Printing an NSImage

Question

I'm migrating Cocoa-Java code to Cocoa + JNI since Cocoa-Java is deprecated. The code prints an image stored in a file. The new Cocoa code is basically:

NSImage *image = [[NSImage alloc] initWithContentsOfFile:spoolFile];
if ( [image isValid] ) {
    NSImageView *view = [[NSImageView alloc] init];
    [view setImage:image];
    [view setImageScaling:NSScaleProportionally];

    NSPoint p;
    NSSize s;

    p.x = static_cast<float>( boundsX );
    p.y = static_cast<float>( boundsY );
    [view setBoundsOrigin:p];

    s.width  = static_cast<float>( boundsWidth );
    s.height = static_cast<float>( boundsHeight );
    [view setBoundsSize:s];

    NSPrintInfo *info = [NSPrintInfo sharedPrintInfo];
    [info setHorizontalPagination:NSClipPagination];
    [info setVerticalPagination:NSClipPagination];
    [info setHorizontallyCentered:NO];
    [info setVerticallyCentered:NO];

    p.x = static_cast<float>( boundsX );
    p.y = static_cast<float>( [info paperSize].height - boundsHeight - boundsY );
    [view translateOriginToPoint:p];

    NSPrintOperation *printOp =
        [NSPrintOperation printOperationWithView:view printInfo:info];
    [printOp setShowsPrintPanel:NO];
    [printOp runOperation];
}

Running this code eventually crashes with:

Thread 0 Crashed:
0   com.apple.AppKit   0x9484ac75 -[NSConcretePrintOperation(NSInternal) _tryToSetCurrentPageNumber:] + 345
1   com.apple.AppKit   0x948d88cf -[NSView(NSPrintingInternal) _printForCurrentOperation] + 524
2   com.apple.AppKit   0x948d85c5 -[NSConcretePrintOperation _renderView] + 358
3   com.apple.AppKit   0x9491f0c0 -[NSConcretePrintOperation runOperation] + 362

Why? How can I simply print an image that's stored in a file?

Answer 1

Is that a typo the second time you assign to p.y? It doesn't look like you define info until 2 lines later...

Also, wouldn't it be simpler to use NSMakePoint() and NSMakeSize() by passing ints, instead of constructing them by hand and using static_cast<float>? That seems like a very C++ approach...

For example, something like this could work?

NSImage *image = [[NSImage alloc] initWithContentsOfFile:spoolFile];
if ([image isValid]) {
    NSPrintInfo *info = [NSPrintInfo sharedPrintInfo];
    [info setHorizontalPagination:NSClipPagination];
    [info setVerticalPagination:NSClipPagination];
    [info setHorizontallyCentered:NO];
    [info setVerticallyCentered:NO];

    NSImageView *view = [[NSImageView alloc] init];
    [view setImage:image];
    [view setImageScaling:NSScaleProportionally];
    [view setBoundsOrigin:NSMakePoint(boundsX, boundsY)];
    [view setBoundsSize:NSMakeSize(boundsWidth, boundsHeight)];
    [view translateOriginToPoint:NSMakePoint(boundsX, [info paperSize].height -
                                                      boundsHeight - boundsY)];

    NSPrintOperation *printOp = [NSPrintOperation printOperationWithView:view printInfo:info];
    [printOp setShowsPrintPanel:NO];
    [printOp runOperation];
}

Answer 2

NSImageView *view = [[NSImageView alloc] init];

That's invalid. You need to use initWithFrame: to initialize a view. You'll probably want to pass a frame consisting of NSZeroPoint and the image's size.

As for the use of setBoundsOrigin: and setBoundsSize:: I'm not sure those will work, assuming you mean to crop the image. You can try them (after fixing the above problem), but I would feel safer to create a new image from the desired section of the old one. You would do this by creating an empty image of the desired size, locking focus on it, drawing the correct section of the old image at the origin in the new image, and unlocking focus on the new image, then giving the new image instead of the old to the image view.