{"id":39663,"date":"2004-04-23T06:59:00","date_gmt":"2004-04-23T06:59:00","guid":{"rendered":"https:\/\/blogs.msdn.microsoft.com\/oldnewthing\/2004\/04\/23\/how-to-retrieve-text-under-the-cursor-mouse-pointer\/"},"modified":"2004-04-23T06:59:00","modified_gmt":"2004-04-23T06:59:00","slug":"how-to-retrieve-text-under-the-cursor-mouse-pointer","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20040423-00\/?p=39663","title":{"rendered":"How to retrieve text under the cursor (mouse pointer)"},"content":{"rendered":"

\n\nMicrosoft Active Accessibilty<\/a> is the technology that\nexposes information about objects on the screen to accessibility\naids such as screen readers.\nBut that doesn’t mean that only screen readers can use it.\n<\/p>\n

\nHere’s a program that illustrates the use of Active Accessibility\nat the most rudimentary level: Reading text. There’s much more to\nActive Accessibility than this. You can navigate the objects on the\nscreen, read various properties, even invoke commands on them,\nall programmatically.\n<\/p>\n

\nStart with our\n\nscratch program<\/a> and change these two functions:\n<\/p>\n

\nBOOL\nOnCreate(HWND hwnd, LPCREATESTRUCT lpcs)\n{\n  SetTimer(hwnd, 1, 1000, RecalcText);<\/font>\n  return TRUE;\n}\nvoid\nPaintContent(HWND hwnd, PAINTSTRUCT *pps)\n{\n  if (g_pszText) {\n      RECT rc;\n      GetClientRect(hwnd, &rc);\n      DrawText(pps->hdc, g_pszText, lstrlen(g_pszText),\n               &rc, DT_NOPREFIX | DT_WORDBREAK);\n  }<\/font>\n}\n<\/pre>\n
\nOf course, the fun part is the function RecalcText<\/code>,\nwhich retrieves the text from beneath the cursor:\n<\/p>\n
\n#include <oleacc.h>\nPOINT g_pt;\nLPTSTR g_pszText;\nvoid CALLBACK RecalcText(HWND hwnd, UINT, UINT_PTR, DWORD)\n{\n  POINT pt;\n  if (GetCursorPos(&pt) &&\n    (pt.x != g_pt.x || pt.y != g_pt.y)) {\n    g_pt = pt;\n    IAccessible *pacc;\n    VARIANT vtChild;\n    if (SUCCEEDED(AccessibleObjectFromPoint(pt, &pacc, &vtChild))) {\n      BSTR bsName = NULL;\n      BSTR bsValue = NULL;\n      pacc->get_accName(vtChild, &bsName);\n      pacc->get_accValue(vtChild, &bsValue);\n      LPTSTR pszResult;\n      DWORD_PTR args[2] = { (DWORD_PTR)(bsName ? bsName : L\"\"),\n                            (DWORD_PTR)(bsValue ? bsValue : L\"\") };\n      if (FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |\n                        FORMAT_MESSAGE_FROM_STRING |\n                        FORMAT_MESSAGE_ARGUMENT_ARRAY,\n                        TEXT(\"Name: %1!ws!\\r\\n\\r\\nValue: %2!ws!\"),\n                        0, 0, (LPTSTR)&pszResult, 0, (va_list*)args)) {\n        LocalFree(g_pszText);\n        g_pszText = pszResult;\n        InvalidateRect(hwnd, NULL, TRUE);\n      }\n      SysFreeString(bsName);\n      SysFreeString(bsValue);\n      VariantClear(&vtChild);\n      pacc->Release();\n    }\n  }\n}\n<\/pre>\n
\nLet’s take a look at this function.\nWe start by grabbing the cursor position\nand seeing if it changed since the last time we checked.\nIf so, then we ask\nAccessibleObjectFromPoint<\/code> to identify the object\nat those coordinates and give us an IAccessible<\/code>\npointer plus a child identifier.  These two pieces of information\ntogether represent the object under the cursor.\n<\/p>\n
\nNow it’s a simple matter of asking for\nthe name (get_accName<\/code>)\nand value (get_accValue<\/code>)\nof the object and format it nicely.\n<\/p>\n
\nNote that we handled the NULL case of the BSTR in accordance with\n\nEric’s Complete Guide to BSTR Semantics<\/a>.\n<\/p>\n
\nFor more information about accessibility,\ncheck out\nSara Ford’s WebLog<\/a>,\nin particular the bit titled\n\nWhat is Assistive Technology Compatibility<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"
Microsoft Active Accessibilty is the technology that exposes information about objects on the screen to accessibility aids such as screen readers. But that doesn’t mean that only screen readers can use it. Here’s a program that illustrates the use of Active Accessibility at the most rudimentary level: Reading text. There’s much more to Active Accessibility […]<\/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-39663","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":"
Microsoft Active Accessibilty is the technology that exposes information about objects on the screen to accessibility aids such as screen readers. But that doesn’t mean that only screen readers can use it. Here’s a program that illustrates the use of Active Accessibility at the most rudimentary level: Reading text. There’s much more to Active Accessibility […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/39663","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=39663"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/39663\/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=39663"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=39663"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=39663"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}