Given any screen resolution, is there a way that I can figure out the amount of points in an inch? For instance, if I wanted to create an NSView that was 8.5 inches by 11 inches (like a sheet of a paper), is there an algorithm that will allow me to obtain the correct point values for the frame across many different types of Macs and screen resolutions?
It's not straightforward. I'm not sure there's a good way. I can provide an approach, but I haven't confirmed that this works reliably:
First, you can use CGDisplayScreenSize() to get the screen's physical size in millimeters. You can obtain the CGDirectDisplayID for a screen from NSScreen, which you can, in turn, get from the window. Obtain the screen's deviceDescription and get the value for the "NSScreenNumber" key. That may need to be cast to CGDirectDisplayID.
The problem from there is that the display mode may not fill the screen. It could be letterboxed or pillarboxed. Or, it might be stretched. This should be fairly uncommon these days, but still possible. You can obtain the display mode using CGDisplayCopyDisplayMode(). To determine if it's stretched, you can examine its ioFlags to see if they contain the bitmask kDisplayModeStretchedFlag (declared in IOKit).
If it's stretched, the screen's frame will have to be mapped to its size in millimeters separately for the X and Y axes. You assume the screen's frame.width (in points) maps to the full physical width, and similarly for the height.
If the mode is not stretched, you'll have to check the aspect ratio of the frame and the screen physical size to see if it's letter- or pillarboxed. If the aspect ratios are very close, then it's presumably not. That case is similar to the stretched case, but the width and height mappings should be equivalent.
If the aspect ratios differ significantly, then you compare them. If the screen's physical aspect ratio is larger than the frame's, then the screen is physically wider than the mode is using (pillarboxed). So, you compute the mapping from points to millimeters from the two heights. If the physical aspect ratio is smaller than the logical one, then the mode is letterboxed and you use the widths to compute the mapping.
Related
I need to obtain the horizontal and vertical monitor resolution, independent of the display scaling in use by Windows. At scaling of 100%, there is no problem; GetSystemMetrics(SM_CXSCREEN) returns the actual horizontal resolution of the monitor in pixels. On a 1920 x 1080 monitor, that function returns 1920. However, if the scaling is set to 125% on the same computer, GetSystemMetrics(SM_CXSCREEN) returns 1536. The problem with that is, if I use that number in a call to BitBlt() to copy the screen, it copies only a partial screen, the left three quarters or so. My program does not know that it has to use 1920 to capture the entire screen, because Windows is telling it the horizontal monitor resolution is 1536. I tried using GetDeviceCaps() and using GetMonitorInfo() to get the monitor resolution, but they return the same values as GetSystemMetrics(). Windows is reporting a monitor resolution it is not actually using for BitBlt() and also for SetPixel(). The latter function draws to a location as though the screen resolution were 1920. For example, at scaling of 125%, SetPixel() draws a pixel at the x coordinate of 1500 not near the right edge of the screen, but at about three quarters from the left. SetPixel() will draw near the right edge of the screen if I tell it to draw at the x coordinate 1900, so evidently it is not interpreting screen coordinates as reported by GetSystemMetrics().
How can I get the actual monitor resolution in pixels, regardless of the scaling?
I found a solution:
RECT rBox;
HDC hdcScreen = GetDC(NULL);
GetClipBox(hdcScreen, &rBox);
When GetClipBox() returns, rBox contains dimensions in pixels of the entire screen, regardless of scaling factor. They are the same dimensions for all scaling factors. With screen resolution set to 1920 x 1080, the function sets rBox.left to 0 and rBox.right to 1920.
I am loading a view (shaped a circle) from a circle. I want to make sure, the circle's size adapts to various screen sizes. So far I tried placing the view inside another view, pinning the margins to the superview and then setting the superview's aspect ratio to 1:1. This gives me a circle. However, now, I want to change its size. Currently, the superview's size is specified by another subview in it, a label. Depending on the contents of the label, the superview's size changes (I have set the label's font size to Autoshrink). If I try to add a constant to the margin constraints it works, but looks the same size across different screen sizes. Also, I tried adding a multiplier, while the multiplier works for trailing and bottom margins, top and leading margins don't get affected by setting the multiplier. Below is a screenshot of the IB (Today View is the shape in the question).
You have a good start - aligning both center X & Y, 1:1 ratio. All you need to add is two sets of top/bottom and leading/trailing constraints with different priorities. Here's an example, which combined with the three constraints you have, would center a view in all orientations with a 10 point border along the narrower axis:
Priority == 750
Top == 10 points
Bottom == 10 Points
Leading == 10 points
Trailing == 10 points
Priority == 1000
Top >= 10 points
Bottom >= 10 Points
Leading >= 10 points
Trailing >= 10 points
You may see errors/warnings while doing this because IB doesn't know how to render it, but once you've completed this, you'll have what you need.
EDIT:
From memory, there are points and pixels. When and where possible, try to think in terms of points. About the only time you may wish to think in terms of pixels is with images. (There may be other measurements of graphics, but again, I'm writing from memory.)
Points should be consistent across device size - so if you have a 100x100 square in a 4 inch iPhone screen, it will be the same size on a 12.9 inch iPad Pro.
More importantly, the margins can be set the same using auto layout. A 25 point margin will be the same on both of those screen. So in my example above, you will get pretty much the largest rectangle possible across all devices since you are setting margins, not view size.
