iphone - 您可以将手机创建的图像添加到 MKOverlay 中吗？

Question

我一直在关注 WWDC 第 127 期 - 使用叠加层自定义地图。他们说您可以从应用程序包或网络获取图像以用作 MKOverlay。我想知道手机是否可以使用其 API 生成图像。

有人做过吗？您可以提供教程吗？

谢谢。

[编辑] 我实际上还需要一个关于如何将由手机创建或从网络下载的图像添加到地图的教程。 我看到的只是 WWDC 演示，但你需要会议门票，但我显然没有。

Answer 1

下面是一些使用 Quartz 绘制 UIImage 的代码。希望它对您有所帮助，并且您可以了解想法

void mainFunction() {
    // background size
    CGSize sizeBack = CGSizeMake(layerFrame.size.width*scaledFactor,layerFrame.size.height*scaledFactor);
    UIGraphicsBeginImageContext(sizeBack);
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetRGBFillColor(context, 0., 0., 0., 1.);
    drawBorder(context, scaledRect);

    UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    if (destinationLayer) {
       [destinationLayer setContents:(id)img.CGImage];
    }
}

CGPathRef createRoundedRectanglePath(CGRect mainRect, CGFloat roundRatio) {

    roundRatio = fabs(roundRatio);
    roundRatio = MIN(1, roundRatio);
    CGFloat offset = roundRatio * MIN(mainRect.size.width, mainRect.size.height)/2;

    CGPoint c1 = CGPointMake(0,0);
    CGPoint c2 = CGPointMake(mainRect.size.width,0);
    CGPoint c3 = CGPointMake(mainRect.size.width,mainRect.size.height);
    CGPoint c4 = CGPointMake(0,mainRect.size.height);

    CGPoint pA = CGPointMake(c1.x + offset, c1.y);
    CGPoint pB = CGPointMake(c2.x - offset, c2.y);
    CGPoint pC = CGPointMake(c2.x, c2.y + offset);
    CGPoint pD = CGPointMake(c3.x, c3.y - offset);
    CGPoint pE = CGPointMake(c3.x - offset, c3.y);
    CGPoint pF = CGPointMake(c4.x + offset, c4.y);
    CGPoint pG = CGPointMake(c4.x, c4.y - offset);
    CGPoint pH = CGPointMake(c1.x, c1.y + offset);


    CGMutablePathRef result = CGPathCreateMutable();
    CGPathMoveToPoint(result, NULL, pA.x, pA.y);

    CGPathAddLineToPoint(result, NULL, pB.x, pB.y);
    CGPathAddQuadCurveToPoint(result, NULL, c2.x, c2.y, pC.x, pC.y);

    CGPathAddLineToPoint(result, NULL, pD.x, pD.y);
    CGPathAddQuadCurveToPoint(result, NULL, c3.x, c3.y, pE.x, pE.y);

    CGPathAddLineToPoint(result, NULL, pF.x, pF.y);
    CGPathAddQuadCurveToPoint(result, NULL, c4.x, c4.y, pG.x, pG.y);

    CGPathAddLineToPoint(result, NULL, pH.x, pH.y);
    CGPathAddQuadCurveToPoint(result, NULL, c1.x, c1.y, pA.x, pA.y);

    CGPathCloseSubpath(result);

    CGPathRef path = CGPathCreateCopy(result);
    CGPathRelease(result);
    return path;
}

void drawBorder(CGContextRef context, CGRect rect) {
    CGContextSaveGState(context);
    /* Outside Path */
    CGPathRef thePath = createRoundedRectanglePath(rect, 0.2);

    /* Fill with Gradient Color */
    CGFloat locations[] = { 0.0, 1.0 };
    CGColorRef startColor = [UIColor colorWithRed:1.
                                            green:1.
                                             blue:1.
                                            alpha:1.].CGColor;
    CGColorRef endColor = [UIColor colorWithRed:208./255.                                          
                                          green:208./255.
                                           blue:208./255.
                                          alpha:1.].CGColor;


    NSArray *colors = [NSArray arrayWithObjects:(id)startColor, (id)endColor, nil];

    CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), 0);
    CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), rect.size.height);

    CGContextAddPath(context, thePath);
    CGContextClip(context);
    drawLinearGradient(context, startPoint, endPoint, locations, (CFArrayRef*)colors);

    /* Stroke path */
    CGPathRelease(thePath);
    thePath = createRoundedRectanglePath(rect, 0.2);
    CGContextSetStrokeColor(context, CGColorGetComponents([UIColor colorWithRed:0 green:0 blue:1. alpha:1.].CGColor));
    CGContextAddPath(context, thePath);
    CGContextSetLineWidth(context, 1.);
    CGContextDrawPath(context, kCGPathStroke);
    CGContextRestoreGState(context);
    CGPathRelease(thePath);
}