Windows 为什么自定义光标图像显示不正确?
背景 我已经编写了一个函数,它根据与给定设备上下文关联的位图创建自定义光标。我使用它来创建拖放光标,这些光标显示为“撕裂”,有点像“Trello”中使用的光标 我已经使用该函数一段时间了,没有出现任何问题,但是当我将它与一个新的树组件一起使用时,我正在处理它,开始创建部分空白的游标。 我已经验证了该问题出现在Delphi 2010和Delphi Berlin中,并且我还验证了它在Windows 7和Windows 10中都已损坏 下面是一张显示光标应该是什么样子的照片(抱歉,找不到快速屏幕抓取光标的方法): 这是当它部分空白时的样子(好吧,它不仅仅是部分空白-它实际上是看不见的): 故障排除 排除故障后,我发现,如果在调用GetDragCursor之前将PNG图像写入与DC相关联的位图,则光标会出错 下面是我能想到的最简单的代码,它演示了这个问题: 具有两个TPaintBox组件的窗体:MyPaintBoxWorks和MyPaintBoxBreakWindows 为什么自定义光标图像显示不正确?,windows,delphi,bitmap,cursor,gdi,Windows,Delphi,Bitmap,Cursor,Gdi,背景 我已经编写了一个函数,它根据与给定设备上下文关联的位图创建自定义光标。我使用它来创建拖放光标,这些光标显示为“撕裂”,有点像“Trello”中使用的光标 我已经使用该函数一段时间了,没有出现任何问题,但是当我将它与一个新的树组件一起使用时,我正在处理它,开始创建部分空白的游标。 我已经验证了该问题出现在Delphi 2010和Delphi Berlin中,并且我还验证了它在Windows 7和Windows 10中都已损坏 下面是一张显示光标应该是什么样子的照片(抱歉,找不到快速屏幕抓取光
- 当您单击MyPaintBoxWorks时,您将获得预期的光标李>
- 当你点击MyPaintboxBreaked时,你只会得到png图像李>
uses
Types,
pngimage;
//////////////////////////////////////////////////////////////////////
procedure TMyForm.FormPaint(Sender: TObject);
begin
MyPaintBoxWorks.Canvas.Brush.Color := clGreen;
MyPaintBoxWorks.Canvas.Rectangle( 0, 0,
MyPaintBoxWorks.Width, MyPaintBoxWorks.Height );
MyPaintBoxBroken.Canvas.Brush.Color := clRed;
MyPaintBoxBroken.Canvas.Rectangle( 0, 0,
MyPaintBoxBroken.Width, MyPaintBoxBroken.Height );
end;
function GetDragCursor( Handle: HDC;
Width, Height: integer;
CursorX, CursorY: integer ): TCursor; forward;
//////////////////////////////////////////////////////////////////////
procedure TMyForm.MyPaintBoxWorksMouseDown( Sender: TObject;
Button: TMouseButton;
Shift: TShiftState;
X, Y: Integer);
begin
Screen.Cursor := GetDragCursor( MyPaintBoxWorks.Canvas.Handle,
MyPaintBoxWorks.Width, MyPaintBoxWorks.Height,
X, Y );
end;
//////////////////////////////////////////////////////////////////////
procedure TMyForm.MyPaintBoxBrokenMouseDown( Sender: TObject;
Button: TMouseButton;
Shift: TShiftState;
X, Y: Integer );
var
Img: TPngImage;
begin
Img := TPngImage.Create;
Img.LoadFromFile( 'D:\TestImage.png' );
Img.Draw( MyPaintBoxBroken.Canvas, Rect( 20, 20, 40, 40 ) );
Screen.Cursor := GetDragCursor( MyPaintBoxBroken.Canvas.Handle,
MyPaintBoxBroken.Width, MyPaintBoxBroken.Height,
X, Y );
end;
//////////////////////////////////////////////////////////////////////
function GetDragCursor( Handle: HDC;
Width, Height: integer;
CursorX, CursorY: integer ): TCursor;
var
MaskDC : HDC;
OrgMaskBmp : HBITMAP;
MaskBmp : HBITMAP;
ColourDC : HDC;
OrgColourBmp : HBITMAP;
ColourBmp : HBITMAP;
IconInfo : TIconInfo;
Brush : HBRUSH;
begin
// Create Colour bitmap
// ====================
ColourDC := CreateCompatibleDC( Handle );
ColourBmp := CreateCompatibleBitmap( Handle, Width, Height );
OrgColourBmp := SelectObject( ColourDC, ColourBmp );
BitBlt( ColourDC, 0, 0, Width, Height, Handle, 0, 0, SRCCOPY );
SelectObject( ColourDC, OrgColourBmp );
