如何从剪贴板保存PngImage

时间：2012-09-04 07:17:07

标签： delphi png transparency clipboard

如何将pngimage保存到文件复制的AdobeFirewoks（剪贴板）或Photoshop，而不会失去透明度。

我正在使用delphi2009。

提前谢谢。

@TLama 我试过这段代码，但没有透明度。如果我做得对，我也不知道。 

  png := TPngimage.Create;
  try
    png.LoadFromClipboardFormat(CF_BITMAP,
      Clipboard.GetAsHandle(CF_BITMAP), CF_BITMAP);
    image1.Picture.Assign(png);
  finally
    png.Free;
  end;

3 个答案:

答案 0 :(得分：5)

根据我的同事使用以下测试代码确认Adobe Photoshop CS 13.0 x32确认的实证结果指出，不能仅仅因为它不复制而不会丢失透明度而无法保存Adobe Photoshop复制的剪贴板中的图像alpha通道数据。

Adob​​e Photoshop（至少在上面提到的版本中）使用24位像素格式进行剪贴板图像数据传输。而且，由于它是24位位图，因此不能有alpha通道。不知道有谁让Adobe Fireworks验证，但肯定他们使用自己的注册剪贴板格式来传输图像，包括他们产品之间的alpha通道。

Adob​​e Photoshop剪贴板使用的CF_BITMAP或CF_DIB格式据称支持alpha通道，正如有些人所说（我还没有尝试过），但仅适用于32位像素格式，不适用于24位像素格式。唯一支持透明度的剪贴板格式是CF_DIBV5，但与其他格式一样，图像必须以32位像素格式存储以保留Alpha通道：

以下代码显示有关当前复制的剪贴板内容的信息：

uses
  ActiveX;

function GetClipboardFormatString(Format: Word): string;
var
  S: string;
begin
  case Format of
    1: S := 'CF_TEXT';
    2: S := 'CF_BITMAP';
    3: S := 'CF_METAFILEPICT';
    4: S := 'CF_SYLK';
    5: S := 'CF_DIF';
    6: S := 'CF_TIFF';
    7: S := 'CF_OEMTEXT';
    8: S := 'CF_DIB';
    9: S := 'CF_PALETTE';
    10: S := 'CF_PENDATA';
    11: S := 'CF_RIFF';        
    12: S := 'CF_WAVE';
    13: S := 'CF_UNICODETEXT';
    14: S := 'CF_ENHMETAFILE';
    15: S := 'CF_HDROP';
    16: S := 'CF_LOCALE';
    17: S := 'CF_DIBV5';
    $0080: S := 'CF_OWNERDISPLAY';
    $0081: S := 'CF_DSPTEXT';
    $0082: S := 'CF_DSPBITMAP';
    $0083: S := 'CF_DSPMETAFILEPICT';
    $008E: S := 'CF_DSPENHMETAFILE';
    $0200: S := 'CF_PRIVATEFIRST';
    $02FF: S := 'CF_PRIVATELAST';    
    $0300: S := 'CF_GDIOBJFIRST';
    $03FF: S := 'CF_GDIOBJLAST';
  else
    begin      
      SetLength(S, 255);
      SetLength(S, GetClipboardFormatName(Format, PChar(S), 255));      
      if Length(S) = 0 then
        S := 'Unknown, unregistered clipboard format';
      Result := S + ' (' + IntToStr(Format) + ')';
      Exit;
    end;
  end; 
  Result := 'Standard clipboard format (' + S + ')';
end;

function GetClipboardFormats: string;
var
  S: string;
  FormatEtc: TFormatEtc;
  DataObject: IDataObject;
  EnumFormatEtc: IEnumFormatEtc;
begin
  Result := '';
  if Succeeded(OleGetClipboard(DataObject)) then
  begin
    if Succeeded(DataObject.EnumFormatEtc(DATADIR_GET, EnumFormatEtc)) then
    begin
      S := DupeString('-', 65) + sLineBreak +
        'Clipboard data formats: ' + sLineBreak +
        DupeString('-', 65) + sLineBreak;
      while EnumFormatEtc.Next(1, FormatEtc, nil) = S_OK do
        S := S + GetClipboardFormatString(FormatEtc.cfFormat) + sLineBreak;
      Result := S;
    end;
  end;
end;

