I'm trying to create a function to create a TBitmap.
This bitmap will be a Glyph with Transparent background, and it will be only a character of the Wingdings font.
After this, I will use this glyph to assign to a TBitBtn (button).
This is my current code:
function CreateTransparent(aChar: Char; aFontSize, aWidth, aHeight: Integer; aColor: TColor): TBitmap;
function _GPColor(Col: TColor): TGPColor;
begin
Result := ColorRefToARGB(ColorToRGB(Col));
end;
var
f: TGPFont;
r, rTx: TGPRectF;
b: TGPSolidBrush;
c: TGPGraphics;
tx: TGPStringFormat;
bt: TGPBitmap;
h: HBITMAP;
bk, fg: Cardinal;
s: string;
attr: TGPImageAttributes;
begin
s := aChar;
fg := _GPColor(aColor);
bt := TGPBitmap.Create(abs(aWidth), aHeight, PixelFormat32bppARGB);
try
c := TGPGraphics.Create(bt);
f := TGPFont.Create('Wingdings', aFontSize, FontStyleRegular, UnitPixel);
b := TGPSolidBrush.Create( MakeColor(0, 0, 0, 0) );
tx := TGPStringFormat.Create;
try
// configura o device
tx.SetLineAlignment(StringAlignmentCenter);
r.X := 0;
r.Y := 0;
r.Width := 2000;
r.Height := aHeight;
c.MeasureString(WideString(s), -1, f, r, rTx);
if (aWidth < 0) and (rTx.Width > Abs(aWidth)) then
begin
c.Free;
bt.Free;
aWidth := Ceil(rTx.Width);
bt := TGPBitmap.Create(aWidth, aHeight, PixelFormat32bppARGB);
c := TGPGraphics.Create(bt);
end;
c.SetTextRenderingHint(TextRenderingHintAntiAlias);
// inicializa as variáveis
r.X := 0;
r.Y := 0;
r.Width := bt.GetWidth;
r.Height := bt.GetHeight;
// escreve o texto
b.SetColor(fg);
c.DrawString(WideString(s), -1, f, r, tx, b);
finally
f.Free;
b.Free;
tx.Free;
c.Free;
end;
Result := TBitmap.Create;
if bt.GetHBITMAP(0, h)= ok then
TBitmap(Result).Handle := h;
finally
bt.Free;
end;
end;
Usage:
myGlyph := CreateTransparent('N', 14, 16, 16, clGray);
The problem:
The resulting bitmap isn't transparent, the background becomes black!
Can someone tell me what I need to do to "fill" the background as transparent?
According to what I understood , you want the background of bitmap to be transparent ?
If so , you need to use alpha channel bitmap ..
By default the background color is black so you only need to set the property AlphaFormat of your bitmap to afDefined :
...
Result := TBitmap.Create;
Result.AlphaFormat := afDefined;
if bt.GetHBITMAP(0, h) = ok then
TBitmap(Result).Handle := h;
...
And this is the result :
Related
I use this code to scan very fast Bitmap.
Everything is Ok When PixelFormat = pf24bit but my program only work with 256 image color and for this reason PixelFormat = pf8bit.
When PixelFormat = pf8bit this code show error.
var
w, h: Integer;
CurrRow, OffSet: Integer;
x: byte;
pRed, pGreen, pBlue: PByte;
begin
CurrRow := Integer(aBitmap.Scanline[0]);
OffSet := Integer(aBitmap.Scanline[1]) - CurrRow;
Result:= False;
for h := 0 to aBitmap.Height - 1 do
begin
for w := 0 to aBitmap.Width - 1 do
begin
pBlue := PByte(CurrRow + w * 3);
pGreen := PByte(CurrRow + w * 3 + 1);
pRed := PByte(CurrRow + w * 3 + 2);
end;
inc(CurrRow, OffSet);
end;
now I use this code to swap color but dont work because scanline dont check color
procedure ReplaceColor(aBitmap: TBitmap; swap1, swap2: TRGBQuad);
var
w, h, k: Integer;
pScanline: pByte;
Red, Green, Blue, palindex: Byte;
PalEntries: array[0..255] of TRGBQuad;
begin
if aBitmap.Palette <> 0 then
GetPaletteEntries(aBitmap.Palette, 0, 255, PalEntries);
for h := 0 to aBitmap.Height - 1 do
begin
pScanline := pByte(aBitmap.Scanline[h]);
for w := 0 to aBitmap.Width - 1 do
begin
Blue:= PalEntries[pScanline^].rgbBlue ;
Red:= PalEntries[pScanline^].rgbRed ;
Green:= PalEntries[pScanline^].rgbGreen ;
if (Blue = swap1.rgbBlue) and (Red = swap1.rgbRed) and
(Green = swap1.rgbGreen) then
begin
Blue := swap2.rgbBlue;
Green := swap2.rgbGreen;
Red := swap2.rgbRed;
end
else if (Blue = swap2.rgbBlue) and (Red = swap2.rgbRed) and
(Green = swap2.rgbGreen) then
begin
Blue := swap1.rgbBlue;
Green := swap1.rgbGreen;
Red := swap1.rgbRed;
end;
Inc(pScanline);
end;
end;
end;
The code fails for pf8bit because it is not written to handle pf8bit. It is written to handle pf24bit instead.
