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August 28, 2020 06:21
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Getting screenshot on iOS OpenGL ES
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- (UIImage*) takePicture { | |
int s = 1; | |
UIScreen* screen = [UIScreen mainScreen]; | |
if ([screen respondsToSelector:@selector(scale)]) { | |
s = (int) [screen scale]; | |
} | |
GLint viewport[4]; | |
glGetIntegerv(GL_VIEWPORT, viewport); | |
int width = viewport[2]; | |
int height = viewport[3]; | |
int myDataLength = width * height * 4; | |
GLubyte *buffer = (GLubyte *) malloc(myDataLength); | |
GLubyte *buffer2 = (GLubyte *) malloc(myDataLength); | |
glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer); | |
for(int y1 = 0; y1 < height; y1++) { | |
for(int x1 = 0; x1 <width * 4; x1++) { | |
buffer2[(height - 1 - y1) * width * 4 + x1] = buffer[y1 * 4 * width + x1]; | |
} | |
} | |
free(buffer); | |
CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, buffer2, myDataLength, releaseData); | |
int bitsPerComponent = 8; | |
int bitsPerPixel = 32; | |
int bytesPerRow = 4 * width; | |
CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB(); | |
CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault; | |
CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault; | |
CGImageRef imageRef = CGImageCreate(width, height, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, bitmapInfo, provider, NULL, NO, renderingIntent); | |
CGColorSpaceRelease(colorSpaceRef); | |
CGDataProviderRelease(provider); | |
UIImage *image = [ UIImage imageWithCGImage:imageRef scale:s orientation:UIImageOrientationUp ]; | |
return image; | |
} |
@notedit It could because you need another settings for CGDataProvider or in glReadPixels, or even something else. Debug and check each setting/parameter. For @vikram123456 it works and for me too, so look in your code.
For ios 7+ one can use the following snippet:
UIGraphicsBeginImageContext(self.view.frame.size);
[self.view drawViewHierarchyInRect:self.view.frame afterScreenUpdates:YES];
image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
I also got a black image because glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer) fills buffer with zeroes
@namiazad Were you able to solve the issue? Even I am getting empty buffer
This works great.
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@sakrist: Thank You so Much.. This above code worked so well for me... I would love to thank u once again because I passed 2 days for getting UIImage from GlImage