I'm creating a control that allows the user to create a visual element that can be printed. The challenge is the user can change the size of visual but needs to know the actual size of the visual they are creating. In other words I have the size of the element in pixels but I need to know what the actual size of the element will be in inches.
For example if I create a button that is 96 pixels wide, I would expect it to be 1 inch long, yet the size of the button is different on different monitors with different resolutions.
Is this possible?
It is not possible in cases where you don't know the actual PPI of your monitor (such as with a projector), but here is an attempt at calculating it from a Rectangle of 96x96 device independent pixels:
var ppi = 220; //The PPI on my monitor.
var devicePixels = GetElementPixelSize(MyRectangle); //Convert WPF pixels to device pixels
var widthInInches = devicePixels.Width / ppi; //Convert pixels to inches based on the PPI.
Using this code (from How do I convert a WPF size to physical pixels?)
public Size GetElementPixelSize(UIElement element)
{
Matrix transformToDevice;
var source = PresentationSource.FromVisual(element);
if (source != null)
transformToDevice = source.CompositionTarget.TransformToDevice;
else
using (var source2 = new HwndSource(new HwndSourceParameters()))
transformToDevice = source2.CompositionTarget.TransformToDevice;
if (element.DesiredSize == new Size())
element.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
return (Size)transformToDevice.Transform((Vector)element.DesiredSize);
}
In my case, 96 translates to 144px. 144/220 is 0.65656565 inches.
To get the ppi, take a look at this question: acquire monitor physical dimension
It is not an easy task, and there is no guarantee that simply because it is rendered a certain size, it will also look that way on print. A printer also has a DPI and a paper size, after all.
You really should google on WPF, DPI and Scaling because the scaling system of WPF has some important characteristics. From the search you will find this site for a first read about the topic.
About your question is this possible? Yes it surely is! ;)
The new iPhone 5 display has a new aspect ratio and a new resolution (640 x 1136 pixels).
What is required to develop new or transition already existing applications to the new screen size?
What should we keep in mind to make applications "universal" for both the older displays and the new widescreen aspect ratio?
Download and install latest version of Xcode.
Set a Launch Screen File for your app (in the general tab of your target settings). This is how you get to use the full size of any screen, including iPad split view sizes in iOS 9.
Test your app, and hopefully do nothing else, since everything should work magically if you had set auto resizing masks properly, or used Auto Layout.
If you didn't, adjust your view layouts, preferably with Auto Layout.
If there is something you have to do for the larger screens specifically, then it looks like you have to check height of [[UIScreen mainScreen] bounds] as there seems to be no specific API for that. As of iOS 8 there are also size classes that abstract screen sizes into regular or compact vertically and horizontally and are recommended way to adapt your UI.
If you have an app built for iPhone 4S or earlier, it'll run letterboxed on iPhone 5.
To adapt your app to the new taller screen, the first thing you do is to change the launch image to: Default-568h#2x.png. Its size should be 1136x640 (HxW). Yep, having the default image in the new screen size is the key to let your app take the whole of new iPhone 5's screen.
(Note that the naming convention works only for the default image. Naming another image "Image-568h#2x.png" will not cause it to be loaded in place of "Image#2x.png". If you need to load different images for different screen sizes, you'll have to do it programmatically.)
If you're very very lucky, that might be it... but in all likelihood, you'll have to take a few more steps.
Make sure, your Xibs/Views use auto-layout to resize themselves.
Use springs and struts to resize views.
If this is not good enough for your app, design your xib/storyboard
for one specific screen size and reposition programmatically for the
other.
In the extreme case (when none of the above suffices), design the two Xibs and load the appropriate one in the view controller.
To detect screen size:
if(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
{
CGSize result = [[UIScreen mainScreen] bounds].size;
if(result.height == 480)
{
// iPhone Classic
}
if(result.height == 568)
{
// iPhone 5
}
}
The only really required thing to do is to add a launch image named "Default-568h#2x.png" to the app resources, and in general case (if you're lucky enough) the app will work correctly.
In case the app does not handle touch events, then make sure that the key window has the proper size. The workaround is to set the proper frame:
[window setFrame:[[UIScreen mainScreen] bounds]]
There are other issues not related to screen size when migrating to iOS 6. Read iOS 6.0 Release Notes for details.
