Print of multi page document cocoa - objective-c

Question

I am developing a document-based application. This document can have multiple pages. so I have an array of NSView objects available with me. Now I want to provide print functionality in this app, but NSPrintOpertion takes only one NSView object so I am not able to generate print preview as well as print off multiple pages of the document.
Is there any way in cocoa to print a multi-page document?

Answer 1

Printing in Cocoa does not come for free, unfortunately. You have to implement your own NSView subclass that handles the drawing. It has to have access to your data and to draw the correct data onto each page, depending on the page number.
Here is a sample source code that can print any NSTableView. I used it here to show how you have to calculate the position of things to draw on the page:
MyPrintView.h:
#import <Cocoa/Cocoa.h>
#interface MyPrintView : NSView {
NSString *printJobTitle;
}
#property (copy, readwrite) NSString *printJobTitle;
- (id)initWithTableView:(NSTableView *)tableToPrint andHeader:(NSString *)header;
#end
MyPrintView.m:
#import "MyPrintView.h"
#interface MyPrintView ()
#property (nonatomic, weak) NSTableView *tableToPrint;
#property (nonatomic, strong) NSString *header;
#property (nonatomic, strong) NSDictionary *attributes;
#property (nonatomic, strong) NSFont *listFont;
#property (nonatomic) float headerHeight;
#property (nonatomic) float footerHeight;
#property (nonatomic) float lineHeight;
#property (nonatomic) float entryHeight;
#property (nonatomic) NSRect pageRect;
#property (nonatomic) int linesPerPage;
#property (nonatomic) int currentPage;
#end
#implementation MyPrintView
#synthesize printJobTitle;
- (id)initWithTableView:(NSTableView *)tableToPrint andHeader:(NSString *)header
{
// Initialize with dummy frame
self = [super initWithFrame:NSMakeRect(0, 0, 700, 700)];
if (self) {
self.tableToPrint = tableToPrint;
self.header = header;
self.listFont = [NSFont fontWithName:#"Helvetica Narrow" size:10.0];
CGFloat x = self.listFont.capHeight;
x = self.listFont.ascender;
x = self.listFont.descender;
self.lineHeight = self.listFont.boundingRectForFont.size.height;
self.entryHeight = [self.listFont capHeight] * 3;
self.headerHeight = 20 + self.entryHeight;
self.footerHeight = 20;
if (self.listFont) {
self.attributes = #{ NSFontAttributeName: self.listFont };
} else {
self.attributes = nil;
}
printJobTitle = #"My Print Job";
}
return self;
}
#pragma mark Pagination
- (BOOL)knowsPageRange:(NSRangePointer)range
{
NSPrintInfo *printInfo = [[NSPrintOperation currentOperation] printInfo];
self.pageRect = [printInfo imageablePageBounds];
NSRect newFrame;
newFrame.origin = NSZeroPoint;
newFrame.size = [printInfo paperSize];
[self setFrame:newFrame];
// Number of lines per page
self.linesPerPage = (self.pageRect.size.height - self.headerHeight - self.footerHeight) / self.entryHeight - 1;
// Number of full pages
NSUInteger noPages = self.tableToPrint.numberOfRows / self.linesPerPage;
// Rest of lines on last page
if (self.tableToPrint.numberOfRows % self.linesPerPage > 0) {
noPages++;
}
range->location = 1;
range->length = noPages;
return YES;
}
- (NSRect)rectForPage:(NSInteger)page
{
self.currentPage = (int)page - 1;
return self.pageRect;
}
- (NSAttributedString *)pageHeader
{
return [[NSAttributedString alloc] initWithString:self.header];
}
#pragma mark Drawing
- (BOOL)isFlipped
{
// Origin top left
return YES;
}
// We need this to find any transformers which are used to display the values of a certain column
static NSValueTransformer *TransformerFromInfoDict( NSDictionary *dict )
{
NSDictionary *options = dict[NSOptionsKey];
if (options == nil) return nil;
NSValueTransformer *transformer = options[NSValueTransformerBindingOption];
