Ios 如何从UIVIEW中仅获取绘图零件（用作绘图板）？

以上链接我在这个项目中作为drawingpad应用程序的参考。 现在，我只想从绘图板的绘图部分。 就像这里是在绘图板上，我在里面画了一个。现在我只想画一个我在绘图板上画过的区域。不是全部

 - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
    {
        if (self.textView && !self.textView.hidden) {
            [self commitAndHideTextEntry];
            return;
        }

        // add the first touch
        UITouch *touch = [touches anyObject];
        previousPoint1 = [touch previousLocationInView:self];
        currentPoint = [touch locationInView:self];

        // init the bezier path
        self.currentTool = [self toolWithCurrentSettings];
        self.currentTool.lineWidth = self.lineWidth;
        self.currentTool.lineColor = self.lineColor;
        self.currentTool.lineAlpha = self.lineAlpha;

        if ([self.currentTool isKindOfClass:[ACEDrawingTextTool class]]) {
            [self initializeTextBox: currentPoint];
        }
        else {
            [self.pathArray addObject:self.currentTool];

            [self.currentTool setInitialPoint:currentPoint];
        }

        // call the delegate
        if ([self.delegate respondsToSelector:@selector(drawingView:willBeginDrawUsingTool:)]) {
            [self.delegate drawingView:self willBeginDrawUsingTool:self.currentTool];
        }
    }

    - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
    {
        // save all the touches in the path
        UITouch *touch = [touches anyObject];

        previousPoint2 = previousPoint1;
        previousPoint1 = [touch previousLocationInView:self];
        currentPoint = [touch locationInView:self];

        if ([self.currentTool isKindOfClass:[ACEDrawingPenTool class]]) {
            CGRect bounds = [(ACEDrawingPenTool*)self.currentTool addPathPreviousPreviousPoint:previousPoint2 withPreviousPoint:previousPoint1 withCurrentPoint:currentPoint];

            CGRect drawBox = bounds;
            drawBox.origin.x -= self.lineWidth * 2.0;
            drawBox.origin.y -= self.lineWidth * 2.0;
            drawBox.size.width += self.lineWidth * 4.0;
            drawBox.size.height += self.lineWidth * 4.0;

            [self setNeedsDisplayInRect:drawBox];
        }
        else if ([self.currentTool isKindOfClass:[ACEDrawingTextTool class]]) {
            [self resizeTextViewFrame: currentPoint];
        }
        else {
            [self.currentTool moveFromPoint:previousPoint1 toPoint:currentPoint];
            [self setNeedsDisplay];
        }

    }

    - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
    {
        // make sure a point is recorded
        [self touchesMoved:touches withEvent:event];

        if ([self.currentTool isKindOfClass:[ACEDrawingTextTool class]]) {
            [self startTextEntry];
        }
        else {
            [self finishDrawing];
        }
    }


- (void)finishDrawing
{
    // update the image
    [self updateCacheImage:NO];

    // clear the redo queue
    [self.bufferArray removeAllObjects];

    // call the delegate
    if ([self.delegate respondsToSelector:@selector(drawingView:didEndDrawUsingTool:)]) {
        [self.delegate drawingView:self didEndDrawUsingTool:self.currentTool];
    }

    // clear the current tool
    self.currentTool = nil;
}
    - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
    {
        // make sure a point is recorded
        [self touchesEnded:touches withEvent:event];
    }

    #pragma mark - Text Entry

    - (void) initializeTextBox: (CGPoint)startingPoint {

        if (!self.textView) {
            self.textView = [[UITextView alloc] init];
            self.textView.delegate = self;
            self.textView.returnKeyType = UIReturnKeyDone;
            self.textView.autocorrectionType = UITextAutocorrectionTypeNo;
            self.textView.backgroundColor = [UIColor clearColor];
            self.textView.layer.borderWidth = 1.0f;
            self.textView.layer.borderColor = [[UIColor grayColor] CGColor];
            self.textView.layer.cornerRadius = 8;
            [self.textView setContentInset: UIEdgeInsetsZero];


            [self addSubview:self.textView];
        }

        int calculatedFontSize = self.lineWidth * 3; //3 is an approximate size factor

        [self.textView setFont:[UIFont systemFontOfSize:calculatedFontSize]];
        self.textView.textColor = self.lineColor;
        self.textView.alpha = self.lineAlpha;

        int defaultWidth = 200;
        int defaultHeight = calculatedFontSize * 2;
        int initialYPosition = startingPoint.y - (defaultHeight/2);

        CGRect frame = CGRectMake(startingPoint.x, initialYPosition, defaultWidth, defaultHeight);
        frame = [self adjustFrameToFitWithinDrawingBounds:frame];

        self.textView.frame = frame;
        self.textView.text = @"";
        self.textView.hidden = NO;
    }


    - (IBAction)takeScreenshot:(id)sender
    {
        [redoimage removeAllObjects];
    //    _previewImageView.frame=CGRectMake(x, y, w,h);
        self.previewImageView.image = self.drawingView.image;////herer i can get image from the drawpad.