Sometimes (for pre-storyboard apps), if the layout is going to be sufficiently different, it's worth specifying a different xib according to device (see this question - you'll need to modify the code to deal with iPhone 5) in the viewController init, as no amount of twiddling with autoresizing masks will work if you need different graphics.
-(id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
NSString *myNibName;
if ([MyDeviceInfoUtility isiPhone5]) myNibName = #"MyNibIP5";
else myNibName = #"MyNib";
if ((self = [super initWithNibName:myNibName bundle:nibBundleOrNil])) {
...
This is useful for apps which are targeting older iOS versions.
Here you can find a nice tutorial (for MonoTouch, but you can use the information for Non-MonoTouch-projects, too):
http://redth.info/get-your-monotouch-apps-ready-for-iphone-5-ios-6-today/
Create a new image for your splash/default screen (640 x 1136 pixel) with the name "Default-568h#2x.png"
In the iOS Simulator, go to the Hardware -> Device menu, and select "iPhone (Retina 4-inch)"
Create other images, e.g. background images
Detect iPhone 5 to load your new images:
public static bool IsTall
{
get {
return UIDevice.currentDevice.userInterfaceIdiom
== UIUserInterfaceIdiomPhone
&& UIScreen.mainScreen.bounds.size.height
* UIScreen.mainScreen.scale >= 1136;
}
}
private static string tallMagic = "-568h#2x";
public static UIImage FromBundle16x9(string path)
{
//adopt the -568h#2x naming convention
if(IsTall())
{
var imagePath = Path.GetDirectoryName(path.ToString());
var imageFile = Path.GetFileNameWithoutExtension(path.ToString());
var imageExt = Path.GetExtension(path.ToString());
imageFile = imageFile + tallMagic + imageExt;
return UIImage.FromFile(Path.Combine(imagePath,imageFile));
}
else
{
return UIImage.FromBundle(path.ToString());
}
}
It's easy for migrating iPhone5 and iPhone4 through XIBs.........
UIViewController *viewController3;
if ([[UIScreen mainScreen] bounds].size.height == 568)
{
UIViewController *viewController3 = [[[mainscreenview alloc] initWithNibName:#"iphone5screen" bundle:nil] autorelease];
}
else
{
UIViewController *viewController3 = [[[mainscreenview alloc] initWithNibName:#"iphone4screen" bundle:nil] autorelease];
}
I solve this problem here. Just add ~568h#2x suffix to images and ~568h to xib's. No needs more runtime checks or code changes.
I had added the new default launch image and (in checking out several other SE answers...) made sure my storyboards all auto-sized themselves and subviews but the retina 4 inches still letterboxed.
Then I noticed that my info plist had a line item for "Launch image" set to "Default.png", which I thusly removed and magically letterboxing no longer appeared. Hopefully, that saves someone else the same craziness I endured.
I guess, it is not going to work in all cases, but in my particular project it avoided me from duplication of NIB-files:
Somewhere in common.h you can make these defines based off of screen height:
#define HEIGHT_IPHONE_5 568
#define IS_IPHONE ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone)
#define IS_IPHONE_5 ([[UIScreen mainScreen] bounds ].size.height == HEIGHT_IPHONE_5)
In your base controller:
- (void)viewDidLoad
{
[super viewDidLoad];
if (IS_IPHONE_5) {
CGRect r = self.view.frame;
r.size.height = HEIGHT_IPHONE_5 - 20;
self.view.frame = r;
}
// now the view is stretched properly and not pushed to the bottom
// it is pushed to the top instead...
// other code goes here...
