problem with StretchDIBits

cstpr

#15536

June 11, 2018

Sorry if this post seems confusing. My English is not really good.

I have just started the handmade hero series and been up to day 5. This was when Casey changed the code so that StretchDIBits could stretch the bitmap according to the size and ratio of the window. But my code is failing to do that. StretchDIBits still passes to the window a bitmap of the same size every single time like it is done in day 4. And it ends up like this every single time

Can anyone check and see if I am missing anything. Thanks a lot!

#include <windows.h>
#include <stdint.h>

#define internal static
#define local_persist static
#define global_variable static

typedef int8_t int8;
typedef int16_t int16;
typedef int32_t int32;
typedef int64_t int64;

typedef uint8_t uint8;
typedef uint16_t uint16;
typedef uint32_t uint32;
typedef uint64_t uint64;

struct win32_offscreen_buffer
{
    BITMAPINFO Info;
    void *Memory;
    int Width;
    int Height;
    int Pitch;
};

struct win32_window_dimension
{
    int Width;
    int Height;
};

global_variable bool GlobalRunning;
global_variable win32_offscreen_buffer GlobalBackBuffer;

win32_window_dimension
Win32GetWindowDimension(HWND Window)
{
    win32_window_dimension Result;
    
    RECT ClientRect;
    GetClientRect(Window, &ClientRect);                        
    Result.Width = ClientRect.right - ClientRect.left;
    Result.Height = ClientRect.bottom - ClientRect.top;

    return (Result);
}

internal void
RenderWeirdGradient(win32_offscreen_buffer Buffer, int XOffset, int YOffset)
{   
    uint8 *Row = (uint8 *)Buffer.Memory;
    for (int Y = 0;
         Y < Buffer.Height;
         ++Y)
    {
        uint32 *Pixel = (uint32 *)Row;
        for (int X = 0;
             X < Buffer.Width;
             ++X)
        {
            uint8 Blue = (X + XOffset);
            uint8 Green = (Y + YOffset);
            
            *Pixel++ = ((Green << 8) | Blue);
        }

        Row += Buffer.Pitch;
    }


}

internal void
Win32ResizeDIBSection(win32_offscreen_buffer *Buffer, int Width, int Height)
{
    
    if (Buffer->Memory)
    {
        VirtualFree(Buffer->Memory, 0, MEM_RELEASE);
    }
    
    Buffer->Width = Width;
    Buffer->Height = Height;
    
    int BytesPerPixel = 4;
    
    Buffer->Info.bmiHeader.biSize = sizeof(Buffer->Info.bmiHeader);
    Buffer->Info.bmiHeader.biWidth = Buffer->Width;
    Buffer->Info.bmiHeader.biHeight = -Buffer->Height;
    Buffer->Info.bmiHeader.biPlanes = 1;
    Buffer->Info.bmiHeader.biBitCount = 32;
    Buffer->Info.bmiHeader.biCompression = BI_RGB;

    int BitmapMemorySize = (Buffer->Width*Buffer->Height)*BytesPerPixel;
    Buffer->Memory = VirtualAlloc(0, BitmapMemorySize, MEM_COMMIT, PAGE_READWRITE);

    Buffer->Pitch = Width*BytesPerPixel;
}

internal void
Win32DisplayBufferInWindow(HDC DeviceContext,
                           int WindowWidth, int WindowHeight,
                           win32_offscreen_buffer Buffer)
{
    StretchDIBits(DeviceContext,
                  /*
                  X, Y, Width, Height,
                  X, Y, Width, Height,
                  */
                  0, 0, WindowWidth, WindowHeight,
                  0, 0, Buffer.Width, Buffer.Height,
                  Buffer.Memory,
                  &Buffer.Info,
                  DIB_RGB_COLORS, SRCCOPY);