I did a dive into screen sizes last year, and these are the current screen sizes:
//iPad Pro 1366x1024
//iPad 1024x768
//iPad Mini 1024x468
//iPhone 6 Plus 736x414
//iPhone 6 677x375
//iPhone 5 568x320
//iPhone 4 480x320
So based on this the above constraints would yield a 300x300 square on an iPhone 4 (iPhone SE also) as the narrowest axis will be 320 less two 10 point margins. And on an iPad Pro 12.9 inch it will be a 1004x1004 square.
When you create constraints in code, you can also create a layoutMarginGuide with this code:
let margins = view.layoutMarginsGuide
This should be the same thing as keeping the "contain to margins" checkbox checked in IB. Essentially this is the recommended size of margins for each device. (I believe this should also include the status bar, tab and navigation bars, and even the iPhone "phone call top banner (sic)". But I've had some issues with this so YMMV.)
EDIT 2:
Putting this all together, what you are defining through "auto layout" is a very fluid way of maximizing the size of a square (or in your case, a square turned into a circle). By setting two sets of margins, one set equal to but with a high priority, you are letting auto layout know that it may break this over required constraints. The second set with greater than or equal to values is required.
Thus, in a 480x320 device, the top/bottom margin constraints that cannot be met ("equal to") can be broken, and in landscape the leading/trailing ones that cannot be met will be broken. Remember, you already set the center X/Y, so the view will be centered, and you set the 1:1 ratio so it will be square. (As long as you did not touch the priorities - the default is required.
I need to include many images of unknown origin in a report. I have no idea what the images might be: portrait or landscape fotos, large or small, or even something with an atypical shape, like a 400x80 logo.
I'd like to scale down images with the following rule: proportionally downscale until the larger side is 200. And resulting image shouldn't take more space than needed (i.e. 1000x600 should be downscaled to 200x120, not to 200x200), so that there are no unneeded blank margins around non-square images.
Is what I need possible with JasperReports?
EDIT:
To clarify: "real size" mode is almost what I need. However, I don't see a way to limit height of resulting image. As a result, if the image I want to print is a portrait foto (or has even larger height compared to width), generated PDF looks ugly; in this case I would prefer to somehow downscale it to a smaller width.
I solved the Problem of resizing images of various sizes to a fixed size with "RetainShape" by writing an ImageResizer, based on the idea of the ImageTransformer from https://stackoverflow.com/a/39320863/8957103 , using https://github.com/rkalla/imgscalr for scaling the image.
While trying to create a repeated tile overlay, I've found many questions (like this one)
mentioning that repeated images in Cocos2d must have height and width dimensions that are powers of two.
This raises two questions. First, why is this a limitation? Second, and more importantly, how can I create a repeating, scrolling image that has dimensions that are not a power of two? What if I have a really wide background (say 4000 pixels) and I want it to repeat across the X axis. What should I do in that context? I can't believe the "correct" answer is to add an additional 96 pixels to the width, and increase the height of the image to 4096, as well. That's wasted bytes!
This answer has excellent info on why the need for power of 2 textures.
Why do images for textures on the iPhone need to have power-of-two dimensions?
As for your second question, the texture does not have to be square, just both the width and height have to be a power of 2. So you could have an image that is 4096x128 repeating as your background. Keep in mind also that textures, no matter what the size, are always stored in memory in an uncompressed power of two size. So an image with width of 4000 and and an image with width of 4096 are actually using the same amount of memory.
Can anybody please tell me what is the exact difference between stretching and scaling an image? Because you can anyway set the size of image and imageView both to match your requirements.
It depends on how you define stretching, but I would divide scaling into two distinct options based on whether or not the aspect ratio is preserved. Often it is desired to preserve the aspect ratio when scaling an image.
I would consider an increase in one dimension, but not proportionally in the other to be a "stretch". Similarly, a decrease in one dimension, but not proportionally in the other would be a "squash".
You may find this Daring Fireball post interesting.
Stretching sounds like showing small size (10x10) image at (100x100) or (100x10). so some times it gets pix-elated.
And scaling means to show a image to different size either small or big with maintaining its aspect ratio (programmetically), so it will look not improper, because when you stretch to different aspect ratio then some objects in image gets improper visibility.
Stretching (in iphone IB) means '9-slice scaling', scaling means just scaling.
When stretching you can determine which part of the image may be used for stretching and which part may not. For example when you have a rounded square, you do not want the roundings to stretch, especially when you're only stretching horizontally or vertically.
You indicate that you only want to use the middle pixel to stretch by (in IB) setting the X & Y values to 0.50 (half way) and the width & height values to 0.00 (minimum amount of pixels)
Lookup contentStretch in the docs for more info
when you don,t keep the congruence of your image, you see the image incongruous and height and width of your image is not suitable for showing. for resolving this issue you can multiply your image's width and height to to a constant coefficient.
Stretching and scaling don't mean anything different except maybe in connotation.
Is there a particular piece of text somewhere that you are trying to understand? Maybe we can help with that.
stretching image is stretching the size of a small image.
on the other hand scaling of image is scaling the image accoring the the viewport's width and viewport's height....
scaling can be done by small as well as large image.
you should take a good quality image and then should scale it
sprite.setscale(x,y);