// Create Mask bitmap
// ==================
MaskDC := CreateCompatibleDC( Handle );
MaskBmp := CreateCompatibleBitmap( Handle, Width, Height );
OrgMaskBmp := SelectObject( MaskDC, MaskBmp );
// Fill with white
Brush := CreateSolidBrush( $FFFFFF );
FillRect( MaskDC, Rect( 0, 0, Width, Height ), Brush );
DeleteObject( Brush );
// Fill masked area with black
Brush := CreateSolidBrush( $000000 );
FillRect( MaskDC, Rect( 0, 0, Width, Height ), Brush );
DeleteObject( Brush );
SelectObject( MaskDC, OrgMaskBmp );
// Create and set cursor
// =====================
with iconInfo do
begin
fIcon := FALSE;
xHotspot := CursorX;
yHotspot := CursorY;
hbmMask := MaskBmp;
hbmColor := ColourBmp;
end;
Screen.Cursors[1] := CreateIconIndirect( iconInfo );
Result := 1;
end;
我已经详细研究了函数和Microsofts文档,没有发现函数有任何错误
我还学习了TPngImage.Draw,看不出它有什么明显的错误(我不希望如此)。职能:
- 调用TPngImage.DrawPartialTrans,依次调用
- 通过CreateDIBSection创建位图
- 扫描像素并计算alpha混合RGB值
- 使用指针算法在像素缓冲区中移动
- 调用BitBlt将最终图像复制到DC
- 注释掉写入像素缓冲区的代码,或
- 仅扫描图像中的前几行,或
- 注释掉对BitBlt的最后调用
procedure TPngImage.DrawPartialTrans(DC: HDC; Rect: TRect);
{Adjust the rectangle structure}
procedure AdjustRect(var Rect: TRect);
var
t: Integer;
begin
if Rect.Right < Rect.Left then
begin
t := Rect.Right;
Rect.Right := Rect.Left;
Rect.Left := t;
end;
if Rect.Bottom < Rect.Top then
begin
t := Rect.Bottom;
Rect.Bottom := Rect.Top;
Rect.Top := t;
end
end;
type
{Access to pixels}
TPixelLine = Array[Word] of TRGBQuad;
pPixelLine = ^TPixelLine;
const
{Structure used to create the bitmap}
BitmapInfoHeader: TBitmapInfoHeader =
(biSize: sizeof(TBitmapInfoHeader);
biWidth: 100;
biHeight: 100;
biPlanes: 1;
biBitCount: 32;
biCompression: BI_RGB;
biSizeImage: 0;
biXPelsPerMeter: 0;
biYPelsPerMeter: 0;
biClrUsed: 0;
biClrImportant: 0);
var
{Buffer bitmap creation}
BitmapInfo : TBitmapInfo;
BufferDC : HDC;
BufferBits : Pointer;
OldBitmap,
BufferBitmap: HBitmap;
Header: TChunkIHDR;
{Transparency/palette chunks}
TransparencyChunk: TChunktRNS;
PaletteChunk: TChunkPLTE;
TransValue, PaletteIndex: Byte;
CurBit: Integer;
Data: PByte;
{Buffer bitmap modification}
BytesPerRowDest,
BytesPerRowSrc,
BytesPerRowAlpha: Integer;
ImageSource, ImageSourceOrg,
AlphaSource : pByteArray;
ImageData : pPixelLine;
i, j, i2, j2 : Integer;
{For bitmap stretching}
W, H : Cardinal;
Stretch : Boolean;
FactorX, FactorY: Double;
begin
{Prepares the rectangle structure to stretch draw}
if (Rect.Right = Rect.Left) or (Rect.Bottom = Rect.Top) then exit;
AdjustRect(Rect);
{Gets the width and height}
W := Rect.Right - Rect.Left;
H := Rect.Bottom - Rect.Top;
Header := Self.Header; {Fast access to header}
Stretch := (W <> Header.Width) or (H <> Header.Height);
if Stretch then FactorX := W / Header.Width else FactorX := 1;
if Stretch then FactorY := H / Header.Height else FactorY := 1;
{Prepare to create the bitmap}