function GetClipboardInfoDIB: string;
var
  S: string;
  ClipboardData: HGLOBAL;
  BitmapInfoHeader: PBitmapInfoHeader;
const
  BI_JPEG = 4;
  BI_PNG = 5;
begin
  Result := '';
  if OpenClipboard(0) then
  try
    ClipboardData := GetClipboardData(CF_DIB);
    if ClipboardData <> 0 then
    begin
      BitmapInfoHeader := GlobalLock(ClipboardData);
      if Assigned(BitmapInfoHeader) then
      try
        S := DupeString('-', 65) + sLineBreak +
          'Clipboard data of CF_DIB format: ' + sLineBreak +
          DupeString('-', 65) + sLineBreak +
          'Width: ' + IntToStr(BitmapInfoHeader.biWidth) + ' px' + sLineBreak +
          'Height: ' + IntToStr(BitmapInfoHeader.biHeight) + ' px' + sLineBreak +
          'Bit depth: ' + IntToStr(BitmapInfoHeader.biBitCount) + ' bpp' + sLineBreak +
          'Compression format: ';
        case BitmapInfoHeader.biCompression of
          BI_RGB:   S := S + 'Uncompressed format (BI_RGB)';
          BI_RLE8: S := S + 'RLE format for bitmaps with 8 bpp (BI_RLE8)';
          BI_RLE4: S := S + 'RLE format for bitmaps with 4 bpp (BI_RLE4)';
          BI_BITFIELDS: S := S + 'Not compressed with color masks (BI_BITFIELDS)';
          BI_JPEG: S := S + 'Compressed using JPEG file format (BI_JPEG)';
          BI_PNG:   S := S + 'Compressed using PNG file format (BI_PNG)';
        end;
        S := S + sLineBreak;
        Result := S;
      finally
        GlobalUnlock(ClipboardData);
      end;      
    end;
  finally
    CloseClipboard;
  end;
end;

function GetClipboardInfoDIBV5: string;
var
  S: string;
  ClipboardData: HGLOBAL;
  BitmapInfoHeader: PBitmapV5Header;
const
  BI_JPEG = 4;
  BI_PNG = 5;
begin
  Result := '';
  if OpenClipboard(0) then
  try
    ClipboardData := GetClipboardData(CF_DIBV5);
    if ClipboardData <> 0 then
    begin
      BitmapInfoHeader := GlobalLock(ClipboardData);
      if Assigned(BitmapInfoHeader) then
      try
        S := DupeString('-', 65) + sLineBreak +
          'Clipboard data of CF_DIBV5 format: ' + sLineBreak +
          DupeString('-', 65) + sLineBreak +
          'Width: ' + IntToStr(BitmapInfoHeader.bV5Width) + ' px' + sLineBreak +
          'Height: ' + IntToStr(BitmapInfoHeader.bV5Height) + ' px' + sLineBreak +
          'Bit depth: ' + IntToStr(BitmapInfoHeader.bV5BitCount) + ' bpp' + sLineBreak +
          'Compression format: ';
        case BitmapInfoHeader.bV5Compression of
          BI_RGB:   S := S + 'Uncompressed format (BI_RGB)';
          BI_RLE8: S := S + 'RLE format for bitmaps with 8 bpp (BI_RLE8)';
          BI_RLE4: S := S + 'RLE format for bitmaps with 4 bpp (BI_RLE4)';
          BI_BITFIELDS: S := S + 'Not compressed with color masks (BI_BITFIELDS)';
          BI_JPEG: S := S + 'Compressed using JPEG file format (BI_JPEG)';
          BI_PNG:   S := S + 'Compressed using PNG file format (BI_PNG)';
        end;
        S := S + sLineBreak;
        Result := S;
      finally
        GlobalUnlock(ClipboardData);
      end;      
    end;
  finally
    CloseClipboard;
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  S: string;
begin
  S := GetClipboardFormats;
  if IsClipboardFormatAvailable(CF_DIB) then
    S := S + sLineBreak + GetClipboardInfoDIB;
  if IsClipboardFormatAvailable(CF_DIBV5) then
    S := S + sLineBreak + GetClipboardInfoDIBV5;
  ShowMessage(S);
end;

