Is it possible to convert an NSGradient to an NSColor
- (void) viewWillDraw {
NSGradient *grad = [[NSGradient alloc] initWithStartingColor:[NSColor lightGrayColor] endingColor:[NSColor darkGrayColor]];
[super setBackgroundColor:*gradient*;
}
This is my method, I want to be able to pass the NSGradient in as an NSColor, which obviously i cant, is there any way to convert it to one?
On 10.8, you can create, in the following order:
A block that draws the gradient however you like.
An image that is backed by the block.
A color that repeats the image as a pattern.
In this way, you can create a color that looks like anything, including a gradient.
That said, this may not work correctly with window resizing if you try to have the gradient adapt to the size of the background (by using the rect passed to the block) and the background is of a text view in a scroll view. (When I tried it awhile back, the pattern didn't redraw the block; it simply tiled, which looked weird in at least one dimension.) If either your gradient or your window is fixed in size, then you will not have that problem.
NSGradient is not Convertible to NSColor.
The NSGradient class provides support for drawing gradient fill
colors, also known as shadings in Quartz. This class provides
convenience methods for drawing radial or linear (axial) gradients for
rectangles and NSBezierPath objects.
As you want to set the viewBackground to to an effect (Gradient effect) you need to do as:
[grad drawInRect:<the rect of your view> angle:270]; //angle is upto your requirement,
Related
I want to create an NSImage of an NSScrollView object, so I can use the flat graphic for animation purposes.
When I render my scrollview object into a graphic and add it back to my window, it works but looks really bad like it's been scaled to 99% or something. I want the image to not be scaled and 100% pixel accurate. (Note: the image isn't scaled, it's the same size, it just looks like it's been poorly rescaled - the text looks rough and poor compared to the view onscreen in the scrollview)
My code:
(scrollView is my NSScrollView object)
NSData *pdf = [scrollView dataWithPDFInsideRect:[scrollView bounds]];
NSImage *image = [[NSImage alloc] initWithData:pdf];
NSImageView *imageView = [[NSImageView alloc] initWithFrame:[scrollView bounds]];
[imageView setImage: image];
[mainGUIPanel addSubview: imageView];
I've tried a heap of things, messed with pixel sizes, bounds, used IB to create the destination NSView and put the image inside that but just cannot get the image to not look bad. Any ideas?
Edit:
I tried writing the pdf data to a pdf file and viewed it, and it looked ok. So the bitmap image is being captured ok, it's just on the display that it looks like it's being scaled somewhat.
Edit2:
Also tried getting the bitmap like this:
NSBitmapImageRep *bitmap = [scrollView bitmapImageRepForCachingDisplayInRect:[scrollView bounds]];
[scrollView cacheDisplayInRect:[scrollView bounds] toBitmapImageRep:bitmap];
NSImage * image = [[NSImage alloc] initWithSize:[bitmap size]];
[image addRepresentation: bitmap];
Same results - the bitmap looks exactly the same, bad and scaled when displayed.
This leads me to believe that capturing the bitmap data either way works fine, it's creating the view and rendering the image that is doing the scaling. How can I make sure that the view and image are shown at the correct size and scaling?
Edit3:
Ok, I started a new blank project and set this up, and it works perfectly - the new imageview is identical to the grabbed bitmap. So I suspect my issue is stemming from some rendering/compositing issue when drawing the bitmap to the view. Investigating further...
It turns out the issue stems from the scrollView that I am rendering from. This has a transparent background (Draw Background is off in IB) and the text is the scrollView looks good. If I turn "Draw Background ON", with a transparent background color, the text is rendered badly, exactly as it is when I capture the image programatically.
So, in my app, even though Draw Background is off, the scrollView image is captured as though Draw Background is on. So I need to understand why the text is rendered badly when Draw Background is on and set to transparent, and hopefully this will lead me towards a solution.
Also tried creating an NSClipview with background drawing turned off and putting the bitmap view into that, but it sill renders the same. I can't find a way to render the transparent image to the screen without horrible artifacting.
Ok, I've found a solution. Instead of getting a grab of the transparent background scrollview object itself, I'm instead getting a grab of the parent view (essentially the window background), and restricting the bounds to the size of the scrollview object.
This captures both the background, and the contents of the scrollview, and displays correctly without any issues of transparency.
Is there a way to create a colored fill pattern dynamically in Cocoa?
In particular instead of using a fixed pattern from an image file via
NSColor *fillPattern = [NSColor colorWithPatternImage:patternImage];
I'd like to create a pattern by dynamically choosing the appropriate colors at runtime.
Background is highlighting a colored object by rendering stripes or squares in the ''opposite'' color on top of it - whatever opposite might mean in this context, but that's a different story..
Being applied to potentially hundreds of objects in a drawing app it needs to be a rather fast method so I suppose just swapping colors in patternImage won't be good enough.
(It did work just fine back in QuickDraw..!)
Why not just draw to an in-memory image and use that for your pattern?
