Re: Need an alternative for StretchBlt()?? - C / C++ / MFC Discussion Boards

Re: Need an alternative for StretchBlt()??

Kiran Satish1-Nov-07 13:45

Kiran Satish

1-Nov-07 13:45

I tried to fill the DC with RED color and it still shows up as 300x300 black image Confused | :confused:

...

tempDC.SelectObject(&tempBMP);<br />
tempDC.FillSolidRect(0,0,300,300,RGB(255,0,0));<br />
dc.BitBlt( 0, 0, 300,300, &tempDC, 300, 300, SRCCOPY);

-PNT

PKNT

Re: Need an alternative for StretchBlt()??

C^hris L^osinger1-Nov-07 14:04

C^hris L^osinger

1-Nov-07 14:04

when you call CreateCompatibleBitmap, try giving it the DC you're going to BitBlt it to, not the temp DC.

image processing toolkits | batch image processing

Re: Need an alternative for StretchBlt()??

Kiran Satish2-Nov-07 8:03

Kiran Satish

2-Nov-07 8:03

Yeh.. tht made it work... but if you dont mind, could you tell me why it is like tht??

thanks,
-PNT

PKNT

Re: Need an alternative for StretchBlt()??

C^hris L^osinger2-Nov-07 8:15

C^hris L^osinger

2-Nov-07 8:15

the Bitmap needs to be compatible with the DC you're BitBlt'ing to. when you use the memory DC for the C*C*Bitmap call, the bitmap created will be monochrome. if you use an output DC, it will match the settings of that DC.

or, as Microsoft puts it:

image processing toolkits | batch image processing

Re: Need an alternative for StretchBlt()??

Kiran Satish6-Nov-07 13:13

Kiran Satish

6-Nov-07 13:13

It working definitely better than before, but what I am trying to do now is, rather than doing this work everytime I update/refresh the window, is there any way I can reduce this work, but doing this only once for each zoom constant? For now, this is how it goes..

CClientDC dc(this);<br />
CDC tempDC;<br />
tempDC.CreateCompatibleDC(NULL);<br />
CBitmap tempBMP;<br />
tempBMP.CreateCompatibleBitmap(&dc, w*zoom_const,h*zoom_const);<br />
tempDC.SelectObject(&tempBMP);	<br />
dib->Draw(&tempDC, 0,0,w*zoom_const,h*zoom_const,0,0,w,h);		<br />
dc.BitBlt( 0, 0, w*zoom_const,h*zoom_const, &tempDC, sp.x, sp.y, SRCCOPY);

where sp is the scroll position. But lets say I scrolled the image, in this case the zoom constant is still the same, I just need to update the position of the image wrt view window. I see stretching the bitmap all the time is very time consuming Unsure | :~

.

thanks,
-PNT

PKNT

Re: Need an alternative for StretchBlt()??

C^hris L^osinger6-Nov-07 14:49

C^hris L^osinger

6-Nov-07 14:49

create a CBitmap object member of your window class. every time your zoom level changes:

1. delete the contents of that CBitmap
2. create a new (compatible) bitmap of the appropriate size
3. do your StretchBlt onto that

the code to do that is basically the same as what you have above, but you drawing into m_zoomedBitmap (or whatever) instead of tempBMP, and you use StretchBlt there.

then, when it's time to do the OnPaint/OnDraw, draw that member CBitmap with a normal BitBlt.

image processing toolkits | batch image processing

Re: Need an alternative for StretchBlt()??

Kiran Satish7-Nov-07 6:50

Kiran Satish

7-Nov-07 6:50

I tried exactly what you said (I hope), declared a CBitmap member in Document class and using it instead of tempBMP like below..

CClientDC dc(this);<br />
if (zoom_const >1)<br />
{<br />
CDC tempDC;<br />
tempDC.CreateCompatibleDC(NULL);<br />
if (m_bZoomUpdate)//update bitmap for the first time when zoom_const changes<br />
{<br />
GetDocument()->m_zoomedBMP.CreateCompatibleBitmap(&dc, w*zoom_const,h*zoom_const);<br />
tempDC.SelectObject(&GetDocument()->m_zoomedBMP);<br />
dib->Draw(&tempDC, 0,0,w*GetDocument()->zoom_const,h*GetDocument()->zoom_const,0,0,w,h);		<br />
m_bZoomUpdate = false;<br />
}<br />
else<br />
tempDC.SelectObject(&GetDocument()->m_zoomedBMP);<br />
dc.BitBlt( 0, 0, w*zoom_const,h*zoom_const, &tempDC, sp.x, sp.y, SRCCOPY);<br />
}<br />
else //zoom_const =1<br />
dib->Draw(&dc, 0,0,w*zoom_const,h*zoom_const,sp.x,sp.y,w,h);

It works... and the drawing is as normal with no delays... Now time for getting the exact location of a pixel in zoom mode D'Oh! | :doh:

.

thanks,
-PNT.

PKNT

Re: Need an alternative for StretchBlt()??

Kiran Satish8-Nov-07 7:17

Kiran Satish

8-Nov-07 7:17

It's working fine on both small and large image files. But the only problem that I found is the stretching doesnt work after reaching certain zoom level. I tried 3 different sizes of images,
one is 1000x1000 and it works fine for the whole zoom range that I have (1x - 5x)
second image is 3616x3581 and it works fine untill 2.1x and shows only a white image after that (at 2.2x its dimensions are 7593x7520)
and the third image is 5540x3615 and it works only untill 1.7x and from then shows only white image (at 1.8x its dimensions are 9972x6507).

