i bit new core graphics , keep error , second image not showing when merge them:
- (uiimage*)imagebycombiningimage:(uiimage*)gfirstimage withimage:(uiimage*)gsecondimage atpositionx:(int)xposition withpositiony:(int)yposition{ uiimage *firstimage = nil; uiimage *secondimage = nil; firstimage = gfirstimage; secondimage = gsecondimage; // int ratio = secondimage.size.height/secondimage.size.width; // int newwidth = firstimage.size.width/3; // int newheight = (firstimage.size.height/3)*ratio; cgsize scaledsize = cgsizemake(firstimage.size.width, firstimage.size.height); cgsize badgescaledsize = scaledsize; if(firstimage.size.width > 500){ scaledsize = cgsizemake(firstimage.size.width/4, firstimage.size.height/3); } if(firstimage.size.width < firstimage.size.height){ badgescaledsize = cgsizemake((firstimage.size.width/4)*prevpinchscale, (firstimage.size.height/4)*prevpinchscale); } if(firstimage.size.width > firstimage.size.height){ badgescaledsize = cgsizemake((firstimage.size.width/4)*prevpinchscale, (firstimage.size.height/4)*prevpinchscale); } secondimage = [secondimage resizedimagewithcontentmode:uiviewcontentmodescaleaspectfit bounds:badgescaledsize interpolationquality:0.5]; cgsize newimagesize = cgsizemake(firstimage.size.width, firstimage.size.height); uigraphicsbeginimagecontext(newimagesize); nslog(@"first image size width: %f, size height: %f", firstimage.size.width, firstimage.size.height); nslog(@"first image size width: %f, size height: %f", newimagesize.width, newimagesize.height); [firstimage drawatpoint:cgpointmake(0, 0)]; [secondimage drawatpoint:cgpointmake(xposition, yposition)]; uiimage *image = nil; image = uigraphicsgetimagefromcurrentimagecontext(); nslog(@"got image of width: %f , height: %f", image.size.width, image.size.height); uigraphicsendimagecontext(); return image; } the error follows:
<error>: cgcontextconcatctm: invalid context 0x0 <error>: cgcontextsetinterpolationquality: invalid context 0x0 <error>: cgcontextdrawimage: invalid context 0x0 <error>: cgbitmapcontextcreateimage: invalid context 0x0
those errors not being thrown code, rather inside uiimage+resize.m assuming using. code runs fine if remove line
secondimage = [secondimage resizedimagewithcontentmode:uiviewcontentmodescaleaspectfit bounds:badgescaledsize interpolationquality:0.5]; if @ method find calls method makes 4 calls getting errors from.
- (uiimage *)resizedimage:(cgsize)newsize transform:(cgaffinetransform)transform drawtransposed:(bool)transpose interpolationquality:(cginterpolationquality)quality { cgrect newrect = cgrectintegral(cgrectmake(0, 0, newsize.width, newsize.height)); cgrect transposedrect = cgrectmake(0, 0, newrect.size.height, newrect.size.width); cgimageref imageref = self.cgimage; // build context that's same dimensions new size cgcontextref bitmap = cgbitmapcontextcreate(null, newrect.size.width, newrect.size.height, cgimagegetbitspercomponent(imageref), 0, cgimagegetcolorspace(imageref), cgimagegetbitmapinfo(imageref)); // rotate and/or flip image if required orientation cgcontextconcatctm(bitmap, transform); // set quality level use when rescaling cgcontextsetinterpolationquality(bitmap, quality); // draw context; scales image cgcontextdrawimage(bitmap, transpose ? transposedrect : newrect, imageref); // resized image context , uiimage cgimageref newimageref = cgbitmapcontextcreateimage(bitmap); uiimage *newimage = [uiimage imagewithcgimage:newimageref]; // clean cgcontextrelease(bitmap); cgimagerelease(newimageref); return newimage; } it seems value bitmap invalid. check make sure on cgbitmapcontextcreate call, passing real values , not creating context of size 0x0.
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