怎样得到屏幕上的某一点的像素的颜色值？

[sunwewillsharedoit]

在线等待.
第一个解决问题的将得到这100分

[jeff]

var
Canvas: TCanvas;
Color: TColor;
x,y: Integer;
begin
x:=???;
y:=???;
Canvas:=TCanvas.Create;
Canvas.Handle:=GetDC(0); //GetDc(0)用来获得屏幕的Handle，而不是Form的Handle
Canvas.Pen.Color:=clRed;
Canvas.Pen.Style:=psSolid;
with Canvas do
begin
MoveTo(100,100); //测试在屏幕上画一个红线，成功。
LineTo(200,200);
end;
Color:=Canvas.Pixels[x,y];
canvas.Free;
end;

[sunwewillsharedoit]

你好！
我是说得到指定一点的像素的颜色值.
比如说（200，600）的像素的颜色值.

[sunwewillsharedoit]

你好jufeng_zhu!
我试试

[sunwewillsharedoit]

我的这段程序报错：
procedure TForm1.Button1Click(Sender: TObject);
var
Canvas: TCanvas;
x,y,i,j: Integer;
begin

x:=20;
Canvas:=TCanvas.Create;

for i:=1 to 50 do

Canvas.Pixels[x+i,5]:=clRed;//

Canvas.Free;
end;
错误信息是：
canvas does not allow drawing!
为什么？

[l_xiaofeng]

procedure TForm1.Button1Click(Sender: TObject);
var
// Canvas: TCanvas;
x,y,i,j: Integer;
begin

x:=20;
// Canvas:=TCanvas.Create;

for i:=1 to 50 do

Canvas.Pixels[x+i,5]:=clRed;//

// Canvas.Free;
end;

[jeff]

如果你向屏幕画东西，一定不要少
Canvas.Handle:=GetDC(0);
你的程序我试了，加上这句后就可以了．
procedure TForm1.Button1Click(Sender: TObject);
var
Canvas: TCanvas;
x,y,i,j: Integer;
begin

x:=20;
Canvas:=TCanvas.Create;
Canvas.Handle:=GetDC(0);
for i:=1 to 50 do

Canvas.Pixels[x+i,5]:=clRed;//

Canvas.Free;
end;

[DelphiIdiot]

procedure Tgetcol.FormClick(Sender: TObject);
var t : tcolor;
r,g,b : byte;
begin
t := canvas.pixels[tx,ty];
r := getRvalue(t);
g := getGvalue(t);
B := getBvalue(t);
LABEL2.COLOR := T;
LABEL1.CAPTION := '$00' + HEXB(R) + HEXB(G) + HEXB(B);
end;
一个完整的例子，运行后在屏幕下方有个小条子，然后鼠标点击屏幕上任意点，
小条子上将用16进制显示颜色值：
unit Ugetcor;

interface

uses
SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
Forms, Dialogs, StdCtrls, ExtCtrls, Buttons;

type
Tgetcol = class(TForm)
Panel1: TPanel;
Label1: TLabel;
Label2: TLabel;
procedure FormClick(Sender: TObject);
procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
procedure Panel1Click(Sender: TObject);
procedure FormDblClick(Sender: TObject);
procedure FormResize(Sender: TObject);
private
tx,ty : integer;
procedure WMEraseBkng(var MSg:TWMEraseBkgnd);message WM_ERASEBKGND;
public
{ Public declarations }
end;

var
getcol: Tgetcol;
implementation

{$R *.DFM}
const
Digits : array[0..$F] of Char = '0123456789ABCDEF';

function HexB(B : Byte) : string;
{-Return hex string for byte}
begin
HexB[0] := #2;
HexB[1] := Digits[B shr 4];
HexB[2] := Digits[B and $F];
end;

procedure Tgetcol.WMEraseBkng(var MSg:TWMEraseBkgnd);
begin
Msg.Result:=1;
end;

procedure Tgetcol.FormClick(Sender: TObject);
var t : tcolor;
r,g,b : byte;
begin
t := canvas.pixels[tx,ty];
r := getRvalue(t);
g := getGvalue(t);
B := getBvalue(t);
LABEL2.COLOR := T;
LABEL1.CAPTION := '$00' + HEXB(R) + HEXB(G) + HEXB(B);
end;

procedure Tgetcol.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
tx := x;
ty := y;
end;

procedure Tgetcol.Panel1Click(Sender: TObject);
begin
CLOSE;
end;

procedure Tgetcol.FormDblClick(Sender: TObject);
begin
close;
end;

procedure Tgetcol.FormResize(Sender: TObject);
begin
panel1.top := height - panel1.height -1;
panel1.left := width - panel1.width -1;
panel1.visible := true;
end;

end.



Top

[DelphiIdiot]

双击小条子后退出程序

[DelphiIdiot]

对了，搂主自称过“重庆美女”，上次招亲可完成了？~~~~~~~~~

[李_军]

getpixel

[李_军]

getdc(0)

[nnwq]

up