zoom on picture

[euklides]

In your opinion, is there a way to zoom (to display an enlarged area) on a part of an picture ?
Thank you for your ideas on this subject.

[OldMoses]

I've used zooming functions in my vector tracker, but I haven't tried zooming on images. I think that _PUTIMAGE has the necessary parameters to do something like that.

[Petr]

Hi. Yes, _PUTIMAGE can this do, also MAPTRIANGLE can do it.

PUTIMAGE example:

Code: QB64: [Select]

1. img = _SCREENIMAGE
2. SCREEN _COPYIMAGE(img, 32)
3. PCOPY _DISPLAY, 1
4.  
5. DO
6.     PCOPY 1, _DISPLAY
7.     WHILE _MOUSEINPUT: WEND
8.     MX = _MOUSEX: MY = _MOUSEY
9.     LINE (MX - 100, MY - 100)-(MX + 100, MY + 100), &HFFFFFFFF, B
10.     '    _PUTIMAGE (MX - 99, MY - 99)-(MX + 99, MY + 99), img, 0, (MX - 50, MY - 50)-(MX + 50, MY + 50) 'zoom 2x
11.     _PUTIMAGE (MX - 99, MY - 99)-(MX + 99, MY + 99), img, 0, (MX - 25, MY - 25)-(MX + 25, MY + 25) 'zoom 4x
12.     _DISPLAY
13. LOOP
14.  
15.  

and MAPTRIANGLE example:

Code: QB64: [Select]

1. img = _SCREENIMAGE
2. SCREEN _COPYIMAGE(img, 32)
3. PCOPY _DISPLAY, 1
4.  
5. DO
6.     PCOPY 1, _DISPLAY
7.     WHILE _MOUSEINPUT: WEND
8.     MX = _MOUSEX: MY = _MOUSEY
9.     '     LINE (MX - 100, MY - 100)-(MX + 100, MY + 100), &HFFFFFFFF, B
10.     '    _PUTIMAGE (MX - 99, MY - 99)-(MX + 99, MY + 99), img, 0, (MX - 50, MY - 50)-(MX + 50, MY + 50) 'zoom 2x
11.     '    _PUTIMAGE (MX - 99, MY - 99)-(MX + 99, MY + 99), img, 0, (MX - 25, MY - 25)-(MX + 25, MY + 25) 'zoom 4x
12.  
13.     CIRCLE (MX, MY), 100, &HFFFFFFFF
14.  
15.     FOR circl = 0 TO _PI(2) STEP .02
16.         dXa = MX + COS(circl) * 99
17.         dYa = MY + SIN(circl) * 99
18.  
19.         dXb = MX + COS(circl + .02) * 99
20.         dYb = MY + SIN(circl + .02) * 99
21.  
22.         dX1 = MX + COS(circl) * 30
23.         dY1 = MY + SIN(circl) * 30
24.  
25.         dX2 = MX + COS(circl + .02) * 30
26.         dY2 = MY + SIN(circl + .02) * 30
27.  
28.         '  zoom ratio is 30:99   ->  1 : 3,3
29.         _MAPTRIANGLE (MX, MY)-(dX1, dY1)-(dX2, dY2), img TO(MX, MY)-(dXa, dYa)-(dXb, dYb), 0
30.  
31.     NEXT
32.     _DISPLAY
33. LOOP
34.  
35.  

[euklides]

Thank you Petr for your magnifying glass effect. 

Perhaps just I will need to use a square greater then 100 points.

Very nice !

[euklides]

Ok, I tried. It works !!! And you can change the square size too.

But, how to quit the magnifying glass effect and go back to have the normal view of the picture (or the normal screen you had before this zoom effect) ?

[Petr]

But, how to quit the magnifying glass effect and go back to have the normal view of the picture (or the normal screen you had before this zoom effect) ?

Code: QB64: [Select]

1. img = _SCREENIMAGE
2. SCREEN _COPYIMAGE(img, 32)
3. PCOPY _DISPLAY, 1 '    save screen image as image page 1
4.  
5. DO UNTIL _KEYHIT = 32 'space for quit from zoom
6.     PCOPY 1, _DISPLAY
7.     WHILE _MOUSEINPUT: WEND
8.     MX = _MOUSEX: MY = _MOUSEY
9.     LINE (MX - 100, MY - 100)-(MX + 100, MY + 100), &HFFFFFFFF, B
10.     '    _PUTIMAGE (MX - 99, MY - 99)-(MX + 99, MY + 99), img, 0, (MX - 50, MY - 50)-(MX + 50, MY + 50) 'zoom 2x
11.     _PUTIMAGE (MX - 99, MY - 99)-(MX + 99, MY + 99), img, 0, (MX - 25, MY - 25)-(MX + 25, MY + 25) 'zoom 4x
12.     _DISPLAY
13. LOOP
14.  
15. PCOPY 1, _DISPLAY 'return saved screen back
16.