提前 InvalidateRect

Question

.h:

struct RRECT
{
    int x;
    int y;
    int width;
    int height;
};

Bitmap* bitmap;
RRECT position;
void Button::SetImage(HDC g)
{
    Graphics graphics(g);
    DrawImage(bitmap,0,0,width,height);
}
void Button::CreateImage(HDC hdc)
{
    invalidateButton(hwnd);
    SetImage(hdc);
}
void Button::invalidateButton(HWND hWnd)
{
    RECT rect = Helper::getAbsoluteRect(position);
    InvalidateRect(hWnd, &rect, true);

}

WM_PAINT:

PAINTSTRUCT ps;
        HDC hdc = BeginPaint(hwnd, &ps);
    childCloseButton = new Button(new Bitmap(L"close2.png"), new Bitmap(L"close.png"), new Bitmap(L"close2.png"), hdc);
        childCloseButton->position.x = p.x - 35;
        childCloseButton->position.y = 10;
        childCloseButton->position.height = bitmap->GetHeight();
        childCloseButton->position.width = bitmap->GetWidth();
    childCloseButton->CreateImage(gt);
    EndPaint(hwnd, &ps);

I am trying to update the region before drawing a new image, but it updates after I have drawn the image, how do I make the region update first, and then the picture is drawn if I remove InvalidateRect from the invalidateButton() method, and add it to WM_PAINT :

PAINTSTRUCT ps;

HDC hdc = BeginPaint(hwnd, &ps);
childCloseButton = new Button(new Bitmap(L"close2.png"), new Bitmap(L"close.png"), new Bitmap(L"close2.png"), hdc);
childCloseButton->position.x = p.x - 35;
childCloseButton->position.y = 10;
childCloseButton->position.height = bitmap->GetHeight();
childCloseButton->position.width = bitmap->GetWidth();
childCloseButton->CreateImage(gt);
childCloseButton->invalidateButton(hwnd);
childCloseButton->position.x = p.x - 35;
childCloseButton->position.y = 10;
childCloseButton->CreateImage(gt);
EndPaint(hwnd, &ps);

its working good

EDIT

LoadFils(){
childCloseButton = new Button(new Bitmap(L"close2.png"), new Bitmap(L"close.png"), new Bitmap(L"close2.png"), hdc);
    childCloseButton->position.x = p.x - 35;
    childCloseButton->position.y = 10;
    childCloseButton->position.height = bitmap->GetHeight();
    childCloseButton->position.width = bitmap->GetWidth();

}

WM_CREATE:
{
    LoadFils();
}

WM_PAINT:{

    childCloseButton->CreateImage(gt);
    childCloseButton->position.x = 55;
    childCloseButton->position.y = 25;
    childCloseButton->CreateImage(gt);

}

Answer 1

The purpose of WM_PAINT is to only DRAW A WINDOW'S CONTENT , do nothing else in there. All of your image preparation needs to be done outside of the WM_PAINT handler. Have WM_PAINT simply draw the current image as-is. You can InvalidateRect() the window whenever the conditions of the drawing change.

Try something more like this:

struct RRECT
{
    int x;
    int y;
    int width;
    int height;
};

class Button
{
public:
    Bitmap* bitmap;
    RRECT position;
    HWND parentWnd;
    ...
    Button(Bitmap*, Bitmap*, Bitmap*);
    void Draw(HDC);
    void Invalidate();
};

Button::Button(Bitmap*, Bitmap*, Bitmap*)
{
    ...
}

void Button::Draw(HDC g)
{
    Graphics graphics(g);
    graphics.DrawImage(bitmap, Point(position.x, position.y));
}

void Button::Invalidate()
{
    InvalidateRect(parentWnd, &position, TRUE);
}

Button* childCloseButton;

void LoadFils(HWND hwnd)
{
    childCloseButton = new Button(new Bitmap(L"close2.png"), new Bitmap(L"close.png"), new Bitmap(L"close2.png"));
    childCloseButton->parentWnd = hwnd;
    childCloseButton->position.x = ...;
    childCloseButton->position.y = ...;
    childCloseButton->position.height = bitmap->GetHeight();
    childCloseButton->position.width = bitmap->GetWidth();
    childCloseButton->Invalidate();
}

...

case WM_CREATE: {
    LoadFils(hwnd);
    break;
}

case WM_PAINT: {
    PAINTSTRUCT ps;
    HDC hdc = BeginPaint(hwnd, &ps);
    childCloseButton->Draw(hdc);
    EndPaint(hwnd, &ps);
    break;
}