The code is expecting each scanline to consist of width number of 3-byte (24 bits) pixels containing the actual RGB values. But in pf8bit, each scanline contains 1-byte (8 bit) pixels which are indexes into the bitmap's color palette. You are not accounting for that at all.
Try something more like this instead:
var
w, h: Integer;
pScanline: PByte;
Red, Green, Blue: Byte;
PalEntries: array[0..255] of TRGBQuad;
begin
Result := False;
if aBitmap.Palette <> 0 then
GetPaletteEntries(aBitmap.Palette, 0, 255, PalEntries);
for h := 0 to aBitmap.Height - 1 do
begin
pScanline := PByte(aBitmap.Scanline[h]);
for w := 0 to aBitmap.Width - 1 do
begin
case aBitmap.PixelFormat of
pf8Bit: begin
Blue := PalEntries[pScanline^].rgbBlue;
Green := PalEntries[pScanline^].rgbGreen;
Red := PalEntries[pScanline^].rgbRed;
Inc(pScanline);
end;
pf24Bit: begin
Blue := PRGBTriple(pScanline).rgbtBlue;
Green := PRGBTriple(pScanline).rgbtGreen;
Red := PRGBTriple(pScanline).rgbtRed;
Inc(pScanline, SizeOf(TRGBTriple));
end;
// etc for other color depths...
end;
end;
end;
end;
You need to do some research on how bitmaps actually work, particularly in relation to the format of the scanlines at the various color depths.
Bitmaps overview
i want to draw a bitmap on a canvas with opacity where the bitmap has a transparent color.
i could create a bitmap with transparent color and draw it to a
canvas i could create a bitmap and draw it to a canvas with opacity
but i couldn't combine it. if i combine it the opacity is ignored.
here is the code i wrote:
procedure TForm1.FormPaint(Sender: TObject);
var b1,b2:TBitmap;
begin
// Example how it opacity works:
b1 := TBitmap.Create;
b1.SetSize(20,20);
b1.Canvas.Brush.Color := clBlue;
b1.Canvas.Rectangle(0,0,20,20);
Canvas.Draw(10,10,b1,$ff); // Works
Canvas.Draw(40,10,b1,$66); // Works
// I need it in combination with TransparentColor:
b2 := TBitmap.Create;
// next 3 lines are different from above
b2.Transparent := true;
b2.TransparentColor := clFuchsia;
b2.Canvas.Brush.Color := clFuchsia;
b2.SetSize(20,20);
b2.Canvas.Brush.Color := clBlue;
b2.Canvas.Ellipse(0,0,20,20);
Canvas.Draw(10,40,b2,$ff); // Works (full opacity)
Canvas.Draw(40,40,b2,$66); // Ignores the $66 Opacity
b1.Free;
b2.Free;
end;
produces:
how could i draw (f.e. a blue circle) with transparent background and just 40% opacity?
i would prefere a solution without direct winapi (like bitblt, ...) if possible.
i tried a few hacks like bitshifting a alpha channel to a TColor value but it didn't work.
here i what i tried:
procedure TForm1.FormPaint(Sender: TObject);
var b:TBitmap;
begin
b := TBitmap.Create;
b.PixelFormat := pf32bit;
b.AlphaFormat := afDefined;
b.Canvas.Brush.Color := 0 and ($ff shl 32); // Background Transperency
b.SetSize(20,20);
b.Canvas.Brush.Color := clBlue + (($ff-$66) shl 32);
b.Canvas.Ellipse(0,0,20,20);
Canvas.Draw(10,10,b);
b.Free;
end;
produces:
thanks in advance!
