[Drawkit] Pan / Hand Tool?

[Graham Cox]

Hi Allan,

Right now the pan tool is not part of DK, but it is an extremely  
simple tool. It'll probably end up in DK, especially as I want to  
implement a way to 'flip' to the pan tool when the spacebar is pressed  
while using other tools, though that's harder to do than it looks from  
the user's POV.

Anyway, the current implementation is as follows:

#import <GCDrawKit/DKDrawingTool.h>


@interface DKOPanTool : DKDrawingTool
{
	NSPoint		mAnchor;
	NSPoint		mViewOrigin;
	BOOL		mDragging;
}

@end

// -------------------


#import "DKOPanTool.h"
#import <GCDrawKit/DKDrawingView.h>
#import <GCDrawKit/DKLayer.h>

@implementation DKOPanTool


- (int)				mouseDownAtPoint:(NSPoint) p targetObject: 
(DKDrawableObject*) obj layer:(DKLayer*) layer event:(NSEvent*) event  
delegate:(id) aDel
{
	#pragma unused(obj, p, aDel)
	
	mDragging = YES;
	mAnchor = [event locationInWindow];
	DKDrawingView* zv = (DKDrawingView*)[layer currentView];
	
	float scale = [zv scale];
	
	NSClipView* clippy = (NSClipView*)[zv superview];
	mViewOrigin = [clippy documentVisibleRect].origin;
	
	mViewOrigin.x *= scale;
	mViewOrigin.y *= scale;
	
	//NSLog(@"will begin pan at point: %@, clip view origin = %@",  
NSStringFromPoint( p ), NSStringFromPoint( mViewOrigin ));
	
	[[NSCursor closedHandCursor] set];
	
	return 0;
}


- (void)			mouseDraggedToPoint:(NSPoint) p partCode:(int) pc layer: 
(DKLayer*) layer event:(NSEvent*) event delegate:(id) aDel
{
	#pragma unused(pc, p, aDel)
	
	DKDrawingView* zv = (DKDrawingView*)[layer currentView];
	NSPoint newOrigin = NSMakePoint( mViewOrigin.x - ([event  
locationInWindow].x - mAnchor.x), mViewOrigin.y + ([event  
locationInWindow].y - mAnchor.y));
	
	// take into account the zoom factor of the view
	
	float scale = [zv scale];
	
	newOrigin.x /= scale;
	newOrigin.y /= scale;
	
	[zv scrollPoint:newOrigin];
}


- (BOOL)			mouseUpAtPoint:(NSPoint) p partCode:(int) pc layer: 
(DKLayer*) layer event:(NSEvent*) event delegate:(id) aDel;
{
	#pragma unused( p, pc, layer, event, aDel )
	
	[[NSCursor openHandCursor] set];
	
	mDragging = NO;
	return NO;
}


- (NSCursor*)		cursor
{
	if( mDragging )
		return [NSCursor closedHandCursor];
	else
		return [NSCursor openHandCursor];
}



@end




On 01/09/2009, at 11:54 AM, Allan Daly wrote:

> Hi Graham,
>
> I've got my copy of Ortelius up and running. What fun. Nice job and  
> congrats.
>
> I see that you have a "hand" tool implemented in there that pans  
> around the screen when you're zoomed in. This is something I have  
> been thinking about doing in my app and I wonder if this is a  
> standard tool now in DK (didn't see it when I looked around) or if  
> not if I could please ask you to please send along a few notes on  
> the best route to implement that.
>
> Thanks.
>
> -Allan