}
In a constants.h file you can add these define statements:
#define IS_IPAD UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad
#define IS_IPHONE UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone
#define IS_WIDESCREEN (fabs((double)[[UIScreen mainScreen] bounds].size.height - (double)568) < DBL_EPSILON)
#define IS_IPHONE_5 (!IS_IPAD && IS_WIDESCREEN)
To determine if your app can support iPhone 5 Retina use this:
(This could be more robust to return the type of display, 4S Retina, etc., but as it is written below, it just returns if the iPhone supports iOS5 Retina as a YES or NO)
In a common ".h" file add:
BOOL IS_IPHONE5_RETINA(void);
In a common ".m" file add:
BOOL IS_IPHONE5_RETINA(void) {
BOOL isiPhone5Retina = NO;
if(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) {
if ([UIScreen mainScreen].scale == 2.0f) {
CGSize result = [[UIScreen mainScreen] bounds].size;
CGFloat scale = [UIScreen mainScreen].scale;
result = CGSizeMake(result.width * scale, result.height * scale);
if(result.height == 960){
//NSLog(#"iPhone 4, 4s Retina Resolution");
}
if(result.height == 1136){
//NSLog(#"iPhone 5 Resolution");
isiPhone5Retina = YES;
}
} else {
//NSLog(#"iPhone Standard Resolution");
}
}
return isiPhone5Retina;
}
First of all create two xibs and attach all delegates,main class to the xib and then u can put in this condition mentioned below in your appdelegate.m file in
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
if ([[UIScreen mainScreen] bounds].size.height == 568)
{
self.ViewController = [[ViewController alloc] initWithNibName:#"ViewControlleriphone5" bundle:nil];
}
else
{
self.ViewController = [[ViewController alloc] initWithNibName:#"ViewControlleriphone4" bundle:nil];
}
you can use it any where in the program depending upon your requirements even in your ViewController classes. What matters the most is that you have created two xib files separate for iphone 4(320*480) and iphone 5(320*568)
Try the below method in a singleton class:
-(NSString *)typeOfDevice
{
if(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
{
CGSize result = [[UIScreen mainScreen] bounds].size;
if(result.height == 480)
{
return #"Iphone";
}
if(result.height == 568)
{
return #"Iphone 5";
}
}
else{
return #"Ipad";;
}
return #"Iphone";
}
You can use the Auto Layout feature and create the design using iPhone 5 screen resolution and it will work for the both 4" and 3.5" devices, but in this case you should have a enough knowledge of layout manager.
Checking bounds with 568 will fail in landscape mode. iPhone 5 launches only in portrait mode but if you want to support rotations then the iPhone 5 "check" will need to handle this scenario as well.
Here's a macro which handles orientation state:
#define IS_IPHONE_5 (CGSizeEqualToSize([[UIScreen mainScreen] preferredMode].size, CGSizeMake(640, 1136)))
The use of the 'preferredMode' call is from another posting I read a few hours ago so I did not come up with this idea.
First show this image. In that image you show warning for Retina 4 support so click on this warning and click on add so your Retina 4 splash screen automatically add in your project.
and after you use this code :
if([[UIScreen mainScreen] bounds].size.height == 568)
{
// For iphone 5
}
else
{
// For iphone 4 or less
}
I never faced such an issue with any device as I've had one codebase for all, without any hardcoded values. What I do is to have the maximum sized image as resource instead of one for each device. For example, I would have one for retina display and show it as aspect fit so it will be views as is on every device.
Coming to deciding the frame of button, for instance, at run time. For this I use the % value of the patent view, example , if I want the width to be half of parent view take 50 % of parent and same applies for height and center.
With this I don't even need the xibs.
You can use this define to calculate if you are using the iPhone 5 based on screen size:
#define IS_IPHONE_5 ( fabs( ( double )[ [ UIScreen mainScreen ] bounds ].size.height - ( double )568 ) < DBL_EPSILON )
then use a simple if statement :
if (IS_IPHONE_5) {
// What ever changes
}
Peter, you should really take a look at Canappi, it does all that for you, all you have to do is specify the layout as such:
button mySubmitButton 'Sumbit' (100,100,100,30 + 0,88,0,0) { ... }
From there Canappi will generate the correct objective-c code that detects the device the app is running on and will use:
(100,100,100,30) for iPhone4
(100,**188**,100,30) for iPhone 5
Canappi works like Interface Builder and Story Board combined, except that it is in a textual form. If you already have XIB files, you can convert them so you don't have to recreate the entire UI from scratch.
