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Mobile Tutorial: Using a MultiView Component to Display Alternate Views of Information (iOS and Android)

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About the TMultiView Component

The FMX.MultiView.TMultiView component represents a container (the master pane) for other controls, and provides a way for you to easily present alternate views of information. The TMultiView component allows you to implement a master-detail interface, which can be used for any supported target platform.

  • The master pane can display a collection of any visual controls, such as edit boxes, labels, lists, and so forth.
  • The detail pane typically displays information based on the properties of the controls in the master pane.

The following screen illustrates an example master-detail interface. In the master pane (the left docked panel), you enter a geographical position, and then click Search to cause the detail pane (the right panel) to display the appropriate Google map.

TMultiViewSample.png

Master Pane Presentation Modes

The TMultiView class defines a set of properties that allow you to control the interface behavior. For example, the TMultiView.Mode property specifies the master pane presentation mode as described in the following table:

TMultiView.Mode Master Pane Presentation
Drawer In the Drawer mode, the master pane can be whether hidden or can slide to overlap the detail pane.
Panel Master and detail panels are always displayed, independently of a device type and orientation. The master panel is docked to the left or right of the MultiView component.
PlatformBehaviour An application automatically selects the master pane presentation mode. See the Platform Dependent Behavior Mode subsection.
Popover Pop-up menu.
NavigationPane Navigation pane.
Custom The user can customize the master pane presentation. The custom presentation class should be set in the CustomPresentationClass property. See the Custom Mode subsection.

Note: At design time, after you change the TMultiView.Mode property value in the Object Inspector, the master pane might become invisible. To work around this issue, on the Form Designer, select the TMultiView component, and then in the Object Inspector, set the Visible property to True.

Note: At design time, you can show/hide TMultiView by two ways:

  1. In Structure View, right-click a TMultiView node and select the Show or Hide commands.
  2. In Structure View, double-click a TMultiView node.

Drawer Mode

If you set the TMultiView.Mode property to Drawer (using TDrawerAppearance.Mode=OverlapDetailView), the master pane is initially hidden. To display the master pane, the user swipes right from the left edge of the screen, as shown in the following animated image:

TMultiView Drawer.gif

Popover Mode

You can also set the TMultiView.Mode property to Popover to make the master pane a pop-up menu that is displayed next to the Master button specified in the TMultiView.MasterButton property.

TMultiView Popover.png

Important: In the Popover mode, you must set the TMultiView.MasterButton property. This property refers to a UI element that displays or hides the master panel. In the above screen, the Master button is the Show/Hide button.

Navigation Pane Mode

If you set the TMultiView.Mode property to NavigationPane, the master pane is initially displayed as a minimized docked panel. You can control the initial width of this panel with the CollapsedWidth property (by default, CollapsedWidth=50).

Initially minimized Navigation Pane

NavigationPane collapsed.png

Tip To clip any portion of child elements moved outside the minimized Navigation Pane, set the TMultiview.ClipChildren property to True.

To expand the navigation panel to display all child controls, tap the Master button specified in the TMultiView.MasterButton property.

Expanded Navigation Pane

NavigationPane enlarged.png

Important: In the Navigation Pane mode, you must set the TMultiView.MasterButton property. This property refers to a UI element that collapses or expands the master panel. In the above screen, the Master button is the Master button.png

Platform Dependent Behavior Mode

You can let the application automatically select the master pane presentation mode, if the TMultiView.Mode property is set to PlatformBehaviour. For this setting, the application behavior depends on the device type and orientation, as described in the following table:

Device Type Device Orientation   Master Pane Presentation
Phone Landscape, Portrait Drawer (push/overlap)
Tablet Landscape Docked panel
Tablet Portrait Drawer (push/overlap)

Custom Mode

In Custom mode, you can customize the master pane presentation to conform to your tasks. To customize the master pane presentation, perform the following basic steps:

  1. Declare your own class, such as MyPresentationClass that descends from TMultiViewPresentation or from other classes that were declared in the FMX.MultiView.Presentations unit.
  2. In the MyPresentationClass, optionally, override the following virtual methods defined in the base class: These methods define the master pane behavior.
  3. In the Form Designer, select the TMultiView component, and then in the Object Inspector, set its property Mode to Custom.
  4. Implement the onFormCreate event handler as follows:
    • For Delphi:
     
    procedure TForm1.FormCreate(Sender: TObject);
    begin
      MultiView1.CustomPresentationClass := MyPresentationClass;
    end;
    • For C++:
    void __fastcall TForm1::FormCreate(TObject *Sender)
    {
      MultiView1->CustomPresentationClass = __classid(MyPresentationClass);
    }

This topic helps you develop a simple application that illustrates the use of the TMultiView component.

Designing the User Interface

  1. Create a blank Multi-Device Application, by selecting:
    • For Delphi: File > New > Multi-Device Application - Delphi > Blank Application
    • For C++: File > New > Multi-Device Application - C++Builder > Blank Application
  2. Select the TMultiView component in the Tool Palette, and drop it on the Form Designer.
  3. Drop other controls, such as buttons, edit boxes or any other controls you need onto the MultiView container.
  4. In the Tool Palette, select a component you want to use as a detail pane (such as TPanel), and drop any controls onto this panel.
  5. In the Object Inspector, specify the appropriate properties of the TMultiView component.

To clarify this procedure, the following sections consider a particular example: an application that controls the mobile device camera.

