Scaling according to DPI sample

This sample describes how to build an app that scales according to the dots per inch (dpi) (pixel density) of the screen by loading images of the right scale or by overriding default scaling. This sample uses the Windows.Graphics.Display API.

 
 
 
 
 
4.5 Star
(2)
26,708 times
Add to favorites
11/26/2013
E-mail Twitter del.icio.us Digg Facebook

Solution explorer

C++
C#
JavaScript
VB.NET
// Copyright (c) Microsoft. All rights reserved.
#include "pch.h"
#include "MainPage.xaml.h"
#include "Common\SuspensionManager.h"

using namespace SDKSample;
using namespace SDKSample::Common;

using namespace Concurrency;
using namespace Platform;
using namespace Windows::ApplicationModel;
using namespace Windows::ApplicationModel::Activation;
using namespace Windows::Foundation;
using namespace Windows::Foundation::Collections;
using namespace Windows::UI::Core;
using namespace Windows::UI::Xaml;
using namespace Windows::UI::Xaml::Controls;
using namespace Windows::UI::Xaml::Controls::Primitives;
using namespace Windows::UI::Xaml::Data;
using namespace Windows::UI::Xaml::Input;
using namespace Windows::UI::Xaml::Interop;
using namespace Windows::UI::Xaml::Media;
using namespace Windows::UI::Xaml::Navigation;

/// <summary>
/// Initializes the singleton application object.  This is the first line of authored code
/// executed, and as such is the logical equivalent of main() or WinMain().
/// </summary>
App::App()
{
    InitializeComponent();
    this->Suspending += ref new SuspendingEventHandler(this, &SDKSample::App::OnSuspending);
}

/// <summary>
/// Invoked when the application is launched normally by the end user.  Other entry points will
/// be used when the application is launched to open a specific file, to display search results,
/// and so forth.
/// </summary>
/// <param name="args">Details about the launch request and process.</param>
void App::OnLaunched(LaunchActivatedEventArgs^ args)
{
    auto rootFrame = dynamic_cast<Frame^>(Window::Current->Content);

    // Do not repeat app initialization when the Window already has content,
    // just ensure that the window is active
    if (rootFrame == nullptr)
    {
        // Create a Frame to act as the navigation context and associate it with
        // a SuspensionManager key
        rootFrame = ref new Frame();
        SuspensionManager::RegisterFrame(rootFrame, "AppFrame");

        auto prerequisite = task<void>([](){});
        if (args->PreviousExecutionState == ApplicationExecutionState::Terminated)
        {
            // Restore the saved session state only when appropriate, scheduling the
            // final launch steps after the restore is complete
            prerequisite = SuspensionManager::RestoreAsync();
        }
        prerequisite.then([=](task<void> prerequisite)
        {
            try
            {
                prerequisite.get();
            }
            catch (Platform::Exception^)
            {
                //Something went wrong restoring state.
                //Assume there is no state and continue
            }

            if (rootFrame->Content == nullptr || args->Arguments != nullptr)
            {
                // When the navigation stack isn't restored or there are launch arguments
                // indicating an alternate launch (e.g.: via toast or secondary tile), 
                // navigate to the appropriate page, configuring the new page by passing required 
                // information as a navigation parameter
                if (!rootFrame->Navigate(TypeName(MainPage::typeid), args->Arguments))
                {
                    throw ref new FailureException("Failed to create initial page");
                }
            }
            // Place the frame in the current Window
            Window::Current->Content = rootFrame;
            // Ensure the current window is active
            Window::Current->Activate();

        }, task_continuation_context::use_current());
    }
    else
    {
        if (rootFrame->Content == nullptr || args->Arguments != nullptr)
        {
            // When the navigation stack isn't restored or there are launch arguments
            // indicating an alternate launch (e.g.: via toast or secondary tile), 
            // navigate to the appropriate page, configuring the new page by passing required 
            // information as a navigation parameter
            if (!rootFrame->Navigate(TypeName(MainPage::typeid), args->Arguments))
            {
                throw ref new FailureException("Failed to create initial page");
            }
        }
        // Ensure the current window is active
        Window::Current->Activate();
    }
}

/// <summary>
/// Invoked when application execution is being suspended.  Application state is saved
/// without knowing whether the application will be terminated or resumed with the contents
/// of memory still intact.
/// </summary>
/// <param name="sender">The source of the suspend request.</param>
/// <param name="e">Details about the suspend request.</param>
void App::OnSuspending(Object^ sender, SuspendingEventArgs^ e)
{
    (void) sender;    // Unused parameter

    auto deferral = e->SuspendingOperation->GetDeferral();
    SuspensionManager::SaveAsync().then([=]()
    {
        deferral->Complete();
    });
}