problems showing image with gdi+

[leos]

I am working on a GPS utility. I want to show only a part of a map (jpg image file on disk) into a form.

My script is working but not as i have expected:

#include <GUIConstantsEx.au3>

#include <GDIPlus.au3>

Global $hForm1, $hBitmap, $hGraphic, $nMsg

$hForm1 = GUICreate("Map", 700, 700, 100, 20)

GUISetState(@SW_SHOW, $hForm1)

_GDIPlus_Startup()

$hBitmap = _GDIPlus_BitmapCreateFromFile(@ScriptDir & "\bitmap.jpg"); create a bitmap object from file

$hGraphic = _GDIPlus_GraphicsCreateFromHWND($hForm1); create a graphic object in form1

_GDIPlus_GraphicsDrawImage($hGraphic, $hBitmap, 0, 0); draws the bitmap image in the graphic

While 1

$nMsg=GUIGetMsg()

If $nMsg=$GUI_EVENT_CLOSE Then

; Clean up resources

_GDIPlus_GraphicsDispose($hGraphic)

_GDIPlus_ImageDispose($hBitmap)

_WinAPI_DeleteObject($hBitmap)

; Shut down GDI+ library

_GDIPlus_Shutdown()

Exit

EndIf

WEnd

The problem is that the image shown in the graphic has not the same scale as the original image in the jpg file shown on screen by a graphic utility.

Image in the graph is something like 30% bigger than the source image and, because of the magnification, original image looses it's sharpness.

What can I do to keep the same image size in both contexts (Autoit GUI and size of the jpg image shown 100% size by usual graphic viewers like Irfanview, Paint..?

Edited April 1, 2009 by leos

[Malkey]

I am working on a GPS utility. I want to show only a part of a map (jpg image file on disk) into a form.

My script is working but not as i have expected:

#include <GUIConstantsEx.au3>

#include <GDIPlus.au3>

Global $hForm1, $hBitmap, $hGraphic, $nMsg

$hForm1 = GUICreate("Map", 700, 700, 100, 20)

GUISetState(@SW_SHOW, $hForm1)

_GDIPlus_Startup()

$hBitmap = _GDIPlus_BitmapCreateFromFile(@ScriptDir & "\bitmap.jpg"); create a bitmap object from file

$hGraphic = _GDIPlus_GraphicsCreateFromHWND($hForm1); create a graphic object in form1

_GDIPlus_GraphicsDrawImage($hGraphic, $hBitmap, 0, 0); draws the bitmap image in the graphic

While 1

$nMsg=GUIGetMsg()

If $nMsg=$GUI_EVENT_CLOSE Then

; Clean up resources

_GDIPlus_GraphicsDispose($hGraphic)

_GDIPlus_ImageDispose($hBitmap)

_WinAPI_DeleteObject($hBitmap)

; Shut down GDI+ library

_GDIPlus_Shutdown()

Exit

EndIf

WEnd

The problem is that the image shown in the graphic has not the same scale as the original image in the jpg file shown on screen by a graphic utility.

Image in the graph is something like 30% bigger than the source image and, because of the magnification, original image looses it's sharpness.

What can I do to keep the same image size in both contexts (Autoit GUI and size of the jpg image shown 100% size by usual graphic viewers like Irfanview, Paint..?

I am not sure if this is a solution. It may help.

#include <GUIConstantsEx.au3>
#include <GDIPlus.au3>

Global $hForm1, $hBitmap, $hGraphic, $nMsg

_GDIPlus_Startup()

$hBitmap = _GDIPlus_BitmapCreateFromFile(@ScriptDir & "\bitmap.jpg"); create a bitmap object from file

$iX = _GDIPlus_ImageGetWidth($hBitmap)
$iY = _GDIPlus_ImageGetHeight($hBitmap)
;ConsoleWrite("$iX  = " & $iX & "  $iY  = " & $iY & @CRLF)

$hForm1 = GUICreate("Map", $iX, $iY, 100, 20)
GUISetState(@SW_SHOW, $hForm1)


$hGraphic = _GDIPlus_GraphicsCreateFromHWND($hForm1); create a graphic object in form1
_GDIPlus_GraphicsDrawImage($hGraphic, $hBitmap, 0, 0); draws the bitmap image in the graphic

While 1
    $nMsg = GUIGetMsg()
    If $nMsg = $GUI_EVENT_CLOSE Then
        ; Clean up resources
        _GDIPlus_GraphicsDispose($hGraphic)
        _GDIPlus_ImageDispose($hBitmap)
        _WinAPI_DeleteObject($hBitmap)
        ; Shut down GDI+ library
        _GDIPlus_Shutdown()
        Exit
    EndIf
WEnd

[leos]

Thank's, but the problem is now, somehow, similar.

Now, both images are identical regarding vertical and horizontal size in pixels but now, the image from the form represents only a part of the image in the file.

My problem with gdi+ is that a bitmap image from a file, with horizontal dimension x pixels and vertical size y pixels is NOT represented in a form at same dimensions.

Edited later:

Problem solved.

The bitmap rescaling appeared due to the difference in resolution.

JPEG file resolution was 72dpi and screen resolution is 96dpi.

In that case, GDI+ functions (_GDIPlus_BitmapCreateFromFile, _GDIPlus_GraphicsDrawImage) automatically scale the image when displaying it in a form.

After setting jpeg file resolution at 96dpi, the image of the file shown in form, constructed with GDI+ functions, is identical with

the image of the file shown by a graphical utility like Irfanview (at full size)

Edited April 1, 2009 by leos