Designing the Master Pane

  1. Select the TMultiView component in the Tool Palette, and drop it on the Form Designer.
  2. Drop two TButton components into the TMultiview container, and then in the Object Inspector specify the following properties of those buttons:
    • Set the Name property to bStartCamera and bStopCamera, respectively.
    • Set the Text property to Start Camera and Stop Camera, respectively.
  3. Drop a TLabel component into the TMultiview container, and then in the Object Inspector, set its Text property to Camera type:.
  4. Drop two TButton components into the TMultiview container, and then in the Object Inspector specify the following properties of those buttons:
    • Set the Name property to bFrontCamera and bBackCamera, respectively.
    • Set the Text property to Front and Back, respectively.

Designing the Detail Pane

  1. Select the TPanel component in the Tool Palette, and drop it on the Form Designer.
  2. In the Object Inspector, set the TPanel.Align property to Client.
  3. Drop the TCameraComponent into the TPanel container.
  4. Drop the TImage into the TPanel container, and set the following properties:
    • Name = imgCameraView
    • Align = Client

TMultiView Design.png

Tip: Put all elements of the details pane into a unique container (a TPanel component in our example). This container should be specified in the TMultiView.TargetControl property.

Implementing the Camera Buttons Functionality

To complete the application development, you should implement event handlers for the application buttons and the GetImage private method that gets an image from the device camera.

To implement the OnClick event handlers

  1. On the Form Designer, double-click the Start Camera button, and insert the following code:
    • For Delphi:
    procedure TForm1.bStartCameraClick(Sender: TObject);
    begin
       CameraComponent1.Active := true;
    end;
    • For C++:
    void __fastcall TForm1::bStartCameraClick(TObject *Sender)
    {
    CameraComponent1->Active = true;
    }
  2. Double-click the Stop Camera button, and insert the following code:
    • For Delphi:
    procedure TForm1.bStopCameraClick(Sender: TObject);
    begin
       CameraComponent1.Active := false;
    end;
    • For C++:
    void __fastcall TForm1::bStopCameraClick(TObject *Sender)
    {
    CameraComponent1->Active = false;
    }
  3. Double-click the Front button, and insert the following code:
    • For Delphi:
    procedure TForm1.bFrontCameraClick(Sender: TObject);
    begin
      CameraComponent1.Active := False;
      CameraComponent1.Kind := FMX.Media.TCameraKind.FrontCamera;
      CameraComponent1.Active := True;
    end;
    • For C++:
    void __fastcall TForm1::bFrontCameraClick(TObject *Sender) {
    	// select Front Camera
    	CameraComponent1->Active = false;
    	CameraComponent1->Kind = TCameraKind::FrontCamera;
    	CameraComponent1->Active = true;
    }
  4. Double-click the Back button, and insert the following code:
    • For Delphi:
    procedure TForm1.bBackCameraClick(Sender: TObject);
    begin
      CameraComponent1.Active := False;
      CameraComponent1.Kind := FMX.Media.TCameraKind.BackCamera;
      CameraComponent1.Active := True;
    end;
    • For C++:
    void __fastcall TForm1::bBackCameraClick(TObject *Sender) {
    	// select Back Camera
    	CameraComponent1->Active = false;
    	CameraComponent1->Kind = TCameraKind::BackCamera;
    	CameraComponent1->Active = true;
    }

To implement the onSampleBufferReady event handler

  • In the Form Designer, double-click the CameraComponent1 and implement the following code:
    • For Delphi:
    procedure TForm1.CameraComponent1SampleBufferReady(Sender: TObject;
      const ATime: Int64);
    begin
           TThread.Synchronize(TThread.CurrentThread, GetImage);
    end;
    • For C++:
    void __fastcall TForm1::CameraComponent1SampleBufferReady(TObject *Sender,
    		  const __int64 ATime)
    {
    	GetImage();
    }

For the TForm1 class, you should implement the private method GetImage. The onSampleBufferReady event handler calls this method to get the image from the device camera.

Do the following:

  1. In the private section of the TForm1 class, declare the GetImage method:
    • For Delphi:
     private
        { Private declarations }
        procedure GetImage;
    • For C++:
    • In the header file (.h file), add the following code:
    private:	// User declarations
    	void __fastcall GetImage();
  2. Implement the GetImage method as follows:
    • For Delphi:
    procedure TForm1.GetImage;
    begin
      CameraComponent1.SampleBufferToBitmap(imgCameraView.Bitmap, True);
    end;
    • For C++:
    void __fastcall TForm1::GetImage()
    {
    	CameraComponent1->SampleBufferToBitmap(imgCameraView->Bitmap, true);
    }

Setting the TMultiView Component Properties

In the Form Designer, select the TMultiView component, and then in the Object Inspector, set the following properties:

  • TargetControl = Panel1
  • Mode = Drawer
  • Visible = True
  • Expand the DrawerOptions node, and set the Mode property to OverlapDetailView.
  • Expand the ShadowOptions node, and set the Color property to Beige. (This property defines the color of the master panel shadow. You can use any available color.)

Running the Example Application

To run this application, do the following:

  1. In the Project Manager, select the target platform (supported platforms: Android or iOS).
  2. Press Shift+Ctrl+F9 to run the application without debugging.
  3. To open the master panel, swipe right from the left edge of the device screen.
  4. To activate the device camera, on the master panel, click Start Camera.
  5. Optionally, you can select the front or back camera (if available) by using the Front or Back button, respectively.

Camera Apps.png

To close the master panel, slide it left.

Mobile Product Samples that Use TMultiView

Go to the Mobile Samples folder in C:\Users\Public\Documents\Embarcadero\Studio\19.0\Samples.

See Also

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