    //    self.previewImageView.hidden = NO;
        CGSize nsize={100,100};
        CGImageRef imageref = [self.drawingView.image CGImage];



       UIImage *newimg=[self ManipulateImagePixelData:imageref];

      UIImage *newimage=[self scaleImage:newimg toSize:nsize];
       // self.previewImageView.image=newimage;

    }
    ////////// this code use geting pixel data from the Uimage/////
    -(UIImage *) ManipulateImagePixelData:(CGImageRef) inImage
    {
        // Create the bitmap context
        CGContextRef cgctx = [self CreateARGBBitmapContext:inImage];
        if (cgctx == NULL)
        {
            // error creating context
            return NULL;
        }

        // Get image width, height. We'll use the entire image.
        size_t w = CGImageGetWidth(inImage);
        size_t h = CGImageGetHeight(inImage);
        CGRect rect = {{0,0},{w,h}};

        // Draw the image to the bitmap context. Once we draw, the memory
        // allocated for the context for rendering will then contain the
        // raw image data in the specified color space.
        CGContextDrawImage(cgctx, rect, inImage);
        CGImageRef imageRef = CGBitmapContextCreateImage(cgctx);
        UIImage * finalImage = [UIImage imageWithCGImage:imageRef];
        // Now we can get a pointer to the image data associated with the bitmap
    //    // context.
    //    void *data = CGBitmapContextGetData (cgctx);
    //    if (data != NULL)
    //    {
    //        
    //        // **** You have a pointer to the image data ****
    //        
    //        // **** Do stuff with the data here ****
    //        
    //    }

        // When finished, release the context
        CGContextRelease(cgctx);
        // Free image data memory for the context
    //    if (data)
    //    {
    //        free(data);
    //    }
        return finalImage;
    }


    - (CGContextRef) CreateARGBBitmapContext:(CGImageRef) inImage
    {
        CGContextRef    context = NULL;
        CGColorSpaceRef colorSpace;
        void *          bitmapData;
        int             bitmapByteCount;
        int             bitmapBytesPerRow;

        // Get image width, height. We'll use the entire image.
        size_t pixelsWide = CGImageGetWidth(inImage);
        size_t pixelsHigh = CGImageGetHeight(inImage);

        // Declare the number of bytes per row. Each pixel in the bitmap in this
        // example is represented by 4 bytes; 8 bits each of red, green, blue, and
        // alpha.
        bitmapBytesPerRow   = (pixelsWide * 4);
        bitmapByteCount     = (bitmapBytesPerRow * pixelsHigh);

        // Use the generic RGB color space.

        colorSpace = CGColorSpaceCreateDeviceRGB();
        if (colorSpace == NULL)
        {
            fprintf(stderr, "Error allocating color space\n");
            return NULL;
        }

        // Allocate memory for image data. This is the destination in memory
        // where any drawing to the bitmap context will be rendered.
        bitmapData = malloc( bitmapByteCount );
        if (bitmapData == NULL)
        {
            fprintf (stderr, "Memory not allocated!");
            CGColorSpaceRelease( colorSpace );
            return NULL;
        }

        // Create the bitmap context. We want pre-multiplied ARGB, 8-bits
        // per component. Regardless of what the source image format is
        // (CMYK, Grayscale, and so on) it will be converted over to the format
        // specified here by CGBitmapContextCreate.
        context = CGBitmapContextCreate (bitmapData,
                                         pixelsWide,
                                         pixelsHigh,
                                         8,      // bits per component
                                         bitmapBytesPerRow,
                                         colorSpace,
                                         kCGImageAlphaPremultipliedFirst);
        if (context == NULL)
        {
            free (bitmapData);
            fprintf (stderr, "Context not created!");
        }

        // Make sure and release colorspace before returning
        CGColorSpaceRelease( colorSpace );

        return context;
    }

---

提前感谢。

[自行完成图纸]；加上这个function@DivinDesert我添加了[self finishDrawing]函数。Oops在您实际绘制的位置添加函数，以便我可以提供帮助you@DivineDesert我画在我的视野里。然后我从UIView中获取图像。在这里，我使用2个文件1.ACEDrawingView和2.acedrawingTools，从这个链接的应用程序中查看：