EDIT: my system: delphi xe 5 on windows 7 64bit (but using the 32bit compiler)
What happens can be seen in procedure TBitmap.DrawTransparent in the unit Graphics.
If the property of the image is set to transparent as show for b2 in your example the Bitmap will be drawn with
Graphics.TransparentStretchBlt which is using StretchBlt with differnt masks to draw the image and is not able to use the alpha channel.
A not tranparent Bitmap , your b1, will be draw with
AlphaBlend.
To reach your goal you might use another bitmap b2, set the Alphachannel to 0, paint b2 with opacity $66 on b3, set set the Alphachannel to 255 for every pixel which is clFuchsia in b2 and then paint this bitmap with the desired opacity
type
pRGBQuadArray = ^TRGBQuadArray;
TRGBQuadArray = ARRAY [0 .. 0] OF TRGBQuad;
TRefChanel=(rcBlue,rcRed,rcGreen);
procedure SetBitmapAlpha(ABitmap: TBitMap; Alpha: Byte);
var
pscanLine32: pRGBQuadArray;
nScanLineCount, nPixelCount : Integer;
begin
with ABitmap do
begin
PixelFormat := pf32Bit;
HandleType := bmDIB;
ignorepalette := true;
alphaformat := afDefined;
for nScanLineCount := 0 to Height - 1 do
begin
pscanLine32 := Scanline[nScanLineCount];
for nPixelCount := 0 to Width - 1 do
with pscanLine32[nPixelCount] do
begin
rgbReserved := Alpha;
end;
end;
end;
end;
procedure AdaptBitmapAlpha(ABitmap,TranspBitmap:TBitmap);
var
pscanLine32,pscanLine32_2: pRGBQuadArray;
nScanLineCount, nPixelCount : Integer;
begin
with ABitmap do
begin
PixelFormat := pf32Bit;
HandleType := bmDIB;
ignorepalette := true;
alphaformat := afDefined;
for nScanLineCount := 0 to Height - 1 do
begin
pscanLine32 := Scanline[nScanLineCount];
pscanLine32_2 := TranspBitmap.Scanline[nScanLineCount];
for nPixelCount := 0 to Width - 1 do
with pscanLine32[nPixelCount] do
begin
// all picels with are not clFuchsia in the transparent bitmap
if NOT ((pscanLine32_2[nPixelCount].rgbBlue=255) AND (pscanLine32_2[nPixelCount].rgbRed=255) AND (pscanLine32_2[nPixelCount].rgbGreen=0) ) then
begin
rgbReserved := 255;
end
else
begin
rgbBlue := 0;
rgbRed := 0;
rgbGreen := 0;
end;
end;
end;
end;
end;
procedure TAForm.FormPaint(Sender: TObject);
var b1,b2,b3:TBitmap;
BF: TBlendFunction;
begin
// Example how it opacity works:
b1 := TBitmap.Create;
b1.SetSize(20,20);
b1.Canvas.Brush.Color := clBlue;
b1.Canvas.Rectangle(0,0,20,20);
Canvas.Draw(10,10,b1,$ff); // Works
Canvas.Draw(40,10,b1,$66); // Works
// I need it in combination with TransparentColor:
b3 := TBitmap.Create;
b3.PixelFormat := pf32Bit;
b2 := TBitmap.Create;
b2.PixelFormat := pf32Bit;
// next 3 lines are different from above
b2.Transparent := true;
b2.TransparentColor := clFuchsia;
b2.Canvas.Brush.Color := clFuchsia;
b2.SetSize(20,20);
b2.Canvas.Brush.Color := clBlue;
b2.Canvas.Ellipse(0,0,20,20);
Canvas.Draw(10,40,b2,$ff); // Works (full opacity)
b3.SetSize(20,20);
SetBitmapAlpha(b3,0);
b3.Canvas.Draw(0,0,b2,$66);
AdaptBitmapAlpha(b3,b2);
Canvas.Draw(40,40,b3,$66);
b1.Free;
b2.Free;
b3.Free;
end;
thanks to bummi (accepted answer)!
