I'm having difficulties understanding why the below code doesn't work, what I want to achieve is an image being displayed in the top left corner of a NSView, but nothing is showing...
NSImage *map0 = [NSImage imageNamed:#"map0.png"];
NSRect rect = NSMakeRect(0, 0, 400, 400);
[map0 drawInRect:rect fromRect:NSZeroRect operation:NSCompositeSourceAtop fraction:1.0f];
[map drawRect:rect];
EDIT:
map is the NSView into which I would like to draw the image into
You never call drawRect: directly. This routine has various pre-conditions that are provided by Cocoa, such as the creation of a CGContextRef. You implement drawRect:. Cocoa calls it.
Your drawInRect:fromRect:operation:fraction: call should be put into the drawRect: of map, which should be a subclass of NSView. This specific problem is usually better solved with an NSImageView rather than a custom NSView, but if the drawing is more complex, then a custom NSView is appropriate.
Related
I am working on a small application on Mac that I need to create customed cursor and move it. I used NSImageView to implement it. However when I call setFrameOrigin (the same to setFrame) it will leaves images on the previous place.
Here is my code:
#property (nonatomic, strong) NSImageView *eraserView;
this is the define
_eraserView = [[NSImageView alloc] initWithFrame:CGRectMake(100, 100, 32, 32)];
_eraserView.image = [NSImage imageNamed:#"EraserCursor"];
[self.view addSubview:_eraserView];
[_eraserView setHidden:YES];
here is the initialization. Everything goes well until now but:
- (void)setImageatPoint:(NSPoint)point
{
[_eraserView setFrameOrigin:point];
}
- (void)hidePenImage
{
[_eraserView setHidden:YES];
}
- (void)unhidePenImage: (BOOL)isEraser
{
[_eraserView setHidden:NO];
}
These are methods I use to change the state of the NSImageView. They will be called by another class using delegate when corresponding events of trackpad occurs.
However every time I change the state of the NSImageView, it seems like it is drawn on the superview.
I debugged it and found there was no extra subviews. And when I use setHidden it has no effect on those tracks. I think it somehow did something to the CALayer, but I have no idea how to fix it.
Screenshots would help but in general if you move a view or change the area of the view that is drawn, you need to redraw.
To do this it kind of depends on how your drawing happens. Calling setNeedsDisplay may not be enough if your implementation of drawRect only draws a sub rect of the view bounds. Cocoa only draws what it is told to draw.
You can erase sections of the view that should be empty by drawing (filling) where it should be empty. That means drawing a color ( NSColor clearColor if nothing else) in the area that was previously drawn.
I want to change background color for many nsview. I override drawRect: on subclass NSview but i don't know how to set background color for myview( is reference IBOUTLET). please help me. Thanks so much
Code for CustomView.h
#import <Cocoa/Cocoa.h>
#interface CustomView : NSView
#end
Code for CustomView.m
#import "CustomView.h"
#implementation CustomView
- (void) drawRect:(NSRect)dirtyRect {
[[NSColor whiteColor] setFill];
NSRectFill(dirtyRect);
[super drawRect:dirtyRect];
}
#end
And in main class, i added #import "CustomView.h" but i don't know how to set background for myview.
Welcome to Cocoa drawing.
Cocoa drawing uses Quartz which is a PDF model.
Drawing in this occurs in a back to front procedural order.
In Quartz drawing there is a drawing environment state object called the Graphics Context.
This is an implicit object in many of the drawing ops in AppKit.
(in Core Graphics or other APIs it could need to be explicitly called)
You tell the Graphics Context what the current color and other parameters are, then draw something, then change parameters and draw more, etc...
In AppKit, you do this by sending a message to the NSColor object, which is weird. but that's how it works.
In your drawRect: method you should call super first usually, because you probably want your drawing on top of that...
- (void) drawRect:(NSRect)dirtyRect {
[super drawRect:dirtyRect];
// This next line sets the the current fill color parameter of the Graphics Context
[[NSColor whiteColor] setFill];
// This next function fills a rect the same as dirtyRect with the current fill color of the Graphics Context.
NSRectFill(dirtyRect);
// You might want to use _bounds or self.bounds if you want to be sure to fill the entire bounds rect of the view.
}
If you want to change the color, you'll need an #property NSColor
You might need more than one for your drawing.
That allows you to set the color.
You might want the view to use KVO and observe its own color property then draw itself if the color property changes.
You could do a lot of different things to set the color. (a button or pallette elsewhere) But all of them would eventually result in sending a message to set the color of a property of your view for drawing.
Finally, if you want to update the drawing, you need to call [myView setNeedsDisplay:YES]; where myView is a reference to an instance of the NSView subclass.
There is also display but that's forceful.
setNeedsDisplay: says to schedule it on the next run of the event loop (runLoop). display kind of makes everything jump to that right away.
The event loop comes back around fast enough you shouldn't force it.
Of note, setNeedsDisplay: is the entire view.
In a fancy ideal world with complex views, you might want to more appropriately optimize things by calling setNeedsDisplayInRect: where you designate a specific CG/NSRect of the view as needing to be redrawn.
This allows the system to focus redrawing to the smallest union rect possible in the window.