You can manually check the screen size to determine which device you're on:
#define DEVICE_IS_IPHONE5 ([[UIScreen mainScreen] bounds].size.height == 568)
float height = DEVICE_IS_IPHONE5?568:480;
if (height == 568) {
// 4"
} else {
// 3"
}
You could add this code:
if(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone){
if ([[UIScreen mainScreen] respondsToSelector: #selector(scale)]) {
CGSize result = [[UIScreen mainScreen] bounds].size;
CGFloat scale = [UIScreen mainScreen].scale;
result = CGSizeMake(result.width * scale, result.height * scale);
if(result.height == 960) {
NSLog(#"iPhone 4 Resolution");
}
if(result.height == 1136) {
NSLog(#"iPhone 5 Resolution");
}
}
else{
NSLog(#"Standard Resolution");
}
}
This is a real universal code, you can create 3 different story board:
Set your project Universal mode, and set your main story iPhone with the iPhone5 storyboard and the ipad main with iPad target storyboard, now add new storyboard target for iphone and modify the resolution for iphone 4s or less now implement your AppDelegate.m
iPhone4/4s (is the same for 3/3Gs) one for iPhone5 and make the project universal, with a new Storyboard target for iPad, now in to AppDelegate.m under the didFinishLaunching add this code:
if(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone){
UIStoryboard *storyBoard;
CGSize result = [[UIScreen mainScreen] bounds].size;
CGFloat scale = [UIScreen mainScreen].scale;
result = CGSizeMake(result.width *scale, result.height *scale);
//----------------HERE WE SETUP FOR IPHONE4/4s/iPod----------------------
if(result.height == 960){
storyBoard = [UIStoryboard storyboardWithName:#"iPhone4_Storyboard" bundle:nil];
UIViewController *initViewController = [storyBoard instantiateInitialViewController];
[self.window setRootViewController:initViewController];
}
//----------------HERE WE SETUP FOR IPHONE3/3s/iPod----------------------
if(result.height == 480){
storyBoard = [UIStoryboard storyboardWithName:#"iPhone4_Storyboard" bundle:nil];
UIViewController *initViewController = [storyBoard instantiateInitialViewController];
[self.window setRootViewController:initViewController];
}
}
return YES;
}
So you have created a Universal app for iPhone 3/3Gs/4/4s/5 All gen of iPod, and All type of iPad
Remember to integrate all IMG with myImage.png and myImage#2x.png
According to me the best way of dealing with such problems and avoiding couple of condition required for checking the the height of device, is using the relative frame for views or any UI element which you are adding to you view for example: if you are adding some UI element which you want should at the bottom of view or just above tab bar then you should take the y origin with respect to your view's height or with respect to tab bar (if present) and we have auto resizing property as well. I hope this will work for you
Rather than using a set of conditionals you can resize your view automatically using the screen size.
int h = [[UIScreen mainScreen] bounds].size.height;
int w = [[UIScreen mainScreen] bounds].size.width;
self.imageView.frame = CGRectMake(20, 80, (h-200), (w-100));
In my case I want a view that fills the space between some input fields at the top and some buttons at the bottom, so fixed top left corner and variable bottom right based on screen size. My app fills the image view with the photo taken by the camera so I want all the space I can get.
If you need to convert an already existing app to universal, you need to select corresponding xib file->show Utilities-> Show Size inspector.
In Size inspector you can see Autosizing, by using this tool you can convert to existing iOS App.
Using xCode 5, select "Migrate to Asset Catalog" on Project>General.
Then use "Show in finder" to find your launch image, you can dummy-edit it to be 640x1136, then drag it into the asset catalog as shown in the image below.
Make sure that both iOS7 and iOS6 R4 section has an image that is 640x1136. Next time you launch the app, the black bars will disappear, and your app will use 4 inch screen
Point worth notice - in new Xcode you have to add this image file Default-568h#2x.png to assets
Use the Auto Layout feature for views. It will adjust automatically to all resolutions.
Create two xibs for a controller having controller name with suffix either ~iphone or ~ipad. At compile time, Xcode will take the right xib based on the device.
Use size classes, if you want to create a single xib for both iPhone and iPad, if the view is simple enough to port to iPhone and iPad.
There is a slight problem when testing on both iOS device and iOS Simulator. It appears that simulator (XCode 6.0.1) gives switched values for width and height in [[UIScreen mainScreen] bounds].size depending on a device orientation.
