Is there any way to Convert NSView Contain Subviews into NSImage? - objective-c

Question

Is there any way to Convert NSView Contain many Subviews with background color into NSImage ?
Sample code will be great
NSBitmapImageRep *rep = [[NSBitmapImageRep alloc] initWithFocusedViewRect:[_collageView bounds]];
[_collageView unlockFocus];
// NSData *exportedData = [rep representationUsingType:NSJPEGFileType properties:nil];
NSData *exportedData = [rep representationUsingType:NSPNGFileType properties:nil];
NSSavePanel *savepanel = [NSSavePanel savePanel];
savepanel.title = #"Save chart";
[savepanel setAllowedFileTypes:[NSArray arrayWithObject:#"png"]];
[savepanel beginSheetModalForWindow:self.view.window completionHandler:^(NSInteger result)
{
if (NSFileHandlingPanelOKButton == result)
{
NSURL* fileURL = [savepanel URL];
if ([fileURL.pathExtension isEqualToString:#""])
fileURL = [fileURL URLByAppendingPathExtension:#"png"];
[exportedData writeToURL:fileURL atomically:YES];
}
}];
i also used the following code to
[_collageView lockFocus];
NSBitmapImageRep *bits = [[NSBitmapImageRep alloc]initWithFocusedViewRect: [_collageView bounds]];
[_collageView unlockFocus];
NSImage *image1 = [[NSImage alloc] init];
[image1 addRepresentation: bits];
[self.ImageView setImage:image1];
but not working

Answer 1

Your approach copies the bitmap from the windows server. This is the rendered content of the view. Typically you do not want to do that.
It is a better way to lock the focus on an NSImage, which builds up the graphic contexts and then draw into that image using -drawRect: or whatever drawing methods you have. You can add subviews by simply iterating them.
// perhaps in a category of NSView
- (void)drawRecursively
{
[self drawRect:self.bounds];
for (NSView *subview in self.subviews)
{
[subview drawRecursively];
}
}
To start that
NSImage *image = [[NSImage alloc] initWithSize:theView.bounds.size];
[image lockFocus]; // Set-up the context for the image
[theView drawRecursively];
[image unlockFocus];
Typped in Safari.
Edit: Before going to the subviews, you have to perform a transformation for them. Forgot that.