Fillchar(BitmapInfo, sizeof(BitmapInfo), #0);
BitmapInfoHeader.biWidth := W;
BitmapInfoHeader.biHeight := -Integer(H);
BitmapInfo.bmiHeader := BitmapInfoHeader;
{Create the bitmap which will receive the background, the applied}
{alpha blending and then will be painted on the background}
BufferDC := CreateCompatibleDC(0);
{In case BufferDC could not be created}
if (BufferDC = 0) then RaiseError(EPNGOutMemory, EPNGOutMemoryText);
BufferBitmap := CreateDIBSection(BufferDC, BitmapInfo, DIB_RGB_COLORS, BufferBits, 0, 0);
{In case buffer bitmap could not be created}
if (BufferBitmap = 0) or (BufferBits = Nil) then
begin
if BufferBitmap <> 0 then DeleteObject(BufferBitmap);
DeleteDC(BufferDC);
RaiseError(EPNGOutMemory, EPNGOutMemoryText);
end;
{Selects new bitmap and release old bitmap}
OldBitmap := SelectObject(BufferDC, BufferBitmap);
{Draws the background on the buffer image}
BitBlt(BufferDC, 0, 0, W, H, DC, Rect.Left, Rect.Top, SRCCOPY);
{Obtain number of bytes for each row}
BytesPerRowAlpha := Header.Width;
BytesPerRowDest := (((BitmapInfo.bmiHeader.biBitCount * W) + 31)
and not 31) div 8; {Number of bytes for each image row in destination}
BytesPerRowSrc := (((Header.BitmapInfo.bmiHeader.biBitCount * Header.Width) +
31) and not 31) div 8; {Number of bytes for each image row in source}
{Obtains image pointers}
ImageData := BufferBits;
AlphaSource := Header.ImageAlpha;
Longint(ImageSource) := Longint(Header.ImageData) +
Header.BytesPerRow * Longint(Header.Height - 1);
ImageSourceOrg := ImageSource;
case Header.BitmapInfo.bmiHeader.biBitCount of
{R, G, B images}
24:
FOR j := 1 TO H DO
begin
{Process all the pixels in this line}
FOR i := 0 TO W - 1 DO
begin
if Stretch then i2 := trunc(i / FactorX) else i2 := i;
{Optmize when we don´t have transparency}
if (AlphaSource[i2] <> 0) then
if (AlphaSource[i2] = 255) then
begin
pRGBTriple(@ImageData[i])^ := pRGBTriple(@ImageSource[i2 * 3])^;
ImageData[i].rgbReserved := 255;
end
else
with ImageData[i] do
begin
rgbRed := ($7F + ImageSource[2+i2*3] * AlphaSource[i2] + rgbRed *
(not AlphaSource[i2])) div $FF;
rgbGreen := ($7F + ImageSource[1+i2*3] * AlphaSource[i2] +
rgbGreen * (not AlphaSource[i2])) div $FF;
rgbBlue := ($7F + ImageSource[i2*3] * AlphaSource[i2] + rgbBlue *
(not AlphaSource[i2])) div $FF;
rgbReserved := not (($7F + (not rgbReserved) * (not AlphaSource[i2])) div $FF);
end;
end;
{Move pointers}
inc(Longint(ImageData), BytesPerRowDest);
if Stretch then j2 := trunc(j / FactorY) else j2 := j;
Longint(ImageSource) := Longint(ImageSourceOrg) - BytesPerRowSrc * j2;
Longint(AlphaSource) := Longint(Header.ImageAlpha) +
BytesPerRowAlpha * j2;
end;
{Palette images with 1 byte for each pixel}
1,4,8: if Header.ColorType = COLOR_GRAYSCALEALPHA then
FOR j := 1 TO H DO
begin
{Process all the pixels in this line}
FOR i := 0 TO W - 1 DO
