Ensure read clipboard option checks for text format

[delphidabbler]

Ensure that the read clipboard option checks that the clipboard contains text and raises exception if not.

[delphidabbler]

If text is present, use Unicode text format if available. If not use ANSI format and convert text, assuming system default ANSI encoding.

[delphidabbler]

Current code assumes Unicode text format. Is this a safe assumption?

[delphidabbler]

This isn't reading but, for info,

pashi/Src/IO.Writers.UClipboard.pas

Line 34 in 787c0ba

procedure TClipboardWriter.Write(const S: string; const Encoding: TEncoding);

ignores Encoding parameter and always copies (Unicode) string S to clipboard as CF_UNICODETEXT.

[delphidabbler]

pashi/Src/IO.Readers.UClipboard.pas

Line 34 in 787c0ba

function TClipboardReader.Read: TArray<string>;

always tries to read unicode text from clipboard with

DataHandle := ClipMgr.GetDataHandle(CF_UNICODETEXT);

but does check DataHandle before reading text from clipboard:

if DataHandle = 0 then
begin
  SetLength(Result, 0);
  Exit;
end;
// read Unicode text from clipboard

No attempt is made to also check for, and convert ANSI text. Could this be because Windows always places a Unicode version of text on clipboard even if only ANSI text is copied? Need to check this in a test program & cfs.

[delphidabbler]

In PasHiGUI

pashi/Src/GUI/FmMain.pas

Line 469 in 787c0ba

procedure TMainForm.HandleData(const DataObj: IDataObject);

ultimately handles paste operations.

This code does check for ANSI text on the clipboard. It quite correctly does this after checking for Unicode text:

    // earlier tests in if statement check for file drops etc.
    else if DOAdapter.HasFormat(CF_UNICODETEXT) then
      LoadText(DOAdapter.ReadDataAsUnicodeText(CF_UNICODETEXT))
    else if DOAdapter.HasFormat(CF_TEXT) then
      LoadText(DOAdapter.ReadDataAsAnsiText(CF_TEXT))
    // next we trap unknown formats

---

As an aside, TMainForm.HandleDataObject would be a better name for TMainForm.HandleData.

[delphidabbler]

Also for info about writing, PasHiGUI ultimately calls

pashi/Src/GUI/UOutputData.pas

Line 109 in 787c0ba

procedure TClipboardOutputData.WriteData(const Stm: TStream);

to write to clipboard. This method simply calls the VCL Clipboard global object to do the actual operation:

Clipboard.AsText := StringFromStream(Stm);

and StringFromStream (see UUtils.pas) checks format of the given stream from any BOM preamble & converts it to a Unicode stream.

So I assume that the VCL puts this text on the clipboard as Unicode. Probably best to check with cfs.

[delphidabbler]

In summary, PasHi & PasHiGUI use different methods of accessing the clipboard.

Reading code is different in each program: PasHi uses low level API calls while PasHiGUI uses OLE.

Writing code uses the low level API again in PasHi, while PasHiGUI uses the VCL Clipboard object.

This is a mess thats crying out for shared code. It would be much better to standardise on one method of access, preferably the OLE object.

Maybe a new TClipboardAdapter class is called for to get the OLE clipboard object and use code derived from PasHiGUI's TDataObjectAdapter class to help handle the IDataObject instances obtained from the clipboard.

See Src/GUI/UDataObjectAdapter.pas for TDataObjectAdapter.

[delphidabbler]

This issue has grown beyond its original premise.

So a new issue #73 has been created to replace this one.

This issue is now being closed as a duplicate.