Here is what I'm trying to accomplish: I'm working on an open source TI calculator emulator where I'm currently trying to add skin support. The skin image is just an NSImageView with its image set to the skin image. I override the mouseDown: method and get the location of the mouse in the NSImageView coordinates using convertPointFromBase: with locationInWindow return value as the point to convert.
I then grab the underlying NSBitmapImageRep from the NSImageView using bestRepresentationForDevice: with a nil argument. Finally I call getPixel:atX:y on the NSBitmapImageRep with point.x and point.y for the location.
However, the origin of the NSImageView begins in the bottom left (as usual), whereas the coordinates for the NSBitmapImageRep begin in the top left. I can't seem to find an obvious way to compensate for this, so the hit testing for button clicks doesn't function properly. Any help is greatly appreciated.
I never considered overriding isFlipped to return YES in my NSImageView subclass. That takes care of the problem.
Seems pretty easy to me, just calculate the y coordinate based on the height of the rect:
NSPoint pointInFlippedRect(NSPoint inPoint, NSRect aRect)
{
return NSMakePoint(inPoint.x , NSHeight(aRect) - inPoint.y);
}
Related
I'm new to this and it's hard for me to even ask my question right because I don't know the right terminology. I've done some objective c coding so I'm a little bit beyond beginner except when it comes to working with UIs.
I would like to know the best practices to accomplish this - i.e. the right way.
I have a window with some buttons at the top of it. Below that is a region that will have an image or webview. This will be of variable size so to make it look nice I'd like to have the area behind it have a nice tiled pattern.
I've experimented with a few things that work but everything feels a bit hackish. Is there a control that automatically provides a tiled background and lets me put other controls inside of it? For that matter, is there any kind of control that allows putting other controls inside of it? (I'm used to this in GTK but it doesn't appear to be common in Cocoa)
Also, considering that the image can change sizes based on the buttons above, should I be using core animation and it's layers (I've read about them but not used them)?
One fairly simple way to do this is to use a custom NSView subclass for the background view. In its -drawRect: method, write code to take the image and draw it repeatedly to fill the bounds of the view. The algorithm to do this is pretty simple. Start at the top left (or any corner really), draw the image, then increment the x position by the width of the image, and draw again. When the x position exceeds the maximum x coordinate of the view, increment y by the height of the image and draw the next row, and so on until you've filled the whole thing. This should do the trick:
#interface TiledBackgroundView : NSView
#end
#implementation TiledBackgroundView
- (void)drawRect:(NSRect)dirtyRect
{
NSRect bounds = [self bounds];
NSImage *image = ...
NSSize imageSize = [image size];
// start at max Y (top) so that resizing the window looks to be anchored at the top left
for ( float y = NSHeight(bounds) - imageSize.height; y >= -imageSize.height; y -= imageSize.height ) {
for ( float x = NSMinX(bounds); x < NSWidth(bounds); x += imageSize.width ) {
NSRect tileRect = NSMakeRect(x, y, imageSize.width, imageSize.height);
if ( NSIntersectsRect(tileRect, dirtyRect) ) {
NSRect destRect = NSIntersectionRect(tileRect, dirtyRect);
[image drawInRect:destRect
fromRect:NSOffsetRect(destRect, -x, -y)
operation:NSCompositeSourceOver
fraction:1.0];
}
}
}
}
#end
No control automatically tiles a background for you.
Remember that NSViews (usually subclasses) do all the drawing - so, for instance, that gray area would be a subclass of NSView and you could put the images inside of it.
To actually draw the tiled image (by the NSView subclass), Madsen's method is usable, but not the most convenient. The easiest way is something along the lines of:
NSColor *patternColor = [NSColor colorWithPatternImage:[NSImage imageNamed:#"imageName"]];
[patternColor setFill];
NSRectFill(rectToDraw);
which you should put in the -drawRect: method of your custom view class. It creates an NSColor which represents a tiled image. Note that it can also be a subclass of a scroll/clip view, etc.
I am not too familiar with Core Animation but it is useful for manipulating views, and might be a direction you want to look at concerning the view drawing the image (and that view only).