NSImage* patternImage = [[NSImage alloc] initWithSize:someSize];
[patternImage lockFocus];
//draw your pattern
[patternImage unlockFocus];
NSColor* patternColor = [NSColor colorWithPatternImage:patternImage];
//do something with the pattern color
//remember to release patternImage if you're not using ARC
Performance-wise, you generally should be looking at optimising drawing by paying attention to the rect passed in to drawRect: and making sure you only draw what is necessary. If you do that then I can't see the pattern drawing performance being a major problem.
Background is highlighting a colored object by rendering stripes or squares in the ''opposite'' color on top of it - whatever opposite might mean in this context, but that's a different story..
You'll want to use one of Quartz's blend modes (most of them are present in Photoshop, Pixelmator, and Opacity, so you can experiment in one of those apps to determine which one you need).
You should then be able to fill with a static image—or a dynamic pattern, if it's really necessary—and Quartz will blend it in appropriately.
There's no way to do this in AppKit alone; you'll need to get a CGContext from the current NSGraphicsContext and do it in Quartz.
I have a custom NSView that is used for displaying a background color. This works. However, I have shadows in that image that are not preserved.
All transparent or semi-transparent areas of the image are rendered as black. How do I fix this?
- (void)drawRect:(NSRect)dirtyRect {
NSColor *pattern = [NSColor colorWithPatternImage:[NSImage imageNamed:#"bg"]];
[pattern setFill];
NSRectFill(dirtyRect);
}
Thanks.
NSRectFill() is a shortcut for NSRectFillUsingOperation(rect, NSCompositeCopy). This means that it won't composite the color's alpha channel with the background, it simply draws the source color in the rectangle you pass in. Instead, you should use:
NSRectFillUsingOperation(rect, NSCompositeSourceOver);
The NSCompositeSourceOver compositing operation will display the source image wherever the source image is opaque and the destination image elsewhere.
I am trying to make a NSScrollView with clipped corners, similar to the Twitter app:
I have a NSScrollView subclass which I added the following code:
- (void)drawRect:(NSRect)dirtyRect {
NSBezierPath *pcath = [NSBezierPath bezierPathWithRoundedRect:[self bounds] xRadius:kDefaultCornerRadius yRadius:kDefaultCornerRadius];
[path setClip];
[super drawRect:dirtyRect];
}
I expected the content of the NSScrollView to have rounded corners, but it is not respecting the clipped path. How can I do this?
UPDATE & CLARIFICATION
I know how to make a custom NSScroller, I know how to make it transparent overlay. All I am asking is how to make the NSSCrollView clip its corners, including everything it contains. The NSScrollView is inside a NSView which has a background that could change, meaning a view overlay to fake the rounded corners is not an option.
After much fiddling, I just discovered that NSScrollView's can be made to have rounded corners by simply giving it a backing layer and setting that layer's corner radius provided you also do the same to it's internal NSClipView. Both are required, which now makes sense, since it's the clip view that actually provides the viewable window into the NSScrollView's document view.
NSScrollView * scrollView = ...;
// Give the NSScrollView a backing layer and set it's corner radius.
[scrollView setWantsLayer:YES];
[scrollView.layer setCornerRadius:10.0f];
// Give the NSScrollView's internal clip view a backing layer and set it's corner radius.
[scrollView.contentView setWantsLayer:YES];
[scrollView.contentView.layer setCornerRadius:10.0f];
You can apply a mask to a view's layer:
[myScrollView setWantsLayer: YES];
[myScrollView layer].mask = ...;
The mask is another CALayer. So in this case you'd create a CALayer, set its background colour to opaque, set its bounds to match the scrollview, and give it a cornerRadius of, say, 8.0.
The result would be that the scroll view and all its contents would appear to be masked to a roundrect with a corner radius of 8px.
Have you tried overriding
- (BOOL)isOpaque {
return NO;
}
And setting the scroll view's -setDrawsBackground: to NO and just leave the view without clipping and just draw the corners with [NSColor clearColor] since this will also clear the underlying color and simulate a round effect.
I have an app that currently has this line:
[myView setWantsLayer:YES];
In order to draw a GUI element via NSBezierPath. This line is required, otherwise when the user types in an adjacent (and overlapping) NSTextField, the contents of myView shudders.
I discovered that calling CoreAnimation loads the OpenGL framework, but does not unload it. See this question.
I think I can get around this by drawing the NSBezierPath to NSImage and then to display the NSImage in lieu of the NSBezierPath, but I haven't found a single source that shows me how to go about this.
Edit:
I should note that I want to save this BEFORE The NSBezierPath is displayed - so solutions that draw an existing view to an NSImage are not useful.
Question:
Can someone point me in the right direction for converting NSBezierPath to an NSImage?
You can draw anything directly into an NSImage, and you can create a blank NSImage. So, create an image whose size is the size of the bounds of the path, translate the path so that it's at the origin of the image, and then lock focus on the image, draw the path, and unlock focus.