The Xcode asset catalogue editor supports an Alignment property for images. It very much seems like this is intended as a mechanism for setting a UIImage's alignmentRectInsets, and Apple's Asset catalogue reference strongly suggests this too:
alignment-insets
Dictionary
The insets for alignmentRectInsets in UIImage or for alignmentRect in NSImage. The inset tag can be omitted.
However, when I load images from a catalogue that I've set an Alignment on with the editor, it don't get an alignment.
I'm loading images using [UIImage imageNamed:].
Is this a known bug, or is there some subtlety I am missing?
I've done some testing and I think I've found why it wasn't working.
There's a (small) Bug
If you don't set all of the alignment values in the asset catalogue editor to something other than 0, then none of the alignment values will be honoured when you load that image resource. As it is perfectly reasonable for some alignment values to be 0, I believe this is a bug and I'll raise it on Radar. However – this said, the feature is still pretty useful and I plan to use it.
Pixels & Points
It's worth knowing that the Alignment, that you set in the asset catalogue editor for a multi-scale PNG, is defined in pixels and not in points.
When you load the asset and then ask the image for its alignmentRectInsets, the result is reported in points. Ie, the scale factor of that particular asset will be applied to the values that you set in the editor.
An example: if you set an alignment of 30, 30, 30, 30 on your #3x asset, then load the UIImage, you'll see it's alignmentRectInsets are 10, 10, 10, 10.
Vector Assets
I also tested a vector asset. Here, you have one vector image, and you specify one set of alignment values for it.
In this case of a single vector asset, the Alignment in the asset catalogue editor is defined in points and not in pixels. This is the opposite situation to a multi-scale PNG!
When you load the asset and ask for its aligmentRectInsets, then you'll see the same values reported, regardless of scale the UIKit loads for that image.
… This actually makes sense, and wouldn't work if done differently. But it seems like it might catch people out.
Related
The Problem
I am loading the classic serife.fon file from Microsoft Windows using FreeType.
Here is how I set the size:
FT_Set_Pixel_Sizes(face, 0, fontHeight);
I use 0 for the fontWidth so that it will be auto-calculated based on the height.
How do I find the correct value for fontHeight such that the resulting font will be exactly 9 pixels tall?
Notes
Using trial and error, I know that the correct value is 32 - but I don't understand why.
I am not sure how relevant this is for bitmap fonts, but according to the docs:
pixel_size = point_size * resolution / 72
Substituting in the values:
point_size = 32
resolution = 96 (from FT_Get_WinFNT_Header)
gives:
pixel_size = 42.6666666
This is a long way from our target height of 9!
The docs do go on to say:
pixel_size computed in the above formula does not directly relate to the size of characters on the screen. It simply is the size of the EM square if it was to be displayed. Each font designer is free to place its glyphs as it pleases him within the square.
But again, I am not sure if this is relevant for bitmap fonts.
fon files are exe files with a fnt payload, where the fnt payload can be a vector or raster font. If this is a raster font (which is most likely) then the dfPixHeight value in the fnt header will tell you what size it's meant to be, which is exposed by FreeType2 as the pixel_height field of the FT_WinFNT_Header.
(And of course, note that using any size other than "the actual raster-size of the FNT" is going to lead to hilarious headaches because bitmap scaling is the kind of madness that's so bad, OpenType instead went with "just embed as many bitmaps as you need, at however many sizes you need, because that's the only way your bitmaps are going to look good")
The FNT-specific FT2 documentation can be found over on https://www.freetype.org/freetype2/docs/reference/ft2-winfnt_fonts.html but you may need to read it in conjunction with https://jeffpar.github.io/kbarchive/kb/065/Q65123 (or https://web.archive.org/web/20120215123301/http://support.microsoft.com/kb/65123) to find any further mappings that you might need between names/fields as defined in the FNT spec and FT2's naming conventions.
From Apples documentation I read:
An alternative to creating bitmap images is to use template images or symbol images instead. Template images specify the shape you want to draw, but not the associated color information. Symbol images are similar to template images but are vector based, so they scale to different sizes. Both types of images simplify the process for supporting Dark Mode. They also reduce the number of image assets you must ship with your app.
Do I understand this correct that I can not use a vector based symbol image set as a replacement for bitmap but scalable?
Update
My situation:
I've an Image Set in my iOS project. There I can add three bitmaps for the three scaling options iOS devices support. Those images must be of type *.png
Now I would like to replace those three bitmaps with a single vector graphic file *.svg. This seems not possible. If I want to use vector graphic images I've to add another asset type called "symbol image set" (Xcode -> Editor -> Add Assets -> New Symbol Image Set).
So far so good but now my question. Those "symbol image set" assets only the the shape but not the color information into account. That's why I would like the "old" way where the color information is taken into account but the file being a vector graphics file (*.svg).
You don't actually need a Symbol Set for what you are trying to achieve.
All you need is a vector image in pdf format, marking it as Single Scale
Then, you can mark the asset as template (meaning you can tint it with any color) or original if you want to retain its original colors.