i put his solution in a class helper. here is the code if anybody need it:
unit uBitmapHelper;
interface
uses
Vcl.Graphics;
type
TBitmapHelper = class Helper for TBitmap
private
type
TRgbaRec = packed record
r,g,b,a:Byte;
end;
PRgbaRec = ^TRgbaRec;
PRgbaRecArray = ^TRgbaRecArray;
TRgbaRecArray = array [0 .. 0] of TRgbaRec;
public
procedure TransparentMaskedDraw(ACanvas:TCanvas;AX:Integer;AY:Integer;AMask:TColor;AOpacity:Byte);
end;
implementation
{ TBitmapHelper }
procedure TBitmapHelper.TransparentMaskedDraw(ACanvas:TCanvas;AX,AY:Integer;AMask:TColor;AOpacity:Byte);
var i,j:Integer;
line1,line2:PRgbaRecArray;
mask:PRgbaRec;
tmp:TBitmap;
begin
mask := #AMask;
tmp := TBitmap.Create;
tmp.SetSize(self.Width,self.Height);
tmp.PixelFormat := pf32Bit;
tmp.HandleType := bmDIB;
tmp.IgnorePalette := true;
tmp.AlphaFormat := afDefined;
for i := 0 to tmp.Height - 1 do begin
line1 := tmp.Scanline[i];
for j := 0 to tmp.Width - 1 do begin
line1[j].a := 0;
end;
end;
tmp.Canvas.Draw(0,0,self,AOpacity);
for i := 0 to tmp.Height - 1 do begin
line1 := tmp.ScanLine[i];
line2 := self.ScanLine[i];
for j := 0 to tmp.Width - 1 do begin
if not((line2[j].r = mask.r) and (line2[j].g = mask.g) and (line2[j].b = mask.b)) then begin
line1[j].a := $ff;
end else begin
line1[j].r := 0;
line1[j].g := 0;
line1[j].b := 0;
end;
end;
end;
ACanvas.Draw(AX,AY,tmp,AOpacity);
tmp.Free;
end;
end.
The oldest answer is fine, please find some easy reshuffle.
This example also shows how to put one png-image with opacity on another by respecting the transparency.
procedure TForm2.FormCreate(Sender: TObject);
//define your own transparent color by setting RGB-values
const cTransR=255; cTransG=255; cTransB=255;
clTrans= $10000*cTransB + $100*cTransG + cTransR;
var bmp1,bmp2:TBitmap;
pngTemp: TPngImage;
I:integer;
procedure SetAlphaTransparent(VAR LBitmap:TBitmap);
type TRGBQuadArray = ARRAY [0..0] OF TRGBQuad;
var I, J: integer;
LscanLine32:^TRGBQuadArray;
begin
// I found no other way than scanning pixel by pixel to recover default opacity
for I := 0 to LBitmap.Height - 1 do begin
LscanLine32:=LBitmap.ScanLine[I];
for J := 0 to LBitmap.Width - 1 do
with LscanLine32[J] do
if NOT((rgbRed=cTransR)AND(rgbGreen=cTransG)AND(rgbBlue=cTransB)) then
rgbReserved := 255; // make pixel visible, since transparent is default
end;
end;
Procedure SetAlphaProperty(Var LBitmap:TBitmap; LWidth, LHeight:integer);
begin
// You will need a different format Bitmap to allow alpha values
LBitmap.PixelFormat := pf32Bit;
LBitmap.HandleType := bmDIB;
LBitmap.alphaformat := afDefined;
LBitmap.Canvas.Brush.Color := clTrans;
LBitmap.SetSize(LWidth,LHeight);
end;
begin
// create any background on your Form, by placing IMG:Timage on the From
pngTemp := TPngImage.Create;
pngTemp.LoadFromFile( GetCurrentDir()+'\figure1.png' );
IMG.Canvas.Draw((IMG.Width-pngTemp.Width) div 2, // fit png into the center
(IMG.Height-pngTemp.Height) div 2,pngTemp);
pngTemp.Free;
// First example how it opacity works with transparency
bmp1 := TBitmap.Create;
SetAlphaProperty(bmp1,35,35);
// a circle has a surrouding area, to make transparent
bmp1.Canvas.Brush.Color := clBlue;
bmp1.Canvas.Ellipse(5,5,30,30);
SetAlphaTransparent(bmp1);
// show some circles with different opacity
for I := 0 to 7 do
IMG.Canvas.Draw(I*40-30,10,bmp1,(8-I)*32);
bmp1.Free;
// Another example using a different png-file
bmp2 := TBitmap.Create;
SetAlphaProperty(bmp2,Img.Width,Img.Height);
// load a transparent png-file and put it into the alpha bitmap:
pngTemp := TPngImage.Create;
pngTemp.LoadFromFile( GetCurrentDir()+'\figure2.png' );
pngTemp.Transparent := true;
bmp2.Canvas.Draw((bmp2.Width-pngTemp.Width) div 2,// fit png into the center
(bmp2.Height-pngTemp.Height) div 2,pngTemp);
pngTemp.Free;
// draw the second image with transparancy and opacity onto the first one
SetAlphaTransparent(bmp2);
IMG.Canvas.Draw(0,0,bmp2,$66);
bmp2.Free;
end;
I'm trying to create a mask window with "loading" text, to alert the user about a busy state of my application.
