lazarus.fresnel/src/pas2js/importextensionex.pas2js.wasmapi.pp

{
    This file is part of the Fresnel Library.
    Copyright (c) 2025 by the FPC & Lazarus teams.

    Pas2js Fresnel interface - Webassembly rendering API

    See the file COPYING.modifiedLGPL.txt, included in this distribution,
    for details about the copyright.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

 **********************************************************************}
unit importextensionex.pas2js.wasmapi;

{$mode ObjFPC}

interface

uses
  JS, WebOrWorker, wasienv, webassembly;

type

  (*
    TImportExtension extended class that introduces

    - mechanism for cahing the DataView, to be extended with memory growth notification
    - methods to get/set utf16 strings from wasm memory without utf8 roundtrips
  *)

  { TImportExtensionEx }

  TImportExtensionEx = class (TImportExtension)
  private
    FWebAssemblyMemory : TJSArrayBuffer;
    FMemoryDataView : TJSDataView;
    FEnvMemoryDataView : TJSDataView;

  protected
    function GetUTF16FromMem(p : TWasmPointer; sizeInChars : Integer) : String;
    procedure SetUTF16ToMem(p : TWasmPointer; const text : String);

    procedure SetWebAssemblyMemory(aMemory : TJSArrayBuffer);
    function GetModuleMemoryDataView : TJSDataView; reintroduce; deprecated 'Use MemoryDataView';
    function GetMemoryDataView : TJSDataView;


  public
    property MemoryDataView : TJSDataView read GetMemoryDataView;
    property WebAssemblyMemory : TJSArrayBuffer read FWebAssemblyMemory write SetWebAssemblyMemory;

  end;

implementation

{ TImportExtensionEx }

// GetUTF16FromMem
//
function TImportExtensionEx.GetUTF16FromMem(p: TWasmPointer; sizeInChars: Integer): String;

begin
  Result:=Env.GetUTF16StringFromMem(P,SizeInChars);
end;

// SetUTF16ToMem
//
procedure TImportExtensionEx.SetUTF16ToMem(p: TWasmPointer; const text: String);
begin
  Env.SetUTF16StringInMem(P,Text);
end;

// SetWebAssemblyMemory
//
procedure TImportExtensionEx.SetWebAssemblyMemory(aMemory: TJSArrayBuffer);
begin
  if FWebAssemblyMemory = aMemory then
    Exit;

  FWebAssemblyMemory := aMemory;
  if aMemory <> nil then
    FMemoryDataView := TJSDataView.New(aMemory)
  else FMemoryDataView := nil;
end;

// GetModuleMemoryDataView
//
function TImportExtensionEx.GetModuleMemoryDataView: TJSDataView;
begin
  Result := inherited getModuleMemoryDataView;
end;

// GetMemoryDataView
//
function TImportExtensionEx.GetMemoryDataView: TJSDataView;
var
  envMemory : JSValue;
  envWebAssemblyMemory : TJSWebAssemblyMemory absolute envMemory;
begin
  if FWebAssemblyMemory = nil then
  begin
    envMemory := InstanceExports.Memory;
    if envMemory then
    begin
      if (FEnvMemoryDataView = nil) or (FEnvMemoryDataView.buffer <> envWebAssemblyMemory.buffer) then
        FEnvMemoryDataView := TJSDataView.New(envWebAssemblyMemory.buffer);
      Exit(FEnvMemoryDataView);
    end
    else
      Console.error('Memory not accessible from this call chain');
  end;

  Result := FMemoryDataView;
end;

end.