Answer 2

I have actually implemented the drawing of a view hierarchy offscreen myself.
It is non-trivial, even for a very simple view hierarchy where all views are
subclasses NSControl and have -(BOOL) isFlipped { return YES; }
Here's one small portion of that code, which will give you an idea of the pain of doing this:
- (void)drawRect:(NSRect)iDirtyBigRect
{
#ifdef DISABLE_PSEUDOVIEW
debugRectsBeingDrawn();
return;
#endif
if ( !drawableShape )
{
if ( [[[self window] contentView] wantsLayer] )
{
CGRect cgRect = NSRectToCGRect([self bounds]);
drawableShape = HIShapeCreateMutableWithRect( &cgRect );
}
else
{
DUMP( #"our superview should have set up our drawableShape!" );
[self setNeedsDisplay:YES];
return;
}
}
else if ( iDirtyBigRect.size.width <= 0 )
{
// Our drawable shape is empty.
// This can happen for several valid reasons:
// 1) dirtyShape is fully masked by opaqueShape
// 2) for some reason, we were called to obey needsDisplay when not needed
DLog( #"nothing to draw %#", self );
return; // must return, otherwise we risk drawing outside our bounds
}
//NSArray *hardSubviews = [self subviews];
for ( NSView *pseudoSubview in pseudoSubviews )
{
if ( ![pseudoSubview isHidden] &&
[pseudoSubview window] == offscreenWindow ) // only draw pseudo view if it's in offscreen window
{
NSRect rectToDraw = [pseudoSubview frame];
// if ( rectToDraw.size.width == 0 )
// {
// DLog( #"clipped to superview %#", pseudoSubview );
// }
CGRect cgRect = NSRectToCGRect(rectToDraw);
if ( HIShapeIntersectsRect(drawableShape, &cgRect) )
{
// the magic: transform to subview coordinates
NSAffineTransform* xform = [NSAffineTransform transform];
[xform translateXBy:rectToDraw.origin.x yBy:rectToDraw.origin.y];
if ( [pseudoSubview isFlipped] != [self isFlipped] )
{
if ( ![pseudoSubview isKindOfClass: [NSColorWell class]] )
{
DUMP( #"hmmm flippedness different %d %d", [pseudoSubview isFlipped], [self isFlipped] );
}
[xform translateXBy:0.0 yBy:rectToDraw.size.height];
[xform scaleXBy:1.0 yBy:-1.0];
}
[xform concat];
HIMutableShapeRef newShape = HIShapeCreateMutableWithRect( &cgRect );
HIShapeIntersect( newShape, drawableShape, newShape ); // clip to subview frame
HIShapeOffset( newShape, -cgRect.origin.x, -cgRect.origin.y ); // translate to subview coords
CGRect dirtyRect;
HIShapeGetBounds(newShape, &dirtyRect);
// if ( dirtyRect.size.width <= 0 )
// {
// DUMP( #"why?" );
// }
if ( [pseudoSubview isKindOfClass:[PseudoView class]] )
{
//DLog( #"drawing Pseudo %# dirtyRect %# ", pseudoSubview, NSStringFromRect(NSRectFromCGRect(dirtyRect)));
PseudoView *pView = (PseudoView *)pseudoSubview;
if ( pView->drawableShape )
{
CFRelease( pView->drawableShape );
pView->drawableShape = NULL;
}
// create subview personal drawableShape from my drawable shape
pView->drawableShape = newShape;
if ( [pseudoSubview isOpaque] )
gDrawDirtyPixels += dirtyRect.size.width * dirtyRect.size.height;
if ( dirtyRect.size.width > 0 )
[pseudoSubview drawRect: NSRectFromCGRect(dirtyRect)];
}
else
{
//DLog( #"drawing non-Pseudo %# rectToDraw %# ", pseudoSubview, NSStringFromRect( rectToDraw ));
UInt64 t1 = CpuCycles();
CFRelease( newShape );
// sacrifice efficiency to avoid bugs...
// always draw the entire view.
[pseudoSubview drawRect:[pseudoSubview bounds]]; // NSRectFromCGRect(dirtyRect)]; // [pseudoSubview bounds]];
UnitTestQuartz( [pseudoSubview bounds] );
// NSLog( #"drawRect %# %# sUnitTestQuartzToggle %f\n -- superv %#\n -- self %#", pseudoSubview, NSStringFromRect(rectToDraw), sUnitTestQuartzToggle*100, [pseudoSubview superview], self );
UInt64 t2 = CpuCycles();
int diff = (int)(t2-t1);
gDrawControl += diff;
}
[xform invert]; // restore
[xform concat];
}
}
}
//if ( [self isKindOfClass:[PseudoRootView class]] )
// [offscreenWindow setViewsNeedDisplay:NO];
}

Answer 3

I am able to solve my problem with the following Code
// Setup the image to render
NSRect imgRect = _collageView.frame;
NSSize imgSize = imgRect.size;
NSBitmapImageRep *rep = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL
pixelsWide:imgSize.width
pixelsHigh:imgSize.height
bitsPerSample:8
samplesPerPixel:4
hasAlpha:YES
isPlanar:NO
colorSpaceName:NSDeviceRGBColorSpace
bitmapFormat:NSAlphaFirstBitmapFormat
bytesPerRow:0
bitsPerPixel:0];
NSGraphicsContext *context = [NSGraphicsContext graphicsContextWithBitmapImageRep:rep];
[NSGraphicsContext saveGraphicsState];
[NSGraphicsContext setCurrentContext:context];
// Render
CGContextRef zCgContextRef = (CGContextRef) [context graphicsPort];
[[_collageView layer] renderInContext:zCgContextRef];
// Get the Data for the image
NSData *exportedData = [rep representationUsingType:NSJPEGFileType properties:nil];
// Start the savepanel
NSSavePanel *savepanel = [NSSavePanel savePanel];
savepanel.title = #"Save chart";
[savepanel setAllowedFileTypes:[NSArray arrayWithObject:#"jpg"]];
[savepanel beginSheetModalForWindow:self.view.window completionHandler:^(NSInteger result)
{
if (NSFileHandlingPanelOKButton == result)
{
NSURL* fileURL = [savepanel URL];
if ([fileURL.pathExtension isEqualToString:#""])
fileURL = [fileURL URLByAppendingPathExtension:#"jpg"];
[exportedData writeToURL:fileURL atomically:YES];
}
}];