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  Easy Windows API 2D Graphics
  Submitted by

Hi, I noticed there hasn't been a new "code of the day" for a little while, and I wanted to contribute. I'm sure everyone will find this elementary, but I've just started getting into programming again (when I last left DOS 5.0 was a new operating system) and so I haven't done much. The first thing I wanted to do is convert my old DOS graphics demos to work in windows, so I wrote this class to allow for drawing to a window as easily as writing to the screen in DOS. Here is my simple windows 2D graphics class. Feel free to do with this code whatever you wish. -Joshua Carmody

Download Associated File: bmpwin.cpp (14,551 bytes)

// COTD Entry submitted by Joshua Carmody []

#include <windows.h>

/*************************************************************************/ // drawingSurface class. Allows for very easy drawing to a window. /*************************************************************************/ class drawingSurface { public: drawingSurface(int width, int height); // Constructor ~drawingSurface(); // Destructor void setPixel(int x, int y, unsigned long color); // Set Pixel data in our pointer to the specified color void drawLine(int x1, int y1, int x2, int y2, unsigned long color); // Draw a line from x1,y1 to x2,y2 in the specified color void display(int x, int y, HWND windowHandle); // Copies window pixels from memory pointer to screen. void erase(unsigned long color); // Completely fills the bitmap with the specified color int getWidth(); // Return the bitmap's width. int getHeight(); // Return the bitmap's height. protected: HBITMAP scratchPadBitmap; // Temporary Bitmap unsigned long *windowContents; // Pointer to pixel data to display in the window int windowWidth, windowHeight; // Store the window's dimensions };

/*************************************************************************/ // drawingSurface constructor. Creates a "drawing surface" (DIB) for the // application to draw to. Takes two parameters, width, and height. /*************************************************************************/ drawingSurface::drawingSurface(int width, int height) { windowWidth = width; // Store the width windowHeight = height; // Store the height HANDLE heap = GetProcessHeap(); // Get a memory block from windows // Allocate memory for the BITMAPINFO and BITMAPINFOHEADER structures. // The BITMAPINFO structure is just a BITMAPINFOHEADER structure with // RGBQUADs at the end, so we use this code so both structures share the // same memory. BITMAPINFO *format = (BITMAPINFO *)HeapAlloc(heap, 0, sizeof(BITMAPINFOHEADER) + (sizeof(RGBQUAD) * 3)); BITMAPINFOHEADER *header = (BITMAPINFOHEADER*)format;

header->biSize = sizeof(BITMAPINFOHEADER); // This structure is as big as it is. This is a stupid value required by windows header->biWidth = width; // Width of the bitmap header->biHeight = -height; // Height of the bitmap. Negative values indicate a top-down bitmap instead of a bottom-up header->biPlanes = 1; // 1 plane. Always 1 plane. Never changes. header->biBitCount = 32; // 32 bits per pixel, TrueColor header->biCompression = BI_RGB; // No compression header->biSizeImage = 0; // The size of the image, we can ommit this for a non-compressed image header->biXPelsPerMeter = 0; // number of pixels per horizontal meter (we don't care) header->biYPelsPerMeter = 0; // number of pixels per vertical meter (we don't care) header->biClrUsed = 0; // How many colors are used? 0 means maxiumum header->biClrImportant = 0; // How many colors are "important", 0 means all of 'em // Create the DIB scratchPadBitmap = CreateDIBSection( NULL, // DC for the DIB top be compatible with, doesn't matter for 32-bit images format, // Bitmap Information DIB_RGB_COLORS, // Direct RGB values, instead of paletted values (void**)&windowContents, // A pointer to receive a pointer to the bitmap's bytes NULL, // This parameter and the next one have to deal with file mapping, 0 // a subject I don't completely understand. );

HeapFree(heap,0,format); // Free previously allocated memory }

/*************************************************************************/ // Destructor for drawingSurface, cleans up vairables and frees memory. /*************************************************************************/ drawingSurface::~drawingSurface() { DeleteObject(scratchPadBitmap); }

/*************************************************************************/ // setPixel, sets the pixel at x, y to color inside the DIB /*************************************************************************/ void drawingSurface::setPixel(int x, int y, unsigned long color) { *(windowContents + (x + (y * windowWidth))) = color; }

