In this tutorial, we will render a loaded page onto a screen window, within a specified screen rectangle area. Note we don't show you the whole program here, only the handling of WM_PAINT message is shown. You need to put the code into the right place according to the development tool you choose to use.

Let us assume we have a handle to the window, which is stored in hWnd variable.

…
HWND hWnd;
FPDF_DOCUMENT pdf_doc;	// you must load document before page can be loaded
FPDF_PAGE pdf_page; // you must load page before it can be rendered
…
// Get handle to Device Context (DC) for the window
HDC hDC = GetDC(hWnd);
// Call FPDF_RenderPage function to render the whole page
FPDF_RenderPage(hDC, pdf_page, 10, 10, 400, 500, 0, 0);

The codes above will render the whole page onto the window, with the left-top corner of the page at point {10, 10} (coordinate relative to the left-top corner of the window), and the page will be fit into a rectangle with the width of 400 pixels and height of 500 pixels. The page will not be rotated.