For this, I first created a single form with:
BorderStyle = bsNone
Color = clBlack
AlphaBlend = True
AlphaBlendValue = 180;
As the second step, I want to create another Form, but this one will has dynamic content.
I need to create a transparent bitmap with some status text and use the UpdateLayeredWindow to draw the window as the text.
Take a look and my desired result:
Remember: the text will be different in some cases, like:
Recalculating
Loading resources
Loading report
That's the reason what I need a dynamic bitmap generation.
QUESTION
How can I create a transparent bitmap with text and use it on a form with UpdateLayeredWindow?
I'm trying this, but without success ( to try the code put a Button5 and Label2 on a form):
procedure Inc(var p: pointer);
begin
p := Pointer(Integer(p) + 1);
end;
var
s: string;
frm: TForm;
f: HFont;
tx: HDC;
bmp, old: HBITMAP;
rc: TRect;
h: BITMAPINFOHEADER;
pvBits: Pointer;
t: tagBITMAPINFO;
x,y: integer;
a, r, g, b: byte;
sz: TSize;
p: tpoint;
BlendFunction: TBlendFunction;
begin
tx := CreateCompatibleDC(0);
s := label2.Caption;
f := SelectObject(tx, label2.Font.Handle);
fillchar(rc, SizeOf(rc), 0);
DrawText(tx, PChar(s), length(s), rc, DT_CALCRECT);
fillchar(h, SizeOf(h), 0);
pvBits := nil;
h.biSize := SizeOf(h);
h.biWidth := rc.Right - rc.Left;
h.biHeight := rc.Bottom - rc.Top;
h.biPlanes := 1;
h.biBitCount := 32;
h.biCompression := BI_RGB;
FillChar(t, SizeOf(t), 0);
t.bmiHeader := h;
bmp := CreateDIBSection(tx, t, 0, pvBits, 0, 0);
old := SelectObject(tx, bmp);
if old > 0 then
begin
SetTextColor(tx, $00FFFFFF);
SetBkColor(tx, $00000000);
SetBkMode(tx, TRANSPARENT);
DrawText(tx, PChar(s), length(s), rc, DT_NOCLIP);
r := GetRValue($FF);
g := GetGValue($FF);
b := GetBValue($FF);
for x := 0 to h.biWidth-1 do
for y := 0 to h.biHeight-1 do
begin
a := Byte(pvBits^);
Inc(pvBits);
Byte(pvBits^) := (b * a) shr 8;
Inc(pvBits);
Byte(pvBits^) := (g * a) shr 8;
Inc(pvBits);
Byte(pvBits^) := (r * a) shr 8;
Inc(pvBits);
Byte(pvBits^) := a;
end;
SelectObject(tx, old);
end;
SelectObject(tx, f);
deleteDC(tx);
sz.cx := h.biWidth;
sz.cy := h.biHeight;
p := Point(0,0);
BlendFunction.BlendOp := AC_SRC_OVER;
BlendFunction.BlendFlags := 0;
BlendFunction.SourceConstantAlpha := 255;
BlendFunction.AlphaFormat := AC_SRC_ALPHA;
frm := TForm.CreateNew(self);
frm.BorderStyle := bsNone;
frm.Position := poOwnerFormCenter;
frm.Show;
UpdateLayeredWindow(frm.Handle, 0, nil, #sz, bmp, #p, 0, #BlendFunction, ULW_ALPHA);
end;
Assuming you can use Windows API functions from Delphi (since you've tagged winapi), one easy way is:
CreateDIBSection() to create a 32 bit bitmap
FillRect() to fill the background, DrawText() to draw the text
Fix up the alpha
Use that bitmap with UpdateLayeredWindow()
Fixing up the alpha is done by directly modifying the bitmap bits that you get back from CreateDIBSection(). Note that UpdateLayeredWindow() requires pre-multiplied alpha, so you have to multiple the RGB components by the alpha value in advance.