I have two ImageViews, one called imageView and the other called subView (which is a subview of imageView).
I want to blend the images on these views together, with the user being able to switch the alpha of the blend with a pan. My code works, but right now, the code is slow as we are redrawing the image each time the pan gesture is moved. Is there a faster/more efficient way of doing this?
BONUS Q: I want to allow for my subView image to drawn zoomed in. Currently I've set my subView to be UIViewContentModeCenter, however I can't seem to draw a zoomed in part of my image with this content mode. Is there any way around this?
My drawrect:
- (void)drawRect:(CGRect)rect
{
float xCenter = self.center.x - self.currentImage1.size.width/2.0;
float yCenter = self.center.y - self.currentImage1.size.height/2.0;
subView.alpha = self.blendAmount; // Customize the opacity of the top image.
UIGraphicsBeginImageContext(self.currentImage1.size);
CGContextRef c = UIGraphicsGetCurrentContext();
CGContextSetBlendMode(c, kCGBlendModeColorBurn);
[imageView.layer renderInContext:c];
self.blendedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[self.blendedImage drawAtPoint:CGPointMake(xCenter,yCenter)];
}
You need to use GPU for image processing which is far faster than using CPU (as you're doing right now).
You can use Core Image framework which is very fast and easy to use but requires iOS 5, or you can use Open GL directly but you need to be experienced and have some knowledge about Open GL Shading.
I have an Image inside UIScrollView which i can zoom in and out.
I have a button that let the user rotate the Image 90 degrees:
(void)RotateImage {
CGAffineTransform rotateTrans = CGAffineTransformMakeRotation(-90.0 / 180.0 * 3.14);
BaseImg.transform = rotateTrans;
}
After the imaged is rotated i cannot zoom in and out.. the image is going crazy on the screen and going back to the UNRotated state.
What am i doing wrong? code examples will be great!
Thanks :)
UIScrollView likes to take over the transforms of the views it contains. There are two solutions:
Rotate the image without changing the containing view.
Create a UIView subclass that displays an image within a sublayer.
To rotate the image, see How to Rotate a UIImage 90 degrees?. If you're always and only doing 90 degree rotation, see #Peter Sarnowski's solution. To adapt it to what you're doing here, assuming that BaseImg is a UIImageView:
- (void) rotateImage
{
UIImage *sourceImage = [baseImg image];
UIImage *rotatedImage = [UIImage imageWithCGImage:[sourceImage CGImage] scale:1.0 orientation:UIImageOrientationRight];
[baseImg setImage:rotatedImage];
}
This will only rotate once. To have rotateImage work repeatedly, read the existing orientation property and move it on to the next in clockwise or anticlockwise order.
If the image is not square, you may also need to resize baseImg to reflect its new aspect ratio.
To create a UIView subclass, you need to have it store a CALayer as a sublayer of the view layer. Store the image in the sublayer, and transform the sublayer at will. This is faster, and allows arbitrary rotation, but you need to calculate your own scaling to prevent the rotate image going outside the view bounds.
To simply rotate image the code is perfect but to add zoom in and out and then add rotation you need to retain its transforms.Here is a sample code that can help you.
https://github.com/elc/iCodeBlogDemoPhotoBoard
I have an application where, in one window, there is an NSImageView. The user should be able to drag and drop ANY FILE/FOLDER (not only images) into the image view, so I subclassed NSImageView class to add support for those types.
The reason why I chose an NSImageView instead of a normal view is because I also wanted to display an animation (say an arrow pointing downwards and going up and down) when the user hovers over with files ready to drop. My question is this: what would be the best way (most efficient, quickest, least CPU usage, etc) to do this?