So this might be a problem when determinating the right physical screen size. This code helps also to distinct all 2014. iPhone model generations:
iPhone4s
iPhone5 (and iPhone5s)
iPhone6 (and iPhone6+)
It can also be easily changed to make the distinction between e.g. iPhone6 from iPhone6+.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
CGSize iOSDeviceScreenSize = [[UIScreen mainScreen] bounds].size;
if ([UIDevice currentDevice].userInterfaceIdiom == UIUserInterfaceIdiomPhone)
{
if (iOSDeviceScreenSize.width > 568 || // for iOS devices
iOSDeviceScreenSize.height > 568) // for iOS simulator
{ // iPhone 6 and iPhone 6+
// Instantiate a new storyboard object using the storyboard file named Storyboard_iPhone6
storyboard = [UIStoryboard storyboardWithName:#"MainStoryboard_iPhone6" bundle:nil];
NSLog(#"loaded iPhone6 Storyboard");
}
else if (iOSDeviceScreenSize.width == 568 || // for iOS devices
iOSDeviceScreenSize.height == 568) // for iOS simulator
{ // iPhone 5 and iPod Touch 5th generation: 4 inch screen (diagonally measured)
// Instantiate a new storyboard object using the storyboard file named Storyboard_iPhone5
storyboard = [UIStoryboard storyboardWithName:#"MainStoryboard_iPhone5" bundle:nil];
NSLog(#"loaded iPhone5 Storyboard");
}
else
{ // iPhone 3GS, 4, and 4S and iPod Touch 3rd and 4th generation: 3.5 inch screen (diagonally measured)
// Instantiate a new storyboard object using the storyboard file named Storyboard_iPhone4
storyboard = [UIStoryboard story boardWithName:#"MainStoryboard_iPhone" bundle:nil];
NSLog(#"loaded iPhone4 Storyboard");
}
}
else if ([UIDevice currentDevice].userInterfaceIdiom == UIUserInterfaceIdiomPad)
{ // The iOS device = iPad
storyboard = [UIStoryboard storyboardWithName:#"MainStoryboard_iPadnew" bundle:nil];
NSLog(#"loaded iPad Storyboard");
}
// rest my code
}
I would suggest to use Autoresizing Mask in your applications according to your UI interface, it saves a lot of trouble and is better than making different UI for iPhone 4 and 5 screens.
What's the best way to convert a WPF (resolution-independent) width and height to physical screen pixels?
I'm showing WPF content in a WinForms Form (via ElementHost) and trying to work out some sizing logic. I've got it working fine when the OS is running at the default 96 dpi. But it won't work when the OS is set to 120 dpi or some other resolution, because then a WPF element that reports its Width as 96 will actually be 120 pixels wide as far as WinForms is concerned.
I couldn't find any "pixels per inch" settings on System.Windows.SystemParameters. I'm sure I could use the WinForms equivalent (System.Windows.Forms.SystemInformation), but is there a better way to do this (read: a way using WPF APIs, rather than using WinForms APIs and manually doing the math)? What's the "best way" to convert WPF "pixels" to real screen pixels?
EDIT: I'm also looking to do this before the WPF control is shown on the screen. It looks like Visual.PointToScreen could be made to give me the right answer, but I can't use it, because the control isn't parented yet and I get InvalidOperationException "This Visual is not connected to a PresentationSource".
Transforming a known size to device pixels
If your visual element is already attached to a PresentationSource (for example, it is part of a window that is visible on screen), the transform is found this way:
var source = PresentationSource.FromVisual(element);
Matrix transformToDevice = source.CompositionTarget.TransformToDevice;
If not, use HwndSource to create a temporary hWnd:
Matrix transformToDevice;
using(var source = new HwndSource(new HwndSourceParameters()))
transformToDevice = source.CompositionTarget.TransformToDevice;
Note that this is less efficient than constructing using a hWnd of IntPtr.Zero but I consider it more reliable because the hWnd created by HwndSource will be attached to the same display device as an actual newly-created Window would. That way, if different display devices have different DPIs you are sure to get the right DPI value.