}

LRESULT CALLBACK
Win32MainWindowCallback(HWND Window,
                        UINT Message,
                        WPARAM WParam,
                        LPARAM LParam)
{
    LRESULT Result = 0;
    
    switch(Message)
    {
        case WM_DESTROY:
        {
            GlobalRunning = false;
        } break;

        case WM_CLOSE:
        {
            GlobalRunning = false;
        } break;

        case WM_ACTIVATEAPP:
        {
            OutputDebugStringA("WM_ACTIVATEAPP\n");
        } break;

        case WM_PAINT:
        {
            PAINTSTRUCT Paint;
            HDC DeviceContext =  BeginPaint(Window, &Paint);

            win32_window_dimension Dimension = Win32GetWindowDimension(Window);
            
            Win32DisplayBufferInWindow(DeviceContext,
                                       Dimension.Width,
                                       Dimension.Height,
                                       GlobalBackBuffer);
            EndPaint(Window, &Paint);
        } break;

        default:
        {
            Result = DefWindowProc(Window, Message, WParam, LParam);
        } break;
    }

    return(Result);
}


int CALLBACK
WinMain(HINSTANCE Instance, // a handle to our executable
        HINSTANCE PrevInstance,
        LPSTR CommandLine,
        int ShowCode)
{
    WNDCLASS WindowClass = {};

    Win32ResizeDIBSection(&GlobalBackBuffer, 1280, 720);
    
    WindowClass.style = CS_OWNDC|CS_HREDRAW|CS_VREDRAW;
    WindowClass.lpfnWndProc = Win32MainWindowCallback;
    WindowClass.hInstance = Instance;
    //WindowClass.hIcon = ;
    WindowClass.lpszClassName = "HandmadeHeroWindowClass";

    if(RegisterClassA(&WindowClass))
    {
        HWND Window =
            CreateWindowExA(0,
                            WindowClass.lpszClassName,
                            "Handmade Hero",
                            WS_OVERLAPPEDWINDOW|WS_VISIBLE,
                            CW_USEDEFAULT,
                            CW_USEDEFAULT,
                            CW_USEDEFAULT,
                            CW_USEDEFAULT,
                            0,
                            0,
                            Instance,
                            0);
        if(Window)
        {
            HDC DeviceContext = GetDC(Window);
            
            int XOffset = 0;
            int YOffset = 0;
            
            GlobalRunning = true;
            while(GlobalRunning)
            {
                MSG Message;
                while (PeekMessage(&Message, 0, 0, 0, PM_REMOVE))
                {
                    if (Message.message == WM_QUIT)
                    {
                        GlobalRunning = false;
                    }
                    
                    TranslateMessage(&Message);
                    DispatchMessageA(&Message);
                }

                RenderWeirdGradient(GlobalBackBuffer, XOffset, YOffset);
                
                win32_window_dimension Dimension = Win32GetWindowDimension(Window);
                Win32DisplayBufferInWindow(DeviceContext,
                                           Dimension.Width,
                                           Dimension.Height,
                                           GlobalBackBuffer);

                ++XOffset;
                YOffset += 2;
            }
        }
        else
        {
            // TODO(casey) Logging
        }
    }
    else
    {
        
        // TODO(casey): Logging
    }
    
    return (0);
}

Edited by cstpr on June 11, 2018, 4:10pm Reason: Initial post

Mārtiņš Možeiko

#15537

June 11, 2018

The screenshot your are showing is exactly how output should look like. What exactly do you think is wrong?

cstpr

#15541

June 11, 2018

What I mean is the ratio of the animation stays exactly the same even though the window is resized. The only thing changed is the rendering speed. So it turned out like this

But, the correct way should be like this

Anyway, I tried to paste Casey's code over my source code and it works the same way in VS, the animation's ratio just does not change at all. But when I put that same code from my preorder download into a new separate
VS project It worked correctly. What happens?

Edited by cstpr on June 11, 2018, 7:21pm

Mārtiņš Možeiko

#15544

June 12, 2018

Ah I see what you mean now.
Interest, but I don't see that on my machine. I copy&pasted your code and run it - I see those blue/rectangles being resized for me, stretching & narrowing depending on window size... So not sure what's wrong with it.

Can you resize window and then breakpoint inside Win32DisplayBufferInWindow. And examine argument values - WindowWidth, WindowHeight, Buffer.Width, Buffer.Height. Are they reasonable?

Edited by Mārtiņš Možeiko on June 12, 2018, 5:05am