The following code is C but hopefully will give you the idea:
LPVOID pBits; // bits from CreateDIBSection
const int width, height; // size of bitmap
const int alpha; // level of transparency
RGBQUAD* pPtr = (RGBQUAD*)pBits;
for (int y = 0; y < height; ++y)
{
for (int x = 0; x < width; ++x, ++pPtr)
{
pPtr->rgbBlue = (alpha * pPtr->rgbBlue) / 255;
pPtr->rgbGreen = (alpha * pPtr->rgbGreen) / 255;
pPtr->rgbRed = (alpha * pPtr->rgbRed) / 255;
pPtr->rgbReserved = alpha;
}
}
Any library/code to fade the edges of a bitmap in a gradient manner?
Something like this:
Edit: final code
Ok came up with this code after your example, it's ~10 times faster after optimization with scanlines. Ideally I think I should convert it to use a 32bit bitmap instead and modify the actual alpha layer, but this works for now, ty!
procedure FadeEdges(b: TBitmap; Depth, Start, Col: TColor);
Var f, x, y, i: Integer;
w,h: Integer;
pArrays: Array of pRGBArray;
xAlpha: Array of byte;
sR, sG, sB: Byte;
a,a2: Double;
r1,g1,b1: Double;
Lx,Lx2: Integer;
procedure AlphaBlendPixel(X, Y: Integer);
begin
pArrays[y,x].rgbtRed := Round(r1 + pArrays[y,x].rgbtRed * a2);
pArrays[y,x].rgbtGreen := Round(g1 + pArrays[y,x].rgbtGreen * a2);
pArrays[y,x].rgbtBlue := Round(b1 + pArrays[y,x].rgbtBlue * a2);
end;
procedure AlphaBlendRow(Row: Integer; Alpha: Byte);
Var bR, bG, bB, xA: Byte;
t: Integer;
s,s2: Double;
begin
s := alpha / 255;
s2 := (255 - Alpha) / 255;
for t := 0 to b.Width-1 do begin
bR := pArrays[Row,t].rgbtRed;
bG := pArrays[Row,t].rgbtGreen;
bB := pArrays[Row,t].rgbtBlue;
pArrays[Row,t].rgbtRed := Round(sR*s + bR*s2);
pArrays[Row,t].rgbtGreen := Round(sG*s + bG*s2);
pArrays[Row,t].rgbtBlue := Round(sB*s + bB*s2);
end;
end;
begin
b.PixelFormat := pf24bit;
// cache scanlines
SetLength(pArrays,b.Height);
for y := 0 to b.Height-1 do
pArrays[y] := pRGBArray(b.ScanLine[y]);
// pre-calc Alpha
SetLength(xAlpha,Depth);
for y := 0 to (Depth-1) do
xAlpha[y] := Round(Start + (255 - Start)*y/(Depth-1));
// pre-calc bg color
sR := GetRValue(Col);
sG := GetGValue(Col);
sB := GetBValue(Col);
// offsets
w := b.Width-Depth;
h := b.Height-Depth;
for i := 0 to (Depth-1) do begin
a := xAlpha[i] / 255;
a2 := (255 - xAlpha[i]) / 255;
r1 := sR * a;
g1 := sG * a;
b1 := sB * a;
Lx := (Depth-1)-i;
Lx2 := i+w;
for y := 0 to b.Height - 1 do begin
AlphaBlendPixel(Lx, y); // Left
AlphaBlendPixel(Lx2, y); // right
end;
end;
for i := 0 to (Depth-1) do begin
AlphaBlendRow((Depth-1)-i, xAlpha[i]); // top
AlphaBlendRow(i+(h), xAlpha[i]); // bottom
end;
SetLength(xAlpha,0);
SetLength(pArrays,0);
end;
Final result: (left = original, right = blended on hovering with a ListView)
edit: further speed improvements, twice as fast as original proc.
