change color of specific label win32 - winapi

Question

I have a set of labels [8][8] each with it's own Id, from a routine I call to change label color giving the hWnd, but then nothing happens, but if i don't specify an Id on case WM_CTLCOLORSTATIC: all labels change color
DWORD WINAPI changecolor(LPVOID lpParameter){
clrLabelBkGnd = RGB(255, 255, 0x00);
InvalidateRect(hWndLabel[0][0], NULL, TRUE);
return 0;
}
CALL back function
case WM_CTLCOLORSTATIC:
ctrlID = GetDlgCtrlID((HWND)lParam);
if (ctrlID == 1000) {
hdc = reinterpret_cast<HDC>(wParam);
SetBkColor(hdc, clrLabelBkGnd);
return reinterpret_cast<LRESULT>(hBrushLabel);
}
else break;
main program
/* fill the labels IDs*/
for (int i = 0; i < 8; i++){
for (int j = 0; j < 8; j++){
labelId[i][j] = (i * 8 + j)+1000;
}
}
In this example when I specify id 1000 which exist hWndLabel[0][0] nothing is colored, but if I don't specify id or if i put id > 1000 in case WM_CTLCOLORSTATIC: all labels are colored even by calling only hWndLabel[0][0]

Answer 1

This part is wrong:
case WM_CTLCOLORSTATIC:
if (LOWORD(wParam) == 1000) {
hdc = reinterpret_cast<HDC>(wParam);
Since wParam is the handle to the device context, why are you using it's low word as the ID of the control?
Take a look at WM_CTLCOLORSTATIC:
wParam
Handle to the device context for the static control window.
lParam
Handle to the static control.
What you need to use is lParam.
DWORD ctrlID = GetDlgCtrlID((HWND)lParam));
if (ctrlID == 1000)
{
}
UPDATE: Based on the comments you provided, you need to have a mechanism to retain the ID of the label that has been invalidated.
DWORD WINAPI changecolor(LPVOID lpParameter)
{
clrLabelBkGnd = RGB(255, 255, 0x00);
someVariableToHoldLabelIdWithRightScope = labelId[0][0]; // Or GetDlgCtrlID(hWndLabel[0][0]);
InvalidateRect(hWndLabel[0][0], NULL, TRUE);
return 0;
}
Then, when you handle the color:
case WM_CTLCOLORSTATIC:
ctrlID = GetDlgCtrlID((HWND)lParam);
if (ctrlID == someVariableToHoldLabelIdWithRightScope)
{
hdc = reinterpret_cast<HDC>(wParam);
SetBkColor(hdc, clrLabelBkGnd);
return reinterpret_cast<LRESULT>(hBrushLabel);
}
else break;
If you invalidate more than one label at a time, then one variable like this is not enough. You need to have a list/array/queue of IDs.

Answer 2

Marius answered your question - you are misusing the parameters of WM_CTLCOLORSTATIC, which is why your painting is not working correctly.
I would suggest a different solution to your problem. Have a list of colors, one set of Text/BkGnd colors for each label. Make changecolor() update the color entries for just the specified label as needed and then invalidate that label to trigger a repaint. WM_CTLCOLORSTATIC can then use the current colors of whichever label is currently being painted. No need to keep track of the changed Control ID between the call to changecolor() and the triggering of WM_CTLCOLORSTATIC (doing so is error prone anyway - think of what would happen if you wanted to change another label's coloring before WM_CTLCOLORSTATIC of a previous change is processed).
I would suggest a std::map to associate each label HWND to a struct holding that label's colors, eg:
#include <map>
struct sLabelColors
{
COLORREF clrText;
COLORREF clrBkGnd;
HBRUSH hBrushBkGnd;
};
std::map<HWND, sLabelColors> labelColors;
hWndLabel[0][0] = CreateWindowEx(...);
if (hWndLabel[0][0] != NULL)
{
sLabelColors &colors = labelColors[hWndLabel[0][0]];
colors.clrText = GetSysColor(COLOR_WINDOWTEXT);
colors.clrBkGnd = GetSysColor(COLOR_WINDOW);
colors.hBrushBkGnd = NULL;
}
case WM_CTLCOLORSTATIC:
{
HDC hdc = reinterpret_cast<HDC>(wParam);
sLabelColors &colors = labelColors[(HWND)lParam];
SetTextColor(hdc, colors.clrText);
SetBkColor(hdc, colors.clrBkGnd);
if (!colors.hBrushBkGnd) colors.hBrushBkGnd = CreateSolidBrush(colors.clrBkGnd);
return reinterpret_cast<LRESULT>(colors.hBrushBkGnd);
}
case WM_PARENTNOTIFY:
{
if (LOWORD(wParam) == WM_DESTROY)
{
HWND hWnd = (HWND)lParam;
std::map<HWND, sLabelColors>::iterator iter = labelColors.find((HWND)lParam);
if (iter != labelColors.end())
{
if (iter->hBrushBkGnd) DeleteObject(iter->hBrushBkGnd);
labelColors.erase(iter);
}
}
break;
}
DWORD WINAPI changecolor(LPVOID lpParameter)
{
sLabelColors &colors = labelColors[hWndLabel[0][0]];
if (colors.hBrushBkGnd) {
DeleteObject(colors.hBrushBkGnd);
colors.hBrushBkGnd = NULL;
}
colors.clrBkGnd = RGB(255, 255, 0x00);
InvalidateRect(hWndLabel[0][0], NULL, TRUE);
return 0;
}