Scenario 2
Background
You are developing a Windows Store app named Picture Sharer. The app will allow users to capture, modify,
caption, and share pictures.
Application Structure
The SharelmageButton and GetContactsButton controlsuse the same foreground color. The foreground color
might change in the future.
The following code defines a custom button style named ButtonStyleRed:
Relevant portions of the app files are shown. (Linenumbers are included for reference only and include a two-character prefix that denotes the specific file to which they belong.)
Business Requirements
The app must meet the following business requirements:
– Allow users to capture and retrieve pictures, modify pictures by adding a shading effect, and add captions to
images.
– Support only Landscape and Landscape-flipped orientations.
– Ensure that users can select and modify images from the PictureChooserPaqe page.
– Ensure that users can change the magnification ofthe selected image and resize the image by using pinch
and stretch gestures. Scaling should be fluid and precisely controlled by the user.
The app must be localized for the French Canadian market.
Technical Requirements
The app must meet the following technical requirements:
– Scroll bars must not be visible.
– The CaptionTextBlock and CaptionTextBox controls must appear side by side, without overlapping and on the
same line. The CaptionTextBox control should appearto the right of the CaptionTextBlock control.
– The ContactPicker object must be filtered to display only email addresses.
– Minimize the code that is required to implement optical zoom functionality.
You must perform the following tasks:
– Handle the Click event of the GetPictureButton control to switch from the current page to the
PictureChooserPage page.
– After the user selects an image on the PictureChooserPage page, ensure that the app navigates back to the
PictureSharerMainPage page.
– Track the current screen orientation and page size by updating the _currentViewState, _currentHeight, and
_currentWidth fields every time the screen orientation or page size changes.
– Create a style named ButtonStyleWhite that inherits all the style settings of the ButtonStyleRed style except
the border color; the border color must be white. The ButtonStyleWhite style must automatically updatewith any
changes that are made to the ButtonStyleRed style.
– Create a resource named ButtonForegroundColor to implement the button foreground color so that it can be
referenced in XAML by using the following standard syntax:
Foreground=”{StacicResource ButtonForegroundColor}”
– Ensure that the OnNavigatedTo() method updates the current picture when a new picture is selected.
– Change the background for the root Grid element to a vertical gradient that transitions from black at the top to
maroon at the bottom. Create a resource named GridBackgroundGradientBrush to hold the requested gradient.
While testing the app, you observe the following results:
– An exception is being thrown in the GetContactsCompleted event handler when the retrieved email address is
assigned to the RecipientsTextBlock control. The exception message states:
“The application called an interface that was marshalled for a different thread.”
– When users navigate away from the PictureSharerMainPage page, information that was entered in the
CaptionTextBox control is lost.
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How should you complete the relevant code? (To answer, drag the appropriate code segments to the correct
locations in the answer area. Each code segment maybe used once, more than once, or not at all. You may
need to drag the split bar between panes or scroll to view content.)
Answer:
Explanation:
