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uJSExtension.pas
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uJSExtension.pas
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unit uJSExtension;
{$MODE Delphi}
{$I ..\..\..\..\source\cef.inc}
interface
uses
{$IFDEF DELPHI16_UP}
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls, Vcl.ComCtrls,
{$ELSE}
LCLIntf, LCLType, LMessages, Messages, SysUtils, Variants, Classes, Graphics,
Controls, Forms, Dialogs, StdCtrls, ExtCtrls, ComCtrls,
{$ENDIF}
uCEFChromium, uCEFWindowParent, uCEFInterfaces, uCEFApplication, uCEFTypes, uCEFConstants,
uCEFWinControl;
const
MINIBROWSER_SHOWTEXTVIEWER = WM_APP + $100;
MINIBROWSER_CONTEXTMENU_SETJSEVENT = MENU_ID_USER_FIRST + 1;
MINIBROWSER_CONTEXTMENU_JSVISITDOM = MENU_ID_USER_FIRST + 2;
MINIBROWSER_CONTEXTMENU_SHOWDEVTOOLS = MENU_ID_USER_FIRST + 3;
MINIBROWSER_CONTEXTMENU_OFFLINE = MENU_ID_USER_FIRST + 4;
MOUSEOVER_MESSAGE_NAME = 'mouseover';
CUSTOMNAME_MESSAGE_NAME = 'customname';
type
{ TJSExtensionFrm }
TJSExtensionFrm = class(TForm)
NavControlPnl: TPanel;
Edit1: TEdit;
GoBtn: TButton;
CEFWindowParent1: TCEFWindowParent;
Chromium1: TChromium;
StatusPnl: TPanel;
Timer1: TTimer;
procedure FormShow(Sender: TObject);
procedure GoBtnClick(Sender: TObject);
procedure Chromium1BeforeContextMenu(Sender: TObject;
const browser: ICefBrowser; const frame: ICefFrame;
const params: ICefContextMenuParams; const model: ICefMenuModel);
procedure Chromium1ContextMenuCommand(Sender: TObject;
const browser: ICefBrowser; const frame: ICefFrame;
const params: ICefContextMenuParams; commandId: Integer;
eventFlags: Cardinal; out Result: Boolean);
procedure Chromium1ProcessMessageReceived(Sender: TObject;
const browser: ICefBrowser; const frame: ICefFrame; sourceProcess: TCefProcessId;
const message: ICefProcessMessage; out Result: Boolean);
procedure Chromium1AfterCreated(Sender: TObject; const browser: ICefBrowser);
procedure Timer1Timer(Sender: TObject);
procedure Chromium1BeforePopup(Sender: TObject;
const browser: ICefBrowser; const frame: ICefFrame; const targetUrl,
targetFrameName: ustring;
targetDisposition: TCefWindowOpenDisposition; userGesture: Boolean;
const popupFeatures: TCefPopupFeatures; var windowInfo: TCefWindowInfo;
var client: ICefClient; var settings: TCefBrowserSettings;
var extra_info: ICefDictionaryValue;
var noJavascriptAccess: Boolean; var Result: Boolean);
procedure FormCreate(Sender: TObject);
procedure FormCloseQuery(Sender: TObject; var CanClose: Boolean);
procedure Chromium1Close(Sender: TObject; const browser: ICefBrowser;
var aAction : TCefCloseBrowserAction);
procedure Chromium1BeforeClose(Sender: TObject;
const browser: ICefBrowser);
protected
FText : string;
// Variables to control when can we destroy the form safely
FCanClose : boolean; // Set to True in TChromium.OnBeforeClose
FClosing : boolean; // Set to True in the CloseQuery event.
FOffline : boolean;
procedure BrowserCreatedMsg(var aMessage : TMessage); message CEF_AFTERCREATED;
procedure BrowserDestroyMsg(var aMessage : TMessage); message CEF_DESTROY;
procedure ShowTextViewerMsg(var aMessage : TMessage); message MINIBROWSER_SHOWTEXTVIEWER;
procedure WMMove(var aMessage : TWMMove); message WM_MOVE;
procedure WMMoving(var aMessage : TMessage); message WM_MOVING;
procedure WMEnterMenuLoop(var aMessage: TMessage); message WM_ENTERMENULOOP;
procedure WMExitMenuLoop(var aMessage: TMessage); message WM_EXITMENULOOP;
function SwitchOfflineMode : integer;
public
{ Public declarations }
end;
var
JSExtensionFrm: TJSExtensionFrm;
procedure CreateGlobalCEFApp;
implementation
{$R *.lfm}
uses
uSimpleTextViewer, uCEFMiscFunctions, uTestExtensionHandler, uCEFDictionaryValue;
// BASIC CONCEPTS
// ==============
// Chromium uses several processes to carry out all the tasks needed to handle a web page :
// 1. The main application process is called "BROWSER PROCESS" and it runs the UI.
// 2. The layout and interpretation of HTML is done in the "RENDERER PROCESS".
// Read this for more details about Chromium's architecture :
// http://www.chromium.org/developers/design-documents/multi-process-architecture
// Each process is isolated from the rest and you need to use some kind of inter-process
// communication (IPC) to send information between them. This isolation and protection is
// guaranteed by the operating system and it's the main reason Chromium uses several processes.
// In many cases, you need to use JavaScript or visit the DOM to return some results to Pascal.
// The DOM and JavaScript live in the RENDERER PROCESS, while the Pascal code of your application
// lives in the BROWSER PROCESS.
// As commented before, the operating system isolates each process and this means that you
// can't access anything declared in one process like variables, fields, classes, controls, etc.
// from a different process.
// However, CEF has several ways to send information between processes and you can also use your
// own inter-process communication methods.
// If you need to execute some JavaScript code all you need is to call TChromium.ExecuteJavaScript
// from your application's code in the BROWSER PROCESS and CEF will take care of executing that
// code in the RENDERER PROCESS.
// If you need to send a message to the RENDERER PROCESS from the BROWSER PROCESS you can use
// TChromium.SendProcessMessage.
// To send messages to the BROWSER PROCESS from the RENDERER PROCESS you can use
// ICefFrame.SendProcessMessage
// -------------- TChromium.SendProcessMessage --------------
// | | ------------------------------> | |
// | BROWSER | | RENDERER |
// | | | |
// | PROCESS | ICefFrame.SendProcessMessage | PROCESS |
// | | <------------------------------ | |
// -------------- --------------
// To receive the messages sent from the RENDERER PROCESS you need to use the
// TChromium.OnProcessMessageReceived event. This event is executed in a CEF thread that belongs
// to the BROWSER PROCESS.
// To receive the messages sent from the BROWSER PROCESS you need to use the
// TCefApplication.OnProcessMessageReceived event (GlobalCEFApp.OnProcessMessageReceived).
// This event is executed in a CEF thread that belongs to the RENDERER PROCESS.
// JAVASCRIPT EXTENSIONS
// =====================
// CEF exposes a large number of JS features for integration in client applications.
// You can use JS types, arrays, functions, extensions, objects, etc.
// All of those features are described in detail here :
// https://bitbucket.org/chromiumembedded/cef/wiki/JavaScriptIntegration.md
// One of the most interesting JS features available in CEF are the JavaScript extensions because they
// can be used to execute custom Pascal code from JavaScript.
// If you put all you know so far together you can get any result or information in Pascal from
// JavaScript following these steps :
// 1. Use TChromium.ExecuteJavaScript to execute your custom JavaScript code.
// 2. That custom JavaScript code is executed in the RENDERER PROCESS and it can call functions in your
// custom JavaScript extension, which executes Pascal code. This Pascal code is also executed in
// the RENDERER PROCESS.
// 3. The Pascal code in the JavaScript extension can use ICefFrame.SendProcessMessage to send
// information back to the BROWSER PROCESS.
// 4. The BROWSER PROCESS receives the information in the TChromium.OnProcessMessageReceived event.
// To create a JavaScript extension in CEF you have to create a new class that inherits from
// TCefv8HandlerOwn and it has to override the "execute" function. Open uTestExtensionHandler.pas
// to see an example and read this for more details about the "execute" parameters :
// https://magpcss.org/ceforum/apidocs3/projects/(default)/CefV8Handler.html
// In order to use that extension, you must register it in the GlobalCEFApp.OnWebKitInitialized event
// as you can see in the GlobalCEFApp_OnWebKitInitialized procedure on this PAS unit.
// You have to call the CefRegisterExtension function with 3 parameters :
// 1. name : The extension name.
// 2. code : Any valid JS code but in this case it includes 2 "native function" forward declarations.
// 3. Handler : An instance of your TCefv8HandlerOwn subclass.
// Notice that the code used with the CefRegisterExtension function in this demo is declaring
// "myextension.mouseover" as a function that calls the "mouseover" native function, and the
// "myextension.sendresulttobrowser" function that calls the "sendresulttobrowser" native function.
// The "execute" function in the custom TCefv8HandlerOwn subclass will compare the "name" parameter
// with the name of the of the native function used in the code that registered this extension.
// As you can see in this demo, TTestExtensionHandler.Execute compares the "name" parameter with
// "mouseover" and "sendresulttobrowser" to execute the code you want for each of those custom functions.
// TTestExtensionHandler.Execute is executed in the RENDERER PROCESS and it uses a process message
// to send some results to he BROWSER PROCESS.
// It uses TCefv8ContextRef.Current.Browser.MainFrame to call the SendProcessMessage procedure for
// the main frame.
// The message is a TCefProcessMessageRef instance and you can set the information you want to send using
// its ArgumentList property.
// You can add several items to ArgumentList using different indexes in the SetString, SetInt, SetBool,
// SetBinary, etc. functions.
// There is a size limit in the binary parameters of only a few kilobytes. Compress the binary data, use
// alternative IPC methods or use a database protected by a mutex if necessary.
// For more information about this, read the following pages :
// https://bitbucket.org/chromiumembedded/cef/wiki/JavaScriptIntegration.md#markdown-header-functions-and-extensions
// https://bitbucket.org/chromiumembedded/cef/src/b6b033a52bb3f7059d169a4c8389966c8fe2531b/include/capi/cef_v8_capi.h#lines-924
// TESTING THIS DEMO :
// ===================
// 1. Run the demo and wait until google.com is loaded
// 2. Right-click and select the "Set the mouseover event" menu option.
// 3. Move the mouse pointer over the web page and see the HTML elements in the status bar.
// When you select the "Set the mouseover event" menu option, the
// TChromium.OnContextMenuCommand event is triggered and it adds an event listener to the
// document's body. That listener calls one of the functions available in the registered
// extension called "myextension.mouseover".
// The TTestExtensionHandler.Execute function in the extension is executed and it
// uses TCefv8ContextRef.Current.Browser.MainFrame.SendProcessMessage(PID_BROWSER, msg)
// to send a process message with the results to the browser process.
// That message is received in the TChromium.OnProcessMessageReceived event and it shows
// the information in the status bar.
// If you have to debug the code executed by the extension you will need to use the
// debugging methods described in
// https://www.briskbard.com/index.php?lang=en&pageid=cef
// DESTRUCTION STEPS
// =================
// 1. FormCloseQuery sets CanClose to FALSE calls TChromium.CloseBrowser which triggers
// the TChromium.OnClose event.
// 2. TChromium.OnClose sends a CEFBROWSER_DESTROY message to destroy CEFWindowParent1
// in the main thread, which triggers the TChromium.OnBeforeClose event.
// 3. TChromium.OnBeforeClose sets FCanClose := True and sends WM_CLOSE to the form.
procedure GlobalCEFApp_OnWebKitInitialized;
var
TempExtensionCode : string;
TempHandler : ICefv8Handler;
begin
// This is a JS extension example with 2 functions and several parameters.
// Please, read the "JavaScript Integration" wiki page at
// https://bitbucket.org/chromiumembedded/cef/wiki/JavaScriptIntegration.md
TempExtensionCode := 'var myextension;' +
'if (!myextension)' +
' myextension = {};' +
'(function() {' +
' myextension.mouseover = function(a) {' +
' native function mouseover();' +
' mouseover(a);' +
' };' +
' myextension.sendresulttobrowser = function(b,c) {' +
' native function sendresulttobrowser();' +
' sendresulttobrowser(b,c);' +
' };' +
'})();';
try
TempHandler := TTestExtensionHandler.Create;
if CefRegisterExtension('myextension', TempExtensionCode, TempHandler) then
{$IFDEF DEBUG}CefDebugLog('JavaScript extension registered successfully!'){$ENDIF}
else
{$IFDEF DEBUG}CefDebugLog('There was an error registering the JavaScript extension!'){$ENDIF};
finally
TempHandler := nil;
end;
end;
procedure CreateGlobalCEFApp;
begin
GlobalCEFApp := TCefApplication.Create;
GlobalCEFApp.OnWebKitInitialized := GlobalCEFApp_OnWebKitInitialized;
GlobalCEFApp.SetCurrentDir := True;
{$IFDEF DEBUG}
GlobalCEFApp.LogFile := 'debug.log';
GlobalCEFApp.LogSeverity := LOGSEVERITY_INFO;
{$ENDIF}
end;
procedure TJSExtensionFrm.GoBtnClick(Sender: TObject);
begin
Chromium1.LoadURL(Edit1.Text);
end;
procedure TJSExtensionFrm.Chromium1AfterCreated(Sender: TObject; const browser: ICefBrowser);
begin
PostMessage(Handle, CEF_AFTERCREATED, 0, 0);
end;
procedure TJSExtensionFrm.Chromium1BeforeClose(Sender: TObject;
const browser: ICefBrowser);
begin
FCanClose := True;
PostMessage(Handle, WM_CLOSE, 0, 0);
end;
procedure TJSExtensionFrm.Chromium1BeforeContextMenu(Sender: TObject;
const browser: ICefBrowser; const frame: ICefFrame;
const params: ICefContextMenuParams; const model: ICefMenuModel);
begin
// Adding some custom context menu entries
model.AddSeparator;
model.AddItem(MINIBROWSER_CONTEXTMENU_SETJSEVENT, 'Set mouseover event');
model.AddItem(MINIBROWSER_CONTEXTMENU_JSVISITDOM, 'Visit DOM in JavaScript');
model.AddItem(MINIBROWSER_CONTEXTMENU_SHOWDEVTOOLS, 'Show DevTools');
model.AddCheckItem(MINIBROWSER_CONTEXTMENU_OFFLINE, 'Offline');
model.SetChecked(MINIBROWSER_CONTEXTMENU_OFFLINE, FOffline);
end;
procedure TJSExtensionFrm.Chromium1BeforePopup(Sender: TObject;
const browser: ICefBrowser; const frame: ICefFrame; const targetUrl,
targetFrameName: ustring; targetDisposition: TCefWindowOpenDisposition;
userGesture: Boolean; const popupFeatures: TCefPopupFeatures;
var windowInfo: TCefWindowInfo; var client: ICefClient;
var settings: TCefBrowserSettings;
var extra_info: ICefDictionaryValue;
var noJavascriptAccess: Boolean;
var Result: Boolean);
begin
// For simplicity, this demo blocks all popup windows and new tabs
Result := (targetDisposition in [CEF_WOD_NEW_FOREGROUND_TAB, CEF_WOD_NEW_BACKGROUND_TAB, CEF_WOD_NEW_POPUP, CEF_WOD_NEW_WINDOW]);
end;
procedure TJSExtensionFrm.Chromium1Close(Sender: TObject;
const browser: ICefBrowser; var aAction : TCefCloseBrowserAction);
begin
PostMessage(Handle, CEF_DESTROY, 0, 0);
aAction := cbaDelay;
end;
procedure TJSExtensionFrm.Chromium1ContextMenuCommand(Sender: TObject;
const browser: ICefBrowser; const frame: ICefFrame;
const params: ICefContextMenuParams; commandId: Integer;
eventFlags: Cardinal; out Result: Boolean);
var
TempPoint : TPoint;
TempJSCode : string;
begin
Result := False;
// Here is the code executed for each custom context menu entry
case commandId of
MINIBROWSER_CONTEXTMENU_SETJSEVENT :
if (frame <> nil) and frame.IsValid then
begin
TempJSCode := 'document.body.addEventListener("mouseover", function(evt){'+
'function getpath(n){'+
'var ret = "<" + n.nodeName + ">";'+
'if (n.parentNode){return getpath(n.parentNode) + ret} else '+
'return ret'+
'};'+
'myextension.mouseover(getpath(evt.target))}'+
')';
frame.ExecuteJavaScript(TempJSCode, 'about:blank', 0);
end;
MINIBROWSER_CONTEXTMENU_JSVISITDOM :
if (frame <> nil) and frame.IsValid then
begin
TempJSCode := 'var testhtml = document.body.innerHTML; ' +
'myextension.sendresulttobrowser(testhtml, ' + quotedstr(CUSTOMNAME_MESSAGE_NAME) + ');';
frame.ExecuteJavaScript(TempJSCode, 'about:blank', 0);
end;
MINIBROWSER_CONTEXTMENU_SHOWDEVTOOLS :
begin
TempPoint.x := params.XCoord;
TempPoint.y := params.YCoord;
Chromium1.ShowDevTools(TempPoint, nil);
end;
MINIBROWSER_CONTEXTMENU_OFFLINE :
SwitchOfflineMode;
end;
end;
// This is a simple example to set the "offline" mode in the DevTools using the TChromium methods directly.
function TJSExtensionFrm.SwitchOfflineMode : integer;
var
TempParams : ICefDictionaryValue;
begin
try
FOffline := not(FOffline);
TempParams := TCefDictionaryValueRef.New;
TempParams.SetBool('offline', FOffline);
TempParams.SetDouble('latency', 0);
TempParams.SetDouble('downloadThroughput', 0);
TempParams.SetDouble('uploadThroughput', 0);
Result := Chromium1.ExecuteDevToolsMethod(0, 'Network.emulateNetworkConditions', TempParams);
finally
TempParams := nil;
end;
end;
procedure TJSExtensionFrm.Chromium1ProcessMessageReceived(Sender: TObject;
const browser: ICefBrowser; const frame: ICefFrame; sourceProcess: TCefProcessId;
const message: ICefProcessMessage; out Result: Boolean);
begin
Result := False;
if (message = nil) or (message.ArgumentList = nil) then exit;
// This function receives the messages with the JavaScript results
// Many of these events are received in different threads and the VCL
// doesn't like to create and destroy components in different threads.
// It's safer to store the results and send a message to the main thread to show them.
// The message names are defined in the extension or in JS code.
if (message.Name = MOUSEOVER_MESSAGE_NAME) then
begin
StatusPnl.Caption := message.ArgumentList.GetString(0); // this doesn't create/destroy components
Result := True;
end
else
if (message.Name = CUSTOMNAME_MESSAGE_NAME) then
begin
FText := message.ArgumentList.GetString(0);
PostMessage(Handle, MINIBROWSER_SHOWTEXTVIEWER, 0, 0);
Result := True;
end;
end;
procedure TJSExtensionFrm.FormCloseQuery(Sender: TObject;
var CanClose: Boolean);
begin
CanClose := FCanClose;
if not(FClosing) then
begin
FClosing := True;
Visible := False;
Chromium1.CloseBrowser(True);
end;
end;
procedure TJSExtensionFrm.FormCreate(Sender: TObject);
begin
FCanClose := False;
FClosing := False;
end;
procedure TJSExtensionFrm.FormShow(Sender: TObject);
begin
StatusPnl.Caption := 'Initializing browser. Please wait...';
// GlobalCEFApp.GlobalContextInitialized has to be TRUE before creating any browser
// If it's not initialized yet, we use a simple timer to create the browser later.
if not(Chromium1.CreateBrowser(CEFWindowParent1, '')) then Timer1.Enabled := True;
end;
procedure TJSExtensionFrm.WMMove(var aMessage : TWMMove);
begin
inherited;
if (Chromium1 <> nil) then Chromium1.NotifyMoveOrResizeStarted;
end;
procedure TJSExtensionFrm.WMMoving(var aMessage : TMessage);
begin
inherited;
if (Chromium1 <> nil) then Chromium1.NotifyMoveOrResizeStarted;
end;
procedure TJSExtensionFrm.WMEnterMenuLoop(var aMessage: TMessage);
begin
inherited;
if (aMessage.wParam = 0) and (GlobalCEFApp <> nil) then GlobalCEFApp.OsmodalLoop := True;
end;
procedure TJSExtensionFrm.WMExitMenuLoop(var aMessage: TMessage);
begin
inherited;
if (aMessage.wParam = 0) and (GlobalCEFApp <> nil) then GlobalCEFApp.OsmodalLoop := False;
end;
procedure TJSExtensionFrm.ShowTextViewerMsg(var aMessage : TMessage);
begin
// This form will show the HTML received from JavaScript
SimpleTextViewerFrm.Memo1.Lines.Text := FText;
SimpleTextViewerFrm.ShowModal;
end;
procedure TJSExtensionFrm.Timer1Timer(Sender: TObject);
begin
Timer1.Enabled := False;
if not(Chromium1.CreateBrowser(CEFWindowParent1, '')) and not(Chromium1.Initialized) then
Timer1.Enabled := True;
end;
procedure TJSExtensionFrm.BrowserCreatedMsg(var aMessage : TMessage);
begin
StatusPnl.Caption := '';
CEFWindowParent1.UpdateSize;
NavControlPnl.Enabled := True;
GoBtn.Click;
end;
procedure TJSExtensionFrm.BrowserDestroyMsg(var aMessage : TMessage);
begin
CEFWindowParent1.Free;
end;
end.