Thread: Simple WinAPI code problem.

Ok, so you have your image in your resources.... That needs a slight change in procedure as we now need to load the image from your application instance instead of a disk file.

First step all the way back to your program entry point...
Make a global variable from the hInstance parameter. Generally I put this, the main window handle and other frequently used bits. into a small global.h header that I include in all project source files.

Code:

// global.h
#ifndef PROJ_GLOBAL
#define PROJ_GLOBAL

HINSTANCE gInst;
HWND hMain;

// other globals here

#endif // PROJ_GLOBAL

Code:

// program .c file...
#include "global.h"

// entry point
INT CALLBACK WindMain(HINSTANCE hInst, HINSTANCE pInst, LPSTR CLine,INT CShow)
  {  gInst = hInst;

// and the rest

  return 0; }

Despite the common prohibition against global variables, this is far better than the time wasting alternative of having to rediscover the program's instance handle in 750 different places in your code.

Now for the image problem....

Code:

// top of dialog.c
#include "global.h"

// and to load the image
BOOL SetStaticImg(HWND Dlg, INT Item, INT ImageFile)
  { HANDLE img;
    img = LoadImage(gInst, MAKEINTRESOURCE(ImageFile), IMAGE_BITMAP, 0, 0, LR_DEFAULTSIZE);
    if (!img)
      return FALSE;
    SendDlgItemMessage(Dlg,Item,SCM_SETIMAGE,IMAGE_BITMAP,(LPARAM)img);
    return TRUE; }

Which you would call as...

Code:

If (!  SetStaticImg(HDialog,IDC_STATIC, IDB_BITMAP)  )
  Beep(1000,250);

What necessitates all that change is that with the image in the resources it is actually part of your program. You need to tell LoadImage where to look (first parameter) as well as the resource ID of the image...

Yes, the Beep is a diagnostic you will want to take out later. It will screech at you if it fails to load the image.

Novacain also makes a good point that with this construct, if you are setting that image more than once, you should free the previous image from the static control... So...

Code:

BOOL SetStaticImg(HWND Dlg, INT Item, INT ImageFile)
  {  HANDLE img;                     // new image
     HANDLE pimg;                   // previous image

    img = LoadImage(gInst, MAKEINTRESOURCE(ImageFile), IMAGE_BITMAP, 0, 0, LR_DEFAULTSIZE);
    if (!img)
      return FALSE;

    pimg = (HANDLE) SendDlgItemMessage(Dlg,Item,SCM_SETIMAGE,IMAGE_BITMAP,(LPARAM)img);
    if (pimg)
       DeleteObject(pimg);
    return TRUE; }

Like I said... you may need to do more work on this.

I have this dialog:

Code:

BOOL CALLBACK ConcesDlgProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam)
{switch(Message)
    {case WM_INITDIALOG:
     SendDlgItemMessage(hwnd, IDC_COMBOBOX, CB_ADDSTRING, 0, (LPARAM)st1);
     SendDlgItemMessage(hwnd, IDC_COMBOBOX, CB_ADDSTRING, 0, (LPARAM)st2);
     SendDlgItemMessage(hwnd, IDC_COMBOBOX, CB_ADDSTRING, 0, (LPARAM)st3);
    return 1;
    case WM_COMMAND:
    switch(LOWORD(wParam))
    {
           case IDC_COMBOBOX:
                switch (HIWORD(wParam))
                  {case CBN_SELENDOK :
                      COMBOBOXIDS(hwnd,LOWORD(wParam)); return 0;
                   default: return 0;}
           case IDCANCEL:
                EndDialog(hwnd, 0);
                return 1;
    }
    return 1;
    default: return FALSE;}
return TRUE;}

From the bold type function, goes to here:

Code:

VOID COMBOBOXIDS(HWND hwnd,int List)
   {int id;
    id = SendDlgItemMessage(hwnd,List,CB_GETCURSEL,0,0);
    Beep(700,100);
    if (carid < 1)
       {CheckDlgButton(hwnd,List - 4,0);
        CheckDlgButton(hwnd,List - 3,0);
        CheckDlgButton(hwnd,List - 2,0);
        CheckDlgButton(hwnd,List - 1,0); 
        SetDlgItemText(hwnd,List + 1,NULL);}
    else
      {CheckDlgButton(hwnd,List - 4,1);}

  switch(id)
  {case 0:SetDlgItemText(hwnd,IDC_STATIC9,"This is case 0."); break;
   case 1:SetDlgItemText(hwnd,IDC_STATIC9,"This is case 1."); break;
   case 2:SetDlgItemText(hwnd,IDC_STATIC9,"This is case 2."); break;}}

What I'm trying to do is, in a picture control, display a diferent .bmp depending on the selected combobox item. So, basically I would like to add, in each case of the switch(id) a function like "LoadBitmap" or whichever is it that is most suitable to load a bitmap. If that is a problem, even pressing a button would be just fine. My problem is not where, but how...
And I've been trying for days already but it just won't work, though I am able to set a bitmap in the .rc (like one that it is "born" with).
If you need any more info let me know.

