Using Win32 functions in Visual FoxPro Image Gallery
Device Context
..msdn
ChangeDisplaySettings
CreateCompatibleDC
CreateDC
DeleteDC
DeleteObject
EnumDisplayDevices
EnumDisplaySettings
GetDC
GetDeviceCaps
GetObject
GetObjectType
ReleaseDC
SelectObject
Code examples:
Bitmap Class for Visual FoxPro application
Converting twips to pixels and vice versa
Copying picture of the active form to the Clipboard using Enhanced Metafile API functions
Creating a clipping region from the path selected into the device context of a form
Creating a window using CreateWindowEx function
Displaying animated images on FoxPro form with BitBlt and StretchBlt functions
Displaying bitmap using the AlphaBlend function
Displaying the associated icons and descriptions for files and folders
Drawing a rectangle using Windows regular edges and borders
Drawing a window caption using the DrawCaption routine
Drawing cursors for the classes defined by the system (preregistered): BUTTON, EDIT, LISTBOX etc.
Drawing icons associated with the VFP main window
Drawing standard Windows icons
Drawing Windows frame controls using the DrawFrameControl function
Drawing Windows predefined bitmaps using the LoadBitmap functions
Form Magnifier
GDI+ fun: roach-infested desktop
GDI+: Color Transparency
GDI+: copying to the Clipboard (a) image of active FoxPro window/form, (b) image file
GDI+: Creating thumbnails to preview images in a directory
GDI+: custom control, base class
GDI+: how to make VFP controls visually shake and shudder
GDI+: Implementing image scrolling with inertia
GDI+: saving image of FoxPro form to graphics file (BMP, GIF, JPG, PNG, TIF)
GDI+: Scrolling through large image using the mouse
GDI+: sending image of FoxPro form to printer
How to change the name and the size of the font in the MessageBox dialog
How to copy the image of a form to the Clipboard using Bitmap API functions
How to display picture stored in enhanced-format metafile (*.emf)
How to find which fonts Windows uses for drawing captions, menus and message boxes
How to make a VFP form fading out when released (GDI version)
How to make a VFP form fading out when released (GDI+ version)
How to play AVI file on the _screen
How to print a bitmap file
How to print FoxPro form
How to print FoxPro form -- II
How to print picture stored in enhanced-format metafile (*.emf)
How to put a horizontal text scrolling on the form (a news line, marquee)
How to put a vertical text scrolling on the form (a movie cast)
How to view icons stored in executable files (Icon Viewer)
How to view icons stored in executable files (Icon Viewer) - II
Obtaining the bounding rectangle for the specified device context
Placing an arbitrary rectangular area of main VFP window on the Clipboard
Placing On-screen Alert on top of all windows
Printing text on the client area of the main VFP window
Printing text on the main VFP window
Printing text with the Escape function
Reading metrics for the currently selected font
Retrieving graphic capabilities of your display
Splash Screen for the VFP application
Storing content of the Clipboard to a bitmap file
Storing screen shot of a form to bitmap file
Storing screen shot of a form to enhanced metafile (*.emf)
Subclassing CommandButton control to create BackColor property
Using Font and Text functions
Using FrameRgn for displaying system colors
Using GetNearestColor
Using the DrawText function
Using the GradientFill function
Using the LoadImage function to have a bitmap file loaded and displayed on VFP main window
Vertical Label control
Form Magnifier

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Before you begin:

After you activate the magnifier the form`s part under the mouse cursor will be constantly redrawn on the main FoxPro window.

See also:
  • Scrolling text on the form horizontally (a newsreel)
  • Scrolling text on the form vertically (a movie cast)
  • Shaking VFP form controls
  • Playing AVI on _screen
  • Displaying animated images

  • LOCAL oForm
    oForm = CREATEOBJECT("Tform")
    oForm.Show(1)
    * end of main
    
    DEFINE CLASS Tform As Form
        Width=350
        Height=160
        BorderStyle=2
        MaxButton=.F.
        MinButton=.F.
        Autocenter=.T.
        Caption="Magnifier"
        hForm=0
        hDC=0
    
        ADD OBJECT chMagnify As CheckBox WITH Value=.F.,;
        Left=20, Top=20, Autosize=.T., Caption="Activate Magnifier"
    
        ADD OBJECT chInvert As CheckBox WITH Value=.F.,;
        Left=20, Top=56, Autosize=.T., Caption="Invert colors"
    
        ADD OBJECT lbl1 As Label WITH;
        Left=190, Top=20, Autosize=.T., Caption="Scale:"
    
        ADD OBJECT cmbScale As ComboBox WITH Style=2,;
        Left=240, Top=20, Width=70, Height=21
    
        ADD OBJECT cmdClose As CommandButton WITH Cancel=.T.,;
        Left=140, Top=112, Width=70, Height=27, Caption="Close"
    
    PROCEDURE Init
        THIS.declare
    
    PROCEDURE Activate
        IF THIS.hForm = 0
            THIS.hForm = GetFocus()
            THIS.hDC = GetDC(THIS.hForm)
        ENDIF
    