/*************************************************************************/ // drawLine draws a line from x1, y1 to x2, y2 in the specified color /*************************************************************************/ void drawingSurface::drawLine(int x1, int y1, int x2, int y2, unsigned long color) { int i, j, k, deltaX, deltaY, a, testX, testY;

testX = deltaX = (x2 - x1); testY = deltaY = (y2 - y1); if(testX < 0) { testX *= -1; } if(testY < 0) { testY *= -1; }

if(testX > testY) { for(i=0;i<testX;i++) { j = ((i * deltaY) / testX); k = ((deltaX * i) / testX); *(windowContents + ((k + x1) + ((j + y1) * windowWidth))) = color; } } else if(testX <= testY) { for(i=0;i<testY;i++) { j = ((i * deltaX) / testY); k = ((deltaY * i) / testY); *(windowContents + ((j + x1) + ((k + y1) * windowWidth))) = color; } } }

/*************************************************************************/ // Erases the entire bitmap (fills with the specifier color) /*************************************************************************/ void drawingSurface::erase(unsigned long color) { int i, j; for(i=0;i<windowWidth;i++) { for(j=0;j<windowHeight;j++) { *(windowContents + i + (j * windowWidth)) = color; } } }

/*************************************************************************/ // display, Render the DIB inside the specified window at the specifier // coordinates /*************************************************************************/ void drawingSurface::display(int x, int y, HWND windowHandle) { HDC windowDC = GetDC(windowHandle); // Get the DC for this window HDC memoryDC = CreateCompatibleDC(windowDC); // Create a compatible one in memory // Save the old bitmap currently in the memory DC. We do this so we can // put it back before we delete it. I don't know why, but windows makes // you do this. HBITMAP oldBitmap = (HBITMAP)SelectObject(memoryDC, scratchPadBitmap);

// Copy the bitmap data from the memory DC to the one in the window BitBlt( windowDC, // The DC of the destination window x, // The X coordinate to copy to y, // the Y coordinate to copy to windowWidth, // Width of the area we're copying windowHeight, // Height of the area we're copying memoryDC, // DC in memory that holds the source bitmap 0, // X coordinate in source bitmap 0, // Y coordinate in source bitmap SRCCOPY // COPY the data (instead of doing a bitwise AND or something) );

SelectObject(memoryDC, oldBitmap); // Put the old bitmap back before we delete the DC DeleteDC(memoryDC); // Delete the DC ReleaseDC(windowHandle, windowDC); // Release the window's DC }

/*************************************************************************/ // Return the DIB's width /*************************************************************************/ int drawingSurface::getWidth() { return windowWidth; }

/*************************************************************************/ // Return the DIB's height /*************************************************************************/ int drawingSurface::getHeight() { return windowHeight; }

/*************************************************************************/ // the bitmapWindow class. This uses the above drawingSurface class to // easily create a window that we can draw to directly. /*************************************************************************/ class bitmapWindow { public: bitmapWindow(int x, int y, int width, int height, HINSTANCE currentInstance); // Constructor ~bitmapWindow(); // Destructor static int getNumberOfBitmapWindows(); // Returns static int below void setPixel(int x, int y, unsigned long color); // Set Pixel data in our pointer to the specified color void drawLine(int x1, int y1, int x2, int y2, unsigned long color); // Draw a line from x1,y1 to x2,y2 in the specified color void erase(unsigned long color); // Passes the erase request to the drawingSurface void flipIntoView(); // Copies window pixels from memory pointer to screen. protected: HWND windowHandle; // The handle for the window we'll pop up. void registerWindowClass(HINSTANCE currentInstance); // For registering the class of window we'll use static BOOL classIsRegistered; // Have we, or have we not, registered our window class? static int numberOfBitmapWindows; // The number of these classes in use int windowWidth, windowHeight; // Store the window's dimensions drawingSurface *windowContents; // easy DIB class defined above }; // Initialize static vairables BOOL bitmapWindow::classIsRegistered = 0; int bitmapWindow::numberOfBitmapWindows = 0;

