Delphi write pixel colors to memo - windows

Question

I Want to make a program, that can write my TImage pixels rgb color to a memo, the program don't know the resolution.
so how can i recover every pixel color to String variable (R,G,B)?
code
var
Image_width,Image_height,x,y,i,i2:integer;
Colors:TColor;
begin
Image_width:=Image1.Width;
Image_height:=Image1.Height;
memo1.text:='$image_width=*'+IntToStr(Image_Width)+
'$$image_height='+IntToStr(Image_Height)+'*$';
x:=1;
y:=1;
for i := 1 to Image_width do begin
for i2 := 1 to Image_height do begin
Colors:=Image1.Canvas.Pixels[x,y];
memo1.Text:=memo1.Text+ColorToString(Colors);
y:=y+1;
end;
x:=x+1
end;
end
|Edited|
procedure TForm1.Button2Click(Sender: TObject);
var
Image_width,Image_height,x,y:integer;
Colors:TColor;
s:string;
begin
Image_width:=Image1.Width;
Image_height:=Image1.Height;
memo1.text:='$image_width=*'+IntToStr(Image_Width)
+'*$ $image_height=*'+IntToStr(Image_Height)+'*$';
x:=0;
y:=0;
memo1.Lines.BeginUpdate;
for x := 0 to Image_width do begin
for y := 0 to Image_height do begin
Colors:=Image1.Canvas.Pixels[x,y];
memo1.Text:=Memo1.Text+ColorToString(Colors);
end;
memo1.Lines.EndUpdate;
end;
end;
It completes very slow, i think 19 second with a 640x480 picture.
And after the program ready, and it put to memo1, i see something in memo1 but the program "not responding" again..
I tried with the s variable, and the program do the same.

Answer 1

First correction, the pixels start from 0, 0. Not 1, 1 as you have. Replace the initial values before the for loops as follows:
x := 0; // not 1;
y := 0; // not 1;
Actually, assigning y at this point is not required as we will soon see.
Second correction, look closer at the inner for loop. i2 steps from 1 to Image_height and y is incremented in each round of the loop, which is ok. Then a visit to the outer loop increments x and we return to the inner loop. What happens with y? It continues from where it stopped previously, while it should first be reset to 0. The cure is to add a line as follows. This is also why the assignment above is redundant.
for i := 1 to Image_width do
begin
y := 0; // Add this line
for i2 := 1 to Image_height do
begin
Suggestions for improvement
It is unclear what you mean with resolution being unknown. If you mean color depth, or bits per pixel, it may be that your approach using pixels is more straight forward. Otherwise, as has been suggested in the comments, you could consider using scanline instead of pixels for faster access to the actual bitmap data . For an excellent article see: How to use ScanLine property for 24-bit bitmaps?
Repeatedly concatenating the color strings to the Text property is very slow. In fact it was so slow with a 64 x 64 pixel image that I couldn't wait for it to run to the end. To speed it up you can use a separate string variable to which you concatenate the color strings
Colors := Image1.Canvas.Pixels[x, y];
s := s + ColorToString(Colors);
and then after the loops concatenate to the Text property
Memo1.Text := Memo1.Text + s;
If your intention was to add each pixels colorstring as a new line to the memo you can instead use the Add method
Colors := Image1.Canvas.Pixels[x, y];
Memo1.Lines.Add(ColorToString(Colors));
Surrounding the for loops with Memo1.Lines.BeginUpdate; and Memo1.Lines.EndUpdate; further improves speed.
Finally, you could just as well, either use x and y as loop control variables or i and i2 as pixel indexes. I would ditch i and i2, and use x and y as both loop control variables and pixel indexes. But I leave that for you to decide.