How to maintain the aspect ratio when using GPUImage? -

i found instagram has camera window 300*300？ square, im trying use gpuimage make same camera size.so wrote this:

primaryview = [gpuimageview alloc] initwithframe:                                    cgrectmake(0,0,300,300)];//define square view  //define still camera stillcamera = [[gpuimagestillcamera alloc]               initwithsessionpreset:avcapturesessionpreset640x480               cameraposition:avcapturedevicepositionfront];  //make portrait stillcamera.outputimageorientation = uiinterfaceorientationportrait;  //define filter filter = [[gpuimagefilter alloc] init];  //force output 300*300 [filter forceprocessingatsize:((gpuimageview*)self.primaryview).sizeinpixels];  //set things [stillcamera addtarget: filter]; [filter addtarget: primaryview]; [stillcamera startcameracapture]; 

now square view..but view looks flat, distortion, think might wrong aspect ratio.then set fill mode of primary view this:

[primaryview setfillmode:kgpuimagefillmodepreserveaspectratioandfill]; 

then this:

[primaryview setfillmode:kgpuimagefillmodepreserveaspectratio]; 

then this:

[primaryview kgpuimagefillmodestretch]; 

finally! none of these work..so missing, one, help.

-forceprocessingatsize: causes filter output image of size provide, ignoring aspect ratio. squishes image 300x300 square.

if want preserve aspect ratio of image, you'd want use -forceprocessingatsizerespectingaspectratio:.

however, letterbox image. replicate instagram does, want instead cut square region out of center of image. that, use crop filter square aspect ratio.