Delphi. Трюки и эффекты

Альфа-смешивание нижней области

//нижняя область. Используем альфа = 75 % и переменную исходную альфу

//создаем градиентный эффект, используя исходную альфа

ubRed := $00;

ubGreen := $00;

ubBlue := $ff;

for y := 0 to ulBitmapHeight – 1 do

for x := 0 to ulBitmapWidth – 1 do

begin

ubAlpha := Trunc(x / ulBitmapWidth * 255) and $FF;

fAlphaFactor := ubAlpha / $ff;

r := (Round(ubRed * fAlphaFactor) * (1 shl 16)) and $FF;

g := (Round(ubGreen * fAlphaFactor) * (1 shl 8)) and $FF;

b := Round(ubBlue * fAlphaFactor) and $FF;

PULONG(Integer(pvBits) +

(x + y * ulBitmapWidth) * sizeof(ULONG))^ :=

(ubAlpha shl 24) or //0xaa000000

r or //0x00rr0000

g or //0x0000gg00

b; //0x000000bb

end;

bf.BlendOp := AC_SRC_OVER;

bf.BlendFlags := 0;

bf.AlphaFormat := AC_SRC_ALPHA;

bf.SourceConstantAlpha := $bf;

Windows.AlphaBlend(hdcwnd, ulWindowWidth div 5,

ulWindowHeight div 5 + 2 * ulWindowHeight,

ulBitmapWidth, ulBitmapHeight, hCurDC, 0, 0,

ulBitmapWidth, ulBitmapHeight, bf);

DeleteObject(hbmp);

DeleteDC(hCurDC);