In fact, I have already done it, but what made me ask this question is the fact that when I set the images to change at a rate below 0.02 sec it starts to lag. Here is how I did it:
In the NSImageView subclass:
have an ivar: NSTimer* animTimer;
override awakeFromNib, calling [super awakeFromNib] and loading the images into an array (about 45 images) using NSImage
whenever user enters with files, start animTimer with frequency = 0.025 (less and it lags), and a selector that sets the next image in the array (called drawNextImage)
whenever the user exits or ends the drag and drop, call [animTimer invalidate] to stop updating images
Here is how I set the image in the subclass:
- (void)drawNextImage
{
currentImageIndex++; // ivar / kNumberDNDImages is a constant defined as 46
if (currentImageIndex >= kNumberDNDImages) { currentImageIndex = 0;}
[super setImage: [imagesArray objectAtIndex: currentImageIndex]]; // imagesArray is ivar
}
So, how would I do this quick enough? I'd like the frequency to be about 0.01 secs, but less than 0.025 lags, so that is what I have set for the moment. Oh, and my images are the correct size (+ or - one pixel or something) and they are in .png (I need the transparency - jpegs, for example, won't do it).
EDIT:
I have tried to follow NSResponder's suggestion, and have updated my method to this:
- (void)drawNextImage
{
currentImageIndex++;
if (currentImageIndex >= kNumberDNDImages) { currentImageIndex = 0;}
NSRect smallImgRect;
smallImgRect.origin = NSMakePoint(kSmallImageWidth * currentImageIndex, [self.bigDNDImage size].height); // Up left corner - ??
smallImgRect.size = NSMakeSize(kSmallImageWidth, [self.bigDNDImage size].height);
// Bottom left corner - ??
NSPoint imgPoint = NSMakePoint(([self bounds].size.width - kSmallImageWidth) / 2, 0);
[bigDNDImage drawAtPoint: imgPoint fromRect: smallImgRect operation: NSCompositeCopy fraction: 1];
}
I have also moved this method and the other drag and drop methods from the NSImageView subclass to an NSView subclass I already had. Everything is exactly the same, except for the superclass and this method. I also modified some constants.
In my early testing of this, I got some error/warning messages that didn't stop execution talking abou NSGraphicsContext or something. These have disappeared now, but just so you know. I have absolutely no idea why they were appearing and what they mean. If they ever appear again I'll worry about them, not now :)
EDIT 2:
This is what I'm doing now:
- (void)drawNextImage
{
currentImageIndex++;
if (currentImageIndex >= kNumberDNDImages) { currentImageIndex = 0;}
[self drawCurrentImage];
}
- (void)drawCurrentImage
{
NSRect smallImgRect;
smallImgRect.origin = NSMakePoint(kSmallImageWidth * currentImageIndex, 0); // Bottom left, for sure
smallImgRect.size = NSMakeSize(kSmallImageWidth, [self.bigDNDImage size].height);
// Bottom left as well
NSPoint imgPoint = NSMakePoint(([self bounds].size.width - kSmallImageWidth) / 2, 0);
[bigDNDImage drawAtPoint: imgPoint fromRect: smallImgRect operation: NSCompositeCopy fraction: 1];
}
And the catch here is to call drawCurrentImage when drawRect is called (see, it actually was easier to solve than I thought).
Now, I must say I haven't tried this with the composite image, because I couldn't find a good and quick way to merge 40+ images the way I wanted (one next to the other). But for the ones ineterested, I modified this to do the same thing as my NSImageView subclass (reading 40+ images from an array and displaying them) and I found no speed bump: NSView is as laggy below 0.025 as NSImageView. Also I found some problems when using core animation (the image is drawn in weird places instead of the place I tell her to) and some warnings talking about NSGraphicsContext, which I don't know how to solve at all (I'm a complete noob when it comes to drawing and such with Objective-C's tools). So for the time being I'm using NSImageView, unless I find a way to merge all those images and try it with NSView.
Core Animation would probably be quickest, since it'll do everything on the GPU. Create a layer for each image, setting each layer's contents to the CGImage you can make from each image, add them all as sublayers of a single top-level layer, host the top-level layer in a plain NSView, and then just toggle each image layer's hidden property in turn.
I'd probably draw all of the component images into one long image, and draw segments into a view using -drawAtPoint:fromRect:operation:fraction:. I'm sure you could make it faster than that by resorting to OpenGL, though.
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.