Смешать два цвета с использованием коэффициента прозрачности

Советы » Цвета и Палитра » Смешать два цвета с использованием коэффициента прозрачности

// This function mixes two bytes According to value of TRANS 
// The value of TRANS is between 0 (result then will be equal to FG) 
// and 255 (result then will be equal to BG) 

MixBytes(FG, BG, TRANS: byte): byte; asm

push bx // push some regs push cx push dx mov DH,TRANS // remembering Transparency value (or Opacity - as you like) mov BL,FG // filling registers with our values mov AL,DH // BL = ForeGround (FG) mov CL,BG // CL = BackGround (BG) xor

AH,AH // Clear High-order parts of regs xor

BH,BH xor

CH,CH mul BL // AL=AL*BL mov BX,AX // BX=AX xor

AH,AH mov AL,DH xor

AL,$FF // AX=(255-TRANS) mul CL // AL=AL*CL add AX,BX // AX=AX+BX shr

AX,8 // Fine! Here we have mixed value in AL pop dx // Hm... No rubbish after us, ok? pop cx pop bx // Bye, dear Assembler - we go home to Delphi! end

; // Here we mix R,G and B channels of our colors separately. // The value of T is between 0 and 255 as described above. // As you know, TColor value is 4 bytes length integer value where // low byte is red channel, 2nd byte is green and 3rd byte is blue function

MixColors(FG, BG: TColor; T: byte): TColor; var

r,g,b:byte; begin

R := MixBytes(FG and

255,BG and

255,T); // extracting and mixing Red G := MixBytes((FG shr

8) and

255,(BG shr

8) and

255,T); // the same with green B := MixBytes((FG shr

16) and

255,(BG shr

16) and

255,T); // and blue, of course Result := r+g*256+b*65536; // finishing with combining all channels together end


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