\nToday’s Little Program simulates pressing the Play\/Pause\nbutton on your fancy keyboard.\nThis might be useful if you want to write a program that converts\nsome other input (say, gesture detection) into media controller events.\n<\/p>\n
\nOne way of doing this is to take advantage of the\n \nRemember, don’t\n\nfumble around<\/a>.\nIf you want to send a message to a window,\nthen send a message to a window.\nDon’t broadcast a message to every window in the system\n(resulting in mass chaos).\n<\/p>\n \nTake the scratch program and make this simple addition:\n<\/p>\n \nWhen you press the space bar in the scratch application,\nit pretends that you instead pressed the Play\/Pause<\/i>\nbutton on your fancy keyboard with no shift modifiers.\n<\/p>\n \nThe scratch program doesn’t do anything with the key,\nso it ends up falling through to\n \nOf course, this assumes that the program you want to talk to\nlistens globally for the keypress.\nIf you want to make the current foreground program respond\nas if you had pressed the Play\/Pause<\/i>,\nyou can just inject the keypress.\n<\/p>\n \nNote, however, that since we didn’t do anything about the\nstate of modifier keys,\nif the user happens to have the shift key down at the time\nyou injected the message,\nthe application is going to be told,\n“Hey, do your play\/pause thing, and if you change behavior\nwhen the shift key is down, here’s your chance.”\n<\/p>\n \nBut what did you expect from a Little Program?<\/p>\n","protected":false},"excerpt":{"rendered":" Today’s Little Program simulates pressing the Play\/Pause button on your fancy keyboard. This might be useful if you want to write a program that converts some other input (say, gesture detection) into media controller events. One way of doing this is to take advantage of the DefWindowProc function, since the default behavior for the WM_APPCOMMAND […]<\/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-43963","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":" Today’s Little Program simulates pressing the Play\/Pause button on your fancy keyboard. This might be useful if you want to write a program that converts some other input (say, gesture detection) into media controller events. One way of doing this is to take advantage of the DefWindowProc function, since the default behavior for the WM_APPCOMMAND […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/43963","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=43963"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/43963\/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=43963"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=43963"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=43963"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}DefWindowProc<\/code> function,\nsince the default behavior for the\nWM_APPCOMMAND<\/code> message is to pass\nthe message up the parent chain,\nand if it still can’t find a handler,\nit hands the message to the shell for global processing.\n<\/p>\n\nvoid OnChar(HWND hwnd, TCHAR ch, int cRepeat)\n{\n if (ch == ' ') {\n SendMessage(hwnd, WM_APPCOMMAND, (WPARAM)hwnd,\n MAKELONG(0, FAPPCOMMAND_KEY | APPCOMMAND_MEDIA_PLAY_PAUSE));\n }\n}\n HANDLE_MSG(hwnd, WM_CHAR, OnChar);\n<\/pre>\nDefWindowProc<\/code>,\nwhich eventually hands the key to the shell and any other\nregistered shell hooks.\nIf you have a program like Windows Media Player\nwhich registers for shell events,\nit will see the notification and pause\/resume playback.\n<\/p>\n\nint __cdecl main(int, char**)\n{\n INPUT inputs[2] = {};\n inputs[0].type = INPUT_KEYBOARD;\n inputs[0].ki.wVk = VK_MEDIA_PLAY_PAUSE;\n inputs[0].ki.wScan = 0x22<\/a>;\n inputs[0].ki.dwFlags = KEYEVENTF_EXTENDEDKEY;\n inputs[1].type = INPUT_KEYBOARD;\n inputs[1].ki.wVk = VK_MEDIA_PLAY_PAUSE;\n inputs[1].ki.wScan = 0x22;\n inputs[0].ki.dwFlags = KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP;\n SendInput(2, inputs, sizeof(INPUT));\n return 0;\n}\n<\/pre>\n