Once you have the transform, you can convert any size from a WPF size to a pixel size:
var pixelSize = (Size)transformToDevice.Transform((Vector)wpfSize);
Converting the pixel size to integers
If you want to convert the pixel size to integers, you can simply do:
int pixelWidth = (int)pixelSize.Width;
int pixelHeight = (int)pixelSize.Height;
but a more robust solution would be the one used by ElementHost:
int pixelWidth = (int)Math.Max(int.MinValue, Math.Min(int.MaxValue, pixelSize.Width));
int pixelHeight = (int)Math.Max(int.MinValue, Math.Min(int.MaxValue, pixelSize.Height));
Getting the desired size of a UIElement
To get the desired size of a UIElement you need to make sure it is measured. In some circumstances it will already be measured, either because:
You measured it already
You measured one of its ancestors, or
It is part of a PresentationSource (eg it is in a visible Window) and you are executing below DispatcherPriority.Render so you know measurement has already happened automatically.
If your visual element has not been measured yet, you should call Measure on the control or one of its ancestors as appropriate, passing in the available size (or new Size(double.PositivieInfinity, double.PositiveInfinity) if you want to size to content:
element.Measure(availableSize);
Once the measuring is done, all that is necessary is to use the matrix to transform the DesiredSize:
var pixelSize = (Size)transformToDevice.Transform((Vector)element.DesiredSize);
Putting it all together
Here is a simple method that shows how to get the pixel size of an element:
public Size GetElementPixelSize(UIElement element)
{
Matrix transformToDevice;
var source = PresentationSource.FromVisual(element);
if(source!=null)
transformToDevice = source.CompositionTarget.TransformToDevice;
else
using(var source = new HwndSource(new HwndSourceParameters()))
transformToDevice = source.CompositionTarget.TransformToDevice;
if(element.DesiredSize == new Size())
element.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
return (Size)transformToDevice.Transform((Vector)element.DesiredSize);
}
Note that in this code I call Measure only if no DesiredSize is present. This provides a convenient method to do everything but has several deficiencies:
It may be that the element's parent would have passed in a smaller availableSize
It is inefficient if the actual DesiredSize is zero (it is remeasured repeatedly)
It may mask bugs in a way that causes the application to fail due to unexpected timing (eg. the code being called at or above DispatchPriority.Render)
Because of these reasons, I would be inclined to omit the Measure call in GetElementPixelSize and just let the client do it.
Simple proportion between Screen.WorkingArea and SystemParameters.WorkArea:
private double PointsToPixels (double wpfPoints, LengthDirection direction)
{
if (direction == LengthDirection.Horizontal)
{
return wpfPoints * Screen.PrimaryScreen.WorkingArea.Width / SystemParameters.WorkArea.Width;
}
else
{
return wpfPoints * Screen.PrimaryScreen.WorkingArea.Height / SystemParameters.WorkArea.Height;
}
}
private double PixelsToPoints(int pixels, LengthDirection direction)
{
if (direction == LengthDirection.Horizontal)
{
return pixels * SystemParameters.WorkArea.Width / Screen.PrimaryScreen.WorkingArea.Width;
}
else
{
return pixels * SystemParameters.WorkArea.Height / Screen.PrimaryScreen.WorkingArea.Height;
}
}
public enum LengthDirection
{
Vertical, // |
Horizontal // ——
}
This works fine with multiple monitors as well.
I found a way to do it, but I don't like it much:
using (var graphics = Graphics.FromHwnd(IntPtr.Zero))
{
var pixelWidth = (int) (element.DesiredSize.Width * graphics.DpiX / 96.0);
var pixelHeight = (int) (element.DesiredSize.Height * graphics.DpiY / 96.0);
// ...
}
I don't like it because (a) it requires a reference to System.Drawing, rather than using WPF APIs; and (b) I have to do the math myself, which means I'm duplicating WPF's implementation details. In .NET 3.5, I have to truncate the result of the calculation to match what ElementHost does with AutoSize=true, but I don't know whether this will still be accurate in future versions of .NET.
This does seem to work, so I'm posting it in case it helps others. But if anyone has a better answer, please, post away.
Just did a quick lookup in the ObjectBrowser and found something quite interesting, you might want to check it out.
System.Windows.Form.AutoScaleMode, it has a property called DPI. Here's the docs, it might be what you are looking for :
public const
System.Windows.Forms.AutoScaleMode Dpi
= 2
Member of System.Windows.Forms.AutoScaleMode
Summary: Controls scale relative to
the display resolution. Common
resolutions are 96 and 120 DPI.
Apply that to your form, it should do the trick.
{enjoy}