with ImageData[i], Header.BitmapInfo do begin
if Stretch then i2 := trunc(i / FactorX) else i2 := i;
rgbRed := ($7F + ImageSource[i2] * AlphaSource[i2] +
rgbRed * (not AlphaSource[i2])) div $FF;
rgbGreen := ($7F + ImageSource[i2] * AlphaSource[i2] +
rgbGreen * (not AlphaSource[i2])) div $FF;
rgbBlue := ($7F + ImageSource[i2] * AlphaSource[i2] +
rgbBlue * (not AlphaSource[i2])) div $FF;
rgbReserved := not (($7F + (not rgbReserved) * (not AlphaSource[i2])) div $FF);
end;
{Move pointers}
Longint(ImageData) := Longint(ImageData) + BytesPerRowDest;
if Stretch then j2 := trunc(j / FactorY) else j2 := j;
Longint(ImageSource) := Longint(ImageSourceOrg) - BytesPerRowSrc * j2;
Longint(AlphaSource) := Longint(Header.ImageAlpha) +
BytesPerRowAlpha * j2;
end
else {Palette images}
begin
{Obtain pointer to the transparency chunk}
TransparencyChunk := TChunktRNS(Chunks.ItemFromClass(TChunktRNS));
PaletteChunk := TChunkPLTE(Chunks.ItemFromClass(TChunkPLTE));
FOR j := 1 TO H DO
begin
{Process all the pixels in this line}
i := 0;
repeat
CurBit := 0;
if Stretch then i2 := trunc(i / FactorX) else i2 := i;
Data := @ImageSource[i2];
repeat
{Obtains the palette index}
case Header.BitDepth of
1: PaletteIndex := (Data^ shr (7-(I Mod 8))) and 1;
2,4: PaletteIndex := (Data^ shr ((1-(I Mod 2))*4)) and $0F;
else PaletteIndex := Data^;
end;
{Updates the image with the new pixel}
with ImageData[i] do
begin
TransValue := TransparencyChunk.PaletteValues[PaletteIndex];
rgbRed := (255 + PaletteChunk.Item[PaletteIndex].rgbRed *
TransValue + rgbRed * (255 - TransValue)) shr 8;
rgbGreen := (255 + PaletteChunk.Item[PaletteIndex].rgbGreen *
TransValue + rgbGreen * (255 - TransValue)) shr 8;
rgbBlue := (255 + PaletteChunk.Item[PaletteIndex].rgbBlue *
TransValue + rgbBlue * (255 - TransValue)) shr 8;
end;
{Move to next data}
inc(i); inc(CurBit, Header.BitmapInfo.bmiHeader.biBitCount);
until CurBit >= 8;
{Move to next source data}
//inc(Data);
until i >= Integer(W);
{Move pointers}
Longint(ImageData) := Longint(ImageData) + BytesPerRowDest;
if Stretch then j2 := trunc(j / FactorY) else j2 := j;
Longint(ImageSource) := Longint(ImageSourceOrg) - BytesPerRowSrc * j2;
end
end {Palette images}
end {case Header.BitmapInfo.bmiHeader.biBitCount};
{Draws the new bitmap on the foreground}
BitBlt(DC, Rect.Left, Rect.Top, W, H, BufferDC, 0, 0, SRCCOPY);
{Free bitmap}
SelectObject(BufferDC, OldBitmap);
DeleteObject(BufferBitmap);
DeleteDC(BufferDC);
end;
程序TPngImage.DrawPartialTrans(DC:HDC;Rect:TRect);
{调整矩形结构}
程序调整Rect(var Rect:TRect);
变量
t:整数;
开始
如果右对齐<左对齐,则
开始
t:=右直;
右矩形:=左矩形;
矩形左:=t;
结束;
如果矩形底部<矩形顶部,则
开始
t:=垂直底部;
矩形底部:=矩形顶部;
矩形顶部:=t;
结束
结束;
类型
{访问像素}
TPixelLine=TRGBQuad的数组[字];
pPixelLine=^TPixelLine;
常数
{用于创建位图的结构}
BitMapInfo头文件:TBITMapInfo头文件=
(biSize:sizeof(TBitmapInfoHeader);
宽度:100;
身高:100;
双翼飞机:1;
比特数:32;
双压缩:双RGB;
biSizeImage:0;