通过Adobe Photoshop CS 6 13.0将上述透明图像代码输出复制到剪贴板中（点击放大）：

Click to enlarge

有用的东西：

答案 1 :(得分：5)

Photoshop的剪贴板格式非常糟糕。包含存储在剪贴板中的alpha通道的唯一非常有效的数据是......猜？ ...指向Alpha通道内存的指针进入“Photoshop Paste In Place”块......可怕的。如果你复制一些东西，然后重新启动photoshop，alpha就是......丢失:)。

但是，您可以轻松了解剪贴板是否包含Photoshop图像。

询问剪贴板它有什么块。

如果剪贴板有两个块，名为“Photoshop Paste In Place” AND “Object Descriptor”，则可以99.9％确定系统和剪贴板上的Photoshop 正在运行包含参考到Photoshop数据。 （当Photoshop退出时，对象描述符块将从剪贴板中删除，因此alpha将永远丢失）

那么，你有两个选择：

选择1（不推荐）：打开Photoshop的进程内存并从指针中读取原始的32位图像数据...这总体上是非常愚蠢的和不安全的，或

选择2（推荐）：使用COM 从Photoshop中提取图像数据。当然，COM方法是最好的方法。让您的程序生成并运行以下 VBS 脚本：

On Error Resume Next
Set Ps = CreateObject("Photoshop.Application")
Set Shell = CreateObject("WScript.Shell")
Set FileSystem = CreateObject("Scripting.FileSystemObject") 

Dim PNGFileName
PNGFileName = Shell.CurrentDirectory & "\psClipboard.png"

If FileSystem.FileExists(PNGFileName) Then 
    FileSystem.DeleteFile PNGFileName
End If

Set Doc = Ps.Documents.Add(1,1,72,"psClipboard",,3)

Doc.Paste()
Doc.RevealAll()

If Err.Number = 0 Then 
    set PNGSaveOptions = CreateObject("Photoshop.PNGSaveOptions")
    doc.saveAs PNGFileName, PNGSaveOptions
End If

doc.Close()

在脚本的CurrentDirectory中，将生成文件名“ psClipboard.png ”。使用libPng或其他方法在程序中读取此文件，并将其视为来自剪贴板。这个脚本将删除 psClipboard.png ，然后会向Photoshop询问它。如果粘贴返回错误，脚本将停止并且不会生成文件，在这种情况下，剪贴板不包含有效的Photoshop参考数据。

答案 2 :(得分：1)

解决方案explained in this link可能有用。

unit EG_ClipboardBitmap32;
{
  Author William Egge. egge@eggcentric.com
  January 17, 2002
  Compiles with ver 1.2 patch #1 of Graphics32

  This unit will copy and paste Bitmap32 pixels to the clipboard and retain the
  alpha channel.

