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From: Carl Colijn on 3 Apr 2010 16:57
Hi group,

I hit upon a problem I can't explain. I have a dialog on which I
placed a static control with the SS_BITMAP style. On run-time I load a
bitmap with the LoadImage function and show it in the control with the
STM_SETIMAGE message. I also include a manifest file to make the app
use Common Controls version 6, thus enabling Windows XP themes. I run
this app on a Windows XP SP3 machine.

When I save the bitmap with a full palette all shows OK, but when I
only add the needed colors in the bitmap's palette (say e.g. a palette
of only 3 colors) one of the colors in the bitmap shows
"transparent"...?! By removing the manifest the bitmap with the
reduced palette will also show OK. To remove unused colors from the
palette I used the Gimp.

What could be the cause of this? Is it the theme support in XP that
acts wrong / "special" with these bitmaps, or is the saved bitmap
corrupt in some way? (corrupt being either really corrupt or not
conforming to some Windows UI guidelines I'm unaware of.)

I have created a very simple app in C++ (with Code::Blocks) showing
this effect; see below for the sources. The zipped up project includes
all source files, the final .exe and both images. It can download (6.3
KB) from my website at:
http://www.twologs.com/auto_transparent_image.zip

I'd really appreciate some insight / help on this!

Kind regards,
Carl Colijn

TwoLogs - IT Services and Product Development
A natural choice!
http://www.twologs.com
TimeTraces: the powerful and versatile time registration system!
http://timetraces.twologs.com


==================
= Resource.h:
==================
#ifndef INCLUDE_RESOURCE_H
#define INCLUDE_RESOURCE_H

#define IDD_DIALOG 1
#define IDC_IMAGE 2
#define IDI_IMAGE1 3
#define IDI_IMAGE2 4

#endif // INCLUDE_RESOURCE_H


==================
= Main.cpp:
==================
#define _WIN32_IE 0x0400
#include <windows.h>
#include <commctrl.h>
#include "Resource.h"

HINSTANCE g_hInstance;
DWORD g_nBitmapID;

LRESULT CALLBACK DlgProc(HWND hDlg, UINT nMsg, WPARAM nWParam, LPARAM
nLParam) {
if (nMsg == WM_CLOSE) {
EndDialog(hDlg, 0);
SetWindowLong(hDlg, DWL_MSGRESULT, 0);
return true;
} else if (nMsg == WM_INITDIALOG) {
HBITMAP hBitmap = (HBITMAP)LoadImage(g_hInstance,
MAKEINTRESOURCE(g_nBitmapID), IMAGE_BITMAP, 0, 0, LR_CREATEDIBSECTION);
SendDlgItemMessage(hDlg, IDC_IMAGE, STM_SETIMAGE, IMAGE_BITMAP,
(LPARAM)hBitmap);
SetWindowLong(hDlg, DWL_MSGRESULT, TRUE);
return true;
} else {
return false;
}
}

int WINAPI WinMain(HINSTANCE hThisInstance, HINSTANCE hPrevInstance,
LPSTR csArgument, int nFunsterStil) {
INITCOMMONCONTROLSEX oInit;
oInit.dwSize = sizeof(INITCOMMONCONTROLSEX);
oInit.dwICC = ICC_DATE_CLASSES;
InitCommonControlsEx(&oInit);
g_hInstance = hThisInstance;
g_nBitmapID = IDI_IMAGE1;
DialogBoxParam(hThisInstance, MAKEINTRESOURCE(IDD_DIALOG), NULL,
(DLGPROC)DlgProc, 0);
g_nBitmapID = IDI_IMAGE2;
DialogBoxParam(hThisInstance, MAKEINTRESOURCE(IDD_DIALOG), NULL,
(DLGPROC)DlgProc, 0);
return 0;
}


==================
= Resource.rc:
==================
#include <windows.h>
#include "Resource.h"

CREATEPROCESS_MANIFEST_RESOURCE_ID RT_MANIFEST "Manifest.txt"

IDI_IMAGE1 BITMAP "Image1.bmp"
IDI_IMAGE2 BITMAP "Image2.bmp"

IDD_DIALOG DIALOGEX 0, 0, 160, 80
CAPTION "Color Test"
BEGIN
CONTROL "", IDC_IMAGE, WC_STATIC, SS_BITMAP | SS_SUNKEN, 7, 7, 21,
18
END


==================
= Manifest.txt:
==================
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1"
manifestVersion="1.0">
<assemblyIdentity
version="1.0.0.0"
processorArchitecture="X86"
name="Test"
type="win32"
/>
<description></description>
<dependency>
<dependentAssembly>
<assemblyIdentity
type="win32"
name="Microsoft.Windows.Common-Controls"
version="6.0.0.0"
processorArchitecture="X86"
publicKeyToken="6595b64144ccf1df"
language="*"
/>
</dependentAssembly>
</dependency>
</assembly>


==================
= Project set-up instructions:
==================
- Link in Comctl32.lib
- Set optimizations to max
From: Carl Colijn on 4 Apr 2010 11:17
Carl Colijn wrote:

> Hi group,
>
> I hit upon a problem I can't explain. I have a dialog on which I
> placed a static control with the SS_BITMAP style. On run-time I load
> a bitmap with the LoadImage function and show it in the control with
> the STM_SETIMAGE message. I also include a manifest file to make the
> app use Common Controls version 6, thus enabling Windows XP themes.
> I run this app on a Windows XP SP3 machine.
>
> When I save the bitmap with a full palette all shows OK, but when I
> only add the needed colors in the bitmap's palette (say e.g. a palette
> of only 3 colors) one of the colors in the bitmap shows
> "transparent"...?! By removing the manifest the bitmap with the
> reduced palette will also show OK. To remove unused colors from the
> palette I used the Gimp.
>
> What could be the cause of this? Is it the theme support in XP that
> acts wrong / "special" with these bitmaps, or is the saved bitmap
> corrupt in some way? (corrupt being either really corrupt or not
> conforming to some Windows UI guidelines I'm unaware of.)

To answer my own post: the bitmap was loaded via LoadImage with the
flag LR_CREATEDIBSECTION. When the flag LR_DEFAULTCOLOR is used, the
problem goes away. Appearantly the bitmaps with the special behavior
didn't result in a compatible bitmap of sorts? I'm still interested in
the exact reason for this if someone wants to elaborate on it, but the
problem has been resolved.

--
Kind regards,
Carl Colijn

TwoLogs - IT Services and Product Development
A natural choice!
http://www.twologs.com
TimeTraces: the powerful and versatile time registration system!
http://timetraces.twologs.com
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Next: Looking for help writing a bitmap.