Is there any limit on the max size of a compatible bitmap that you can create??

thanks,
-PNT.

PKNT

Re: Need an alternative for StretchBlt()??

C^hris L^osinger10-Nov-07 7:13

C^hris L^osinger

10-Nov-07 7:13

Kiran Satish wrote:
Is there any limit on the max size of a compatible bitmap that you can create??

yes, definitely.

it varies from system to system, though.

image processing toolkits | batch image processing

Re: Need an alternative for StretchBlt()??

Kiran Satish14-Nov-08 13:21

Kiran Satish

14-Nov-08 13:21

I am back with a problem closely related to this topic... everything is fine and was able to magnify the images upto the point when I load images of 40MB in size. Then this function behaves differently on different machines (same OS) except on one machine with 64bit OS (where it can magnify to any scale without problem). On some machines it doesn't even magnify one step and on some machines it magnifies to few steps (after that it just shows either white or black frame when you try to magnify). Here is the code that I am currently using-

if (GetDocument()->zoom_const >100)// if magnification is more than 100%
{
  CDC tempDC;
  tempDC.CreateCompatibleDC(NULL);			
  if (GetDocument()->m_bZoomUpdate)//magnify the image
  {	
    GetDocument()->m_zoomedBMP.DeleteObject(); //m_zoomedBMP is an object of CBitmap
    GetDocument()->m_zoomedBMP.CreateCompatibleBitmap(&dc, w*GetDocument()->zoom_const/100,h*GetDocument()->zoom_const/100);
    tempDC.SelectObject(&GetDocument()->m_zoomedBMP);
    dib->Draw(&tempDC, 0,0,w*GetDocument()->zoom_const/100,h*GetDocument()->zoom_const/100,0,0,w,h);
    GetDocument()->m_bZoomUpdate = false; //reset the magnification flag
  }
  else //otherwise just redraw the already magnified image
    tempDC.SelectObject(&GetDocument()->m_zoomedBMP);
  dc.BitBlt( 0, 0, w*GetDocument()->zoom_const/100,h*GetDocument()->zoom_const/100, &tempDC, sp.x, sp.y, SRCCOPY);
}
else // draw the image at 100%
  dib->Draw(&dc, 0,0,w*GetDocument()->zoom_const/100,h*GetDocument()->zoom_const/100,sp.x,sp.y,w,h);

Is there any other way to do this more efficiently and overcome this problem.

thanks,

PKNT

Re: Need an alternative for StretchBlt()??

C^hris L^osinger14-Nov-08 17:59

C^hris L^osinger

14-Nov-08 17:59

you'll probably need to start cropping the input image down to the part that you're going to draw, instead of trying to resize the whole thing.

image processing toolkits | batch image processing

Re: Need an alternative for StretchBlt()??

Kiran Satish17-Nov-08 6:50

Kiran Satish

17-Nov-08 6:50

I am thinking of this, but dont know how to do, could you please link me to some tutorials on how to do this??

thanks,

PKNT

Re: Need an alternative for StretchBlt()??

C^hris L^osinger17-Nov-08 7:08

C^hris L^osinger

17-Nov-08 7:08

sorry, i don't know of any tutorials.

image processing toolkits | batch image processing

two dialogs placing problem?

Gofur Halmurat30-Oct-07 6:57

Gofur Halmurat

30-Oct-07 6:57

Hello,
i have two dialogs in my project, the first one is main dialog, and the second one is helper dialog, and there is a button on main dialog, if i click the second dialog must appear under the main dialog, but i dont know how to do it,
anyone could help me please?
thanks

Re: two dialogs placing problem?

led mike30-Oct-07 7:06

led mike

30-Oct-07 7:06

I don't even want to think about how to do that, it's just a bad idea. Try thinking of a better solution, see if that helps.

Re: two dialogs placing problem?

CPallini30-Oct-07 7:14

CPallini

30-Oct-07 7:14

led mike wrote:
it's just a bad idea

Why?

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: two dialogs placing problem?

Maximilien30-Oct-07 7:14

Maximilien

30-Oct-07 7:14

Under or Below ?

For me :

Under relates to Z-Order.

Below relates to Y position.

Maximilien Lincourt
Your Head A Splode - Strong Bad

Re: two dialogs placing problem?

Gofur Halmurat30-Oct-07 7:16

Gofur Halmurat

30-Oct-07 7:16

it is below, not under, sorry for that

Re: two dialogs placing problem?

Maximilien30-Oct-07 7:22

Maximilien

30-Oct-07 7:22

Get the window rect (GetWindowRect) of your main dialog.
Get the window rect (GetWindowRect) of your child dialog.

Do a bit of computation on those values, taking into account the border and title bar sizes and you MoveWindow or SetWindowPos to move the child window below the main dialog.

Maximilien Lincourt
Your Head A Splode - Strong Bad

Re: two dialogs placing problem?

Gofur Halmurat30-Oct-07 7:21

Gofur Halmurat

30-Oct-07 7:21

How do we get dialogs coordinates?

Re: two dialogs placing problem?

CPallini30-Oct-07 7:26

CPallini

30-Oct-07 7:26

check out GetWindowRect
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

Re: two dialogs placing problem?

Mark Salsbery30-Oct-07 7:24

Mark Salsbery

30-Oct-07 7:24

A combination of these APIs should do everything you need:

GetDeviceCaps() - get screen dimensions
ShowWindow() - show and hide windows
GetWindowRect() - get dimensions of windows
MapWindowPoints() - convert window points/dimensions relative to other windows
MoveWindow() - Move/resize windows

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]