\n Managing scrollbars is not hard in principle. The basic idea is not that difficult,\n but there are a lot of small details that need to be ironed out. If you don’t get\n the details just right, your program will feel odd in a strange way that you often\n can’t pinpoint, much like a subtle background hum that makes you feel uneasy without\n realizing it. Getting the details right is important to making your program feel crisp\n and clean.\n <\/p>\n
The base program<\/b><\/p>\n
\n Let’s start with a basic program and gradually add scrollbar features to it. The basic\n program merely displays one hundred numbered lines. Add these variables to the scratch\n program:\n <\/p>\n
HFONT g_hfList; \/* Font for list *\/\nint g_cyLine; \/* Height of each line *\/\nint g_cItems = 100; \/* Number of items *\/\n<\/pre>\n\n and add these functions to the scratch program:\n <\/p>\n
BOOL\nOnCreate(HWND hwnd, LPCREATESTRUCT lpcs)\n{\n \/* Create the font we use for the list *\/\n LOGFONT lf;\n SystemParametersInfo(SPI_GETICONTITLELOGFONT, sizeof(lf), &lf, 0);\n g_hfList = CreateFontIndirect(&lf);\n if (!g_hfList) return 0;\n \/* Compute the height for each line *\/\n HDC hdc = GetDC(hwnd);\n HFONT hfPrev = SelectFont(hdc, g_hfList);\n SelectFont(hdc, hfPrev);\n SIZE siz;\n GetTextExtentPoint(hdc, TEXT(\"0\"), 1, &siz);\n g_cyLine = siz.cy;\n ReleaseDC(hwnd, hdc);\n return 1;\n}\nvoid\nOnDestroy(HWND hwnd)\n{\n DeleteObject(g_hfList);\n PostQuitMessage(0);\n}\n\/* This is a separate function for now; you'll see why later *\/\nvoid\nPaintSimpleContent(HWND hwnd, PAINTSTRUCT *pps)\n{\n HFONT hfPrev = SelectFont(pps->hdc, g_hfList); \/* Use the right font *\/\n for (int i = 0; i < g_cItems; i++) { \/* Print all the lines *\/\n char szLine[256];\n int cch = wsprintf(szLine, \"This is line %d\", i);\n TextOut(pps->hdc, 0, i * g_cyLine, szLine, cch);\n }\n SelectFont(pps->hdc, hfPrev);\n}\nvoid\nPaintContent(HWND hwnd, PAINTSTRUCT *pps)\n{\n PaintSimpleContent(hwnd, pps);\n}\n<\/pre>\n\n We now have a base program upon which to build.\n <\/p>\n
\n I’m sorry this is taking so long to get off the ground. But things finally get interesting\n in part 4, honest.\n <\/p>\n","protected":false},"excerpt":{"rendered":"
Managing scrollbars is not hard in principle. The basic idea is not that difficult, but there are a lot of small details that need to be ironed out. If you don’t get the details just right, your program will feel odd in a strange way that you often can’t pinpoint, much like a subtle background […]<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[25],"class_list":["post-43053","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":"
Managing scrollbars is not hard in principle. The basic idea is not that difficult, but there are a lot of small details that need to be ironed out. If you don’t get the details just right, your program will feel odd in a strange way that you often can’t pinpoint, much like a subtle background […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/43053","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=43053"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/43053\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=43053"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=43053"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=43053"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}