Handmade Hero » Forums » Code » [day 4] StretchDIBits() always return 0
minh0722
Minh Nguyen
3 posts
#13079 [day 4] StretchDIBits() always return 0
1 week, 2 days ago Edited by Minh Nguyen on Sept. 13, 2017, 9:59 p.m.

I'm having this weird problem where StretchDIBits() always return 0, in the debugger everything looks normal - the bitmapInfo is correct, width and height is fine. And the window is really weird, initially when it is created it is white (I don't even know why it is white) and when I resize the window to be bigger, it looks like this.Here I resize from the top left corner. Here's the code

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

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

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

//TODO: global for now
global_variable bool running;
global_variable BITMAPINFO bitmapInfo;
global_variable void* bitmapMemory;
global_variable int bitmapWidth;
global_variable int bitmapHeight;

internal void Win32ResizeDIBSection(int width, int height)
{
	if (bitmapMemory)
	{
		VirtualFree(bitmapMemory, 0, MEM_RELEASE);
	}

	bitmapWidth = width;
	bitmapHeight = height;

	bitmapInfo.bmiHeader.biSize = sizeof(bitmapInfo.bmiHeader);
	bitmapInfo.bmiHeader.biWidth = bitmapWidth;
	bitmapInfo.bmiHeader.biHeight = -bitmapHeight;		// use a top-down DIB
	bitmapInfo.bmiHeader.biPlanes = 1;
	bitmapInfo.bmiHeader.biBitCount = 32;				// bits per pixel
	bitmapInfo.bmiHeader.biCompression = BI_RGB;		// uncompressed
	
	// NOTE: no more DC. We can allocate memory ourselves
	int bytesPerPixel = 4;
	int bitmapMemorySize = (width * height) * bytesPerPixel;
	bitmapMemory = VirtualAlloc(nullptr, bitmapMemorySize, MEM_COMMIT, PAGE_READWRITE);

	int pitch = width * bytesPerPixel;
	uint8* row = (uint8*)bitmapMemory;
	for (int y = 0; y < bitmapHeight; ++y)
	{
		uint8* pixel = (uint8*)row;
		for (int x = 0; x < bitmapWidth; ++x)
		{
			/*
			pixel in memory: rr gg bb xx
			*/
			*pixel = 255;
			++pixel;

			*pixel = 0;
			++pixel;

			*pixel = 0;
			++pixel;

			*pixel = 0;
			++pixel;
		}
		row += pitch;
	}
}

internal void Win32UpdateWindow(HDC deviceContext, RECT* windowRect, int x, int y, int width, int height)
{
	int windowWidth = windowRect->right - windowRect->left;
	int windowHeight = windowRect->bottom - windowRect->top;

	int cnt = StretchDIBits(deviceContext,
		/*x, y, width, height,
		x, y, width, height,*/
		0, 0, bitmapWidth, bitmapHeight,
		0, 0, windowWidth, windowHeight,
		&bitmapMemory,
		&bitmapInfo,
		DIB_RGB_COLORS,
		SRCCOPY);
}

LRESULT CALLBACK Win32MainWindowCallback(
	HWND window,
	UINT message,
	WPARAM wParam,
	LPARAM lParam)
{
	LRESULT result = 0;

	switch (message)
	{
		// when window is resized
		case WM_SIZE:
		{
			// get rect of the window excluding the borders
			RECT clientRect;
			GetClientRect(window, &clientRect);
			int width = clientRect.right - clientRect.left;
			int height = clientRect.bottom - clientRect.top;

			char buf[256];
			sprintf(buf, "x: %d\n", clientRect.left);
			OutputDebugStringA(buf);

			sprintf(buf, "y: %d\n", clientRect.top);
			OutputDebugStringA(buf);

			sprintf(buf, "width: %d\n", width);
			OutputDebugStringA(buf);

			sprintf(buf, "height: %d\n", height);
			OutputDebugStringA(buf);


			Win32ResizeDIBSection(width, height);
		} break;

		case WM_DESTROY:
		{
			// TODO: handle this as an error - recreate window?
			running = false;
		} break;

		case WM_CLOSE:
		{
			// TODO: handle this with a message to the user? because we may want to close just an internal window in the game
			running = false;
		} break;

		// when window becomes the active window
		case WM_ACTIVATEAPP:
		{
			OutputDebugStringA("WM_ACTIVATEAPP\n");
		} break;

		case WM_PAINT:
		{
			PAINTSTRUCT paint;
			HDC deviceContext = BeginPaint(window, &paint);

			int x = paint.rcPaint.left;
			int y = paint.rcPaint.top;
			int height = paint.rcPaint.bottom - paint.rcPaint.top;
			int width = paint.rcPaint.right - paint.rcPaint.left;

			RECT clientRect;
			GetClientRect(window, &clientRect);
			
			Win32UpdateWindow(deviceContext, &clientRect, x, y, width, height);
			
			EndPaint(window, &paint);
		} break;

		default:
		{
			//OutputDebugStringA("default\n");
			result = DefWindowProc(window, message, wParam, lParam);
		} break;
	}

	return result;
}

int CALLBACK WinMain(HINSTANCE Instance, HINSTANCE PrevInstance, LPSTR CommandLine, int ShowCode)
{
	WNDCLASS windowClass = {};
	
	// TODO: Check if these flags still matter
	windowClass.style = CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
	windowClass.lpfnWndProc = Win32MainWindowCallback;
	windowClass.hInstance = Instance; // or GetModuleHandle(0);
	//windowClass.hIcon;
	windowClass.lpszClassName = "HandmadeHeroWindowClass";
	
	// register window class before creating the window
	if (RegisterClass(&windowClass))
	{
		HWND windowHandle = CreateWindowExA(
			0,
			windowClass.lpszClassName,
			"Handmade Hero",
			WS_OVERLAPPEDWINDOW | WS_VISIBLE,
			CW_USEDEFAULT,
			CW_USEDEFAULT,
			CW_USEDEFAULT,
			CW_USEDEFAULT,
			0,
			0,
			Instance,
			0);

		if (windowHandle)
		{
			// start message loop
			MSG message;
			running = true;
			while (running)
			{
				BOOL messageResult = GetMessageA(&message, 0, 0, 0);
				if (messageResult > 0)
				{
					TranslateMessage(&message);
					DispatchMessage(&message);
				}
				else
				{
					break;
				}
			}
		}
		else
		{
			// TODO: logging
		}
	}
	else
	{
		//TODO: logging
	}

	return 0;
}
mmozeiko
Mārtiņš Možeiko
1477 posts
1 project
#13080 [day 4] StretchDIBits() always return 0
1 week, 2 days ago Edited by Mārtiņš Možeiko on Sept. 13, 2017, 10:23 p.m.

The error is here:
1
	&bitmapMemory,
StretchDIBits expects void* argument, basically a pointer to memory. But you are passing void** - address of pointer to memory. Change it to "bitmapMemory" and it should work.

Also this is a wrong comment:
1
pixel in memory: rr gg bb xx
Windows default GDI pixels are laid out in memory like this: "bb gg rr xx". So with current code you should see blue color, not red color.
minh0722
Minh Nguyen
3 posts
#13081 [day 4] StretchDIBits() always return 0
1 week, 2 days ago

Jesus, thank you so much. Whole day at work coding took a toll on me.
Yeah that comment was right before casey explained about endianess
mmozeiko
Mārtiņš Možeiko
1477 posts
1 project
#13082 [day 4] StretchDIBits() always return 0
1 week, 2 days ago

Oh right. I probably don't remember most of the stuff anymore that was explained in beginning of HH :)