I can give you some code I wrote a couple of years ago to achieve this. It might be useful as a guide. The code is part of a class that manipulates a bitmap and this is the part that fades the left edge of the bitmap into a white background:
procedure TScreenShotEnhancer.FadeOutLeft(Position, Start: Integer);
var
X, Y: Integer;
F, N: Integer;
I: Integer;
begin
BeginUpdate;
try
N := Position;
for I := 0 to N - 1 do begin
X := Position - I - 1;
F := Round(Start + (255 - Start)*I/N);
for Y := 0 to Height - 1 do
AlphaBlendPixel(X, Y, clWhite, F);
end;
finally
EndUpdate;
end;
end;
The actual work is done in this method:
procedure TScreenShotEnhancer.AlphaBlendPixel(X, Y: Integer; Color: TColor;
Alpha: Byte);
var
backgroundColor: TColor;
displayColor: TColor;
dR, dG, dB: Byte;
bR, bG, bB: Byte;
sR, sG, sB: Byte;
begin
backgroundColor := Bitmap.Canvas.Pixels[X, Y];
bR := GetRValue(backgroundColor);
bG := GetGValue(backgroundColor);
bB := GetBValue(backgroundColor);
sR := GetRValue(Color);
sG := GetGValue(Color);
sB := GetBValue(Color);
dR := Round(sR * alpha / 255 + bR * (255 - alpha) / 255);
dG := Round(sG * alpha / 255 + bG * (255 - alpha) / 255);
dB := Round(sB * alpha / 255 + bB * (255 - alpha) / 255);
displayColor := RGB(dR, dG, dB);
Bitmap.Canvas.Pixels[X, Y] := displayColor;
end;
I have ImageList sized 72x72, handle to the icon (HICON), obtained by SHGetFileInfo (for example a large icon sized 32x32). How to add it to this ImageList keeping transparency, but without stretching? Now I draw the icon in the middle of a temporary bitmap desired size, then add it to the ImageList.
SHGetFileInfo(PChar(Path + sr.Name), sr.FindData.dwFileAttributes, fi, SizeOf(fi), SHGFI_ICON or SHGFI_LARGEICON or SHGFI_USEFILEATTRIBUTES);
Bmp:=TBitmap.Create;
Bmp.PixelFormat:=pf32bit;
Bmp.SetSize(72, 72);
DrawIcon(Bmp.Canvas.Handle, 20, 20, fi.hIcon);
iIcon:=ImageList_AddMasked(ilThumbs.Handle, Bmp.Handle, 0);
Bmp.Free;
But I think a way faster exists (without drawing on temporary bitmap). Also image in ImageList loses transparency and when I set index of this Image in ImageList for ListView item.ImageIndex it looks not pretty (when this item is selected, white background around is present). Is any way to solve this problem?
Thanks.
This is the code that I use to perform this task.
Note that I am assuming that the original icon uses 32 bit colour, with alpha channel. That's reasonable in the settings that I use this code, but I can't be sure whether or not it's reasonable for you.
uses
Windows, Graphics;
function CreateIconFromSmallerIcon(IconSize: Integer; SmallerIcon: HICON): HICON;
procedure GetDIBheaderAndBits(bmp: HBITMAP; out bih: BITMAPINFOHEADER; out bits: Pointer);
var
pbih: ^BITMAPINFOHEADER;
bihSize, bitsSize: DWORD;
begin
bits := nil;
GetDIBSizes(bmp, bihSize, bitsSize);
pbih := AllocMem(bihSize);
Try
bits := AllocMem(bitsSize);
GetDIB(bmp, 0, pbih^, bits^);
if pbih.biSize<SizeOf(bih) then begin
FreeMem(bits);
bits := nil;
exit;
end;
bih := pbih^;
Finally
FreeMem(pbih);
End;
end;
procedure InitialiseBitmapInfoHeader(var bih: BITMAPINFOHEADER);
begin
bih.biSize := SizeOf(BITMAPINFOHEADER);
