73 lines
2.4 KiB
C++
73 lines
2.4 KiB
C++
/*
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* Demonstrates that console clearing sets each cell's character to SP, not
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* NUL, and it sets the attribute of each cell to the current text attribute.
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*
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* This confirms the MSDN instruction in the "Clearing the Screen" article.
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* https://msdn.microsoft.com/en-us/library/windows/desktop/ms682022(v=vs.85).aspx
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* It advises using GetConsoleScreenBufferInfo to get the current text
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* attribute, then FillConsoleOutputCharacter and FillConsoleOutputAttribute to
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* write to the console buffer.
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*/
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#include <windows.h>
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#include <cassert>
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#include <cstdio>
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#include <cstdlib>
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#include "TestUtil.cc"
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int main(int argc, char *argv[]) {
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if (argc == 1) {
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startChildProcess(L"CHILD");
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return 0;
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}
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const HANDLE conout = GetStdHandle(STD_OUTPUT_HANDLE);
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SetConsoleTextAttribute(conout, 0x24);
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system("cls");
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setWindowPos(0, 0, 1, 1);
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setBufferSize(80, 25);
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setWindowPos(0, 0, 80, 25);
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CHAR_INFO buf;
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COORD bufSize = { 1, 1 };
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COORD bufCoord = { 0, 0 };
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SMALL_RECT rect = { 5, 5, 5, 5 };
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BOOL ret;
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DWORD actual;
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COORD writeCoord = { 5, 5 };
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// After cls, each cell's character is a space, and its attributes are the
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// default text attributes.
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ret = ReadConsoleOutputW(conout, &buf, bufSize, bufCoord, &rect);
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assert(ret && buf.Char.UnicodeChar == L' ' && buf.Attributes == 0x24);
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// Nevertheless, it is possible to change a cell to NUL.
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ret = FillConsoleOutputCharacterW(conout, L'\0', 1, writeCoord, &actual);
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assert(ret && actual == 1);
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ret = ReadConsoleOutputW(conout, &buf, bufSize, bufCoord, &rect);
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assert(ret && buf.Char.UnicodeChar == L'\0' && buf.Attributes == 0x24);
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// As well as a 0 attribute. (As one would expect, the cell is
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// black-on-black.)
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ret = FillConsoleOutputAttribute(conout, 0, 1, writeCoord, &actual);
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assert(ret && actual == 1);
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ret = ReadConsoleOutputW(conout, &buf, bufSize, bufCoord, &rect);
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assert(ret && buf.Char.UnicodeChar == L'\0' && buf.Attributes == 0);
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ret = FillConsoleOutputCharacterW(conout, L'X', 1, writeCoord, &actual);
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assert(ret && actual == 1);
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ret = ReadConsoleOutputW(conout, &buf, bufSize, bufCoord, &rect);
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assert(ret && buf.Char.UnicodeChar == L'X' && buf.Attributes == 0);
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// The 'X' is invisible.
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countDown(3);
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ret = FillConsoleOutputAttribute(conout, 0x42, 1, writeCoord, &actual);
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assert(ret && actual == 1);
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countDown(5);
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}
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