Finally, note that although you supply vector images, Xcode by default will produce png versions for all scales behind the scenes. If you need to preserve the vector data (which can help in some cases where you need to upscale) you can enable Preserve Vector Data as well.
how can I set height and width in scaling and can I depend on the image generated (quality and professional scale generation).
how can I set height and width in scaling
You can't. Specify a maxSize for each scaling.sizes entry and Fine Uploader will proportionally scale the image.
can I depend on the image generated (quality
Quality will be limited if you rely on the browser only. There is an entire section in the documentation that explains how you can generate higher-quality resizes by integrating a third-party resize library. I also discuss why you may or may not want to do this. From the documentation:
Fine Uploader's internal image resize code delegates to the drawImage
method on the browser's native CanvasRenderingContext2D object. This
object is used to manipulate a element, which represents a
submitted image File or Blob. Most browsers use linear interpolation
when resizing images. This can lead to extreme aliasing and moire
patterns which is a deal breaker for anyone resizing images for
art/photo galleries, albums, etc. These kinds of artifacts are
impossible to remove after the fact.
If speed is most important, and precise scaled image generation is not
paramount, you should continue to use Fine Uploader's internal scaling
implementation. However, if you want to generate higher quality scaled
images for upload, you should instead use a third-party library to
resize submitted image files, such as pica or limby-resize. As of
version 5.10 of Fine Uploader, it is extremely easy to integrate such
a plug-in into this library. In fact, Fine Uploader will continue to
properly orient the submitted image file and then pass a properly
sized to the image scaling library of your choice to receive
the resized image file, along with the original full-sized image file
drawn onto a for reference. The only caveat is that, due to
issues with scaling larger images in iOS, you may need to continue to
use Fine Uploader's internal scaling algorithm for that particular OS,
as other third-party scaling libraries most likely do not contain
logic to handle this complex case. Luckily, that is easy to account
for as well.
If you'd like to, for example, use pica to generate higher-quality
scaled images, simply pull pica into your project, and contribute a
scaling.customResizer function, like so:
scaling: {
customResizer: !qq.ios() && function(resizeInfo) {
return new Promise(function(resolve, reject) {
pica.resizeCanvas(resizeInfo.sourceCanvas, resizeInfo.targetCanvas, {}, resolve)
})
},
...
}
I am trying to modify the default I-beam cursor image. I'm using [[[NSCursor IBeamCursor] image] representations], passing each one through a CIFilter and adding it to a new image. However, the resulting cursor looks as though it is rendering the low-resolution images.
The High Resolution Guidelines say:
For custom cursors, you can pass a multirepresentation TIFF to the NSCursor class method initWithImage:hotSpot:.
So I would expect this to work. Additionally, if I get the -TIFFRepresentation of the original image and my modified image, and write them to disk, they both look like multi-page TIFF files with the same size images. What could I be doing wrong?
I have a somewhat-temporary solution: manually call -setSize: on each image representation, dividing the pixel height and width by the screen's scale factor. However, this technique doesn't seem like it will work ideally with multiple screens.
You're right on. I've been debugging this all day and I'm pretty sure I've got it nailed. I'm not doing exactly the same thing you are (my images are loaded from a file) but the end result is exactly the same.
The trick is to set the first representation of the multi-representation image to the non-retina size. If you are loading your cursors from an image file, you must take this extra step to adjust the size of the representations to match. It doesn't work 'out-of-the-box' as you would expect.
I've tested this on a machine with two monitors and dragging the window from the retina display to the non-retina display acts as it should, displaying the high/low resolution images for the cursor.
I had a similar problem a while ago: I had my cursor in a PDF, and it always drew as if it was a pixel image at 1:1 size, blown up. There's a solution to that in NSCursor: Using high-resolution cursors with cursor zoom (or retina).
Maybe someone can use that technique to solve this problem? My guess is creating an image with the same size but a different CTM marks it as the same size but Retina. What #jtbrandes is doing probably marks it as a different size and non-Retina. So you're effectively losing the scale factor information. If you create an image with a CTM in the hints, maybe you can draw the filtered images into it and it'll be detected right.
There seems no way to change font size or style in code, right?? It seems the only way is to duplicate the font files and load them all when program starts??
Thanks
SpriteFonts convert a font, with style, size, and other parameters, to a pixel-based format for use as a texture within XNA. Those pixels are static, so yes, there is no way to change them, short of looping through per pixel.
However there is scaling (though it won't look so great scaling larger) to help with size adjustments needed, plus you could, like you said, create multiple SpriteFont files from the same base font for different styles, and dynamically choose one of those sprite font "textures" within your code.
Beyond that, for true fully dynamic runtime usage, you'd need to essentially create these sprite font textures on the fly, in memory. This means you'd have to do what the SpriteFont Content Pipeline project does but at runtime instead. This is possible in WinForms, but as far as I know not really an option for WP7 as you apparently are using.