bih.biWidth := IconSize;
bih.biHeight := 2*IconSize;//height of xor bitmap plus height of and bitmap
bih.biPlanes := 1;
bih.biBitCount := 32;
bih.biCompression := BI_RGB;
end;
procedure CreateXORbitmap(const sbih, dbih: BITMAPINFOHEADER; sptr, dptr: PDWORD);
var
line, xOffset, yOffset: Integer;
begin
xOffset := (IconSize-sbih.biWidth) div 2;
yOffset := (IconSize-sbih.biHeight) div 2;
inc(dptr, xOffset + IconSize*yOffset);
for line := 0 to sbih.biHeight-1 do begin
Move(sptr^, dptr^, sbih.biWidth*SizeOf(DWORD));
inc(dptr, IconSize);//relies on the fact that no padding is needed for RGBA scanlines
inc(sptr, sbih.biWidth);//likewise
end;
end;
var
SmallerIconInfo: TIconInfo;
sBits, xorBits: PDWORD;
xorScanSize, andScanSize: Integer;
xorBitsSize, andBitsSize: Integer;
sbih: BITMAPINFOHEADER;
dbih: ^BITMAPINFOHEADER;
resbitsSize: DWORD;
resbits: Pointer;
begin
Result := 0;
Try
if not GetIconInfo(SmallerIcon, SmallerIconInfo) then begin
exit;
end;
Try
GetDIBheaderAndBits(SmallerIconInfo.hbmColor, sbih, Pointer(sBits));
if Assigned(sBits) then begin
Try
if (sbih.biWidth>IconSize) or (sbih.biHeight>IconSize) or (sbih.biPlanes<>1) or (sbih.biBitCount<>32) then begin
exit;
end;
xorScanSize := BytesPerScanline(IconSize, 32, 32);
Assert(xorScanSize=SizeOf(DWORD)*IconSize);
andScanSize := BytesPerScanline(IconSize, 1, 32);
xorBitsSize := IconSize*xorScanSize;
andBitsSize := IconSize*andScanSize;
resbitsSize := SizeOf(BITMAPINFOHEADER) + xorBitsSize + andBitsSize;
resbits := AllocMem(resbitsSize);//AllocMem zeroises the memory
Try
dbih := resbits;
InitialiseBitmapInfoHeader(dbih^);
xorBits := resbits;
inc(PByte(xorBits), SizeOf(BITMAPINFOHEADER));
CreateXORbitmap(sbih, dbih^, sBits, xorBits);
//don't need to fill in the mask bitmap when using RGBA
Result := CreateIconFromResourceEx(resbits, resbitsSize, True, $00030000, IconSize, IconSize, LR_DEFAULTCOLOR);
Finally
FreeMem(resbits);
End;
Finally
FreeMem(sBits);
End;
end;
Finally
if SmallerIconInfo.hbmMask<>0 then begin
DeleteObject(SmallerIconInfo.hbmMask);
end;
if SmallerIconInfo.hbmColor<>0 then begin
DeleteObject(SmallerIconInfo.hbmColor);
end;
End;
Finally
DestroyIcon(SmallerIcon);
End;
end;
Ok, my solution below:
procedure SetAlpha(Bitmap: TBitmap);
type
PPixelRec = ^TPixelRec;
TPixelRec = packed record
B, G, R, Alpha: Byte;
end;
var
X, Y: Integer;
Pixel: PPixelRec;
begin
for Y := 0 to (Bitmap.Height - 1) do
begin
Pixel := Bitmap.ScanLine[Y];
for X := 0 to (Bitmap.Width - 1) do
begin
Pixel.Alpha:=255;
Inc(Pixel);
end;
end;
end;
//skipped
var Bmp: TBitmap;
fi: TSHFileInfo;
ImageList1: TImageList;
begin
ImageList1:=TImageList.CreateSize(72, 72);
ImageList1.DrawingStyle:=dsTransparent;
ImageList1.ColorDepth:=cd32Bit;
SHGetFileInfo('c:\Windows\notepad.exe', FILE_ATTRIBUTE_NORMAL, fi, SizeOf(fi), SHGFI_ICON or SHGFI_LARGEICON or SHGFI_USEFILEATTRIBUTES);
Bmp:=TBitmap.Create;
Bmp.SetSize(72, 72);
SetAlpha(Bmp);
Bmp.Canvas.Brush.Color:=clWhite;
Bmp.Canvas.FillRect(Rect(0, 0, 72, 72));
DrawIcon(Bmp.Canvas.Handle, 20, 20, fi.hIcon);
fi.iIcon:=ImageList1.Add(Bmp, nil);
ImageList1.Draw(Canvas, 0, 0, fi.iIcon); //just to see that's alright
end;