Originally Posted by Pecado

I have this dialog:

Code:

VOID COMBOBOXIDS(HWND hwnd,int List)
   {int id;
    id = SendDlgItemMessage(hwnd,List,CB_GETCURSEL,0,0);
    Beep(700,100);
    if (carid < 1)
       {CheckDlgButton(hwnd,List - 4,0);
        CheckDlgButton(hwnd,List - 3,0);
        CheckDlgButton(hwnd,List - 2,0);
        CheckDlgButton(hwnd,List - 1,0); 
        SetDlgItemText(hwnd,List + 1,NULL);}
    else
      {CheckDlgButton(hwnd,List - 4,1);}  

   switch(id)
  {case 0:SetDlgItemText(hwnd,IDC_STATIC9,"This is case 0."); break;
   case 1:SetDlgItemText(hwnd,IDC_STATIC9,"This is case 1."); break;
   case 2:SetDlgItemText(hwnd,IDC_STATIC9,"This is case 2."); break;}}

Ok first off... why do you have stuff from my examples in there? That example clears a row of checkboxes if you select the first list item, which says "_reset_" in my code. Do you actually have buttons at those id numbers? If not you're producing a stream of runtime errors.

Not to be rude... but that's what happens when we cut and paste without understanding.

What I'm trying to do is, in a picture control, display a diferent .bmp depending on the selected combobox item. So, basically I would like to add, in each case of the switch(id) a function like "LoadBitmap" or whichever is it that is most suitable to load a bitmap. If that is a problem, even pressing a button would be just fine. My problem is not where, but how...
And I've been trying for days already but it just won't work, though I am able to set a bitmap in the .rc (like one that it is "born" with).
If you need any more info let me know.

Ok... not to panic... if you are using a picture control... look up it's styles and parameters and adjust accordingly. Windows controls all have their own constants and cross pollination most often leads to reproductive failure

First thing, there are two controls used for pictures... the Animation Control and the Static Control... look them up in the SDK ... unless you are uploading an animated GIF, you want a Static Control.

For the static control be sure to set the SS_BITMAP style.

Then you should be able to use LoadImage() in your switch and the STM_SETIMAGE message after you have a handle to change the picture... as I showed you.

Something like....

Code:

VOID ChangeImage(HWND hwnd,int List)
   {int        idx;
     HBITMAP hbm = NULL;
     HBITMAP hbmo;
    idx = SendDlgItemMessage(hwnd,List,CB_GETCURSEL,0,0);
    if (idx < 0)    // guard for no selection
      return;
    switch(idx)
     {  case 0:
           hbm = LoadImage(gInst,MAKEINTRESOURCE(IDB_IMAGE1),IMAGE_BITMAP,0,0,LR_DEFAULTSIZE);
           break;
        case 1:
           hbm = LoadImage(gInst,MAKEINTRESOURCE(IDB_IMAGE2),IMAGE_BITMAP,0,0,LR_DEFAULTSIZE);
           break;
       case 2:
           hbm = LoadImage(gInst,MAKEINTRESOURCE(IDB_IMAGE3),IMAGE_BITMAP,0,0,LR_DEFAULTSIZE);
           break;
       default : 
           return; }
       if (!hbm)
         return; 
       hbmo = SendDlgItemMessage(hwnd, List,STM_SETIMAGE,IMAGE_BITMAP,(LPARAM)hbm);
       if (hbmo)
         DeleteObject(hbmo);   }

This won't be exact... you will need to change the image ids, and make sure youhave a global instance handle... before anything is going to happen. But it should be pretty close....
provided you are using a static control to display the image!

If this doesn't work, I'm going to step back and aske the others to chip in. I'm fast running out of ideas....

Originally Posted by Pecado

Yes I know. I just thought that, as it said that that part of the code was necessary to clear the data if nothing was selected, it was needed for the code to work.

Yes... in my code, not yours...

Probably not now, but eventually I would start understanding everything better and then adjust everything to my needs. I'm just beginning and trying to get the hang of this, I'll make sure to use my own code in the future... and sorry if it annoyed you in some way..

No worries... just Papa Tater givng the kids a little cuff when they get out of line.

My first 6 weeks or so trying to "get" windows was pure frustration. I don't think I wrote a single line of working code the first week, the compiler was threatening to move out on me the end of the second week... But the light does slowly go on and soon enough you C Windows... But, of course, you never stop learning.

Really, you're doing just fine. Nobody learns this in a couple of days.

A friend of mine once commented that "Windows is it's own thing... it's just coincidence that we script it in C". He was right.

Anyway, going back to the cursed .bmp... I am using a Static Control, it has the SS_BITMAP style, but still the .bmp doesn't work with the LoadImage commands.

Well there's only so much that can go wrong there...

• The bmp is not actually in the resources.

• It's not in simple BMP format

• You have it's identifier wrong

• You don't have a valid global instance handle

Listen, I must be doing something (or things) wrong because it is impossible that it "just won't work".

The sad thing is that, like usual, when you do figure it out, it will be something embarassingly simple.

So, I don't want to bother you with this problem anymore, (sincerely I am frustrated with this ) I'll just keep in mind all the info you gave me and in the future, once I get more used to this, I'll come back to the problem.

I was thinking you might want to give yourself a couple of days off, then come back to it with a clearer eye.

One thing I can promise you... it can be done...

Attachment 10246

Originally Posted by Pecado

[CODE]
CONTROL "",IDC_STATIC12, WC_STATIC, SS_BITMAP | 0x00000040, 14, 18, 102, 55
[CODE]

What is the 0x00000040 for? (what style is it adding? try removing it).

EDIT: it is SS_REALSIZECONTROL (resizing the image to fit the control), which is undefined in some versions of the SDK.

After each call add a call to GetLastError(). If the return is not zero (ERROR_SUCCESS) look up what went wrong.

Originally Posted by CommonTater

Code:

       hbmo = SendDlgItemMessage(hwnd, List,STM_SETIMAGE,IMAGE_BITMAP,(LPARAM)hbm);

'List' is the combobox's ID, not the picture control's....