I'm super late, but this is how I do it - there's no need to sub class:
NSView *myview = [NSView new];
[view setWantsLayer:YES];
view.layer.backgroundColor = [NSColor greenColor].CGColor;
I have a window which has a custom NSView and has a bottom bar with controls on it, one of which is an NSColorWheel.
For simplicity sake the Window is 332px high, with the custom NSView being 300px high and the bottom bar being 32px high.
The bottom bar is created as part of my awakeFromNib when the app loads the window using the following code:
[[self window] setAutorecalculatesContentBorderThickness:YES forEdge:NSMinYEdge];
[[self window] setContentBorderThickness: 32.0 forEdge: NSMinYEdge];
In my custom NSView class I fill the rectangle with color. Everything works fine when the app loads using the following in my NSView class:
- (void)drawRect:(NSRect)dirtyRect
{
dirtyRect = [self bounds];
NSColor * mNewColor = [NSColor blackColor];
[mNewColor set];
[NSBezierPath fillRect:dirtyRect];
}
However, if I subsequently call a method that changes the color of the custom NSView when a color wheel in the bottom bar is changed, the bottom bar gets overwritten with the color. The following code illustrates this method (this code is in the custom NSView class:
- (void)changeBackgroundColor:(NSNotification *)notification
{
NSLog(#"Changed background color");
NSRect mRect = [self bounds];
NSColor * mNewColor = [theColorWell color];
[mNewColor set];
[NSBezierPath fillRect:mRect];
[self setNeedsDisplay:YES];
}
Resizing the window instantly corrects the problem, but obviously I don't want the user to have to resize the window for an obvious bug!
What I don't understand is why my bounds appear to be mapping to the parent window and not the custom NSView when I call setNeedsDisplay and yet the bound correctly adjust when I resize the window using the mouse (even if just by 1 pixel).
Do I somehow need to account for the bottom bar on the redraw?
Any and all help much appreciated.
You should do all your drawing in the drawRect: method of your custom NSView. Cocoa automatically sets up the graphics context for you when it calls this method - things may not draw correctly if you perform drawing operations in other methods.
Your code in drawRect: could set the colour to the the current background colour as specified by your NSColorWell and fill the dirtyRect rectangle with this.
Then in the other method just call [self setNeedsDisplay:YES]; and then drawRect: will automatically be called to redraw the view.
See here for more information: http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/CocoaViewsGuide/SubclassingNSView/SubclassingNSView.html#//apple_ref/doc/uid/TP40002978-CH7-SW4 (in particular the Drawing View Content section)
Let's say I have an NSImage that's 100x100. I also have an NSImageView that's 50x50. Is there a way I can place the NSImage at coordinates inside the NSImageView, so I can control which part of it shows? It didn't seem like NSImage had an initWithFrame method...
I did this in my NSImageView subclass, as Andrew suggested.
- (void)drawRect:(NSRect)rect
{
[super drawRect:rect];
NSRect cropRect = NSMakeRect(x, y, w, h);
[image drawAtPoint:NSZeroPoint
fromRect:cropRect
operation:NSCompositeCopy
fraction:1];
}
I don't believe so, but it's trivial to roll your own NSImageView equivalent that supports center/stretch options by drawing the image yourself.
Make your imageview as big as the image, and put it inside a scrollview. Hide the scrollers if you want. No need for subclassing in this case.
NSImageView has a method -setImageAlignment: which lets you control how the image is aligned within the image view. Unfortunately, if you want to display part of the image that doesn't correspond to any of the NSImageAlignment values, you're going to have to draw the image programmatically.
Depends on what your eventual goal is but the easiest thing to me seems to put your NSImageView inside an NSView (or a subclass – doesn't have to be NSScrollView as "#NSResponder" user suggests but this should work well too), set its imageScaling to NSImageScaleProportionallyUpOrDown and its frameSize to image's size. Then you can move your NSImageView freely around the upper view using setFrame:myDesiredFrame. No subclassing, no manual redrawing, etc.
I am looking for a perfect solution to set a background image for a window in a cocoa application. I haven't found a solution to this, I am new in objective c, so please anyone help me...
A window in Cocoa has a root-level view called the "content view". This is the view that contains all the others in a window. By default, it's just a plain, blank NSView. But you could easily create your own custom NSView subclass, override the drawRect: method to draw your background image, and use that for your custom view.
However, it might just be easier to use a plain old NSImageView. The advantage of this is that you can set, for example, autosizing behavior to keep the image pinned to one corner (try this with Installer.app by resizing the installer window). You would also be able to make it semi-opaque so that the background shows through a bit. (Again, I'm thinking of Installer.app; your app could be totally different)
Hope that gets you going in the right direction!
Michael Vannorsdel suggests sublassing NSView for the purpose, and I quote:
You'd really be better off making an
NSView subclass and having it draw
the image you want in drawRect:.
- (void)awakeFromNib
{
myImage = [[NSImage alloc] init....
[self setNeedsDisplay:YES];
}
- (void)drawRect:(NSRect)rect
{
NSSize isize = [myImage size];
[myImage drawInRect:[self bounds] fromRect:NSMakeRect(0.0, 0.0,
isize.width, isize.height) operation: NSCompositeCopy fraction:1.0];
}
Read that whole thread on cocoabuilder, it's quite instructive.