    PROCEDURE Destroy
        IF THIS.hDC <> 0
            = ReleaseDC(THIS.hForm, THIS.hDC)
        ENDIF
    
    PROCEDURE cmdClose.Click
        ThisForm.Release
    
    PROCEDURE cmbScale.Init
        WITH THIS
            .AddItem("Normal")
            .AddItem("x 2")
            .AddItem("x 3")
            .AddItem("x 4")
            .ListIndex=3
        ENDWITH
    
    PROCEDURE MouseMove
    LPARAMETERS nButton, nShift, nXCoord, nYCoord
        THIS.Magnify
    
    PROCEDURE chMagnify.MouseMove
    LPARAMETERS nButton, nShift, nXCoord, nYCoord
        ThisForm.Magnify
    
    PROCEDURE chInvert.MouseMove
    LPARAMETERS nButton, nShift, nXCoord, nYCoord
        ThisForm.Magnify
    
    PROCEDURE lbl1.MouseMove
    LPARAMETERS nButton, nShift, nXCoord, nYCoord
        ThisForm.Magnify
    
    PROCEDURE cmbScale.MouseMove
    LPARAMETERS nButton, nShift, nXCoord, nYCoord
        ThisForm.Magnify
    
    PROCEDURE cmdClose.MouseMove
    LPARAMETERS nButton, nShift, nXCoord, nYCoord
        ThisForm.Magnify
    
    PROCEDURE Magnify
    #DEFINE SRCCOPY 0xCC0020
    #DEFINE NOTSRCCOPY 0x00330008
    #DEFINE cnDstWidth 600
    #DEFINE cnDstHeight 140
    
        IF THIS.chMagnify.Value
            LOCAL cBuffer, nX, nY, hDstWin, hDstDC,;
                nMode, nSrcWidth, nSrcHeight, nScale
    
            hDstWin = GetActiveWindow()
            hDstDC = GetWindowDC(hDstWin)
    
            cBuffer = REPLICATE(Chr(0), 8)
            = GetCursorPos(@cBuffer)
            = ScreenToClient(THIS.hForm, @cBuffer)
    
            nX = buf2dword(SUBSTR(cBuffer, 1,4))
            nY = buf2dword(SUBSTR(cBuffer, 5,4))
    
            nScale = THIS.cmbScale.ListIndex
            nSrcWidth = INT(cnDstWidth/nScale)
            nSrcHeight = INT(cnDstHeight/nScale)
    
            nMode = IIF(THIS.chInvert.Value,;
                NOTSRCCOPY, SRCCOPY)
    
            = StretchBlt(hDstDC, 10, 100,;
                cnDstWidth, cnDstHeight, THIS.hDC,;
                nX-nSrcWidth/2, nY-nSrcHeight/2,;
                nSrcWidth, nSrcHeight, nMode)
    
            = ReleaseDC(hDstWin, hDstDC)
        ENDIF
    
    PROCEDURE declare
        DECLARE INTEGER GetActiveWindow IN user32
        DECLARE INTEGER GetCursorPos IN user32 STRING @lpPoint
        DECLARE INTEGER GetWindowDC IN user32 INTEGER hwnd
        DECLARE INTEGER GetDC IN user32 INTEGER hwnd
        DECLARE INTEGER GetFocus IN user32
    
        DECLARE INTEGER ReleaseDC IN user32;
            INTEGER hWindow, INTEGER hdc
    
        DECLARE INTEGER ScreenToClient IN user32;
            INTEGER hWindow, STRING @lpPoint
    
        DECLARE INTEGER StretchBlt IN gdi32;
            INTEGER hdcDest, INTEGER nXOriginDest,;
            INTEGER nYOriginDest, INTEGER nWidthDest,;
            INTEGER nHeightDest, INTEGER hdcSrc,;
            INTEGER nXOriginSrc, INTEGER nYOriginSrc,;
            INTEGER nWidthSrc, INTEGER nHeightSrc,;
            INTEGER dwRop
    
    ENDDEFINE
    
    FUNCTION buf2dword(lcBuffer)
    RETURN Asc(SUBSTR(lcBuffer, 1,1)) + ;
        BitLShift(Asc(SUBSTR(lcBuffer, 2,1)), 8) +;
        BitLShift(Asc(SUBSTR(lcBuffer, 3,1)), 16) +;
        BitLShift(Asc(SUBSTR(lcBuffer, 4,1)), 24)
    
    
    

    User rating: 7/10 (2 votes)
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    3530 bytes  
    Created: 2003-07-14 21:11:08  
    Modified: 2007-03-15 11:33:17  
    Visits in 7 days: 29  
    Listed functions:
    GetActiveWindow
    GetCursorPos
    GetDC
    GetFocus
    GetWindowDC
    ReleaseDC
    ScreenToClient
    StretchBlt
    Printer friendly API declarations
    My comment:
    StretchBlt function copies a rectangle area of the form to the main FoxPro window.
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