/*************************************************************************/ // Window Handler for our bitmapWindows. /*************************************************************************/ LRESULT CALLBACK bitmapWindowHandler(HWND windowHandle, // Handle to the window this procedure is handling UINT message, // A message related to said window WPARAM wparam, // A parameter vairable LPARAM lparam) // Another { switch(message) { case WM_QUIT: // Quit, if we're supposed to case WM_CLOSE: case WM_DESTROY: PostQuitMessage(0); return 0; default: break; } // Take default action if not told to quit return DefWindowProc(windowHandle, message, wparam, lparam); }

/*************************************************************************/ // constructor for bitmapWindow. Takes 5 parameters. An X coordinate for // the window to appear, a Y coordinate for the window to appear, the // width of the window, the height of the window, and the handle to this // program's instance. /*************************************************************************/ bitmapWindow::bitmapWindow(int x, int y, int width, int height, HINSTANCE currentInstance) { // We only need to register the window class once. if(!classIsRegistered) { registerWindowClass(currentInstance); }

windowWidth = width + 7; // Store the width windowHeight = height + 25; // Store the height // Create a window windowHandle = CreateWindow( "Library_BMP_Window", // Name of the window class (registered above) "Window", // Name of the window, appears in the window title bar WS_BORDER | WS_MINIMIZEBOX | WS_CAPTION | WS_SYSMENU, // Window style x, // X coordinate of the window on-screen y, // Y coordinate of the window on-screen windowWidth, // width of the window windowHeight, // height of the window NULL, // Handle to a parent window (none) NULL, // Handle to a child window (none) currentInstance, // Handle to the current Instance 0 // Pointer to extra data I don't care about );

ShowWindow(windowHandle, SW_SHOW); // Show the window UpdateWindow(windowHandle); // Redundant, just in case windowContents = new drawingSurface(width, height); // Create the drawing surface, this class is defined above numberOfBitmapWindows++; // Keep track of the number of these classes }

/*************************************************************************/ // Destructor, cleans up allocated memory and updates the number of // these windows /*************************************************************************/ bitmapWindow::~bitmapWindow() { DestroyWindow(windowHandle); numberOfBitmapWindows--; }

/*************************************************************************/ // getNumberOfBitmapWindows, returns: the number of bitmap windows! /*************************************************************************/ int bitmapWindow::getNumberOfBitmapWindows() { return numberOfBitmapWindows; }

/*************************************************************************/ // Passes a request to change pixel data on to the drawing surface. /*************************************************************************/ void bitmapWindow::setPixel(int x, int y, unsigned long color) { windowContents->setPixel(x, y, color); }

/*************************************************************************/ // Passes a request to draw a line on to the drawing surface. /*************************************************************************/ void bitmapWindow::drawLine(int x1, int y1, int x2, int y2, unsigned long color) { windowContents->drawLine(x1, y1, x2, y2, color); }

/*************************************************************************/ // Passes a request to erase a line on to the drawingSurface. /*************************************************************************/ void bitmapWindow::erase(unsigned long color) { windowContents->erase(color); }

/*************************************************************************/ // Display's this windows drawing surface /*************************************************************************/ void bitmapWindow::flipIntoView() { windowContents->display(0, 0, windowHandle); }

/*************************************************************************/ // Registers the window class we use /*************************************************************************/ void bitmapWindow::registerWindowClass(HINSTANCE currentInstance) { WNDCLASS windowClass; = CS_OWNDC; // The style of the window. CS_OWNDC means every window has it's own DC windowClass.lpfnWndProc = bitmapWindowHandler; // The function to call when this window receives a message windowClass.cbClsExtra = 0; // Extra bytes to allocate for this class (none) windowClass.cbWndExtra = 0; // Extra bytes to allocate for each window (none) windowClass.hInstance = currentInstance; // This application's instance windowClass.hIcon = LoadIcon(currentInstance, IDI_APPLICATION); // A standard Icon windowClass.hCursor = LoadCursor(currentInstance, IDC_ARROW); // A standard cursor windowClass.hbrBackground = (HBRUSH)COLOR_APPWORKSPACE; // A standard background windowClass.lpszMenuName = NULL; // No menus in this window windowClass.lpszClassName = "Library_BMP_Window"; // A name for this class RegisterClass(&windowClass); // Register the class classIsRegistered = 1; // Did we register the class? Yes, we did. }

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