Área Web

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Acesso a métodos 4D

You can call 4D methods from the JavaScript code executed in a Web area and get values in return. To be able to call 4D methods from a Web area, you must activate the 4D methods accessibility property ("all").

This property is only available if the Web area uses the embedded Web rendering engine.

When this property is on, a special JavaScript object named $4d is instantiated in the Web area, which you can use to manage calls to 4D project methods.

Gramática JSON

Nome	Tipo de dados	Valores possíveis
methodsAccessibility	string	"none" (padrão), "all"

Objectos suportados

Área Web

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Progressão

Nome de uma variável do tipo Longint. This variable will receive a value between 0 and 100, representing the page load completion percentage in the Web area. Atualizado automaticamente por 4D, não pode ser modificado manualmente.

As of 4D v19 R5, this variable is only updated on Windows if the Web area uses the embedded Web rendering engine.

Gramática JSON

Nome	Tipo de dados	Valores possíveis
progressSource	string	Nome de uma variável Longint

Objectos suportados

Área Web

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URL

A String type variable that designates the URL loaded or being loading by the associated Web area. The association between the variable and the Web area works in both directions:

• If the user assigns a new URL to the variable, this URL is automatically loaded by the Web area.
• Any browsing done within the Web area will automatically update the contents of the variable.

Schematically, this variable functions like the address area of a Web browser. Pode representá-lo através de uma área de texto por cima da área Web.

Variável URL e comando WA OPEN URL

The URL variable produces the same effects as the WA OPEN URL command. No entanto, há que assinalar as seguintes diferenças:

• For access to documents, this variable only accepts URLs that are RFC-compliant ("file://c:/My%20Doc") and not system pathnames ("c:\MyDoc"). The WA OPEN URL command accepts both notations.
• If the URL variable contains an empty string, the Web area does not attempt to load the URL. The WA OPEN URL command generates an error in this case.
• If the URL variable does not contain a protocol (http, mailto, file, etc.), the Web area adds "http://", which is not the case for the WA OPEN URL command.
• When the Web area is not displayed in the form (when it is located on another page of the form), executing the WA OPEN URL command has no effect, whereas assigning a value to the URL variable can be used to update the current URL.

Gramática JSON

Nome	Tipo de dados	Valores possíveis
urlSource	string	Um URL.

Objectos suportados

Área Web

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Utilizar o motor de renderização Web integrado

This option allows choosing between two rendering engines for the Web area, depending on the specifics of your application:

• unchecked - JSON value: system (default): In this case, 4D uses the "best" engine corresponding to the system. This means that you automatically benefit from the latest advances in Web rendering, through HTML5 or JavaScript. No entanto, você poderá notar algumas diferenças de renderização entre as plataformas. No Windows, 4D usa Microsoft Edge WebView2. No macOS, 4D usa a versão atual do WebKit (Safari).

On Windows, if Microsoft Edge WebView2 is not installed, 4D uses the embedded engine as system rendering engine. To know if it is installed in your system, look for "Microsoft Edge WebView2 Runtime" in your applications panel.

• checked - JSON value: embedded: In this case, 4D uses Blink engine from Google (CEF). Using the embedded Web engine means that Web area rendering and their functioning in your application are identical regardless of the platform used to run 4D (slight variations of pixels or differences related to network implementation may nevertheless be observed). Using the embedded Web engine means that Web area rendering and their functioning in your application are identical regardless of the platform used to run 4D (slight variations of pixels or differences related to network implementation may nevertheless be observed).

The Blink engine has the following limitations:

• WA SET PAGE CONTENT: usar esse comando exige que pelo menos uma página já esteja carregado na área (através da chamada a WA OPEN URL ou uma atribuição à variável URL associada à área).
• Quando se ativa soltar URLs mediante o seletor WA enable URL drop do comando WA SET PREFERENCE, a primeira soltada deve ir precedida de ao menos uma chamada a WA OPEN URL ou uma atribuição à variável URL associada à área.

Gramática JSON

Nome	Tipo de dados	Valores possíveis
webEngine	string	"embedded", "system"

Objectos suportados

Área Web