Need to improve screen capture speed

[AndyMK]

Hi all, I have been looking in to making a simple remote desktop app and found some good code on the forum. The GDI method works well but is very slow. The clipboard method is very fast but makes clipboard functions useless to other apps while my app is running. I used Blitz+ for a while and it included a function that returned a pointer to the desktop video buffer. Is this possible with Purebasic or is there a faster way to capture the Desktop. I also looked in to a Dx8 method but that was just way over my head. Thanks in advance.

Update:

I just found some code that seems to run very well but i cant seem to resize the image.

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Procedure MakeDesktopScreenshot(ImageNr,x,y,Width,Height) 
   hImage = CreateImage(ImageNr,Width,Height) 
   hDC    = StartDrawing(ImageOutput(imagenr)) 
   DeskDC = GetDC_(GetDesktopWindow_()) 
      BitBlt_(hDC,0,0,Width,Height,DeskDC,x,y,#SRCCOPY) 
   StopDrawing() 
   ReleaseDC_(GetDesktopWindow_(),DeskDC)
   ProcedureReturn hImage 
EndProcedure 

OpenWindow(1,0,0,720,450,"",#PB_Window_SystemMenu|#PB_Window_ScreenCentered) 
  CreateGadgetList(WindowID(1)) 
  hDeskBmp = MakeDesktopScreenshot(2,0,0,1440,900)
  ImageGadget(2,0,0,720,450,hDeskBmp)
  
Repeat
    Delay(100)

    hDeskBmp = MakeDesktopScreenshot(2,0,0,1440,900)
    ;Resize here
    SetGadgetState(2,hDeskBmp)
      
Until WindowEvent()=#PB_Event_CloseWindow

Another Update:

Managed to resize the image by adding

Code: Select all

hImage=ResizeImage(imagenr,720,450)

in between

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StopDrawing()

and

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ReleaseDC_(GetDesktopWindow_(),DeskDC)

but the resize command kills the CPU.

So my question now is, can i resize using a faster method?

[idle]

this should do it a bit quicker than image resize and includes the mouse cursor

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Procedure Screenshot(hImage,srcDc,ScreenWidth,ScreenHeight,tWidth,tHeight)   
   
   Protected pcin.CURSORINFO,iconinfo.ICONINFO
   
   #CAPTUREBLT = $40000000 
   If hImage = 0
       hImage = CreateImage(#PB_Any,tWidth,tHeight,32)
              
   EndIf 
   
   If hImage
    hdc = StartDrawing(ImageOutput(hImage))
              
    ;BitBlt_(hdc,0,0,tWidth,tHeight,srcdc,0,0,#SRCCOPY | #CAPTUREBLT)
     
    p.POINTAPI
    p\x = 0
    p\y = 0
    
    SetStretchBltMode_(hdc,#HALFTONE)
    SetBrushOrgEx_(hdc, 0, 0, @p)
    StretchBlt_(hdc, 0, 0, tWidth, tHeight, srcDc, 0, 0,ScreenWidth,ScreenHeight, #SRCCOPY | #CAPTUREBLT)     

   
    pcin\hCursor = GetCursor_()
    pcin\cbSize = SizeOf(pcin)
    GetCursorInfo_(pcin)
    mx = pcin\ptScreenPos\x
    my = pcin\ptScreenPos\y    
    
    DrawIconEx_(hdc, mx-10,my-10,pcin\hCursor, 0,0,0,0,   #DI_DEFAULTSIZE|#DI_NORMAL)        
    StopDrawing() 
    ReleaseDC_(#Null,srchdc)
    ReleaseDC_(#Null,hdc)
    
      
   EndIf 
   ProcedureReturn hImage

EndProcedure

[SFSxOI]

but what if you want to restrict the screen shot to a particular application window and not the entire desktop?

[idle]

use this

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rect.rect
hwnd = GetForegroundWindow_()
GetWindowRect_(hwnd,@rect)
  
rect\left
rect\top
rect\right
rect\bottom

[SFSxOI]

idle,

that doesn't capture the cursor tho in the window?

[idle]

I see no reason why it wouldn't, are you passing in the hdc to the desktop?

[SFSxOI]

Yep, passing the hdc for desktop. If the mouse is captured by a full screen application it doesn't include the cursor tho. No big deal, I just saw the post and it was something to play around with a little.

[idle]

There are loads of alternatives around, check out netmaestro examples perhaps some of them will do it.

[jesperbrannmark]

Trying to put the two samples together. I think I fail in the screen hDc. Could anyone help me?