if (transformer == nil || (id)transformer == [NSNull null]) {
transformer = nil;
NSString *name = options[NSValueTransformerNameBindingOption];
if (name != nil && (id)name != [NSNull null]) {
transformer = [NSValueTransformer valueTransformerForName: name];
}
}
return transformer;
}
// This is where the drawing takes place
- (void)drawRect:(NSRect)dirtyRect
{
float margin = 20;
float leftMargin = self.pageRect.origin.x + margin;
float topMargin = self.pageRect.origin.y + self.headerHeight;
[NSBezierPath setDefaultLineWidth:0.25];
CGFloat originalWidth = 0;
for (NSTableColumn *col in self.tableToPrint.tableColumns) {
originalWidth += col.width;
}
CGFloat widthQuotient = (self.pageRect.size.width - margin) / originalWidth;
CGFloat inset = (self.entryHeight - self.lineHeight - 1.0)/2.0;
// Column titles
CGFloat horOffset = 0;
for (NSTableColumn *col in self.tableToPrint.tableColumns) {
NSRect rect = NSMakeRect(linkerRand + horOffset, topMargin, widthQuotient * spalte.width, self.entryHeight);
horOffset += widthQuotient * col.width;
[NSBezierPath strokeRect:rect];
NSString *theTitle = #"--";
if ([col respondsToSelector:#selector(title)]) { // OS X 10.10 and higher
theTitle = col.title;
} else {
NSTableHeaderCell *cell = col.headerCell;
theTitle = cell.title;
}
[theTitle drawInRect:NSInsetRect(rect, inset, inset) withAttributes:self.attributes];
}
NSUInteger firstEntryOfPage = self.currentPage * self.linesPerPage;
NSUInteger lastEntryOfPage = ((self.currentPage + 1) * self.linesPerPage) > self.tableToPrint.numberOfRows ? self.tableToPrint.numberOfRows : ((self.currentPage + 1) * self.linesPerPage);
for (NSUInteger i = 0; i < lastEntryOfPage - firstEntryOfPage; i++) {
#autoreleasepool { // to avoid memory hogging
NSUInteger row = firstEntryOfPage + i;
CGFloat horOffset = 0;
for (NSTableColumn *col in self.tableToPrint.tableColumns) {
NSDictionary *bindingInfo = [spalte infoForBinding: #"value"];
NSArray *columnValues = [bindingInfo[NSObservedObjectKey] valueForKeyPath: bindingInfo[NSObservedKeyPathKey]];
NSString *valueAsStr = #"";
id value = [columnValues objectAtIndex:col];
if ((value != nil) && (![value isKindOfClass:[NSNull class]])) {
// Do we have a transformer for that column? Then transform accordingly.
NSValueTransformer *transformer = TransformerFromInfoDict(bindingInfo);
if (transformer != nil)
value = [transformer transformedValue: value];
if ([value isKindOfClass:[NSString class]]) {
valueAsStr = value;
} else if ([value isKindOfClass:[NSNumber class]]) {
NSCell *cell = [col dataCellForRow:zeile];
if (cell.formatter != nil) {
valueAsStr = [cell.formatter stringForObjectValue:value];
} else {
valueAsStr = [value stringValue];
}
} else {
// We don't know what that is
NSLog(#"value class: %#", [value class]);
valueAsStr = #"????!";
}
}
NSRect rect = NSMakeRect(leftMargin + horOffset, topMargin + (i+1) * self.entryHeight, widthQuotient * col.width, self.entryHeight);
horOffset += widthQuotient * col.width;
// Now we can finally draw the entry
[NSBezierPath strokeRect:rect];
NSRect stringRect = NSInsetRect(rect, inset, inset);
[valueAsStr drawInRect:stringRect withAttributes:self.attributes];
}
}
}
}
#end
This is what you have to include in your document class in printDocumentWithSettings which gets called when the user selects "Print...":
[[self.printInfo dictionary] setValue:#YES forKey:NSPrintHeaderAndFooter];
NSString *headerLine = #"My first printed Table View";
MyPrintView *myPrintView = [[MyPrintView alloc] initWithTableView:theTableView andHeader:headerLine];
NSPrintOperation *op = [NSPrintOperation
printOperationWithView:myPrintView
printInfo:[self printInfo]];
[op setShowsPrintPanel:showPrintPanel];
// Run print operation, which shows the print panel if showPanels was YES
[self runModalPrintOperation:op
delegate:self
didRunSelector:nil
contextInfo:NULL];