  The clipboard data will still work with regular paint programs because this
  unit adds a new format only for the alpha channel and is kept seperate from
  the regular bitmap storage.
}

interface

uses
  ClipBrd, Windows, SysUtils, GR32;

procedure CopyBitmap32ToClipboard(const Source: TBitmap32);
procedure PasteBitmap32FromClipboard(const Dest: TBitmap32);
function CanPasteBitmap32: Boolean;

implementation

const
  RegisterName = 'G32 Bitmap32 Alpha Channel';
  GlobalUnlockBugErrorCode = ERROR_INVALID_PARAMETER;

var
  FAlphaFormatHandle: Word = 0;

procedure RaiseSysError;
var
  ErrCode: LongWord;
begin
  ErrCode := GetLastError();
  if ErrCode <> NO_ERROR then
    raise Exception.Create(SysErrorMessage(ErrCode));
end;

function GetAlphaFormatHandle: Word;
begin
  if FAlphaFormatHandle = 0 then
  begin
    FAlphaFormatHandle := RegisterClipboardFormat(RegisterName);
    if FAlphaFormatHandle = 0 then
      RaiseSysError;
  end;
  Result := FAlphaFormatHandle;
end;

function CanPasteBitmap32: Boolean;
begin
  Result := Clipboard.HasFormat(CF_BITMAP);
end;

procedure CopyBitmap32ToClipboard(const Source: TBitmap32);
var
  H: HGLOBAL;
  Bytes: LongWord;
  P, Alpha: PByte;
  I: Integer;
begin
  Clipboard.Assign(Source);
  if not OpenClipboard(0) then
    RaiseSysError
  else
    try
      Bytes := 4 + (Source.Width * Source.Height);
      H := GlobalAlloc(GMEM_MOVEABLE and GMEM_DDESHARE, Bytes);
      if H = 0 then
        RaiseSysError;
      P := GlobalLock(H);
      if P = nil then
        RaiseSysError
      else
        try
          PLongWord(P)^ := Bytes - 4;
          Inc(P, 4);
          // Copy Alpha into Array
          Alpha := Pointer(Source.Bits);
          Inc(Alpha, 3); // Align with Alpha
          for I := 1 to (Source.Width * Source.Height) do
          begin
            P^ := Alpha^;
            Inc(Alpha, 4);
            Inc(P);
          end;
        finally
          if (not GlobalUnlock(H)) then
            if (GetLastError() <> GlobalUnlockBugErrorCode) then
              RaiseSysError;
        end;
      SetClipboardData(GetAlphaFormatHandle, H);
    finally
      if not CloseClipboard then
        RaiseSysError;
    end;
end;

procedure PasteBitmap32FromClipboard(const Dest: TBitmap32);
var
  H: HGLOBAL;
  ClipAlpha, Alpha: PByte;
  I, Count, PixelCount: LongWord;
begin
  if Clipboard.HasFormat(CF_BITMAP) then
  begin
    Dest.BeginUpdate;
    try
      Dest.Assign(Clipboard);
      if not OpenClipboard(0) then
        RaiseSysError
      else
        try
          H := GetClipboardData(GetAlphaFormatHandle);
          if H <> 0 then
          begin
            ClipAlpha := GlobalLock(H);
            if ClipAlpha = nil then
              RaiseSysError
            else
              try
                Alpha := Pointer(Dest.Bits);
                Inc(Alpha, 3); // Align with Alpha
                Count := PLongWord(ClipAlpha)^;
                Inc(ClipAlpha, 4);
                PixelCount := Dest.Width * Dest.Height;
                Assert(Count = PixelCount,
                  'Alpha Count does not match Bitmap pixel Count,
                  PasteBitmap32FromClipboard(const Dest: TBitmap32);');

                // Should not happen, but if it does then this is a safety catch.
                if Count > PixelCount then
                  Count := PixelCount;

                for I := 1 to Count do
                begin
                  Alpha^ := ClipAlpha^;
                  Inc(Alpha, 4);
                  Inc(ClipAlpha);
                end;
              finally
                if (not GlobalUnlock(H)) then
                  if (GetLastError() <> GlobalUnlockBugErrorCode) then
                    RaiseSysError;
              end;
          end;
        finally
          if not CloseClipboard then
            RaiseSysError;
        end;
    finally
      Dest.EndUpdate;
      Dest.Changed;
    end;
  end;
end;

end.

函数PasteBitmap32FromClipboard显然是你需要的。将位图保存为PNG为answered in this question。

相关问题
最新问题