Create the QRCode
CIFilter<CIBlendWithMask> *f = CIFilter.QRCodeGenerator;
f.message = [@"Message" dataUsingEncoding:NSASCIIStringEncoding];
f.correctionLevel = @"Q"; // increase level
CIImage *qrcode = f.outputImage;
Overlay the icon
CIImage *icon = [CIImage imageWithURL:url];
CGAffineTransform *t = CGAffineTransformMakeTranslation(
(qrcode.extent.width-icon.extent.width)/2.0,
(qrcode.extent.height-icon.extent.height)/2.0);
icon = [icon imageByApplyingTransform:t];
qrcode = [icon imageByCompositingOver:qrcode];
Round off the corners
static dispatch_once_t onceToken;
static CIWarpKernel *k;
dispatch_once(&onceToken, ^ {
k = [CIWarpKernel kernelWithFunctionName:name
fromMetalLibraryData:metalLibData()
error:nil];
});
CGRect iExtent = image.extent;
qrcode = [k applyWithExtent:qrcode.extent
roiCallback:^CGRect(int i, CGRect r) {
return CGRectInset(r, -radius, -radius); }
inputImage:qrcode
arguments:@[[CIVector vectorWithCGRect:qrcode.extent], @(radius)]];
…and this code for the kernel should go in a separate .ci.metal source file:
float2 bend_corners (float4 extent, float s, destination dest)
{
float2 p, dc = dest.coord();
float ratio = 1.0;
// Round lower left corner
p = float2(extent.x+s,extent.y+s);
if (dc.x < p.x && dc.y < p.y) {
float2 d = abs(dc - p);
ratio = min(d.x,d.y)/max(d.x,d.y);
ratio = sqrt(1.0 + ratio*ratio);
return (dc - p)*ratio + p;
}
// Round lower right corner
p = float2(extent.x+extent.z-s, extent.y+s);
if (dc.x > p.x && dc.y < p.y) {
float2 d = abs(dc - p);
ratio = min(d.x,d.y)/max(d.x,d.y);
ratio = sqrt(1.0 + ratio*ratio);
return (dc - p)*ratio + p;
}
// Round upper left corner
p = float2(extent.x+s,extent.y+extent.w-s);
if (dc.x < p.x && dc.y > p.y) {
float2 d = abs(dc - p);
ratio = min(d.x,d.y)/max(d.x,d.y);
ratio = sqrt(1.0 + ratio*ratio);
return (dc - p)*ratio + p;
}
// Round upper right corner
p = float2(extent.x+extent.z-s, extent.y+extent.w-s);
if (dc.x > p.x && dc.y > p.y) {
float2 d = abs(dc - p);
ratio = min(d.x,d.y)/max(d.x,d.y);
ratio = sqrt(1.0 + ratio*ratio);
return (dc - p)*ratio + p;
}
return dc;
}