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Structure PointAPI 
  x.l 
  y.l 
EndStructure 
Procedure Screenshot(hImage,srcDc,ScreenWidth,ScreenHeight,tWidth,tHeight)   
  
  Protected pcin.CURSORINFO,iconinfo.ICONINFO
  
  #CAPTUREBLT = $40000000 
  If hImage = 0
    hImage = CreateImage(#PB_Any,tWidth,tHeight,32)
    
  EndIf 
  
  If hImage
    hdc = StartDrawing(ImageOutput(hImage))
    
    ;BitBlt_(hdc,0,0,tWidth,tHeight,srcdc,0,0,#SRCCOPY | #CAPTUREBLT)
    
    p.POINTAPI
    p\x = 0
    p\y = 0
    
    SetStretchBltMode_(hdc,#HALFTONE)
    SetBrushOrgEx_(hdc, 0, 0, @p)
    StretchBlt_(hdc, 0, 0, tWidth, tHeight, srcDc, 0, 0,ScreenWidth,ScreenHeight, #SRCCOPY | #CAPTUREBLT)     
    
    
    pcin\hCursor = GetCursor_()
    pcin\cbSize = SizeOf(pcin)
    GetCursorInfo_(pcin)
    mx = pcin\ptScreenPos\x
    my = pcin\ptScreenPos\y    
    
    DrawIconEx_(hdc, mx-10,my-10,pcin\hCursor, 0,0,0,0,   #DI_DEFAULTSIZE|#DI_NORMAL)        
    StopDrawing() 
    ReleaseDC_(#Null,srchdc)
    ReleaseDC_(#Null,hdc)
    
    
  EndIf 
  ProcedureReturn hImage
EndProcedure

OpenWindow(1,0,0,720,450,"",#PB_Window_SystemMenu|#PB_Window_ScreenCentered) 
img=CreateImage(#PB_Any,1440,900)

img = Screenshot(img,0,0,0,1440,900)
ImageGadget(2,0,0,720,450,img)

Repeat
  Delay(100)
  
  hDeskBmp = Screenshot(img,0,0,0,1440,900)
  ;Resize here
  SetGadgetState(2,img)
  
Until WindowEvent()=#PB_Event_CloseWindow

[idle]

use GetDC_(0) to get the desktops hdc

[ultralazor]

This supports resizing window+gadget. Cursor flicker kills this method though..

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Procedure Screenshot(hImage,srcDc,ScreenWidth,ScreenHeight,tWidth,tHeight)   
  
  Protected pcin.CURSORINFO,iconinfo.ICONINFO
  
  #CAPTUREBLT = $40000000
  If hImage = 0
    hImage = CreateImage(#PB_Any,tWidth,tHeight,32)
    
  EndIf
  
  If hImage
    hdc = StartDrawing(ImageOutput(hImage))
    
    ;BitBlt_(hdc,0,0,tWidth,tHeight,srcdc,0,0,#SRCCOPY | #CAPTUREBLT)
    
    p.POINT
    p\x = 0
    p\y = 0
    
    SetStretchBltMode_(hdc,#HALFTONE)
    SetBrushOrgEx_(hdc, 0, 0, @p)
    StretchBlt_(hdc, 0, 0, tWidth, tHeight, srcDc, 0, 0,ScreenWidth,ScreenHeight, #SRCCOPY | #CAPTUREBLT)     
    
    
    pcin\hCursor = GetCursor_()
    pcin\cbSize = SizeOf(pcin)
    GetCursorInfo_(pcin)
    mx = pcin\ptScreenPos\x
    my = pcin\ptScreenPos\y   
    
    DrawIconEx_(hdc, mx-10,my-10,pcin\hCursor, 0,0,0,0,   #DI_DEFAULTSIZE|#DI_NORMAL)       
    StopDrawing()
    ReleaseDC_(#Null,srchdc)
    ReleaseDC_(#Null,hdc)
    
    
  EndIf
  ProcedureReturn hImage
EndProcedure

If OpenWindow(0,0,0,720,450,"",#PB_Window_MaximizeGadget|#PB_Window_SizeGadget|#PB_Window_MinimizeGadget|#PB_Window_ScreenCentered)
  ;SmartWindowRefresh(0,#True)
  ExamineDesktops()
  mimg=CreateImage(#PB_Any,DesktopWidth(0),DesktopHeight(0))
  ImageGadget(0,0,0,WindowWidth(0),WindowHeight(0),ImageID(mimg))
  mimg=Screenshot(mimg,GetDC_(GetDesktopWindow_()),DesktopWidth(0),DesktopHeight(0),GadgetWidth(0),GadgetHeight(0))
  SetGadgetState(0,ImageID(mimg))

  Repeat
    ResizeGadget(0,0,0,WindowWidth(0),WindowHeight(0))
    mimg=Screenshot(mimg,GetDC_(GetDesktopWindow_()),DesktopWidth(0),DesktopHeight(0),GadgetWidth(0),GadgetHeight(0))
    SetGadgetState(0,ImageID(mimg))
  Until WaitWindowEvent(100)=#PB_Event_CloseWindow
EndIf