biXPelsPerMeter:0;
双渗透计:0;
biClrUsed:0;
biclr值:0);
变量
{缓冲区位图创建}
BitmapInfo:TBitmapInfo;
BufferDC:HDC;
缓冲位:指针;
旧位图,
缓冲位图:HBitmap;
标题:TChunkIHDR;
{透明度/调色板块}
透明区块:TChunktRNS;
PaletteChunk:TChunkPLTE;
TransValue,PaletteIndex:字节;
combit:整数;
资料:PByte;
{缓冲区位图修改}
是的,
BytesPerRowSrc,
BytesPerRowAlpha:整数;
ImageSource,ImageSourceOrg,
AlphaSource:pByteArray;
影像资料:pPixelLine;
i、 j,i2,j2:整数;
{用于位图拉伸}
W、 H:红衣主教;
拉伸:布尔;
FactorX,FactorY:Double;
开始
{准备矩形结构进行拉伸绘制}
如果是(Rect.Right=Rect.Left)或(Rect.Bottom=Rect.Top),则退出;
调整Rect(Rect);
{获取宽度和高度}
W:=右直-左直;
H:=矩形底部-矩形顶部;
Header:=Self.Header;{快速访问标头}
拉伸:=(W标题宽度)或(H标题高度);
如果拉伸,则系数x:=W/页眉。宽度,否则系数x:=1;
如果拉伸,则工厂:=H/割台。其他工厂的高度:=1;
{准备创建位图}
Fillchar(BitmapInfo,sizeof(BitmapInfo),#0);
BitMapInfo标头.biWidth:=W;
BitMapInfo Header.biHeight:=-整数(H);
BitmapInfo.bmiHeader:=BitmapInfo标头;
{创建接收背景的位图,应用}
{alpha混合,然后将在背景上绘制}
BufferDC:=CreateCompatibleDC(0);
{如果无法创建BufferDC}
如果(BufferDC=0),则RaiseError(EPNGOutMemory,EPNGOutMemoryText);
BufferBitmap:=CreateDIBSection(BufferDC、BitmapInfo、DIB_RGB_颜色、BufferBits、0、0);
{如果无法创建缓冲区位图}
如果(BufferBitmap=0)或(BufferBits=Nil),则
开始
如果缓冲位图为0,则删除对象(缓冲位图);
DeleteDC(BufferDC);
RaiseError(EPNGOutMemory,EPNGOutMemoryText);
结束;
{选择新位图并释放旧位图}
OldBitmap:=选择对象(BufferDC,BufferBitmap);
{D
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate(Sender: TObject);
begin
PaintBox1.Height := 16;
end;
procedure TForm1.PaintBox1Paint(Sender: TObject);
begin
PaintBox1.Canvas.Brush.Color := clRed;
PaintBox1.Canvas.Rectangle(0, 0, PaintBox1.Width, PaintBox1.Height );
end;
procedure GPDrawImageOver(Image: TGPImage; dc: HDC; X, Y: Integer);
var
Graphics: TGPGraphics;
begin
Graphics := TGPGraphics.Create(dc);
try
Graphics.SetCompositingMode(CompositingModeSourceOver);
Graphics.DrawImage(Image, X, Y, Image.GetWidth, Image.GetHeight);
finally
Graphics.Free;
end;
end;
procedure TForm1.PaintBox1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
var
Bmp: TBitmap;
Png: TGPImage;
x1, y1: Integer;
px: PRGBQuad;
begin
Bmp := TBitmap.Create;
try
Png := TGPImage.Create('C:\Users\Kobik\Downloads\Internet Explorer.png');
try
Bmp.Width := PaintBox1.Width;
Bmp.Height := Png.GetHeight;
Bmp.PixelFormat := pf32bit;
Bmp.HandleType := bmDIB;
Bmp.IgnorePalette := True;
// paint PaintBox1 canvas on the bitmap
BitBlt(Bmp.Canvas.Handle, 0, 0, PaintBox1.Width, PaintBox1.Height,
PaintBox1.Canvas.Handle, 0, 0, SRCCOPY);
// make the bottom bitmap part transparent
for y1 := 0 to Bmp.Height - 1 do
begin
px := Bmp.ScanLine[y1];
for x1 := 0 to Bmp.Width - 1 do
begin
if y1 < PaintBox1.Height then
px.rgbReserved := 255 // opaque
else
px.rgbReserved := 0; // fully transparent
Inc(px);
end;
end;
// draw png over the bitmap
GPDrawImageOver(Png, Bmp.Canvas.Handle, 0, 0);
finally
Png.Free;
end;
Screen.Cursor := GetDragCursor(Bmp.Canvas.Handle,
Bmp.Width, Bmp.Height, X, Y);
finally
Bmp.Free;
end;
end;