，您的方法中有几个漏洞会阻止您看到实际发生的任何事情。您的问题绝对是其中之一。

回答你的问题：

listenFor:fromObject: 无法识别，因为它实际上不存在。

listenFor 方法的目的是让您的应用程序或特定对象可以对应用程序中其他地方发生的通知或操作做出反应。 所以你想做的是在发生事情时运行一个方法。

你的方法应该是：

[self listenFor:@"imageWasCaptured" fromObject:cam andRunMethod:@"methodName"];

您想在 相机 完成捕捉时进行监听，然后对其进行操作...

---

我注意到的其他事情......

如果你想使用C4Button，那么如下：

takePhotoButton=[UIButton buttonWithType: ROUNDEDRECT];
[takePhotoButton setTitle:@"TakePhoto" forState:UIControlStateNormal];

应该是：

takePhotoButton = [C4Button buttonWithType:ROUNDEDRECT];
[takePhotoButton setTitle:@"TakePhoto" forState:NORMAL];

另外，您正在继承 C4CanvasController。要将 TakePhoto 对象的视图放到主画布上，您需要正确创建它。

为了在主画布中执行此操作，我在工作区中编写了以下内容：

#import "C4Workspace.h"
#import "TakePhoto.h"

@implementation C4WorkSpace {
    TakePhoto *tp;
}

-(void)setup {
    tp = [TakePhoto new];
    tp.canvas.frame = CGRectMake(30,
                                 30,
                                 self.canvas.width - 60,
                                 self.canvas.height - 60);
    tp.canvas.shadowOffset = CGSizeMake(10,10);
    tp.canvas.shadowOpacity = 1.0f;
    tp.canvas.userInteractionEnabled = YES;
    [tp setup];
    tp.mainCanvas = self.canvas;
    [self.canvas addSubview:tp.canvas];
}
@end

最后，为了将你的相机图像放到主画布上，我不得不做一些桥接。我在TakePhoto 中创建了一个属性，可以让我在新控制器中设置主画布。你会注意到上面的代码中声明tp.mainCanvas = self.canvas...

TakePhoto 标头现在看起来像：

#import "C4CanvasController.h"

@interface TakePhoto : C4CanvasController
@property (readwrite, strong) C4Window *mainCanvas;
@end

putImageOnCanvas 方法现在看起来像：

-(void)putCapturedImageOnCanvas{
    C4Image *img = cam.capturedImage;
    img.width=240;
//    img.center=CGPointMake(self.canvas.width*2/3, self.canvas.center.y);
    img.center = CGPointMake([C4Math randomInt:self.mainCanvas.width], [C4Math randomInt:self.mainCanvas.height]);
    [self.mainCanvas addImage:img];
    [self.mainCanvas bringSubviewToFront:self.canvas];
}

最后两行将图像放在画布上，然后确保将 TakePhoto 画布（即带有摄像头的画布）置于前台，这样新添加的图像就不会遮挡它。

因为您使用的是 C4CanvasController 的子类，所以您的应用结构如下所示：

C4WorkSpace.canvas > TakePhoto.canvas > Camera